A positively-charged pillared bentonite (Al-bent) was used as the carrier of nanoscale zerovalent iron
(NZVI) particles for accelerating the reductive removal of anionic Se(VI) from water by NZVI. A synergetic
effect on Se(VI) removal by this NZVI/Al-bent composite was observed, with removal efficiency (95.7%)
much higher than the sum (72.0%) of NZVI reduction (62.1%) and Al-bent adsorption (9.86%). The multiple
roles of Al-bent in the reaction system of Se(VI) with NZVI were comprehensively investigated using XAFS
techniques, XRD analysis, kinetic studies and pH monitoring. The results indicate that the positivelycharged
Al-bent as a good adsorbent to anionic Se(VI) accelerated the reductive transformation of Se(VI)
into less soluble Se(-II). Al-bent also acted as a pH buffering agent, and contributed to the enhanced
stability and reusability of NZVI. In addition, Al-bent could transfer the insoluble reduction products
away from the iron surface according to EXAFS studies. Particularly, Al-bent could activate Fe(II) ions
generated in the reaction system through an appropriate bonding at pH 8.0, and provide NZVI with an
extra reduction capacity. The results indicate the significance of correct matching of bentonite support
to target contaminant for developing novel remediation technique based on this natural mineral
A positively-charged pillared bentonite (Al-bent) was used as the carrier of nanoscale zerovalent iron(NZVI) particles for accelerating the reductive removal of anionic Se(VI) from water by NZVI. A synergeticeffect on Se(VI) removal by this NZVI/Al-bent composite was observed, with removal efficiency (95.7%)much higher than the sum (72.0%) of NZVI reduction (62.1%) and Al-bent adsorption (9.86%). The multipleroles of Al-bent in the reaction system of Se(VI) with NZVI were comprehensively investigated using XAFStechniques, XRD analysis, kinetic studies and pH monitoring. The results indicate that the positivelychargedAl-bent as a good adsorbent to anionic Se(VI) accelerated the reductive transformation of Se(VI)into less soluble Se(-II). Al-bent also acted as a pH buffering agent, and contributed to the enhancedstability and reusability of NZVI. In addition, Al-bent could transfer the insoluble reduction productsaway from the iron surface according to EXAFS studies. Particularly, Al-bent could activate Fe(II) ionsgenerated in the reaction system through an appropriate bonding at pH 8.0, and provide NZVI with anextra reduction capacity. The results indicate the significance of correct matching of bentonite supportto target contaminant for developing novel remediation technique based on this natural mineral
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