Publications by authors named "Weiben Yang"

18 Publications

  • Page 1 of 1

High phosphate removal using La(OH) loaded chitosan based composites and mechanistic study.

J Environ Sci (China) 2021 Aug 30;106:105-115. Epub 2021 Jan 30.

School of Chemistry and Materials Science, Jiangsu Provincial Key Laboratory of Materials Cycling and Pollution Control, Nanjing Normal University, Nanjing 210023, China. Electronic address:

Our present study was to prepare a biomass-supported adsorbents with high adsorptive capacity and high selectivity to prevent the accelerated eutrophication in water body. To this end, different metal hydroxide (La, Zr and Fe) first was successfully loaded on chitosan microspheres. Then the quaternary ammonium group with different content was introduced into the adsorbent by polymerization. By comparison of adsorption properties, chitosan-La(OH)-quaternary ammonium-20% (CS-La-N-20%) has strong adsorption to phosphate (160 mg/g) by immobilizing nano-sized La(OH) within a quaternary-aminated chitosan and it maintain high adsorption in the presence of salt ions. The pH results indicated that the CS-La-N-20% would effectively sequestrate phosphate over a wide pH range between 3 and 7 without significant La leaching. What's more, adsorption capacity on the introduce of positively charged quanternary-aminated groups was significantly higher than that of the unmodified adsorbents at alkaline conditions. The column adsorption capacity reached 1300 bed volumes (BV) when phosphate concentration decreased until 0.5 mg/L at 6 BV/hr. The column adsorption/desorption reveals that no significant capacity loss is observed, indicating excellent stability and repeated use property. Characterizations revealed that phosphate adsorption on CS-La-N-20% through ligand exchange (impregnated nano-La(OH)) and electrostatic attraction (positively charged quanternary-aminated groups). All the results suggested that CS-La-N-20% can serve as a promising adsorbent for preferable phosphate removal in realistic application.
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http://dx.doi.org/10.1016/j.jes.2021.01.009DOI Listing
August 2021

Hydrophobic-modified metal-hydroxide nanoflocculants enable one-step removal of multi-contaminants for drinking water production.

iScience 2021 May 30;24(5):102491. Epub 2021 Apr 30.

Department of Civil and Environmental Engineering, Imperial College London, London, SW7 2AZ, UK.

Flocculation is a mainstream technology for the provision of safe drinking water but is limited due to the ineffectiveness of conventional flocculants in removing trace low-molecular-weight emerging contaminants. We described a synthesis strategy for the development of high-performance nanoflocculants (hydrophobic-organic-chain-modified metal hydroxides [HOC-M]), imitating surfactant-assembling nano-micelles, by integration of long hydrophobic chains with traditional inorganic metal (Fe/Al/Ti)-based flocculants. The core-shell nanostructure was highly stable in acidic stock solution and transformed to meso-scale coagulation nuclei in real surface water. In both jar and continuous-flow tests, HOC-M was superior over conventional flocculants in removing many contaminants (turbidity, UV, and DOC: >95%; TP and NO-N: >90%; trace pharmaceuticals [initial concentration: 100 ng/L]: >80%), producing flocs with better structural and dewatering properties, and lowering the environmental risk of metal leaching. The rationally designed nanoflocculants have large application potential, as a solution to increasing public concern about micro-pollutants and increasing water quality requirements.
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http://dx.doi.org/10.1016/j.isci.2021.102491DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8169996PMC
May 2021

Full-scale thermophilic aerobic co-composting of blue-green algae sludge with livestock faeces and straw.

Sci Total Environ 2021 Jan 29;753:142079. Epub 2020 Aug 29.

School of Chemistry and Materials Science, School of Environment, Jiangsu Provincial Key Laboratory of Material Cycling and Pollution Control, Nanjing Normal University, Nanjing 210046, PR China.

