Time filter

Source Type

Li Z.,State Key Laboratory of Pollutant Control and Resource Reuse | Li Z.,Nanjing University | Wang Y.,State Key Laboratory of Pollutant Control and Resource Reuse | Wang Y.,Nanjing University | And 6 more authors.
Environmental Science and Pollution Research | Year: 2013

This study aims to synthesize 2-hydroxyethyl acrylate (HEA) and 2-acrylamido-2-methylpropane sulfonic (AMPS) acid-based hydrogels by gamma radiation and to investigate their swelling behavior and heavy metal ion adsorption capabilities. The copolymer hydrogels prepared were characterized via scanning electron microscopy, Fourier transformed infrared spectra, thermal gravimetric analysis, and X-ray photoelectron spectroscopy. The research showed that the copolymer hydrogel was beneficial for permeation due to its porous structure. In addition, the experimental group A-2-d [70 % water volume ratio and (n (AMPS)/n (HEA)) = 1:1] was an optimal adsorbent. The optimal pH was 6. 0 and the optimal temperature was 15 °C. Pb2+, Cd2+, Cu2+, and Fe3+ achieved adsorption equilibriums within 24 h, whereas Cr3+ reached equilibrium in 5 h. Pb2+, Cd2+, Cr3+, and Fe3+ maximum load capacity was 1,000 mg L-1, whereas the Cu2+ maximum capacity was 500 mg L-1. The priority order in the multicomponent adsorption was Cr3+>Fe3+>Cu2+>Cd2+>Pb2+. The adsorption process of the HEA/AMPS copolymer hydrogel for the heavy metal ions was mainly due to chemisorption, and was only partly due to physisorption, according to the pseudo-second-order equation and Langmuir adsorption isotherm analyses. The HEA/AMPS copolymer hydrogel was confirmed to be an effective adsorbent for heavy metal ion adsorption. © 2012 Springer-Verlag.


Zhu Q.,State Key Laboratory of Pollutant Control and Resource Reuse | Li Z.,Nanjing University
Chemical Engineering Journal | Year: 2015

A new hybrid adsorbent, hydrous manganese dioxide-poly(N-hydroxymethyl acrylamide/2-hydroxyethyl acrylate) (HMO-P(HMAm/HEA)) hydrogel, was fabricated by supporting nanosized HMO onto a porous P(HMAm/HEA) hydrogel using in situ precipitation method to effectively remove Pb2+, Cu2+, Cd2+ and Ni2+ from water. The prepared HMO-P(HMAm/HEA) was characterized by various methods, including swelling kinetics, mechanical stability, scanning electron microscope, transmission electron microscope, X-ray diffraction, Fourier transform infrared spectra, thermo-gravimetric analysis and X-ray photoelectron spectroscopy. The results showed that the loading of HMO nanoparticles onto P(HMAm/HEA) composite hydrogel was successful and the swelling ratio, mechanical stability and thermal stability were improved after the HMO loading. Contrast experiments indicated that the incorporation of inorganic HMO enhanced adsorption capacity for heavy metal ions. Various influencing parameters on heavy metal ions removal by HMO-P(HMAm/HEA), such as initial pH, initial heavy metal concentration, contact time and competing Ca2+, were estimated. The results showed that adsorption process was pH-dependent, Langmuir monolayer adsorption and followed a pseudo-second-order rate equation. The presence of high concentrations of competing Ca2+ had no significant effect on the adsorption process. The competitive adsorption results showed that the affinity order in multi-component adsorption was Pb2+>Cu2+>Cd2+>Ni2+. Moreover, the FTIR and XPS spectra analyses further indicated that Pb2+, Cu2+, Cd2+ and Ni2+ were adsorbed mainly via the ion-exchange of -OH groups. The results revealed the feasibility of HMO-P(HMAm/HEA) for removal of heavy metal ions from water. © 2015 Elsevier B.V.


Wang J.,State Key Laboratory of Pollutant Control and Resource Reuse | Wang J.,Nanjing University | Li Z.,State Key Laboratory of Pollutant Control and Resource Reuse | Li Z.,Nanjing University
Journal of Hazardous Materials | Year: 2015

