Publications by authors named "Daniel Dianchen Gang"

22 Publications

  • Page 1 of 1

Synergistic adsorption and degradation of sulfamethoxazole from synthetic urine by hickory-sawdust-derived biochar: The critical role of the aromatic structure.

J Hazard Mater 2021 Jun 9;418:126366. Epub 2021 Jun 9.

Department of Civil Engineering, University of Louisiana at Lafayette, Lafayette, LA, 70504, USA; Energy Institute of Louisiana, University of Louisiana at Lafayette, Lafayette, LA, 70504, USA. Electronic address:

This study investigated the adsorptive removal and subsequent degradation of sulfamethoxazole (SMX) from a synthetic urine by biochar (BC). The BCs used in this study were prepared using two different feedstocks with different temperatures. Element analysis and Fourier transform infrared spectroscopy (FTIR) results suggested that the aromaticity of one of the BCs, 700HSBC was significantly different from the 700PSBC although both of them were prepared at the same temperature (700 °C) with similar pore size distributions and specific surface areas. Due to the presence of abundant aromatic structures, 700HSBC showed a higher SMX uptake than 700PSBC, suggesting that the π-π interaction was the main adsorption mechanism. The removal of SMX from the urine was significantly enhanced by adding hydrogen peroxide to the 700HSBC. The carbonate radicals degradation of SMX mechanism was proposed and verified. With 700HSBC having abundant aromatic structures acting as π-electron donors, it could be an efficient activator for peroxymonocarbonate (HCO) to generate carbonate radicals. Hence, it could be concluded that the aromatic structures on BCs play a key role in both of the adsorption and hydrogen peroxide degradation of the SMX resulting in its removal from urine.
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http://dx.doi.org/10.1016/j.jhazmat.2021.126366DOI Listing
June 2021

A comparative study for phosphate adsorption on amorphous FeOOH and goethite (α-FeOOH): An investigation of relationship between the surface chemistry and structure.

Environ Res 2021 08 13;199:111223. Epub 2021 May 13.

Department of Civil Engineering, University of Louisiana at Lafayette, Lafayette, LA, 70504, USA. Electronic address:

Eutrophication is generally caused by excess nitrogen and phosphorus being released into surface waters by runoff. Developing adsorbents for adsorbing phosphate within soil buffer zones and/or water treatment columns may be effective methods to mitigate this problem. In this study, an amorphous FeOOH (AF) and a well-crystallized α-FeOOH (CF) was formulated to compare phosphate adsorption behavior. The physicochemical properties between these species showed significant differences in morphology, crystallization, zeta potential, and specific surface area. The AF exhibited higher phosphate uptake than CF. X-ray photoelectron spectroscopy (XPS) verified that the hydroxyl groups within AF were 13.28% higher than that in CF. The triply coordinated hydroxyl groups (μ-OH) associated with AF and CF appeared at different positions as shown in the diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) analyses, confirming that AF contains more adsorption reactive sites (μ-OH). Mechanisms for monodentate formations and a stable six-member ring structure were proposed. The X-ray absorption near the edge structure (XANES) and XPS results suggested that the iron valence in AF was dominated by Fe (III). XANES also demonstrated that the amorphous structure found in the AF was caused by the disordered tetrahedron and octahedron alignments, leading to a higher phosphate adsorption.
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http://dx.doi.org/10.1016/j.envres.2021.111223DOI Listing
August 2021

Uniform Mesoporous Amorphous Cobalt-Inherent Silicon Oxide as a Highly Active Heterogeneous Catalyst in the Activation of Peroxymonosulfate for Rapid Oxidation of 2,4-Dichlorophenol: The Important Role of Inherent Cobalt in the Catalytic Mechanism.

ACS Appl Mater Interfaces 2020 Dec 8;12(51):57190-57206. Epub 2020 Dec 8.

Beijing International Scientific and Technological Cooperation Base of Water Pollution Control Techniques for Antibiotics and Resistance Genes, School of Civil Engineering, Beijing Jiaotong University, 3 Shangyuancun, Beijing 100044, P. R. China.

