Effective removal of Cr(VI) from aqueous solution based on APTES modified nanoporous silicon prepared from kerf loss silicon waste

Recently, the recycling of kerf loss silicon waste has trigged much attention due to the rapid growth of PV market. In this study, 3-aminopropylethoxysilane (APTES)-functionalized nanoporous silicon (NPSi) hybrid materials were prepared by nanosilver-assisted chemical etching (Ag-ACE) of kerf loss silicon waste derived from diamond-wire saw cutting silicon ingot process. The resulting APTES-NPSi indicated high-effective adsorption ability of Cr(VI) from aqueous solution, which was highly pH dependent, and the maximum adsorption capacity reached up to 103.75 mg/g after 60 min at room temperature. The adsorption kinetics and adsorption isotherms were in good agreement with pseudo-second-order model and Langmuir isotherm. Additionally, the Cr(VI) up-take mechanism was carefully investigated and ascribed to the Cr(VI) adsorption on the protonated anime groups by chemical chelating reaction in which the Cr(VI) was reduced to Cr(III). It was worth mentioning that the APTES-NPSi maintained excellent adsorption capacity after five successive regenerated cycles. Therefore, the work would pave the way for recycling of silicon cutting waste and the potential of Cr(VI) removal from aqueous solution based on the modified NPSi.