A novel polyethylenimine-functionalized ion-imprinted hydrogel (Cu(II)-p(PEI/HEA)) was newly synthesized by 60Co-γ-induced polymerization for the selective removal of Cu(II) from aqueous solution. The adsorption performances including the adsorption capacity and selectivity of the novel hydrogel were much better than those of similar adsorbents reported. The hydrogel was characterized via scanning electron microscope, transmission electron microscopy, Fourier transform infrared spectra, thermal gravimetric analysis and X-ray photoelectron spectroscopy to determine the structure and mechanisms. The adsorption process was pH and temperature sensitive, better fitted to pseudo-second-order equation, and was Langmuir monolayer adsorption. The maximum adsorption capacity for Cu(II) was 40.00mg/g. The selectivity coefficients of ion-imprinted hydrogel for Cu(II)/Pb(II), Cu(II)/Cd(II) and Cu(II)/Ni(II) were 55.09, 107.47 and 63.12, respectively, which were 3.93, 4.25 and 3.53 times greater than those of non-imprinted hydrogel, respectively. Moreover, the adsorption capacity of Cu(II)-p(PEI/HEA) could still keep more than 85% after four adsorption-desorption cycles. Because of such enhanced selective removal performance and excellent regeneration property, Cu(II)-p(PEI/HEA) is a promising adsorbent for the selective removal of copper ions from wastewater. © 2015 Elsevier B.V.


Wu N.,State Key Laboratory of Pollutant Control and Resource Reuse | Wu N.,Nanjing University | Li Z.,State Key Laboratory of Pollutant Control and Resource Reuse | Li Z.,Nanjing University
Chemical Engineering Journal | Year: 2013

A novel poly(Hydroxyethyl methacrylate/Maleamic acid) (p(HEA/MALA)) hydrogel was synthesized by 60Co-γ induced copolymerization, and used to remove Pb2+, Cd2+, Ni2+ and Cu2+ from aqueous solutions. The prepared copolymer was characterized by using the FTIR spectra, TGA analysis and XPS analysis. Batch equilibrium experiments were conducted to investigate the effects of pH, time, initial metal ion concentration and competition properties of the solutions on the adsorption of Pb2+, Cd2+, Ni2+ and Cu2+ ions. FTIR spectra and TGA analysis showed that the p(HEA/MALA) hydrogel was indeed a copolymer of HEA and Maleamic acid. Adsorption kinetics of Pb2+, Cd2+, Ni2+ and Cu2+ ions on p(HEA/MALA) followed pseudo-second-order kinetic model, and the adsorption rates followed the order Cd2+>Pb2+>Ni2+>Cu2+. The isotherm experimental data fitted better to the Langmuir model (R2>0.99) than the Freundlich model, demonstrating that the Pb2+, Cd2+, Ni2+, Cu2+ on p(HEA/MALA) was removed through Langmuir monolayer adsorption. The XPS spectra of p(HEA/MALA) with and without chelate metal ions indicated that Pb2+, Cd2+, Ni2+ and Cu2+ were adsorbed via the chelation of NH2 groups and the ion-exchange of COOH groups. According to the competitive adsorption results, the priority order in multi-component adsorption was Pb2+>Cu2+>Ni2+>Cd2+. These findings suggest that the hydrogel is a promising adsorbent to separate and recover the heavy metal ions from contaminated water. © 2012 Elsevier B.V.


PubMed | State Key Laboratory of Pollutant Control and Resource Reuse
Type: Journal Article | Journal: Environmental science and pollution research international | Year: 2013

This study aims to synthesize 2-hydroxyethyl acrylate (HEA) and 2-acrylamido-2-methylpropane sulfonic (AMPS) acid-based hydrogels by gamma radiation and to investigate their swelling behavior and heavy metal ion adsorption capabilities. The copolymer hydrogels prepared were characterized via scanning electron microscopy, Fourier transformed infrared spectra, thermal gravimetric analysis, and X-ray photoelectron spectroscopy. The research showed that the copolymer hydrogel was beneficial for permeation due to its porous structure. In addition, the experimental group A-2-d [70 % water volume ratio and (n (AMPS)/n (HEA))=1:1] was an optimal adsorbent. The optimal pH was 6.0 and the optimal temperature was 15 C. Pb(2+), Cd(2+), Cu(2+), and Fe(3)+ achieved adsorption equilibriums within 24 h, whereas Cr(3+) reached equilibrium in 5 h. Pb(2)+, Cd(2+), Cr(3+), and Fe(3+) maximum load capacity was 1,000 mg L(-1), whereas the Cu(2+) maximum capacity was 500 mg L(-1). The priority order in the multicomponent adsorption was Cr(3+)>Fe(3+)>Cu(2+)>Cd(2+)>Pb(2+). The adsorption process of the HEA/AMPS copolymer hydrogel for the heavy metal ions was mainly due to chemisorption, and was only partly due to physisorption, according to the pseudo-second-order equation and Langmuir adsorption isotherm analyses. The HEA/AMPS copolymer hydrogel was confirmed to be an effective adsorbent for heavy metal ion adsorption.

Loading State Key Laboratory of Pollutant Control and Resource Reuse collaborators
Loading State Key Laboratory of Pollutant Control and Resource Reuse collaborators