Amorphous cobalt-inherent silicon oxide (Co-SiOx) was synthesized for the first time and employed as a highly active catalyst in the activation of peroxymonosulfate (PMS) for the rapid oxidation of 2,4-dichlorophenol (2,4-DCP). The characterization results revealed that the 0.15Co-SiOx possessed a high specific surface area of 607.95 m/g with a uniform mesoporous structure (24.33 nm). The X-ray diffraction patterns indicate that the substituted cobalt atoms enlarge the unit cell parameter of the original SiO, and the selected area electron diffraction pattern confirmed the amorphous nature of Co-SiOx. More bulk oxygen vacancies (O) existing in the Co-SiOx were identified to be one of the primary contributors to the significantly enhanced catalytic activation of PMS. The cobalt substitution both creates and stabilizes the surficial O and forms the adequately active Co(II)-O pairs which engine the electron transfer process during the catalytic activities. The active Co(II)-O pairs weaken the average electronegativity of Co/Si and Co/O sites, resulting in the prevalent changes in final state energy, which is the main driving cause of the binding energy shifts in the X-ray photoelectron spectroscopy (XPS) spectra of Si and O among all samples. The increase of the relative proportion of Co(III) in the spent Co-SiOx probably causes the binding energy shifts of the Co XPS spectrum compared to that of the Co-SiOx. The amorphous Co-SiOx outperforms stable and quick 2,4-DCP degradation, achieving a much higher kinetic rate of 0.7139 min at pH = 7.02 than others via sulfate radical advanced oxidation processes (AOPs), photo-Fenton AOPs, HO reagent AOPs, and other AOP approaches. The efficient degradation performance makes the amorphous Co-SiOx as a promising catalyst in removing 2,4-DCP or organic-rich pollutants.
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http://dx.doi.org/10.1021/acsami.0c20341DOI Listing
December 2020

Analysis and Risk Assessment of Organic Pollutants in Surface Water from Xujiahe Basin, China.

Bull Environ Contam Toxicol 2020 Sep 25;105(3):453-459. Epub 2020 Aug 25.

Department of Civil Engineering, University of Louisiana At Lafayette, P. O. Box 43598, Lafayette, LA, 70504, USA.

In this study, organic compounds were screened in surface water collected from Xujiahe basin, China by gas chromatography-mass spectrometry (GC-MS). A total of 51 compounds were identified including 14 organochlorine pesticides (OCPs), 9 organophosphorus pesticides (OPs), 16 polycyclic aromatic hydrocarbons (PAHs) and 12 chlorobenzene (CBs). The concentrations of OCPs, PAHs and CBs were generally low. The concentrations of OCPs in Xujiahe reservoir ranged from N.D. to 35.6 ng/L, the concentrations of PAHs ranged from N.D. to 19.8 ng/L and the concentrations of CBs ranged from 10.3 to 124.6 ng/L. The Ecological Structure Activity Relationships (ECOSAR) model was employed to directly predict the integrated toxicity indexes of 51 organic pollutants. The risk quotient (RQ) values of most of the organic compounds in the water samples were acceptable for their ecological risk.
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http://dx.doi.org/10.1007/s00128-020-02970-2DOI Listing
September 2020

A holistic assessment of water quality condition and spatiotemporal patterns in impounded lakes along the eastern route of China's South-to-North water diversion project.

Water Res 2020 Oct 6;185:116275. Epub 2020 Aug 6.

Department of Civil and Environmental Engineering, West Virginia University, Morgantown, WV 26506-6103, United States.

Water quality is one of the key determinants for assessing effectiveness and success of water diversions, but rarely studied at a spatial scale that crosses large river basins. Multiple statistical methods and the water quality index (WQI) were used to assess overall condition and detect spatiotemporal patterns of water quality in a series of impounded lakes along the Eastern Route of China's South-to-North Water Diversion Project. Principal components analysis and analysis of variances identified three groups with distinct water quality characteristics: upstream Gaoyou Lake and Hongze Lake showing relatively higher nutrients, turbidity, and total suspended solids; downstream Dongping lake and Donghu Lake showing higher conductivity, total hardness, and chloride; and Luoma Lake and Nansi Lake intermediate between the two former groups. The WQI indicated overall "Good" water quality with an improving trend from upstream to downstream lakes. The upstream Gaoyou Lake had over 55% of the monitoring sites with "Moderate" water quality in all the seasons. Management should focus on preventing high nitrogen, phosphorus, turbidity, and total suspended solids in upstream lakes, high chloride in downstream lakes, high nitrogen during water diversion seasons, and high phosphorus during non-water diversion seasons. These findings greatly improved our understanding of the spatiotemporal water quality patterns of the impounded lakes, and can be used to develop water quality management strategies. This study exemplifies a methodology for investigating and securing water quality for inter-basin water transfer projects.
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http://dx.doi.org/10.1016/j.watres.2020.116275DOI Listing
October 2020