A high incidence of harmful algal bloom in eutrophic surface waters causes many environmental problems. Thermophilic aerobic composting enables effective treatment and disposal of algal sludge that remains after the dewatering of algae slurries, and provides a value-added organic fertiliser. Previous studies have either only dealt with the composting of a single waste component or were conducted at a lab-/pilot-scale; however, this work is a comprehensive assessment of full-scale mechanized thermophilic aerobic co-composting of algal sludge and other typical biomass-based wastes, including chicken faeces and rice straw, in a water-rich rural area in the Tai lake basin, China. With the optimised feedstock material mass ratio (6.0:1.8:1.0 for straw:algae:faeces; initial C/N ratio of 20; and initial moisture of 60 wt%), the co-composting process effectively achieved the reduction, harmlessness, and reuse of waste. The moisture content (28.36 wt% of wet weight), organic matter content (57.91 wt% of dried weight), total nutrient content (6.59 wt% for TN + TP + TK of dried weight), and heavy metal contents as well as the pH of the final product fully met the Chinese National Agricultural Organic Fertiliser Standard requirements. The reduction rates of microcystin and toxic volatile fatty acid contents were higher than 99.5%, and the seed germination index of the product was 114.5%. A notable economic benefit with a gross profit margin of 167-434% of the process was highlighted. Investigation of the associated mechanisms, including statistical analysis, spectral characterisation, micro-morphological observation, and microbial community analysis, revealed that a decreased particle sizes with a looser structure and an efficient humification effect, resulting from the work of several identified dominant microbial species, contributed to the high product quality. The current study provided a demonstration of the promising full-scale co-composting technology for comprehensive management of the environment in water-rich rural areas and the construction of a sustainable watershed.
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http://dx.doi.org/10.1016/j.scitotenv.2020.142079DOI Listing
January 2021

Role of moderately hydrophobic chitosan flocculants in the removal of trace antibiotics from water and membrane fouling control.

Water Res 2020 Jun 5;177:115775. Epub 2020 Apr 5.

Department of Civil and Environmental Engineering, Imperial College London, South Kensington Campus, London, SW7 2AZ, UK. Electronic address:

In this paper we describe the preparation and testing of a new class of chitosan-based flocculants for the treatment of surface waters containing antibiotic compounds. Three forms of moderately hydrophobic chitosan flocculants (MHCs) were prepared by chemically grafting hydrophobic branches with different lengths onto hydrophilic chitosan and these were evaluated by jar tests and a bench-scale continuous flow ultrafiltration (UF) membrane process with coagulation/sedimentation pre-treatment. Tests were conducted using both synthetic and real surface water in which norfloxacin and tylosin were added as representative antibiotics at an initial concentration of 0.1 μg/L. In jar tests, the MHCs achieved similar high removal efficiencies (REs) of turbidity and UV absorbance, but much higher REs of the two antibiotics (71.7-84.7% and 68.7-76.6% for synthetic and river waters, respectively), compared to several commercial flocculants; the superior performance was attributed to an enhanced hydrophobic interaction and H-bonding between the flocculants and antibiotics. The presence of suspended kaolin particles and humic acid enhanced the antibiotic removal, speculated to be through MHC bridging of the kaolin/humic acid and antibiotic molecules. In the continuous flow tests involving flocculation/sedimentation-UF for 40 days, an optimal MHC achieved a much greater performance than polyaluminium chloride in terms of the overall removal of antibiotics (RE (norfloxacin) of ∼90% and RE (tylosin) of ∼80%) and a greatly reduced rate of membrane fouling; the latter resulting from a more porous and looser structure of cake layer, caused by a surface-modification-like effect of residual MHC on the hydrophobic PVDF membrane. The results of this study have shown that MHCs offer a significant advance over the use of existing flocculants for the treatment of surface water.
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http://dx.doi.org/10.1016/j.watres.2020.115775DOI Listing
June 2020

Pilot-scale composting of typical multiple agricultural wastes: Parameter optimization and mechanisms.

Bioresour Technol 2019 Sep 15;287:121482. Epub 2019 May 15.

