Publications by authors named "Haobo Hou"

48 Publications

Sustainable and efficient stabilization/solidification of Pb, Cr, and Cd in lead-zinc tailings by using highly reactive pozzolanic solid waste.

J Environ Manage 2022 Jan 11;306:114473. Epub 2022 Jan 11.

School of Resource and Environment Science, Wuhan University, Wuhan, 430072, PR China; Hubei Environmental Remediation Material Engineering Technology Research Center, Wuhan, 430072, PR China. Electronic address:

Lead-zinc tailings (LZTs) are industrial by-products containing a large number of heavy metals that seriously harm the ecological environment and human health. This study was performed to propose a sustainable and efficient method for immobilizing Pb, Cr, and Cd in LZTs by using solid waste. To better assess the immobilization performance and mechanism, the leaching toxicity, fraction distribution, unconfined compressive strength, environmental risk assessment, and hydration products were explored. The LZTs were mixed and molded with different constituents of ground granulated blast furnace slag (GGBFS) and rice husk ashes (RHAs) at different curing temperatures. Results suggest that ≥99% of the Pb, Cr, and Cd were immobilized mainly in the form of residual fractions in the LZTs. The amounts of Pb, Cr, and Cd in the bioavailable fractions notably decreased by approximately 99.83%, 99.58%, and 97.05%, respectively. After stabilization/solidification (S/S) disposal, Pb, Cr, and Cd showed low to even no risk. The RHAs were effective to stabilize Pb, and GGBFS was effective to stabilize Cr. However, both materials showed almost equal effects to Cd. Ettringite, C-S-H gel, and portlandite were the main hydration products to immobilize Pb, Cr, and Cd, and these hydration products provided a source of strength. Honey-comb or reticular network C-S-H gel possessed higher specific surface area, higher pore volume, and bigger pore size than the other materials. The proposed method could explain the sustainability and efficiency of the S/S of Pb, Cr, and Cd in LZTs by using RHAs. This study opens up new perspectives for disposing heavy metal by using accessible agricultural solid waste (i.e., RHAs) in rural areas, and the solidified block shows certain economic benefits.
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http://dx.doi.org/10.1016/j.jenvman.2022.114473DOI Listing
January 2022

Influence of persulfate on transformation of phosphorus and heavy metals for improving sewage sludge dewaterability by hydrothermal treatment.

Environ Sci Pollut Res Int 2022 Jan 13. Epub 2022 Jan 13.

School of Environmental Science and Engineering, Huazhong University of Science and Technology, Wuhan, 430074, China.

Activated persulfate oxidation has been proven to be an efficient advanced sludge treatment technique to improve sludge dewaterability. This study investigates the influence of persulfate on the transformation of phosphorus (P) and heavy metals (HMs) during the hydrothermal treatment of sewage sludge. The hydrothermal temperature, time, and persulfate concentration are optimized by a Box-Behnken design to obtain the best sludge dewaterability, which is expressed by capillary suction time (CST). The highest CST reduction efficiency is 90.5% at the optimal hydrothermal temperature, time, and concentration of persulfate, which are 145 °C, 2 h, and 150 mg/g dry sludge (DS), respectively. The distribution and transformation of P and HMs with different persulfate concentrations (100-200 mg/g DS) during the hydrothermal process are investigated. Results show that more than 90% of the P and HMs in the sludge are retained in sludge cakes after the hydrothermal treatment. The addition of SPS can make the P in the sludge cakes transform into more stable P species according to the extraction capacity of sequential extracts. It can be found from the ecological risk indexes of the HMs that the addition of SPS during the hydrothermal treatment of sludge can reduce the environmental risk of HMs. This study provides insights into the P and HM distribution and transformation during hydrothermal treatment with persulfate, providing a reference for sludge recovery strategies.
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http://dx.doi.org/10.1007/s11356-022-18624-1DOI Listing
January 2022

The relationship with the stability between GRP78, CHOP and human carotid atherosclerotic plaque.

Clin Neurol Neurosurg 2022 Jan 25;212:107067. Epub 2021 Nov 25.

Dalian Medical University, Dalian 116024, China; Dalian Municipal Central Hospital Affiliated of Dalian Medical University, Dalian 116033, China. Electronic address:

Background: Current researches on human carotid atherosclerosis (AS) plaques are focused on vulnerable plaques, and various methods have been clinically used to detect vulnerable plaques to prevent adverse events. GRP78 and CHOP, as markers in the endoplasmic reticulum stress (ERS), have a certain relationship with the stability of plaque tissue.

Methods: In this study, 150 plaque specimens were obtained from carotid endarterectomy (CEA). According to pathology, they were divided into two groups: stable plaque and vulnerable plaque. Immunohistochemistry was used to semi-quantitate and localize the target molecule. Western blot and RT-qPCR were used to detect the expression of GRP78 and CHOP in the samples. The receiver operating characteristic curve (ROC curve) judges the significance of the target molecule as a biomarker for the diagnosis of vulnerable plaques.

Results: The results of immunohistochemistry showed that the target molecules of GRP78 and CHOP were mainly expressed in inflammatory cells and vascular endothelial cells; Western blot and RT-qPCR techniques were used to detect the expression of GRP78 and CHOP in different pathlogical types of plaques, which respectively indicated that there were differential expressions. The expression in vulnerable plaques was significantly higher than that in stable plaques (P < 0.05). analysis with ROC, the areas under curves (AUC) of the GRP78 and CHOP data were calculated as 0.792 and 0.850, respectively and the combination showed the largest AUC of 0.870.

Conclusion: In endoplasmic reticulum stress, GRP78 and CHOP are significantly higher expressions in vulnerable plaques than stable's, which indicated that GRP78 and CHOP played a certain role in the occurrence and development of human carotid atherosclerosis and vulnerable plaques; GRP78 and CHOP are promising molecular biomarkers for identifying the endoplasmic reticulum stress situation, atherosclerosis and plaque stability. They also could provide a potential drug targets for the prevention and treatment of atherosclerosis.
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http://dx.doi.org/10.1016/j.clineuro.2021.107067DOI Listing
January 2022

Passivation of multiple heavy metals in lead-zinc tailings facilitated by straw biochar-loaded N-doped carbon aerogel nanoparticles: Mechanisms and microbial community evolution.

Sci Total Environ 2022 Jan 3;803:149866. Epub 2021 Sep 3.