Goethite dispersed corn straw-derived biochar for phosphate recovery from synthetic urine and its potential as a slow-release fertilizer.

Chemosphere 2021 Jan 3;262:127861. Epub 2020 Aug 3.

Beijing International Scientific and Technological Cooperation Base of Water Pollution Control Techniques for Antibiotics and Resistance Genes, School of Civil Engineering, Beijing Jiaotong University, 3 Shangyuancun, Beijing, 100044, PR China. Electronic address:

In this study, goethiete (α-FeOOH) -biochar (BC) composites were successfully developed from a co-precipitation reaction under alkaline conditions (pH = 11.93) and used as the adsorbent for phosphate recovery from urine. The morphology and crystallinity of α-FeOOH-BC composites were characterized by scanning electron microscopy and X-ray diffraction. α-FeOOH loaded BC was found to be amorphous. This may be caused by the Si residue in BC. The Elovich model and the Langmuir model fit better to the kinetic and isotherm results of α-FeOOH-600BC, respectively, indicating that phosphate adsorption is mainly a chemisorption and monolayer adsorption process. The α-FeOOH-600BC with amorphous structure showed higher adsorption capacity than crystalline α-FeOOH, and the maximum phosphate sorption capacity reached 57.39 mg g. Additionally, the extractable phosphate of this material was approximately 967.5 mg P·kg suggesting the α-FeOOH-600BC after adsorption could be a promising alternative as a slow-phosphate-release fertilizer. Fourier-transform infrared and X-ray induced photoelectron spectroscopy results showed that the active sites of the adsorption of phosphate were the Fe-OH bonds that formed inner-sphere complexes (Fe-O-P).
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http://dx.doi.org/10.1016/j.chemosphere.2020.127861DOI Listing
January 2021

The use of artificial neural network (ANN) for modeling adsorption of sunset yellow onto neodymium modified ordered mesoporous carbon.

Chemosphere 2020 Oct 15;256:127081. Epub 2020 May 15.

Department of Civil Engineering, University of Louisiana at Lafayette, P. O. Box 43598, Lafayette, LA, 70504, USA; Center of Environmental Technology, The Energy Institute of Louisiana, University of Louisiana at Lafayette, P. O. Box 43597, Lafayette, LA, 70504, USA. Electronic address:

Discharging coloring products in water bodies has degraded water quality irreversibly over the past several decades. Order mesoporous carbon (OMC) was modified by embedding neodymium(III) chloride on the surface of OMC to enhance the adsorptive removal towards these contaminants. This paper represents an artificial neural network (ANN) based approach for modeling the adsorption process of sunset yellow onto neodymium modified OMC (OMC-Nd) in batch adsorption experiments. Neodymium modified OMC was characterized using N adsorption-desorption isotherm, TEM micrographs, FT-IR and XPS spectra analysis techniques. 2.5 wt% Nd loaded OMC was selected as the final adsorbent for further experiments because OMC-2.5Nd showed highest removal efficiency of 93%. The ANN model was trained and validated with the adsorption experiments data where initial concentration, reaction time, and adsorbent dosage were selected as the variables for the batch study, whereas the removal efficiency was considered as the output. The ANN model was first developed using a three-layer back propagation network with the optimum structure of 3-6-1. The model employed tangent sigmoid transfer function as input in the hidden layer whereas a linear transfer function was used in the output layer. The comparison between modeled data and experimental data provided high degree of correlation (R = 0.9832) which indicated the applicability of ANN model for describing the adsorption process with reasonable accuracy.
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http://dx.doi.org/10.1016/j.chemosphere.2020.127081DOI Listing
October 2020

Enhanced Pb(II) adsorption onto functionalized ordered mesoporous carbon (OMC) from aqueous solutions: the important role of surface property and adsorption mechanism.