School of Environment, School of Chemistry and Materials Science, Jiangsu Provincial Key Laboratory of Material Cycling and Pollution Control, Nanjing Normal University, Nanjing 210046, PR China.

In this work, pilot-scale (100 kg of mixed wastes each time) composting of typical agricultural wastes, including chicken manure, vegetable leaves and rice husks with a mass ratio of 6:3:1, was studied. Effects of thermal phases and transformation time on performance, including moisture, nutrient, and carbon contents and C/N ratios of compost, were investigated. The optimal parameters were 75 ± 5 °C and 18 h; the compost met the requirements of Chinese National Agricultural Organic Fertilizer Standard (NY525-2012). Mechanisms investigations demonstrated that, Bacillus and Sinibacillus played key roles in degrading high-molecular-weighted organic substances into small-molecular-weighted humic- and fulvic-acid-like matters, resulting in smaller particle size and loose structure of the product; rice husk particles acted as a conditioning agent and remained their originally morphology. The mechanism provided informative guidance for optimizing the process in practical application.
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http://dx.doi.org/10.1016/j.biortech.2019.121482DOI Listing
September 2019

Norfloxacin and Bisphenol-A Removal Using Temperature-Switchable Graphene Oxide.

ACS Appl Mater Interfaces 2018 Aug 20;10(34):29083-29091. Epub 2018 Aug 20.

School of Chemistry and Materials Science, Jiangsu Provincial Key Laboratory of Material Cycling and Pollution Control , Nanjing Normal University , Nanjing 210023 , China.

Graphene oxide (GO) is a competitive candidate used for adsorption of emerging organic contaminants (EOCs) from water. To overcome GO's spontaneous aggregation tendency in adsorption and to ease contaminant desorption from the adsorbent for adsorbent regeneration, a modified GO (P-GO), with temperature-switchable hydrophilicity/hydrophobicity, obtained by grafting temperature-responsive poly( N- n-propylacrylamide) was proposed. Two model EOCs, norfloxacin (NOR) and bisphenol A (BPA), with distinct hydrophilicity/hydrophobicity were employed. P-GO showed significant temperature-responsive adsorption behaviors: P-GO was more hydrophilic at a lower temperature and was beneficial for the adsorption of hydrophilic NOR, whereas it turned more hydrophobic at a higher temperature and was preferred for the adsorption of hydrophobic BPA. Compared with GO, P-GO under corresponding optimal conditions had comparable large adsorption amounts for NOR because of an "adsorption site replacement" strategy and notably enhanced adsorption for BPA because of strengthened hydrophobic association. Main interfacial binding interactions were π-π electron donor-acceptor effect and H-bonding for NOR adsorption and hydrophobic association and H-bonding for BPA uptake. On the basis of the temperature-responsive adsorption behaviors and studied interfacial interactions, regeneration of the adsorbent at designed temperatures using water (without additional chemicals) as an eluent is realized. This achievement is important for reducing risks of secondary environmental pollution during regeneration and easing further recovery of organic contaminants if needed.
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http://dx.doi.org/10.1021/acsami.8b07233DOI Listing
August 2018

Coupled heating/acidification pretreatment of chemical sludge for dewatering by using waste sulfuric acid at low temperature.

Chemosphere 2018 Aug 21;205:260-266. Epub 2018 Apr 21.

School of Environment, School of Chemistry and Materials Science, Jiangsu Provincial Key Laboratory of Material Cycling and Pollution Control, Nanjing Normal University, Nanjing 210046, PR China. Electronic address:

A cost-effective approach for pretreatment of chemical sludge for further dewatering, based on the idea of "using waste to treat waste", is provided. It is a coupled heating/acidification pretreatment method, where waste sulfuric acid is employed and relatively low temperatures (<100 °C) are applied. Effects of reaction time, temperature, and dosage of waste acid on dewatering performance (both dewatering speed and degree) are studied. Under the optimal conditions (reaction time: 30 min; temperature: 90 °C; waste acid dosage: 0.175 g/(g dried sludge)), the method of this work demonstrates three advantages compared to the conventional method using lime+polyacrylamide: lower moisture content of treated sludge; higher calorific value for incineration process; and lower cost. Detailed mechanism of the pretreatment for dewatering is investigated via characterizations and statistical analyses of various parameters, among which zeta potential, particle size, protein and polysaccharide contents, soluble chemical oxygen demand (SCOD), reduction of combined water and volatile suspended solid (VSS), are associated with dewatering performance. Both heating and acidification generate disintegration of cells in sludge, giving rise to two phenomena: more organic matters are released into solution and more bound water turns into free water. Meantime, the released organic polymers flocculate sludge particles, further accelerating the solid-liquid separation process.
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http://dx.doi.org/10.1016/j.chemosphere.2018.04.120DOI Listing
August 2018

Separation and Sequential Recovery of Tetracycline and Cu(II) from Water Using Reusable Thermoresponsive Chitosan-Based Flocculant.

ACS Appl Mater Interfaces 2017 Mar 8;9(11):10266-10275. Epub 2017 Mar 8.

College of Biology and the Environment, Nanjing Forestry University , Nanjing 210037, P. R. China.

Coexistence of antibiotics and heavy metals is typically detected in water containing both organic and inorganic contaminants. In this work, a flocculation method using a reusable thermoresponsive chitosan-based flocculant (CS-g-PNNPAM) was applied for separation and sequential recovery of tetracycline (TC) and Cu(II) from water. High synergistic removal rates of both TC and Cu(II) from water (>90%) were reached. Interactive effects among targeted water temperature (T), stock solution temperature (T), and flocculant dosage on flocculation performance were assessed using response surface methodology. To optimize flocculation, operation strategies of adjusting T and dosage according to T based on the interactive effects were given through mathematical analyses. The flocculation mechanism as well as interfacial interactions among CS-g-PNNPAM, TC, and Cu(II) were studied through experimental investigations (floc size monitoring, X-ray photoelectron spectroscopy, and UV spectra) and theoretical calculations (density functional theory and molecular dynamics simulations). Coordination of Cu(II) with TC and the flocculant promoted flocculation; switchable interactions (H bonds and hydrophobic association) of the TC-flocculant at different temperatures were key factors affecting operation strategies. When these interactions were weakened step by step, TC and Cu(II) were sequentially recovered from flocs using certain solutions. Meanwhile, the flocculant in flocs was regenerated and found reusable with high flocculation efficiency.
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http://dx.doi.org/10.1021/acsami.7b00828DOI Listing
March 2017

Interactions between Antibiotics and Graphene-Based Materials in Water: A Comparative Experimental and Theoretical Investigation.

ACS Appl Mater Interfaces 2016 Sep 29;8(36):24273-80. Epub 2016 Aug 29.

School of Chemistry and Materials Science, Jiangsu Provincial Key Laboratory of Material Cycling and Pollution Control, Nanjing Normal University , Nanjing 210023, PR China.

Complex interactions between antibiotics and graphene-based materials determine both the adsorption performance of graphene-based materials and the transport behaviors of antibiotics in water. In this work, such interactions were investigated through adsorption experiments, instrumental analyses and theoretical DFT calculations. Three typical antibiotics (norfloxacin (NOR), sulfadiazine (SDZ) and tetracycline (TC)) and different graphene-based materials (divided into two groups: graphene oxides-based ones (GOs) and reduced GOs (RGOs)) were employed. Optimal adsorption pHs for NOR, SDZ, and TC are 6.2, 4.0, and 4.0, respectively. At corresponding optimal pHs, NOR favored RGOs (adsorption capability: ∼50 mg/g) while SDZ preferred GOs (∼17 mg/g); All adsorbents exhibited similar uptake of TC (∼70 mg/g). Similar amounts of edge carboxyls of both GOs and RGOs wielded electrostatic attraction with NOR and TC, but not with SDZ. According to DFT-calculated most-stable-conformations of antibiotics-adsorbents complexes, the intrinsic distinction between GOs and RGOs was the different amounts of sp(2) and sp(3) hybridization regions: π-π electron donor-acceptor effect of antibiotic-sp(2)/sp(3) and H-bonds of antibiotic-sp(3) coexisted. Binding energy (BE) of the former was larger for NOR; the latter interaction was stronger for SDZ; two species of TC at the optimal pH, i.e., TC(+) and TC(0), possessed larger BE with sp(3) and sp(2) regions, respectively.
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http://dx.doi.org/10.1021/acsami.6b09377DOI Listing
September 2016