School of Resource and Environmental Science, Wuhan University, Wuhan 430072, Hubei, China; Zhaoqing (Wuhan University) Environmental Technology Research Institute, Zhaoqing 526200, Guangdong, China. Electronic address:

Heavy metal (HM) soil pollution has become an increasingly serious problem with the development of industries. Application of biochar in HMs remediation from contaminated environment has attracted considerable research attention during the past decade. Although the mechanism of HMs passivation with biochar has been investigated, effects and mechanisms of interaction among soil-indigenous microbes and novel carbon matrix composites for HMs adsorption and passivation are still unclear. Four different biochar-loaded aerogels, namely, BNCA-1-600, BNCA-1-900, BNCA-2-600, and BNCA-2-900, were synthesized in this study. Adsorption capacity of four kinds of synthetic materials and two types of contrast biochars (BC600 and BC900) to HMs in aqueous solution, passivation capacity of HMs in soil, and effects on soil organic matter and microbial community were explored. Results showed that BNCA-2-900 exhibits excellent adsorption property and a maximum removal capacity of 205.07 mg·g at 25 °C for Pb(II), 105.56 mg·g for Cd(II), and 137.89 mg·g for Zn(II). Leaching concentration of HMs in contaminated soil can meet the national standard of China (GB/T 5085.3-2007) within 120 days. Results of this study confirmed that the additive BNCA-2-900 and coexistence of indigenous microorganisms can effectively reduce bioavailability of HMs. Another potential mechanism may be to remove the passivation of HMs by porous structure and surface functional groups as well as improve the content of organic matter and microbial abundance. The research results may provide a novel perceptive for the development of functional materials and strategies for eco-friendly and sustainable multiple HMs remediation in contaminated soil and water by using a combination of carbon matrix composites and soil-indigenous microorganisms.
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http://dx.doi.org/10.1016/j.scitotenv.2021.149866DOI Listing
January 2022

Early solidification/stabilization mechanism of heavy metals (Pb, Cr and Zn) in Shell coal gasification fly ash based geopolymer.

Sci Total Environ 2022 Jan 26;802:149905. Epub 2021 Aug 26.

School of Environmental Engineering, Wuhan Textile University, Wuhan 430073, China; Engineering Research Centre for Clean Production of Textile Dyeing and Printing, Ministry of Education, Wuhan Textile University, Wuhan 430073, China. Electronic address:

Immobilizing heavy metals (HMs) from municipal solid waste incineration fly ash (MSWIFA) using shell coal gasification fly ash (SFA)-based geopolymer can solve the energy and environmental challenges simultaneously. In this study, we synthesized a geopolymer with SFA, metakaolin (MK), and steel slag (SS) to solidify and stabilize HMs (Pb, Cr, and Zn) and investigated the early immobilization mechanisms. The results show that the prepared geopolymer possessed high early-age mechanical strength and immobilization efficiency to HMs (>90%), even under the effect of excess HMs. The early immobilization mechanism of the geopolymer for the HMs could be described as follows. (1) Most of HMs were remained in the aluminosilicate. (2) The presence of amorphous zeolite precursor and clay minerals may contribute to restrain the HMs leaching; (3) Pb and Zn were trapped by the gel structure in M-O-Al and M-O-Si forms (M = Pb or Zn), whereas Cr (VI) was reduced to Cr (III). (4) Cr might involve in the geopolymerization of [SiO] and [AlO] units. (5) The immobilization process of Pb and Zn in the geopolymer could be described as crystal growth (NG) - phase boundary reaction (I) - NG - I - diffusion (D), whereas that of Cr is prolonged to NG-I-NG-I-NG-I-D.
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http://dx.doi.org/10.1016/j.scitotenv.2021.149905DOI Listing
January 2022

Vertical distribution and occurrence state of the residual leaching agent (ammonium sulfate) in the weathered crust elution-deposited rare earth ore.

J Environ Manage 2021 Dec 28;299:113642. Epub 2021 Aug 28.

Hubei Novel Reactor & Green Chemical Technology Key Laboratory, Key Laboratory for Green Chemical Process of Ministry of Education, School of Chemistry and Environmental Engineering, Wuhan Institute of Technology, Wuhan, 430074, China.

Weathered crust elution-deposited rare earth ore (WCE-DREO) are rich in middle and heavy rare earth, and ammonium sulfate ((NH)SO) was often used as leaching agent to leach rare earths by in-situ leaching method. However, much of (NH)SO would remained in the ore body during the leaching process, and release of it would cause seriously environmental pollution after the mine closure. To efficiently remove it, the rare earth ore properties and vertical distribution and occurrence state of the residual leaching agent at mine roof (GP1), mine waist (GP2), and mine foot (GP3) with different depth were investigated and efficient elution method was proposed in this study. Results showed that the rare earth ore mainly consist of quartz, clay minerals (halloysite, illite, and kaolinite) and rock-forming minerals, and pH and moisture contents of them were ranged from 4.0 to 5.0 and 10-20%, respectively. Residual agent was mainly enriched in the middle and deep layer of the ore body with the main form of ammonium nitrogen (NH-N), and content of it at the three sites followed the order of GP1>GP3>GP2, which was related to the content of the clay minerals and the moisture. Occurrence state experimental results illustrated that about 95% of the NH-N existed as water-soluble ammonium (WS-AN) and adsorbable ammonium (AS-AN), and 5% of it existed as fixed ammonium (FX-AN), and concentration ratio of them was in order: WS-AN > AS-AN ≫ FX-AN. Based on the results above, MgCl solution was used as an eluent to remove the leaching agent from the ore, and results showed that higher than 90% of residual ammonium could be removed from the ore by it. This study provided a valuable guidance for the residual leaching agent removal from the WCE-DREO body.
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http://dx.doi.org/10.1016/j.jenvman.2021.113642DOI Listing
December 2021

Microscopic mechanism about the selective adsorption of Cr(VI) from salt solution on nitrogen-doped carbon aerogel microsphere pyrolysis products.

Sci Total Environ 2021 Dec 28;798:149331. Epub 2021 Jul 28.

