Removal of Pb (II) from aqueous solution by sulfur-functionalized walnut shell

• Published in: Environmental science and pollution research international 2019-05, Vol.26 (13), p.12776-12787
• Main Authors: Lu, Xiu-guo, Guo, Yi-ting
• Format: Article
• Language: English
• Subjects: Adsorbents; Adsorption; Aquatic Pollution; Aqueous solutions; Atmospheric Protection/Air Quality Control/Air Pollution; Earth and Environmental Science; Ecotoxicology; Environment; Environmental Chemistry; Environmental Health; Environmental science; Fourier transforms; Functional groups; Heavy metals; Hydrogen-Ion Concentration; Infrared spectroscopy; Ion exchange; Isotherms; Juglans - chemistry; Kinetics; Lead; Lead - chemistry; Lead - isolation & purification; Low cost; Microscopy, Electron, Scanning; Models, Chemical; Photoelectron Spectroscopy; Photoelectrons; Research Article; Scanning electron microscopy; Spectroscopy, Fourier Transform Infrared; Spectrum analysis; Sulfur; Sulfur - chemistry; Synthesis; Temperature; Thermodynamics; Walnuts; Waste Water Technology; Water - chemistry; Water Management; Water Pollutants, Chemical - chemistry; Water Pollutants, Chemical - isolation & purification; Water pollution; Water Pollution Control; X ray photoelectron spectroscopy
• ISSN: 0944-1344; 1614-7499
• DOI: 10.1007/s11356-019-04753-7

Heavy metal lead poses a great threat to organisms and the environment; the removal of lead has drawn more and more attention in recent years. In this paper, the sulfur-containing functional group was grafted onto the walnut shell with xanthate to synthesize a low-cost biosorbent (SWM) for the removal of lead in water. The synthesized adsorbent was characterized by Fourier-transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and Brunner−Emmet−Teller (BET). The effects of pH, adsorbent dosage, contact time, initial Pb (II) concentration, and temperature on adsorption were investigated, and the adsorption properties of walnut shells before and after modification were compared. Moreover, adsorption kinetics, adsorption isotherms, and adsorption thermodynamics were studied. The sulfur-containing functional group was confirmed to be successfully grafted onto the walnut shell. The results showed that the adsorption performance of SWM was much better than the unmodified walnut shell due to complexation by sulfur-containing functional group and ion exchange. The Pb (II) adsorption onto SWM was found to follow Temkin isotherm model and has a good correlation with the pseudo-second-order kinetic model. In addition, the adsorption process was spontaneous and exothermic. All the results showed that the high adsorption performance and low cost of SWM make it a potential biosorbent in the treatment of lead-contaminated water.