Removal of trace nonylphenol from water in the coexistence of suspended inorganic particles and NOMs by using a cellulose-based flocculant.

Chemosphere 2016 Oct 25;161:482-490. Epub 2016 Jul 25.

School of Chemistry and Materials Science, Jiangsu Provincial Key Laboratory of Materials Cycling and Pollution Control, Nanjing Normal University, Nanjing, 210023, PR China. Electronic address:

A flocculation method was used for the removal of trace nonylphenol (NP) from synthetic surface water containing natural organic matters (humic acid, HA) and suspended inorganic particles (kaolin). A polymeric flocculant (CMCND), with enhanced cationic property and unique switchable hydrophobic/hydrophilic characteristic, was specially designed for this application. CMCND showed a high efficiency for trace NP removal, turbidity and UV254 abatements: under optimized conditions (pH: 4; T: 35 °C; dosage: 40 mg/L), the removal of NP reached up to 79%. By using dosage-pH flocculation diagrams and correlation analyses as tools, kaolin and HA were found to exert synergistic effects on NP removal, with the aid of CMCND; the synergistic effect of HA is higher due to π-π stacking. Zeta potential-dosage profiles clearly demonstrated charge neutralization predominated at pH 4, due to the strong cationic groups in the flocculant. Floc size monitoring displayed that the delayed phase transformation process (from hydrophilicity to hydrophobicity) of CMCND at 35 °C enhanced NP removal. In addition, spectral analyses clarified the interactions among CMCND, NP, kaolin and HA: charge attraction and hydrophobic interaction between CMCND and NP played the key roles. The findings are of significance for removing endocrine-disrupting chemicals in environmental remediation.
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http://dx.doi.org/10.1016/j.chemosphere.2016.07.036DOI Listing
October 2016

Removal of antibiotics from water in the coexistence of suspended particles and natural organic matters using amino-acid-modified-chitosan flocculants: A combined experimental and theoretical study.

J Hazard Mater 2016 Nov 24;317:593-601. Epub 2016 Jun 24.

School of Chemistry and Materials Science, Jiangsu Provincial Key Laboratory of Materials Cycling and Pollution Control, Nanjing Normal University, Nanjing 210023, PR China. Electronic address:

Contamination of trace antibiotics is widely found in surface water sources. This work delineates removal of trace antibiotics (norfloxacin (NOR), sulfadiazine (SDZ) or tylosin (TYL)) from synthetic surface water by flocculation, in the coexistence of inorganic suspended particles (kaolin) and natural organic matter (humic acid, HA). To avoid extra pollution caused by petrochemical products-based modification reagents, environmental-friendly amino-acid-modified-chitosan flocculants, Ctrp and Ctyr, with different functional aromatic-rings structures were employed. Jar tests at various pHs exhibited that, Ctyr, owning phenol groups as electron donors, was favored for elimination of cationic NOR (∼50% removal; optimal pH: 6; optimal dosage: 4mg/L) and TYL (∼60% removal; optimal pH: 7; optimal dosage: 7.5mg/L), due to π-π electron donator-acceptor (EDA) effect and unconventional H-bonds. Differently, Ctrp with indole groups as electron acceptor had better removal rate (∼50%) of SDZ anions (electron donator). According to correlation analysis, the coexisted kaolin and HA played positive roles in antibiotics' removal. Detailed pairwise interactions in molecular level among different components were clarified by spectral analysis and theoretical calculations (density functional theory), which are important for both the structural design of new flocculants aiming at targeted contaminants and understanding the environmental behaviors of antibiotics in water.
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http://dx.doi.org/10.1016/j.jhazmat.2016.06.024DOI Listing
November 2016

A pH- and Temperature-Responsive Magnetic Composite Adsorbent for Targeted Removal of Nonylphenol.