School of Resource and Environmental Science, Wuhan University, Wuhan 430072, Hubei, China; Zhaoqing (Wuhan University) Environmental Technology Research Institute, Zhaoqing 526200, Guangdong, China. Electronic address:

A series of nitrogen-doped carbon aerogels (NCAs) were obtained through phase reaction polymerization and different carbonization temperatures to enhance adsorption efficacy of hexavalent chromium (Cr[VI]) from wastewater significantly. Factors that influence adsorption properties of carbon aerogel microspheres toward Cr(VI), such as pH, adsorbent content, initial Cr(VI) concentrations, and coexisting anion, were investigated. Three isotherm (Langmuir, Freundlich, and Sips) and three kinetic (pseudofirst-order, pseudosecond-order, and Elovich) models were used to interpret the adsorption process. The adsorption capacity of Cr(VI) reached 180.62 mg·g, which was superior to that of most aerogel adsorbents. In addition to the adsorption effect, the XPS results also showed that N-containing groups on the NCA surface reduce the adsorbed Cr(VI) to the less toxic Cr(III). The prepared sorbent demonstrates a negligible loss in adsorption capacity after 6 cycles. NCAs show acceptable application prospects in selective removal of Cr(VI) ions.
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http://dx.doi.org/10.1016/j.scitotenv.2021.149331DOI Listing
December 2021

An integrated geospatial correlation analysis and human health risk assessment approach for investigating abandoned industrial sites.

J Environ Manage 2021 Sep 7;293:112891. Epub 2021 Jun 7.

School of Engineering, University of British Columbia, Okanagan, 3333 University Way, Kelowna, BC, V1V 1V7, Canada. Electronic address:

An integrated geospatial correlation analysis (GCA)-human health risk assessment (HHRA) approach was developed to investigate abandoned industrial sites featured by heterogeneous contamination data. Critical areas of high health risk concerns can be prioritized for remediation using the integrated approach. An abandoned chemical complex site in Hubei, China was investigated as a case study. GCA and HHRA were performed using soil and groundwater sampling data collected in 2016 and 2019. Benzene, chlorobenzene, dichlorobenzenes, 2-nitrochlorobenzene, and α-hexachlorocyclohexane were determined to be critical contaminants in soil. The 2019 sampling data revealed new contaminated locations that were not found in the 2016 sampling campaign. High concentrations (89.81-386.55 mg/L) of vinyl chloride were also found in groundwater samples. Several critical location clusters of high concentrations of dichlorobenzenes, chlorobenzene, and α-hexachlorocyclohexane were found within the site according to the GCA outcomes. These contaminants could pose significant cancer and non-cancer risks to onsite workers. The critical areas were ranked according to cancer and non-cancer risks estimated by HHRA, respectively, for informed remediation planning. Among the critical contaminants, α-hexachlorocyclohexane, 2-nitrochlorobenzene, and 1,4-dichlorobenzene in soil, as well as vinyl chloride in groundwater, contributed a predominant part to the total health risk. The integrated approach can be used to assess the contamination of other similar abandoned industrial complex sites.
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http://dx.doi.org/10.1016/j.jenvman.2021.112891DOI Listing
September 2021

Enhanced sludge dewaterability by Fe-rich biochar activating hydrogen peroxide: Co-hydrothermal red mud and reed straw.

J Environ Manage 2021 Oct 9;296:113239. Epub 2021 Jul 9.

School of Resource and Environmental Science, Wuhan University, Wuhan, 430072, Hubei, China; College of Resources and Environment, Anqing Normal University, Anqing, 246011, Anhui, China. Electronic address:

This study proposed Fe-rich biochar (RMRS-BC) produced by the co-hydrothermal treatment of red mud and reed straw, industrial waste and agricultural waste, as a novel sludge conditioner. It had been proven that heterogeneous and homogeneous Fenton reactions occurred during the sludge conditioning process, in which RMRS-BC activated HO to improve sludge dewaterability. Results demonstrated that the optimal condition was 7.5 wt% dry solids (DS) of RMRS-BC at a mass ratio of 1:1 combined with HO. The corresponding water content of sludge cakes and the capillary suction time reduction efficiency were 57.88 wt% and 69.76%, respectively. The FeO supported in the RMRS-BC structure was used as a catalyst to produce heterogeneous reaction, and the Fe leached from the RMRS-BC after acidification happened homogeneous reaction. Double Fenton reaction in sludge conditioning enhanced the production efficiency of ·OH, the sludge flocs were dispersed into smaller particles, more bound water from the extracellular polymeric substances (EPS) was released, and sludge dewaterability performance was improved. Another main mechanism for enhancing dewaterability was to use RMRS-BC as a skeleton builder to reduce the compressibility of sludge cakes and facilitated free water to flow out. In summary, the Fenton oxidation method activated by RMRS-BC is feasible in improving sludge dewatering.
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http://dx.doi.org/10.1016/j.jenvman.2021.113239DOI Listing
October 2021

Stabilization and passivation of multiple heavy metals in soil facilitating by pinecone-based biochar: Mechanisms and microbial community evolution.

J Hazard Mater 2021 10 6;420:126588. Epub 2021 Jul 6.

School of Resource and Environmental Sciences, Wuhan University, Wuhan 430072, PR China; Zhaoqing (Wuhan University) Environmental Technology Research Institute, Zhaoqing, Guangdong 526200, PR China. Electronic address:

Soil contamination by multiple heavy metals and As is one of the major environmental hazards recognized worldwide. In this study, pinecone-biochar was used for stabilization and passivation of Pb, Cu, Zn, Cr, and As in contaminated soil around a smelter in Hubei province, China. The stabilization rate of heavy metals in soil can exceed 99%, and the leaching amount can meet the national standard of China (GB/T 5085.3-2007, less than 5, 100, 100, 15, and 5 mg/L, respectively.) within 90 days. The study confirmed that the addition of pinecone-biochar and the coexistence of indigenous microorganisms can effectively reduce the bioavailability of heavy metals. Among the heavy metals, As(III) can be oxidized to As(V) and then stabilized, and other heavy metals can be stabilized in a complex and chelated state characterized by X-ray photoelectron spectroscopy. After pinecone-biochar was added, the abundance of microbial community and intensity of metabolic activities became vigorous, the types and contents of dissolved organic matter increased significantly. A novel innovation is that the addition of pinecone-biochar increased the Bacillus and Acinetobacter in soil, which enhanced the function of inorganic ion transport and metabolism to promote the passivation and stabilization of heavy metals throughout the remediation process.
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http://dx.doi.org/10.1016/j.jhazmat.2021.126588DOI Listing
October 2021

High-efficiency degradation of phthalic acid esters (PAEs) by Pseudarthrobacter defluvii E5: Performance, degradative pathway, and key genes.

Sci Total Environ 2021 Nov 25;794:148719. Epub 2021 Jun 25.

