Selective recovery of silver from aqueous solutions by poly (glycidyl methacrylate) microsphere modified with trithiocyanuric acid

The poly (glycidyl methacrylate) microsphere was modified with trithiocyanuric acid to achieve selective adsorption of silver ions from aqueous solutions. X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM) and Fourier transform infrared spectroscopy (FT-IR) were used to characterize the microsphere. In this study, the effects of pH, initial silver ions concentration and contact time on silver ions adsorption, reusability and selectivity of the microsphere were investigated. Experimental results showed that the removal rate of silver ions reached 96.40% under pH 5, the adsorption equilibrium time was about 14 h and the maximum adsorption capacity was 217.17 mg/g at pH 5. Besides, the microsphere has an excellent selectivity for silver ions among Zn(II), Ni(II), Co(III) and Ge(IIII). The adsorption isotherm of Ag + on T-PGMA fitted the Langmuir isotherm model well and the adsorption kinetics followed the pseudo-second-order model, suggesting that the main adsorption is chemical monolayer adsorption. Moreover, the microsphere has a high reusability and the absorbability was slightly decreased from 96.29% to 94.01% after four cycles. All the experimental data indicated that the microsphere is very promising for silver ions adsorption from aqueous solutions.