ACS Appl Mater Interfaces 2015 Nov 2;7(44):24446-57. Epub 2015 Nov 2.

College of Biology and the Environment, Nanjing Forestry University , Nanjing 210037, P.R. China.

A pH- and temperature-responsive magnetic adsorbent [poly(N-isopropylacrylamide) grafted chitosan/Fe3O4 composite particles, CN-MCP], was synthesized for the removal of the endocrine-disrupting chemical nonylphenol. According to the structural characteristics (changeable surface-charge and hydrophilic/hydrophobic properties) of the targeted contaminant, CN-MCP was designed owning special structure (pH- and temperature-responsiveness for the changeable surface-charge and adjustable hydrophilic/hydrophobic properties, respectively). Compared to chitosan magnetic composite particles without grafting modification (CS-MCP) and several other reported adsorbents, CN-MCP exhibited relatively high adsorption capacity for nonylphenol under corresponding optimal conditions (123 mg/g at pH 9 and 20 °C; 116 mg/g at pH 5 and 40 °C). Meanwhile, high selectivity of the novel adsorbent in selective adsorption of nonylphenol from bisolute solution of nonylphenol and phenol was found. Effects of grafting ratio of the grafted polymer branches and coexisting inorganic salts on the adsorption were systematically investigated. Moreover, CN-MCP demonstrated desired reusability during 20 times of adsorption-desorption recycling. The high adsorption capacity, high selectivity, and desired reusability aforementioned revealed the significant application potential of CN-MCP in the removal of NP. On the basis of the adsorption behaviors, isotherms equilibrium, thermodynamics and kinetics studies, and instrumental analyses including X-ray photoelectron spectroscopy, BET specific surface area, zeta potential, and static water contact angle measurements, distinct adsorption mechanisms were found under various conditions: charge attraction between CN-MCP and the contaminant, as well as binding between polymeric branches of CN-MCP and nonyls, contributed to the adsorption at pH 9 and 20 °C; whereas hydrophobic interaction between CN-MCP and nonylphenol played a dominant role at pH 5 and 40 °C. The current study provided a strategy for the structural design of adsorbents according to the features of targeted emerging contaminants, and the continuity of the work was discussed and proposed.
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http://dx.doi.org/10.1021/acsami.5b08709DOI Listing
November 2015

Flocculation of copper(II) and tetracycline from water using a novel pH- and temperature-responsive flocculants.

Chemosphere 2015 Dec 7;141:112-9. Epub 2015 Jul 7.

School of Chemistry and Materials Science, Jiangsu Provincial Key Laboratory of Carbon and Nitrogen Cycle Processes and Pollution Control, Nanjing Normal University, Nanjing 210046, China.

Insufficient research is available on flocculation of combined pollutants of heavy metals and antibiotics, which widely exist in livestock wastewaters. Aiming at solving difficulties in flocculation of this sort of combined pollution, a novel pH- and temperature-responsive biomass-based flocculant, carboxymethyl chitosan-graft-poly(N-isoproyl acrylamide-co-diallyl dimethyl ammonium chloride) (denoted as CND) with two responsive switches [lower critical solution temperature (LCST) and isoelectric point (IEP)], was designed and synthesized. Its flocculation performance at different temperatures and pHs was evaluated using copper(II) and tetracycline (TC) as model contaminants. CND exhibited high efficiency for coremoval of both contaminants, whereas two commercial flocculants (polyaluminum chloride and polyacrylamide) did not. Especially, flocculation performance of the dual-responsive flocculant under conditions of temperature>LCST and IEP(contaminants)
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http://dx.doi.org/10.1016/j.chemosphere.2015.06.050DOI Listing
December 2015

Adsorption of three pharmaceuticals on two magnetic ion-exchange resins.