School of Resource and Environmental Science, Wuhan University, Wuhan 430079, Hubei, China; Zhaoqing (Wuhan University) Environmental Technology Research Institute, Zhaoqing 526200, Guangdong, China. Electronic address:

Phthalic acid esters (PAEs) are a class of biologically accumulated carcinogenic and teratogenic toxic chemicals that exist widely in the environment. This study, Pseudarthrobacter defluvii E5 was isolated from agricultural soils and showed efficient PAEs-degradation and -mineralization abilities for five PAEs, and encouraging PAEs tolerance and bioavailable range for dibutyl phthalate (DBP) and bis(2-ethylhexyl) phthalate (DEHP) (0.25-1200 mg/L). The complete catalytic system in E5 genome enables PAEs to be degraded into monoester, phthalate (PA) and Protocatechuic acid (PCA), which eventually enter the tricarboxylic acid cycle (TCA cycle). The preferred PAEs-metabolic pathway in soil by E5 is the metabolism induced by enzymes encoded by pehA, mehpH, pht Operon and pca Operon. For the first time, two para-homologous pht gene clusters were found to coexist on the plasmid and contribute to PAEs degradation. Further study showed that P. defluvii E5 has a broad application prospect in microplastics-contaminated environments.
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http://dx.doi.org/10.1016/j.scitotenv.2021.148719DOI Listing
November 2021

Citrobacter arsenatis sp. nov., an arsenate-reducing bacterium isolated from freshwater sediment.

Antonie Van Leeuwenhoek 2021 Aug 11;114(8):1285-1292. Epub 2021 Jun 11.

School of Environmental Science and Engineering, Hubei Key Laboratory of Mine Environmental Pollution Control and Remediation, Hubei Polytechnic University, Huangshi, China.

A novel arsenate-reducing bacterium, LY-1, was isolated from freshwater sediment in Huangshi, China. Morphological analysis indicated that the cells were shaped like rods and were gram-negative. The major fatty acids (> 10%) were C, summed feature 3 (C ω7c, C ω6c) and summed feature 8 (C ω7c, C ω6c). An assessment of the phylogeny based on 16S rRNA gene sequences indicated that the strain LY-1 belonged to the genus Citrobacter, while further analysis based on the recN gene indicated that LY-1 occupies a distinct phylogenetic niche within the Citrobacter genus. Moreover, average nucleotide identity and digital DNA-DNA hybridization between the strain LY-1 and the type strains of closely related species of the genus Citrobacter (C. europaeus, C. brakii, C. portucalensis, C. freundii, C. werkmanii, C. cronae, C. youngae, C. pasteurii, C. tructae, C. gillenii, and C. murliniae) were 85.8-93.8% and 31.2-56.9%, respectively. In addition, the LY-1 strain's capacity to metabolize various compounds and its characteristic G + C content of 51.9% were also distinct from other species of the Citrobacter genus. These discriminatory features cumulatively indicate the LY-1 strain as a new species within the Citrobacter genus. We propose the species name Citrobacter arsenatis for this new species, with LY-1 (= CCTCC AB 2019169 = KCTC 72440) as the type strain.
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http://dx.doi.org/10.1007/s10482-021-01601-yDOI Listing
August 2021

Strategically improving the intrinsic proton conductivity of UiO-66-NH by post-synthesis modification.

Dalton Trans 2021 May;50(17):5943-5950

College of Chemistry and Environmental Technology, Wuhan Institute of Technology, Wuhan 430073, Hubei, China.

Metal-organic frameworks (MOFs), as a new class of proton conductors, have attracted much attention in the application of proton exchange membranes due to their precisely defined structure and tailorable functionality. However, for most of the MOF materials, their long-term stability is a huge barrier to practical application. Therefore, the structural stability of MOFs is an important prerequisite for the design and development of proton conductors with ultra-high conductivity. In this study, the stable UiO-66-NH2 is optimized as the precursor, and the modified material of DT-UiO-66 is designed and developed by introducing the 3,5-diamino-1,2,4-triazole molecule into the framework of UiO-66-NH2 through a post-synthesis strategy. Satisfactorily, DT-UiO-66 maintains the stability of the original skeleton. The alternating current impedance measurements indicate that a significantly improved proton conductivity of 4.47 × 10-3 S cm-1 is obtained at 100% relative humidity (RH) and 373 K for DT-UiO-66, which is attributed to the increasing number of proton sources and hopping sites. Moreover, DT-UIO-66 shows an outstanding stability under high temperature and high humidity conditions for at least 16 h, suggesting its potential application as a proton exchange membrane.
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http://dx.doi.org/10.1039/d1dt00400jDOI Listing
May 2021

Influence of rice husk addition on phosphorus fractions and heavy metals risk of biochar derived from sewage sludge.

Chemosphere 2021 Oct 26;280:130566. Epub 2021 Apr 26.

School of Environmental Science and Engineering, Huazhong University of Science and Technology, Wuhan, Hubei, 430074, China. Electronic address:

This study investigated the effects of rice husk dose and pyrolysis temperature on the phosphorus (P) fractions and environmental risk of heavy metals in biochar co-pyrolyzed from sewage sludge and rice husk. Biochar properties were analyzed, and the transformation of P and heavy metals speciation during co-pyrolysis were also discussed. Co-pyrolysis of raw sludge and rice husk (10-50 wt%) could increase the carbonization degree and stability of biochar at 500 °C. The organic P (OP) in raw sludge (68 wt%) was transformed to inorganic P (IP) during co-pyrolysis, indicating that the addition of rice husk could improve biochar-P bioavailability by promoting the transformation of IP. The IP content increased from 71.5 wt% of sludge biochar to 92 wt% of blended biochar (50 wt% sludge and 50 wt% rice husk) at a pyrolysis temperature of 500 °C. With the mass ratio of sludge to rice husk of 5:5, the OP content decreased from 3 mg g to 0.75 mg g as the pyrolysis temperature increased from 300 °C to 700 °C. The P nuclear magnetic resonance spectra and X-ray photoelectron spectroscopy results showed that P species in biochar mainly existed as orthophosphate, which can be directly taken up by plants. After co-pyrolysis, the toxicity and mobility of heavy metals gradually decreased with increasing rice husk dose and pyrolysis temperature. The study indicates that co-pyrolysis of sewage sludge and rice husk could be a promising P reuse strategy.
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http://dx.doi.org/10.1016/j.chemosphere.2021.130566DOI Listing
October 2021

Electrolytic manganese residue-based cement for manganese ore pit backfilling: Performance and mechanism.

J Hazard Mater 2021 Jun 5;411:124941. Epub 2021 Jan 5.

School of Resource and Environmental Sciences, Wuhan University, Wuhan, PR China.

