•A novel magnetic chitosan composite adsorbent was prepared by the sol-gel method.•The adsorbent was characterized by SEM, BET, FTIR, XRD, TGA and VSM methods.•The adsorption fits well with the Langmuir isotherm and pseudo-second-order model.•The adsorbent exhibited high adsorption capacity for the Cu2+ irons.•Easy separation and good reusability make the adsorbent attractive for further practical application.Water pollution caused by Cu2+ ions poses a significant threat to the ecosystem and human health, hence the development of highly cost-effective, highly operation-convenient and highly efficient natural polymer-based adsorbents is urgently needed. To overcome this serious problem, a novel cost-effective magnetic chitosan composite adsorbent (CsFeAC) was prepared with magnetic macroparticles and highly porous activated carbon carrier using the sol-gel method. Several methods, namely SEM, BET, FTIR, XRD, TGA and VSM, were applied to characterize the adsorbent. Batch tests were conducted to investigate Cu2+ adsorption properties of CsFeAC at different pH values, contact time, initial Cu2+ concentrations and temperatures. The adsorption fits better to the Langmuir isotherm and follows the pseudo-second-order model, suggesting that it is a monolayer adsorption and the rate-limiting step is the chemical chelating reaction. The saturated adsorption capacity is found to be 216.6 mg/g. Thermodynamics analysis suggests that the adsorption process is endothermic, with increasing entropy and spontaneous in nature. BET and XRD tests confirm that the higher specific surface area and lower crystallinity of CsFeAC significantly improve the absorption capacity and rate. FTIR spectra reveal that the amino and hydroxyl groups play an important role in the chelating adsorption. The supermagnetic property of CsFeAC facilitates its easy separation characteristic. Further recycling experiments show that CsFeAC still retains 95% of the original adsorption following the 5th adsorption-desorption cycle. All these results demonstrate that CsFeAC is a promising recyclable adsorbent for removing Cu2+.Download high-res image (215KB)Download full-size image

Nine elements (As, Cd, Cr, Cu, Fe, Mn, Ni, Pb, Zn) in sediment samples at 7 sites (Site 1–7) from Suzhou Creek in Shanghai were analyzed with the Community Bareau of Reference (BCR) (sequential extraction (SE)) protocol and simultaneously extracted metals (SEM)/acid volatile sulfide (AVS) procedure to assess the metal bioavailability and toxicology in this area. The results showed that the BCR extraction can be utilized as an additional tool with the AVS method for assessing the potential bioavailability and toxicity of metals in sediments. Pollution from S5 (Site 5) was more severe than from other sites, especially Pb, Cu and Zn. Among all the sites, more than 80% of the total concentration of Fe existed in the residual fraction, As, Cr, Mn also dominated in the residual fraction (more than 50%). While Cd, Ni and Zn (more than 35%) were mainly in the non-stable phase. Cu had a strong affinity with oxidizable phase and Pb varied from site to site. The SEM/AVS ratio was less than one in these sediments and results implied that the majority of Zn and Ni (> 40%) were bound to AVS. In contrast, Pb, Cu and Cd were little bound to AVS due to their low ration of SEM-Pb, Cu, Cd to corresponding total concentration and relatively high porewater concentration.

•Zinc and phosphate containing wastewater was used to synthesize molecular sieve.•94% of zinc and phosphate were removed from wastewater after synthesis.•Synthesized molecular sieve showed catalytic activity in oxidizing 80% of cyclohexane.Zinc-incorporated aluminophosphate molecular sieve (ZnAPO-34) has been successfully synthesized from Zn-contained phosphatizing wastewater. More than 90% of Zn and P were removed from wastewater after synthesis. The synthesized materials were characterized by X-ray diffraction, small angle X-ray diffraction and ammonia temperature programmed desorption. As a result, these samples were proven to be typical ZnAPO-34, which possessed mesoporous structure together with a great number of Brønsted and Lewis acid sites. Furthermore, the synthesized ZnAPO-34 showed 80% catalytic activity and 80% selectivity in cyclohexane oxidation to cyclohexanol. The higher activity and selectivity could be ascribed to the incorporation of Zn in the aluminophosphate molecular sieve.Download full-size image