Environ Sci Pollut Res Int 2020 Jul 15;27(19):23616-23630. Epub 2020 Apr 15.

Center for Environmental Technology, The Energy Institute of Louisiana, P. O. Box 43597, Lafayette, LA, 70504, USA.

Functionalized ordered mesoporous carbon (MOMC-NP) was synthesized by chemical modification using HNO and HPO to enhance Pb(II) adsorption. The phosphate functional group represented by P-O-C bonding onto the surface of OMC was verified by FT-IR and XPS. Batch adsorption experiments revealed the improvement of adsorption capacity by 39 times over the virgin OMC. Moreover, the Pb(II) adsorption results provided excellent fits to Langmuir model and pseudo-second-order kinetic model. The adsorption mechanism of Pb(II) onto MOMC-NP revealed the formation of metal complexes with carboxyl, hydroxyl, and phosphate groups through ion exchange reactions and hydrogen bondings. The calculated activation energy was 22.09 kJ/mol, suggesting that Pb(II) adsorption was a chemisorption. At pH>pH, the main Pb(II) existing species of Pb(II) and Pb(OH) combine with the carboxyl, hydroxyl, and phosphate functional groups via electrostatic interactions and hydrogen bonding. All these findings demonstrated that MOMC-NP could be a useful and potential adsorbent for adsorptive removal of Pb(II). Graphical abstract.
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http://dx.doi.org/10.1007/s11356-020-08487-9DOI Listing
July 2020

The effects of carbon disulfide driven functionalization on graphene oxide for enhanced Pb(II) adsorption: Investigation of adsorption mechanism.

Chemosphere 2020 Jun 31;248:126078. Epub 2020 Jan 31.

Department of Chemical Engineering, University of Louisiana at Lafayette, P. O. Box 43675, Lafayette, LA, 70504, USA; Center for Environmental Technology, The Energy Institute of Louisiana, P. O. Box 43597, Lafayette, LA, 70504, USA.

The surface properties of graphene oxide (GO) have been identified as the key effects on the adsorption of Pb(II) from aqueous solutions in this study. This study reveals the effect of the surface reactivity of GO via Carbon Disulfide (CS) functionalization for Pb(II) adsorption. After successfully preparing CS functionalized GO (GOCS), the specific techniques were applied to investigate Pb(II) adsorption onto GOCS. Results indicated that the new sulfur-containing functional groups incorporated onto GOCS significantly enhanced Pb(II) adsorption capacity on GOCS than that of GO, achieving an improvement of 31% in maximum adsorption capacity increasing from 292.8 to 383.4 mg g. The equilibrium adsorption capacity for GOCS was 280.2 mg g having an improvement of 83.2% over that of 152.97 mg g for GO at the same initial concentration of 150 mg L under the optimal pH of 5.7. Moreover, the results of adsorption experiments showed an excellent fit to the Langmuir and Pseudo-Second-Order models indicating the monolayer and chemical adsorption, respectively. The mechanism for Pb(II) adsorption on GOCS was proposed as the coordination, electrostatic interactions, cation-pi interactions, and Lewis acid-base interactions. The regeneration study showed that GOCS had an appreciable reusability for Pb(II) adsorption with the adsorption capacity of 208.92 mg g after five regeneration cycles. In summary, GOCS has been proved to be a novel, useful, and potentially economic adsorbent for the high-efficiency removal of Pb(II) from aqueous solutions.
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http://dx.doi.org/10.1016/j.chemosphere.2020.126078DOI Listing
June 2020

Modeling mass transfer for adsorptive removal of Pb(II) onto phosphate modified ordered mesoporous carbon (OMC).

J Contam Hydrol 2020 Jan 23;228:103562. Epub 2019 Oct 23.