Slag backfilling with electrolytic manganese residue (EMR) is an economical and environmentally-friendly method. However, high ammonium-nitrogen and manganese ions in EMRs limit this practice. In this study, a method of highly efficient simultaneous stabilization/solidification of ultrafine EMR by making EMR-based cementitious material (named EMR-P) was proposed and tested via single-factor and response surface optimization experiments. Results show that the stabilization efficiency of NH and Mn were above 95%, and the unconfined compressive strength of the EMR-P was 18.85 MPa (megapascal = N/mm). The mechanistic study concluded that the soluble manganese sulfate and ammonium sulfate in EMR were converted into the insoluble precipitates of manganite (MnOOH), gypsum (CaSO), MnNHPO·HO, and struvite (MgNHPO∙6 HO), leading to the stabilization of NH and Mn in the EMR-P. Leaching tests of EMR-P indicated that NH, Mn, and others heavy metals in the leachate were within the permitted level of the GB/T8978-1996. The novelty of this study includes the addition of phosphate and magnesium ions to precipitate ammonium-nitrogen and the combination between calcium ions (from CaHPO∙2 HO) and sulfate (from the EMR) to form calcium sulfate to improve the stability and unconfined compressive strength of cementitious materials (EMR-P).
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http://dx.doi.org/10.1016/j.jhazmat.2020.124941DOI Listing
June 2021

Selective recovery of manganese from electrolytic manganese residue by using water as extractant under mechanochemical ball grinding: Mechanism and kinetics.

J Hazard Mater 2021 08 2;415:125556. Epub 2021 Mar 2.

School of Resource and Environmental Sciences, Wuhan University, PR China; Hubei Environmental Remediation Material Engineering Technology Research Center, Wuhan 430072, PR China. Electronic address:

This research aimed to address the issue of residual manganese in electrolytic manganese residue (EMR), which is difficult to recycle and can easily become an environmental hazard and resource waste. This research developed a method for the efficient and selective recovery of manganese from EMR and the removal of ammonia nitrogen (ammonium sulfate) under the combined action of ball milling and oxalic acid. The optimum process parameters of this method were obtained through single-factor experiment and response-surface model. Results showed that the recovery rate of manganese can exceed 98%, the leaching rate of iron was much lower than 2%, and the leaching rates of manganese and ammonia nitrogen after EMR ball grinding were 1.01 and 13.65 mg/L, respectively. Kinetics and mechanism studies revealed that ammonium salts were primarily removed in the form of ammonia, and that insoluble manganese (MnO) was recovered by the reduction of FeS and FeS in EMR under the action of oxalic acid. Iron was solidified in the form of FeO and Fe(SiO). The technology proposed in this research has great industrial application value for the recycling and harmless treatment of EMR.
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http://dx.doi.org/10.1016/j.jhazmat.2021.125556DOI Listing
August 2021

Analysis of driving factors on China's industrial solid waste generation: Insights from critical supply chains.

Sci Total Environ 2021 Jun 10;775:145185. Epub 2021 Feb 10.

College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China.

Industrial solid waste (ISW) poses a huge potential threat to human health and the environment. To prevent pollution at its source, it is necessary to analyze the socioeconomic drivers and identify the key supply chains that cause changes in ISW generation. In this study, based on monetary input-output tables (MIOTs) in China from 2011 to 2015, structural decomposition analysis (SDA) was used to study the influence of socioeconomic drivers on common industrial solid waste (CISW) and hazardous waste (HW) generation. Structural path decomposition (SPD) was used to further trace the effects of drivers at the supply chain level and obtain more meaningful results for policy formulation. Economic expansion was found to play the most crucial role in the increase in total ISW generation while the reduction of generation intensity effectively slowed the growth trend. From the final demand perspective, fixed capital formation contributed the most to ISW generation growth, accounting for 65.05% of the total final demand effect. Construction was the primary trigger. For CISW, the supply chain with the greatest overall influence was "metal ore mining industry → fixed capital formation" (including intermediate consumption of metal smelting, general and special machinery, and construction), reflecting how fixed capital formation indirectly affected the metal ore mining industry. The supply chain with the greatest influence on HW generation was "paper industry → exports." Based on the findings, corresponding policy adjustments are proposed.
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http://dx.doi.org/10.1016/j.scitotenv.2021.145185DOI Listing
June 2021

A novel method for solidification/stabilization of Cd(II), Hg(II), Cu(II), and Zn(II) by activated electrolytic manganese slag.

J Hazard Mater 2021 05 30;409:124933. Epub 2020 Dec 30.

College of Resources and Environmental Science, South-Central University for Nationalities, Wuhan 430074, PR China.

This study was aimed at removing and stabilizing heavy metals (Hg, Zn, Cu, and Cd). A novel material (named A-EMS) for heavy metal removal was proposed by ball grinding activated electrolytic manganese slag (EMS) with low content of sodium hydroxide. For different application scenarios, the two physical properties of the materials were developed: the powdery A-EMS (powder) was used to remove heavy metals from wastewater. In addition, the blocky A-EMS (porous brick) was used to build barrier walls for tailings ponds to prevent heavy metals from flowing out. The maximum removal amount of Hg(II) Cd(II), Zn(II), and Cu(II) by A-EMS were 475.35, 77.72, 259.70, and 203.20 mg/g in 30 min. The heavy metals ions were removed and fixed on A-EMS mainly through ion exchange and some forms of electrostatic adsorption and hydroxyl complexation. After consolidating the heavy metals, the compressive strength of the materials can reach 20 Mpa and the leaching toxicity met the national standard of China (GB/T 3838-2002) in 60 days. These excellent properties made A-EMS widely used to remove heavy metals in wastewater and to intercept and solidify heavy metals in mine wastewater.
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http://dx.doi.org/10.1016/j.jhazmat.2020.124933DOI Listing
May 2021

Biodegradation of phthalic acid esters (PAEs) by Cupriavidus oxalaticus strain E3 isolated from sediment and characterization of monoester hydrolases.

Chemosphere 2021 Mar 4;266:129061. Epub 2020 Dec 4.