J Environ Sci (China) 2015 May 21;31:226-34. Epub 2015 Feb 21.

School of Chemistry and Materials Science, Jiangsu Provincial Key Laboratory of Materials Cycling and Pollution Control, Nanjing Normal University, Nanjing 210046, China.

The presence of pharmaceuticals in aquatic environments poses potential risks to the ecology and human health. This study investigated the removal of three widely detected and abundant pharmaceuticals, namely, ibuprofen (IBU), diclofenac (DC), and sulfadiazine (SDZ), by two magnetic ion-exchange resins. The adsorption kinetics of the three adsorbates onto both resins was relatively fast and followed pseudo-second-order kinetics. Despite the different pore structures of the two resins, similar adsorption patterns of DC and SDZ were observed, implying the existence of an ion-exchange mechanism. IBU demonstrated a combination of interactions during the adsorption process. These interactions were dependent on the specific surface area and functional groups of the resin. The adsorption isotherm fittings verified the differences in the behavior of the three pharmaceuticals on the two magnetic ion-exchange resins. The presence of Cl- and SO4(2-) suppressed the adsorption amount, but with different inhibition levels for different adsorbates. This work facilitates the understanding of the adsorption behavior and mechanism of pharmaceuticals on magnetic ion-exchange resins. The results will expand the application of magnetic ion-exchange resins to the removal of pharmaceuticals in waters.
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http://dx.doi.org/10.1016/j.jes.2014.09.035DOI Listing
May 2015

A facial electrochemical approach to determinate bisphenol A based on graphene-hypercrosslinked resin MN202 composite.

Food Chem 2014 Sep 1;158:81-7. Epub 2014 Mar 1.

Jiangsu Collaborative Innovation Center of Biomedical Functional Materials, College of Chemistry and Materials Science, Nanjing Normal University, Nanjing 210046, China.

It first reported a novel electrochemical approach for the in situ determination of bisphenol A (BPA) in the milk and mineralised water using graphene-hypercrosslinked resin MN202 composite (MN202) modified electrode. The electrocatalytic oxidation and electroanalytical of BPA on the modified electrode were investigated by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). It is notable that the oxidation peak current of BPA had enhanced remarkably and the oxidation overpotential had decreased significantly. Experimental parameters, such as the accumulation potential and time, scan rate, and the pH value of buffer solution were optimised. Under the optimised conditions, the oxidation peak current was proportional to BPA concentration in a wide range between 0.005 and 20.0 μmol/L, and the detection limit was 1.02 nmol/L (S/N=3). Moreover, the fabricated electrode also exhibited good reproducibility and stability, and employed to in situ determinate BPA in milk and mineralised water successfully.
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http://dx.doi.org/10.1016/j.foodchem.2014.02.123DOI Listing
September 2014

Factors influencing antibiotics adsorption onto engineered adsorbents.

J Environ Sci (China) 2013 Jul;25(7):1291-9

State Key Laboratory of Pollution Control and Resources Reuse, School of the Environment, Nanjing University, Nanjing 210093, China.