Department of Civil Engineering, University of Louisiana at Lafayette, P. O. Box 43598, Lafayette, LA 70504, USA; Center for Environmental Technology, The Energy Institute of Louisiana, University of Louisiana at Lafayette, P. O. Box 43597, Lafayette, LA 70504, USA. Electronic address:

Phosphate modified ordered mesoporous carbon (MOMC-NP) has been synthesized and proven to be an effective adsorbent for Pb(II) removal from aqueous solutions. However, the key application components of the mass transfer operations and diffusion coefficient have not been determined. In this study, a modified Finite Bath Diffusion Control Model was mathematically developed containing a constant related to the radius of the adsorbent particle and the fractional attainment of adsorption. The adsorption experiments were conducted under various initial Pb(II) concentrations ranging from 60 mg L to 100 mg L. The results suggested that the modified Finite Bath Diffusion Control Model was more applicable to the experimental data than the original Finite Bath Diffusion Control Model. The average value of the diffusion coefficient (λD¯) obtained from the modified finite bath diffusion control model was 1.63 × 10 cm s indicating the effective diffusivity in the adsorption of Pb(II) on MOMC-NP. Overall, the modified Finite Bath Diffusion Control Model exhibited the precise description and simulation of the mass transfer kinetics for Pb(II) adsorption onto MOMC-NP. Therefore, the modified Finite Bath Diffusion Control Model could be effectively used to investigate the mass transfer kinetics of the adsorption process.
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http://dx.doi.org/10.1016/j.jconhyd.2019.103562DOI Listing
January 2020

Nonpoint source pollution.

Water Environ Res 2019 Oct 4;91(10):1114-1128. Epub 2019 Sep 4.

Department of Civil Engineering, University of Louisiana at Lafayette, Lafayette, Louisiana.

A comprehensive review of the research papers published in 2018 focusing on nonpoint source (NPS) pollution is presented in this review article. The identification of pollution from different sources and estimation of NPS pollution using various models are summarized in this review paper. Various innovative techniques are also examined to abate NPS pollution. PRACTITIONER POINTS: The non-point source pollution in 2018 is systematically reviewed and documented. This review evaluates and summarizes the identification, quantification, reduction, and management of NPS pollution. Future perspectives of NPS pollution research are discussed.
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http://dx.doi.org/10.1002/wer.1205DOI Listing
October 2019

Combined effects of textural and surface properties of modified ordered mesoporous carbon (OMC) on BTEX adsorption.

J Hazard Mater 2019 09 29;377:381-390. Epub 2019 May 29.

Department of Chemical Engineering, University of Louisiana at Lafayette, P. O. Box 43675, Lafayette, LA 70504, USA; Center for Environmental Technology, The Energy Institute of Louisiana, P. O. Box 43597, Lafayette, LA 70504, USA.

In this study, we first investigated the effects of textural parameters and surface properties of ordered mesoporous carbon (OMC) for the adsorptive removal of Benzene, Toluene, Ethylbenzene, and Xylene (BTEX) from aqueous solutions. The BET surface area, pore volume, and surface functional groups of OMC played a crucial role in affecting the adsorption performance of BTEX. Boric acid was used to increase the pore size and BET surface area of OMC from 5.94 nm to 6.74 nm and from 1276 m/g to 1428 m/g, respectively. Citric acid was used to introduce more oxygen-containing functional groups on the surface of OMC achieving an overall increase of 11.4% of the oxygen content. The batch adsorption experiments were conducted to evaluate the adsorption capacity for OMC and modified towards BTEX and the results showed that modified OMC exhibited a significant improvement for BTEX removal in the following order: Xylenes > Ethylbenzene > Toluene > Benzene. The BTEX adsorption capacities were improved from 8% to 15% with the addition of boric acid compared to the virgin. Surface functionalized using citric acid exhibited the total adsorption capacity of 142 mg/g with an increment of 40.5% compared to virgin OMC.
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http://dx.doi.org/10.1016/j.jhazmat.2019.05.079DOI Listing
September 2019

Adsorptive removal of resorcinol on a novel ordered mesoporous carbon (OMC) employing COK-19 silica scaffold: Kinetics and equilibrium study.

J Environ Sci (China) 2019 Jan 21;75:307-317. Epub 2018 Apr 21.