School of Resource and Environmental Science, Wuhan University, Wuhan, 430079, Hubei, China; Zhaoqing (Wuhan University) Environmental Technology Research Institute, Zhaoqing, 526200, Guangdong, China. Electronic address:

Phthalic acid esters (PAEs) are teratogenic and carcinogenic and mainly metabolized by microorganisms in sediment. A novel strain, Cupriavidus oxalaticus strain E3, was isolated and characterized from sediment for PAEs degradation. The transformation of dibutyl phthalate (DBP) and bis(2-ethylhexyl) phthalate (DEHP) as the sole carbon source by strain E3 was systematically studied in the darkness through the kinetic studies and analysis of intermediates. After the initial lag pause of 5 h-8 h, the strain efficiently degraded 87.4%-94.4% of DBP and 82.5%-85.6% of DEHP at an initial amount of each phthalate of 200 mg/L after 60 h of incubation. The biodegradation rate of DBP and DEHP followed a first-order kinetic model, and degradation rate constants (k) of them by E3 were 1.37 and 0.86 d, respectively. Gas chromatography-mass spectrometry (GC-MS) results revealed that the tentative PAEs degradation pathway, included the transformation from PAEs to phthalic acid (PA) and the complete mineralization of PA. In the phase of PAEs to PA, DBP with short sides reduced the chain length via hydrolyzation, and DEHP with long sides reduced the chain length via hydrolyzation and β-oxidation. The 3D model of monoester hydrolase from C. oxalaticus was predicted and used for docking with mono-2-ethylhexyl phthalate (MEHP) and mono-n-butyl phthalate (MBP). The docking results showed that the conserved catalytic triplet structure (Ser140, His284, and Asp254) acted as active sites and participated in degrading PMEs. This study provided novel insights into the mechanisms of PAEs degradation at a molecular level and widened the scope of functional bacteria by isolating strain E3.
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http://dx.doi.org/10.1016/j.chemosphere.2020.129061DOI Listing
March 2021

Low-temperature thermal desorption and secure landfill for oil-based drill cuttings management: Pollution control, human health risk, and probabilistic cost assessment.

J Hazard Mater 2021 05 14;410:124570. Epub 2020 Nov 14.

School of Engineering, University of British Columbia, Okanagan, 3333 University Way, Kelowna, BC V1V 1V7 Canada. Electronic address:

Oil-based drill cuttings (OBDCs) were managed in two scenarios including low-temperature thermal desorption (LTTD) and secure landfill through a case study. The removal of polycyclic aromatic hydrocarbons (PAHs) and heavy metals in OBDCs by LTTD under different conditions was investigated. Probabilistic human health risk assessment was performed to quantify the health risk posed to waste management workers under the two scenarios, while the associated costs were also analyzed. The results show that LTTD at 300 °C for >20 min could remove 96.27% of PAHs in OBDCs but its removal effect on heavy metals was not significant. It was found that cancer risks posed by PAHs in both securely landfilled and LTTD-treated OBDCs were not significant (<1e-06); however, significant cancer risks (7.95e-05-9.45e-05) were identified for exposure to toxic heavy metals. Increased health risk was observed as a result of exposure to LTTD treatment residues compared to securely landfilled OBDCs. Inhalation of chromium(VI) and oral ingestion of arsenic in OBDCs were critical exposure routes. Both cancer and non-cancer risks in the secure landfill scenario were negligible. The cost analysis results suggest that LTTD combined with stabilization/solidification could be more economically attractive than secure landfill for the handling of OBDCs.
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http://dx.doi.org/10.1016/j.jhazmat.2020.124570DOI Listing
May 2021

An environmental-friendly approach to remove cyanide in gold smelting pulp by chlorination aided and corncob biochar: Performance and mechanisms.

J Hazard Mater 2021 04 7;408:124465. Epub 2020 Nov 7.

School of Environmental Science and Engineering, Huazhong University of Science and Technology, Wuhan, Hubei, 430074, China. Electronic address:

In this study, a new process was developed using ClO and corncob biochar (CB) combined with HAS (a stabilizer) to remove cyanide from gold smelting pulp. The Box-Behnken design was employed to optimize the doses of treatment reagents during cyanide removal. Results showed that the optimal doses of the three reagents were as follows: ClO dose of 20 mg/g dry solid (DS), CB dose of 22 mg/g DS, and an HAS dose of is 24 mg/g DS. The cyanide concentration in the filtrate was the lowest (0.114 mg/L), with a 98.36% removal efficiency after a contact time of 2 h at 25 °C under optimized conditions. Compared with those of ClO and HAS, it was found that the dose of biochar was the dominant factor influencing cyanide removal. Batch sorption experiments of cyanide to biochar indicated that the Langmuir isotherm model fit the sorption data, and the maximum cyanide sorption capacity was expected to be 2.57 ± 0.06 mg/g. Density functional theory (DFT) calculations (interaction energy was -74.42 kcal/mol) indicated that the adsorption peak resulted from cation-π interactions between the cyanide and CB. This study could lead to a novel environmental-friendly approach for the removal of cyanide from gold smelting pulp.
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http://dx.doi.org/10.1016/j.jhazmat.2020.124465DOI Listing
April 2021

Contamination and health risk assessment of heavy metals in China's lead-zinc mine tailings: A meta-analysis.

Chemosphere 2021 Mar 9;267:128909. Epub 2020 Nov 9.

School of Resource and Environmental Science, Wuhan University, Wuhan, 430072, Hubei, China; Zhaoqing (Wuhan University) Environmental Technology Research Institute, Zhaoqing, 526200, Guangdong, China. Electronic address:

The lead-zinc areas of China have faced serious foulteousqulated heavy metal pollution. In this study, data on As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn concentrations in China's lead-zinc mine tailings were collected and screened from published literature (2015-2020). The contamination assessments, geographical distributions, and health risk assessments of the eight heavy metals were analyzed. The results revealed that the mean concentrations of As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn exceeded the corresponding background values for soils. Moreover, most of the lead-zinc mine tailing areas contaminated by heavy metals were located in the southern and eastern regions of China. The health risk assessment results indicated that oral ingestion was the main exposure route of heavy metals in the mine tailings, and children were more vulnerable to adverse effects. For a single metal, As and Pb presented high non-carcinogenic risks, and As and Cu presented the unacceptable carcinogenic risks. This study provides a timely analysis proving the urgent necessity of the treatment of heavy metal pollution in lead-zinc tailings in China.
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http://dx.doi.org/10.1016/j.chemosphere.2020.128909DOI Listing
March 2021

Bio-leaching of manganese from electrolytic manganese slag by Microbacterium trichothecenolyticum Y1: Mechanism and characteristics of microbial metabolites.

Bioresour Technol 2021 Jan 11;319:124056. Epub 2020 Sep 11.

School of Resource and Environmental Sciences, Wuhan University, Wuhan, PR China.

