Instantaneous and efficient removal of glyphosate with low concentration by amine-functionalized SBA-15 chelated with Fe(III)

Glyphosate has drawn great attention due to its potentially detrimental effect to ecosystems, but the selective removal of low-concentration glyphosate from surface water remains challenging. Herein, a novel adsorbent (Fe (III)/NN-SBA-15) for the adsorption of low-concentration glyphosate from aqueous solution was prepared by using ethylenediamine (EDA) chelating with Fe(III) to modify SBA-15. Adsorption study showed that the Fe(III)/ NN-SBA-15 has excellent adsorption capacity for glyphosate (71.4 mg/g). Most importantly, the Fe(III)/NN-SBA15 exhibited fast adsorption kinetics for glyphosate, 99% of glyphosate could be quickly removed within 1 min when the glyphosate concentration from 5 mg/L to 21 mg/L, which was outperforms many other adsorbents previous reported. In addition, the results of the effect of competing ions on the adsorption process showed that Fe(III)/NN-SBA-15 had good selectivity for glyphosate removal from water. According to the FTIR and 31P solidstate NMR spectra, the direct Fe(III)-phosphate complexation played the dominant role in glyphosate removal on Fe(III)/NN-SBA-15. In summary, the high adsorption capacity, fast adsorption kinetics, and good selectivity make Fe(III)/NN-SBA-15 a promising sorbent for high-efficient removal of glyphosate from aqueous solutions with low initial concentration.