Department of Civil Engineering, University of Louisiana at Lafayette, LA 70504, USA; Center for Environmental Technology, The Energy Institute of Louisiana, LA 70504, USA. Electronic address:

Phenolic compounds and their derivatives have been found in industrial wastewater, which pose threats to the natural environment. Ordered mesoporous carbon (OMC) has been identified as an ideal adsorbent possessing high specific surface area and large pore volume to alleviate these pollutants. A novel ordered mesoporous carbon was prepared using COK-19 template with the cubic Fm3m structure for the first time. Ordered mesoporous silica COK-19 was synthesized and reported in 2015. Sucrose as the carbon precursor was impregnated into the mesopores of silica and converted to carbon through carbonization process using sulfuric acid as a catalyst. Ordered mesoporous carbon was obtained after the removal of silica framework using hydrofluoric acid. Boric acid was employed for the preparation of OMCs with tunable pore sizes in the range of 6.9-16.6 nm. Several characterization techniques such as nitrogen adsorption-desorption isotherms, transmission electron microscope (TEM), Fourier transform infrared spectroscopy, Boehm titration and elemental analysis were employed to characterize the OMCs. The pore size analysis and TEM images confirmed that OMC has replicated the mesostructure of the COK-19. Results obtained from adsorption kinetics and isotherms suggest that the Pseudo-second-order model and Langmuir isotherm well described the experimental data.
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http://dx.doi.org/10.1016/j.jes.2018.04.014DOI Listing
January 2019

Nonpoint Source Pollution.

Water Environ Res 2018 Oct;90(10):1872-1898

Department of Civil Engineering, University of Louisiana at Lafayette, Lafayette, LA, 70504, USA.

A review of the literature published during year 2017 on topics relating to nonpoint source pollution (NPS) is presented. This article is written with a view to cater the need of nonpoint source pollution research and to summarize the new advancements in NPS control. Research developments on assessing, monitoring, and controlling the nonpoint source pollution are the main focus of this review. Future research topics related to NPS are also recommended.
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http://dx.doi.org/10.2175/106143017X15131012188033DOI Listing
October 2018

Molecular simulation and experimental validation of resorcinol adsorption on Ordered Mesoporous Carbon (OMC).

J Hazard Mater 2018 Jul 27;354:258-265. Epub 2018 Apr 27.

Department of Civil Engineering, University of Louisiana at Lafayette, P. O. Box 43598, Lafayette, LA, 70504, USA; Center for Environmental Technology, The Energy Institute of Louisiana, P. O. Box 43597, Lafayette, LA, 70504, USA. Electronic address:

Numerous research works have been devoted in the adsorption area using experimental approaches. All these approaches are based on trial and error process and extremely time consuming. Molecular simulation technique is a new tool that can be used to design and predict the performance of an adsorbent. This research proposed a simulation technique that can greatly reduce the time in designing the adsorbent. In this study, a new Rhombic ordered mesoporous carbon (OMC) model is proposed and constructed with various pore sizes and oxygen contents using Materials Visualizer Module to optimize the structure of OMC for resorcinol adsorption. The specific surface area, pore volume, small angle X-ray diffraction pattern, and resorcinol adsorption capacity were calculated by Forcite and Sorption module in Materials Studio Package. The simulation results were validated experimentally through synthesizing OMC with different pore sizes and oxygen contents prepared via hard template method employing SBA-15 silica scaffold. Boric acid was used as the pore expanding reagent to synthesize OMC with different pore sizes (from 4.6 to 11.3 nm) and varying oxygen contents (from 11.9% to 17.8%). Based on the simulation and experimental validation, the optimal pore size was found to be 6 nm for maximum adsorption of resorcinol.
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http://dx.doi.org/10.1016/j.jhazmat.2018.04.072DOI Listing
July 2018

Background electrolytes and pH effects on selenate adsorption using iron-impregnated granular activated carbon and surface binding mechanisms.

Chemosphere 2018 Mar 7;195:166-174. Epub 2017 Dec 7.

Department of Civil and Environmental Engineering, West Virginia University, Morgantown, WV 26506, USA.

