Highly efficient nano-Fe/Cu bimetal-loaded mesoporous silica Fe/Cu-MCM-41 for the removal of Cr(VI): Kinetics, mechanism and performance.

Zero valent iron (Fe0) can reduce Cr(VI) in water, where Fe0 and Fe(Ⅱ) are possible electron donors, but passivation and aggregation easily occur to Fe0. To improve the performance of Fe0, a new hybridization strategy of Fe/Cu bimetal and silica-based mesoporous molecular sieve MCM-41 for the removal of Cr(VI) from water has been proposed. The results show that the two-dimensional mesoporous structure of MCM-41 can provide skeleton support for Fe0, improve the mass transfer rate, and overcome the aggregation bottleneck of Fe0. The Cr(VI) removal rate reached 98.98% (pH = 2) after 40 min. The analytical results revealed Cr(VI) removal process: Cr(VI) adsorbed onto Fe/Cu-MCM-41 by electrostatic attraction and other molecular inter-atomic forces. The second metal, Cu, can inhibit the passivation of Fe0 and promote Fe(Ⅱ)through the formation of Fe/Cu battery, thereby promoting the electron transfer. The resulting Cr(Ⅲ) is precipitated as FeCr 2 O 4 and Cr x Fe 1−x (OH) 3. [Display omitted] • Nano bimetallic Fe/Cu-loaded mesoporous silica Fe/Cu-MCM-41 was synthesized. • Cu acts as catalytic metal could provide active sites for electron transfer. • pH has been found to be an important factor affecting the removal rate of Cr(VI). • Bimetallic-nanomaterial supported system can reduce passivation. [ABSTRACT FROM AUTHOR]