The related microbial metabolomics on biological recovery of manganese (Mn) from Electrolytic Manganese Slag (EMS) has not been studied. This study aimed at open the door to the metabolic characteristics of microorganisms in leaching Mn from EMS by using waste molasses (WM) as carbon source. Results show Microbacterium trichothecenolyticum Y1 (Y1) could effectively leach Mn from EMS in combination with using waste molasses as carbon and energy sources. For the first time, Y1 was identified to be capable of generating and then metabolizing several organic acids or other organic matter (e.g., fumaric acid, succinic acid, malic acid, glyoxylic acid, 3-hydroxybutyric acid, glutaric acid, L(+)-tartaric acid, citric acid, tetrahydrofolic acid, and L-methionine). The production of organic acids by Y1 bacteria was promoted by EMS with the carbon source. This study demonstrated for the first time that metabolic characteristics and carbon source metabolic pathways of Y1 in bioleaching of Mn from EMS.
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http://dx.doi.org/10.1016/j.biortech.2020.124056DOI Listing
January 2021

The experimental optimization and comprehensive environmental risk assessment of heavy metals during the enhancement of sewage sludge dewaterability with ethanol and Fe(Ⅲ)-rice husk.

J Environ Manage 2020 Nov 29;273:111122. Epub 2020 Jul 29.

School of Resource and Environment Science, Wuhan University, Wuhan, 430072, PR China; Hubei Environmental Remediation Material Engineering Technology Research Center, Wuhan, 430072, PR China. Electronic address:

The optimal concentrations of ethanol, Fe and rice husk (RH) to enhance sludge dewaterability were determined by response surface methodology (RSM). Results showed the optimal concentrations of ethanol, Fe and RH were 22.2 g/g DS, 239.9 mg/g DS and 348.9 mg/g DS, respectively, and the CST reduction efficiency reached 72.3%. The transformation behavior and mechanism of the heavy metals (HMs) during conditioning process were determined in terms of total HMs content, leaching tests, and fraction distribution. The environmental risk of HMs was quantitatively evaluated after conditioning in terms of bioavailability and ecotoxicity, potential ecological risks, and pollution levels. Results showed that the high ecological risk of HMs in raw sludge cake is primarily dominated by Cd and the use of Fe alone negatively affected the immobilization of HMs and reduction of leaching toxicity. However, after repeated conditioning with Fe and ethanol, the total HMs content reduction values in sludge cake were 75%, 93%, 100%, 91%, and 74% for Pb, Cr, Cd, Zn, and Cu, respectively. The potential ecological risk index (PERI) and geoaccumulation indicated low or no overall environmental risk after repeated conditioning. Particularly, the risk of Cd was reduced from high risk to low risk after repeated conditioning according to the PERI. Ethanol/Fe-RH can effectively reduce HMs risk from the sludge cake in the dewatering tests.
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http://dx.doi.org/10.1016/j.jenvman.2020.111122DOI Listing
November 2020

Effects of electromagnetic induction on migration and speciation of heavy metals in drying sewage sludge: Mechanistic insights.

Waste Manag 2020 May 11;109:192-201. Epub 2020 May 11.

School of Resource and Environment Science, Wuhan University, 430070 Hubei, Wuhan, China.

Novel and efficient drying method based on electromagnetic induction plate (EMI-P) heating was used to treat sewage sludge (SS). This work focused on the effects of EMI-P action on heavy metals (HMs) in dried SS. Surface functional groups, surface chemistry and microstructures of SS treated were investigated and compared to provide insights into the transformation mechanisms of HMs during EMI-P drying process. The results show that the EMI-P-dried SS showed undesirably total concentrations of Cd and Zn and leaching concentrations of HMs (Cr, Ni, Zn, Cd and As) exceeded the Chinese ground water standard (GB/T14848-2017). Ni, Zn, and As in the EMI-P-dried SS still exhibited high mobility, the leaching percent of Ni, Zn, and As (under 300 V and 500 V) can reach up to 28.56%/10.36%, 26.96%/26.61% and 30.64%/23.14%, respectively. Compared with conventional thermal drying, the EMI-P method can effectively reduce the eco-toxicity derived from HMs by 28.06% under 500 V condition. The stabilization effect of the EMI-P action can be attributed to the following: (1) EMI-P action promoted the generation of surface complexes with HMs, (2) HMs adsorption by silicate minerals was enhanced under high-frequency magnetic fields and (3) honeycomb structures of EMI-P dried SS with micropores provided abundant active sites to bond with HMs.
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http://dx.doi.org/10.1016/j.wasman.2020.05.005DOI Listing
May 2020

Phytohormones-induced senescence efficiently promotes the transport of cadmium from roots into shoots of plants: A novel strategy for strengthening of phytoremediation.

J Hazard Mater 2020 04 13;388:122080. Epub 2020 Jan 13.

College of Resources and Environmental Science, Key Laboratory of Catalysis and Energy Materials Chemistry of Ministry of Education & Hubei Key Laboratory of Catalysis and Materials Science, South-Central University for Nationalities, Wuhan, PR China. Electronic address:

Due to the long growth period of plants, phytoremediation is time costly. Improving the accumulation of cadmium (Cd) in shoots of plants will promote the efficiency of phytoremediation. In this study, two senescence-relative phytohormones, abscisic acid (ABA) and salicylic acid (SA), were applied to strengthening phytoremediation of Cd by tall fescue (Festuca arundinacea S.). Under hydroponic culture, phytohormones treatment increased the Cd content of shoots 11.4-fold over the control, reaching 316.3 mg/kg (dry weight). Phytohormones-induced senescence contributes to the transport of heavy metals, and HMA3 was found to play a key role in this process. Additionally, this strategy could strengthen the accumulation of Cu and Zn in tall fescue shoots. Moreover, in soil pot culture, the strategy increased shoot Cd contents 2.56-fold over the control in tall fescue, and 2.55-fold over the control in Indian mustard (Brassica juncea L.), indicating its comprehensive adaptability and potential use in the field. In summary, senescence-induced heavy metal transport is developed as a novel strategy to strengthen phytoremediation. The strategy could be applied at the end of phytoremediation with an additional short duration (7 days) with comprehensive adaptability, and markedly strengthen the phytoremediation in the field.
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http://dx.doi.org/10.1016/j.jhazmat.2020.122080DOI Listing
April 2020

Enhancement of the sewage sludge dewaterability by using ethanol and Fe(III)-rice husk.

Environ Sci Pollut Res Int 2020 Mar 7;27(8):8696-8706. Epub 2020 Jan 7.