Iron-impregnated granular activated carbon (Fe-GAC) has been shown effective for selenite adsorptive removal from aqueous solutions, but similar effectiveness was not observed with selenate. This study examined the effects of background electrolytes and pH on selenate adsorption on to Fe-GAC, and surface bindings to elucidate the selenate adsorption mechanisms. The decrease magnitude of selenate adsorption capacity under three background electrolytes followed the order: LiCl > NaCl > KCl, as ionic strength increased from 0.01 to 0.1 M. Larger adsorption capacity differences among the three electrolytes were observed under the higher ionic strengths (0.05 and 0.1 M) than those under 0.01 M. Multiplet peak fittings of high resolution X-ray photoelectron spectra for O1s and Fe2p indicated the presence of iron (III) on adsorbent surface. pH variations during the adsorbent preparation within 3-8 in NaCl solutions did not cause appreciable changes in the iron redox state and composition. Raman spectra showed the formation of both monodentate and bidentate inner sphere complexes under pHs <7 and a mixture of outer sphere and inner sphere complexes at pH 8. These results explained the lower selenate adsorption under alkaline conditions. Mechanisms for monodentate and bidentate formations and a stable six-member ring structure were proposed. Two strategies were recommended for modifying Fe-GAC preparation procedure to enhance the selenate adsorption: (1) mixed-metal oxide coatings to increase the point of zero charge (pH); and (2) ferrous iron coating to initially reduce selenate followed by selenite adsorption.
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http://dx.doi.org/10.1016/j.chemosphere.2017.11.161DOI Listing
March 2018

Nonpoint Source Pollution.

Water Environ Res 2017 Oct;89(10):1580-1602

This research article depicts a comprehensive review of scientific research advancement on nonpoint source pollution (NPS) in 2016. The causes, impacts, and methods used to mitigate nonpoint source pollution were reviewed. In addition, the assessment of nonpoint source pollution using different modeling techniques, coupled with evaluation and management tools were reviewed. Innovative technologies to reduce nonpoint source pollution were also reviewed in this paper.
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http://dx.doi.org/10.2175/106143017X15023776270593DOI Listing
October 2017

Equilibrium, kinetic and thermodynamic studies for adsorption of BTEX onto Ordered Mesoporous Carbon (OMC).

J Hazard Mater 2017 Aug 1;336:249-259. Epub 2017 May 1.

Department of Civil Engineering, University of Louisiana at Lafayette, P. O. Box 43598, Lafayette, LA, 70504, USA; Center for Environmental Technology, The Energy Institute of Louisiana, P. O. Box 43597, Lafayette, LA, 70504, USA. Electronic address:

Chemical and petrochemical industries produce substantial amounts of wastewater everyday. This wastewater contains organic pollutants such as benzene, toluene, ethylbenzene and xylenes (BTEX) that are toxic to human and aquatic life. Ordered Mesoporous Carbon (OMC), the adsorbent that possesses the characteristics of an ideal adsorbent was investigated to understand its properties and suitability for BTEX removal. Adsorption isotherms, adsorption kinetics, the effects of initial BTEX concentrations and temperatures on the adsorption process were studied. The OMCs were characterized using surface area and pore size analyzer, transmission electron microscopy (TEM), elemental analysis, thermogravimetric analysis (TGA) and fourier transform infrared spectroscopy (FTIR). The results suggested that the Langmuir Isotherm and Pseudo-Second-Order Models described the experimental data well. The thermodynamic parameters, Gibbs free energy (ΔG°), the enthalpy change (ΔH°) and the entropy change (ΔS°) of adsorption indicated that the adsorption processes were physical, endothermic, and spontaneous. In addition, OMC had 27% higher overall adsorption capacities compared to granular activated carbon (GAC).
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http://dx.doi.org/10.1016/j.jhazmat.2017.04.073DOI Listing
August 2017

Nonpoint Source Pollution.

Water Environ Res 2016 Oct;88(10):1594-619

Department of Civil Engineering, University of Louisiana at Lafayette, Lafayette, LA, 70504, USA.

Research advances on non-point source pollution in the year 2015 have been depicted in this review paper. Nonpoint source pollution is mainly caused by agricultural runoff, urban stormwater, and atmospheric deposition. Modeling techniques of NPS with different tools are reviewed in this article.
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http://dx.doi.org/10.2175/106143016X14696400495497DOI Listing
October 2016

Nonpoint Source Pollution.