The study evaluated the adsorption of two antibiotics by four engineered adsorbents (hypercrosslinked resin MN-202, macroporous resin XAD-4, activated carbon F-400, and multi-walled carbon nanotubes (MWCNT)) from aqueous solutions. The dynamic results demonstrated the dominant influence of pore size in adsorption. The adsorption amounts of antibiotics on XAD-4 were attributed to the hydrophobic effect, whereas steric hindrance or micropore-filling played a main role in the adsorption of antibiotics by F-400 because of its high microporosity. Aside from F-400, similar patterns of pH-dependent adsorption were observed, implying the importance of antibiotic molecular forms to the adsorption process for adsorbents. Increasing the ionic concentration with CaC12 produced particular adsorption characteristics on MWCNT at pH 2.0 and F-400 at pH 8.0, which were attributed to the highly available contact surfaces and molecular sieving, respectively. Its hybrid characteristics incorporating a considerable portion of mesopores and micropores made hypercross linked MN-202 a superior antibiotic adsorbent with high adsorption capacity. Furthermore, the adsorption capacity of MWCNT on the basis of surface area was more advantageous than that of the other adsorbents because MWCNT has a much more compact molecular arrangement.
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http://dx.doi.org/10.1016/s1001-0742(12)60215-0DOI Listing
July 2013

Performance of a non-phosphorus antiscalant on inhibition of calcium-sulfate precipitation.

Water Sci Technol 2012 ;66(1):193-200

College of Chemistry and Materials Science, Nanjing Normal University, Nanjing, China.

The aim of this study is to report on the performance of a novel non-phosphorus antiscalant, acrylic acid (AA)-allylpolyethoxy carboxylate (APEC), being developed for calcium-sulfate scale inhibition in industrial water systems. The performance of AA-APEC on calcium-sulfate scale inhibition was compared with that of the two commercial inhibitors, polyamino polyether methylene phosphonates (PAPEMP) and polyacrylic acid (PAA), containing the same polyethylene glycol segments or carboxyl functional groups as AA-APEC. The study indicated that AA-APEC could act as a highly effective calcium sulfate inhibitor, having strong ability to inhibit the precipitation of calcium sulfate at a dosage of 2 mg L(-1), showing approximately 83.6% inhibition. The results also showed that AA-APEC dosage, the solution pH, inhibiting temperature, concentration of Ca(2+), and SO(4)(2-) all play important roles in inhibiting calcium-sulfate precipitation. The precipitation thermodynamics and kinetics at different temperatures were also discussed. X-ray diffractometer (XRD) and scanning electron microscope (SEM) analysis showed that AA-APEC strongly affected the texture and the morphology of the deposited calcium sulfate. Calcium sulfate has been inhibited through stabilization by adsorption onto crystal growth sites of nascent crystals altering their morphology.
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http://dx.doi.org/10.2166/wst.2012.157DOI Listing
September 2012

Investigation into adsorption mechanisms of sulfonamides onto porous adsorbents.

J Colloid Interface Sci 2011 Oct 8;362(2):503-9. Epub 2011 Jul 8.

College of Chemistry and Materials Science, Nanjing Normal University, Nanjing 210097, China.

The presence of sulfonamide antibiotics in aquatic environments poses potential ecological risks and dangers to human health. In this study, porous resins as adsorbents for the removal of two sulfonamides, sulfadiazine and sulfadimidine, from aqueous solutions were evaluated. Activated carbon F-400 was included as a comparative adsorbent. Despite the different surface properties and pore structures of the three resins, similar patterns of pH-dependent adsorption were observed, implying the importance of sulfonamide molecular forms to the adsorption process on the resins. Sulfonamide adsorption to the three resins exhibited different ionic strengths and temperature dependence consistent with sulfonamide speciation and the corresponding adsorption mechanism. Adsorption of sulfadiazine to F-400 was relatively insensitive to pH and ionic strength as micropore-filling mainly contributed to adsorption. The adsorption mechanism of sulfadiazine to the hypercrosslinked resin MN-200 was similar to that of the macroporous resin XAD-4 at lower pH values, whereas it was almost identical to the aminated resin MN-150 at higher pH. This work provided an understanding of adsorption behavior and mechanism of sulfonamide antibiotics on different adsorbents and should result in more effective applications of porous resin for antibiotics removal from industrial wastewater.
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http://dx.doi.org/10.1016/j.jcis.2011.06.071DOI Listing
October 2011
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