School of Resource and Environment Science, Wuhan University, Wuhan, 430072, People's Republic of China.

Proteins of extracellular polymeric substances (EPS) in sewage sludge play a key role in the sludge dewatering. Ethanol can denature proteins and improve sludge dewaterability. In this study, ethanol was used to precondition and combined with Fe and rice husk (RH) for dewatering enhancement. The experimental results of the capillary suction time (CST) reduction efficiency indicated that the sewage sludge pretreated with ethanol and Fe-RH revealed well cooperative formation mechanism with regard to dewatering performance. Using the response surface methodology (RSM) determined that CST reduction efficiency of sewage sludge reached 78.5% under optimal conditions of ethanol 25.21 g/g dry solid (DS), Fe 185.70 mg/g DS, and RH 406.02 mg/g DS, respectively. Moreover, the results showed that the composite conditioner is effective for the specific resistance to filtration decreased from initial 1.66E + 13 m/kg to 2.44E + 11 m/kg. The analysis of EPS showed that extractable proteins in EPS increased to maximum when the sludge was pretreated by Fe-RH because EPS were destroyed and proteins in EPS were released. After the addition of ethanol, extractable protein content was reduced because of protein precipitation and released interstitial water and bound water. The sludge morphology analysis indicated that the RH as a skeleton builder provided the outflow passages, which enhanced the dewatering performance of sludge. From these results, the combination treatment of ethanol and Fe-RH is a promising synergetic strategy to enhance the dewaterability of sewage sludge.
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http://dx.doi.org/10.1007/s11356-019-06621-wDOI Listing
March 2020

Adsorption mechanism of lead ions on porous ceramsite prepared by co-combustion ash of sewage sludge and biomass.

Sci Total Environ 2020 Feb 3;702:135017. Epub 2019 Nov 3.

School of Resource and Environment Science, Wuhan University, 430070 Hubei, Wuhan, China. Electronic address:

This study attempted to synthesize a novel ceramsite with excellent adsorption property compositing through the co-combustion of biomass and sewage sludge ash (CBSA), gasification of coal fly ash (GCFA) and sewage sludge (SS) to dispose wastewater contaminated by Pb (II). The optimum preparation conditions included a CBSA/SS/GCFA ratio of 70:18:12, preheating at 480 °C, and sintering at 1060 °C for 15 min. The basic and environmental characteristics of the novel ceramsite meet specific standards requirements. The removal rate could reach 99.9% under optimum conditions in a high-concentration solution, and the novel ceramsite could be reused 6 times and maintain in high remove rate. The adsorption mechanism was determined to be as follows: (1) Ceramsite features a mesoporous structure with an abundance of pores on which cationic exchange could occur. (2) Pb (II) enters the pores of the adsorbent and are attracted by anionic groups to deposit on the surface of ceramsite. (3) A large amount of Pb (II) bonds with SiO or AlOSiO to embed in the matrix frame of the adsorbent; the rest of the metal forms precipitates on the frame layer or [PO].
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http://dx.doi.org/10.1016/j.scitotenv.2019.135017DOI Listing
February 2020

Water adsorption and proton conduction of a cobalt(ii) complex assembled by triazine-based polycarboxylate.

Dalton Trans 2019 Oct;48(40):15192-15197

School of Resource and Environmental Science, Wuhan University, Wuhan 430072, Hubei, China.

A new flexible triazine-based polycarboxylate coordination polymer, {[Co3(H3TTHA)2(4,4'-bipy)5(H2O)8]·12H2O}n (1), where H6TTHA = 1,3,5-triazine-2,4,6-triamine hexaacetic acid, has been synthesized under hydrothermal conditions and structurally characterized by infrared spectroscopy, elemental analysis, TGA, XRD and X-ray single-crystal diffraction. Structural analysis indicates that 1 displays a planar structure with alternate rectangular structures of 22.695 × 11.485 Å2. The investigation of water vapor adsorption shows that the adsorption capacity of 1 is comparable to that of the typical adsorption material of MCM-41 with 73.86% (41.03 mmol g-1) water uptake at 90% relative humidity (RH). Based on the resistance to water and high-density hydrophilic units as well as abundant hydrogen-bonding networks in the complex, the proton conductivities of 1 under different conditions were measured. The results indicate that the proton conductivity values are highly temperature and relative humidity dependent, with the highest conductivity of nearly 10-3 S cm-1 at 353 K and 98% RH. The Arrhenius activation energy derived in the wide temperature range of 293-353 K is 0.32 eV, corresponding to a typical Grotthuss mechanism.
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http://dx.doi.org/10.1039/c9dt03038gDOI Listing
October 2019

Estimation of PM2.5 Concentrations in China Using a Spatial Back Propagation Neural Network.

Sci Rep 2019 09 24;9(1):13788. Epub 2019 Sep 24.

School of Resource and Environmental Sciences, Wuhan University, 129 Luoyu Road, Wuhan, 430079, China.

Methods for estimating the spatial distribution of PM concentrations have been developed but have not yet been able to effectively include spatial correlation. We report on the development of a spatial back-propagation neural network (S-BPNN) model designed specifically to make such correlations implicit by incorporating a spatial lag variable (SLV) as a virtual input variable. The S-BPNN fits the nonlinear relationship between ground-based air quality monitoring station measurements of PM, satellite observations of aerosol optical depth, meteorological synoptic conditions data and emissions data that include auxiliary geographical parameters such as land use, normalized difference vegetation index, elevation, and population density. We trained and validated the S-BPNN for both yearly and seasonal mean PM concentrations. In addition, principal components analysis was employed to reduce the dimensionality of the data and a grid of neural network models was run to optimize the model design. The S-BPNN was cross-validated against an analogous but SLV-free BPNN model using the coefficient of determination (R) and root mean squared error (RMSE) as statistical measures of goodness of fit. The inclusion of the SLV led to demonstrably superior performance of the S-BPNN over the BPNN with R values increasing from 0.80 to 0.89 and with the RMSE decreasing from 8.1 to 5.8 μg/m. The yearly mean PM concentration in China during the study period was found to be 41.8 μg/m and the model estimated spatial distribution was found to exceed Level 2 of the China Ambient Air Quality Standards (CAAQS) enacted in 2012 (>35 μg/m) in more than 70% of the Chinese territory. The inclusion of spatial correlation upgrades the performance of conventional BPNN models and provides a more accurate estimation of PM concentrations for air quality monitoring.
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http://dx.doi.org/10.1038/s41598-019-50177-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6760143PMC
September 2019
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