Adsorption of La3+ and Ce3+ by poly-γ-glutamic acid crosslinked with polyvinyl alcohol

With the exploitation of rare earth ore, more and more rare earth elements came into groundwater, caused waste of resources and toxicity to the organisms. This study aimed to find an efficient adsorption material to mitigate the above issue. Through doping polyvinyl alcohol with poly-γ-glutamic acid, an immobilised PSP gel particle was produced and had the adsorption rate of La3+ up to 97.10%. The factors including initial concentration of La3+ or Ce3+, adsorbent dosage, pH and temperature of the solution, which potentially affected the adsorption rate and were studied in batch mode. It was found that the optimum adsorption conditions were composed of 50 mg/L La3+/Ce3+ of initial concentration, 600 mg/L (dry mass) biomass for adsorption, pH 6, temperature 30 °C, 150 r/min rotational speed, and 1 h adsorption time. The selective adsorption of 15 different rare earth ions in mixed aqueous solutions were investigated. However, no significant selective differences were observed. Scanning electron microscopy showed that the morphological characteristic of the novel gel was its porous structure, while polyvinyl alcohol gel had a compact structure. Fourier transform infrared spectroscopy suggested that carboxyl groups in the poly-γ-glutamic acid might played a key role in the adsorption process. The adsorption mechanism forecasted to be cation exchange between –COOH and R3+. The adsorption kinetic and thermodynamic process for La3+ and Ce3+ was consistent with the pseudo-second-order equation and Langmuir adsorption isotherm model. It demonstrated that PSP gels particles were useful for removing REEs from wastewater.

A novel immobilized gel particle material was developed through doping poly-γ-glutamic acid within polyvinyl alcoholFigure optionsDownload as PowerPoint slide