Water Environ Res 2015 Oct;87(10):1576-94

Department of Civil Engineering, University of Louisiana at Lafayette, Lafayette, LA, 70504, USA.

The article presents a comprehensive review of research advancing in 2014 on nonpoint source pollution (NPS). The topics presented relate to nonpoint source pollution (NPS) within agricultural and urban areas. NPS pollution from agricultural areas is the main focus in this review. Management of NPS in agricultural, urban and rural areas is presented. Modeling of NPS pollution in different watersheds with various modeling tools is reviewed.
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http://dx.doi.org/10.2175/106143015X14338845156263DOI Listing
October 2015

Modeling nitrate-nitrogen removal process in first-flush reactor for stormwater treatment.

Bioprocess Biosyst Eng 2012 Aug 28;35(6):865-74. Epub 2011 Dec 28.

Department of Civil & Environmental Engineering, Louisiana State University, Baton Rouge, LA 70803-6405, USA.

Stormwater runoff is one of the most common non-point sources of water pollution to rivers, lakes, estuaries, and coastal beaches. While most pollutants and nutrients, including nitrate-nitrogen, in stormwater are discharged into receiving waters during the first-flush period, no existing best management practices (BMPs) are specifically designed to capture and treat the first-flush portion of urban stormwater runoff. This paper presents a novel BMP device for highway and urban stormwater treatment with emphasis on numerical modeling of the new BMP, called first-flush reactor (FFR). A new model, called VART-DN model, for simulation of denitrification process in the designed first-flush reactor was developed using the variable residence time (VART) model. The VART-DN model is capable of simulating various processes and mechanisms responsible for denitrification in the FFR. Based on sensitivity analysis results of model parameters, the denitrification process is sensitive to the temperature correction factor (b), maximum nitrate-nitrogen decay rate (K (max)), actual varying residence time (T (v)), the constant decay rate of denitrifiying bacteria (v (dec)), temperature (T), biomass inhibition constant (K (b)), maximum growth rate of denitrifiying bacteria (v (max)), denitrifying bacteria concentration (X), longitudinal dispersion coefficient (K (s)), and half-saturation constant of dissolved carbon for biomass (K (Car-X)); a 10% increase in the model parameter values causes a change in model root mean square error (RMSE) of -28.02, -16.16, -12.35, 11.44, -9.68, 10.61, -16.30, -9.27, 6.58 and 3.89%, respectively. The VART-DN model was tested using the data from laboratory experiments conducted using highway stormwater and secondary wastewater. Model results for the denitrification process of highway stormwater showed a good agreement with observed data and the simulation error was less than 9.0%. The RMSE and the coefficient of determination for simulating denitrification process of wastewater were 0.5167 and 0.6912, respectively, demonstrating the efficacy of the VART-DN model.
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http://dx.doi.org/10.1007/s00449-011-0671-3DOI Listing
August 2012

As(III) removal using an iron-impregnated chitosan sorbent.

J Hazard Mater 2010 Oct 9;182(1-3):156-61. Epub 2010 Jun 9.

Department of Civil Engineering, University of Louisiana at Lafayette, Lafayette, LA 70504, USA.

An iron-impregnated chitosan granular adsorbent was newly developed to evaluate its ability to remove arsenic from water. Since most existing arsenic removal technologies are effective in removing As(V) (arsenate), this study focused on As(III). The adsorption behavior of As(III) onto the iron-impregnated chitosan absorbent was examined by conducting batch and column studies. Maximum adsorption capacity reached 6.48 mg g(-1) at pH=8 with initial As(III) concentration of 1007 microg L(-1). The adsorption isotherm data fit well with the Freundlich model. Seven hundred and sixty eight (768) empty bed volumes (EBV) of 308 microg L(-1) of As(III) solution were treated in column experiments. These are higher than the empty bed volumes (EBV) treated using iron-chitosan composites as reported by previous researchers. The investigation has indicated that the iron-impregnated chitosan is a very promising material for As(III) removal from water.
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http://dx.doi.org/10.1016/j.jhazmat.2010.06.008DOI Listing
October 2010
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