Highly efficient removal of hexavalent chromium in aqueous solutionsviachemical reduction of plate-like micro/nanostructured zero valent iron

Abstract

The removal of hexavalent chromium [Cr(VI)] from aqueous solutions using plate-like micro/nanostructured zero valent iron (MNZVI), which is fabricated in mass production by ball-milling of reductive iron powders, is investigated in this study. It has been shown that this plate-like MNZVI has significantly enhanced ability to remove Cr(VI) from aqueous solutions as compared to commercial zero valent iron (CZVI). Cr(VI) in a concentration of 100 ppm at pH ¼ 2 can be removed nearly completely within 20 min by the addition of 1.5 g L À1 MNZVI. The time-dependent removal amount of Cr(VI) can be well described by a pseudo first-order kinetic model. The reaction rate constant for MNZVI is 20 times larger than that for CZVI.Further experiments have revealed that the Cr(VI) removal is also associated with the pH value and initial concentration of Cr(VI) in the solution, in addition to the iron dosage. These enhanced removal performances are attributed to the iron-induced reduction process of Cr(VI) and the high specific surface area of MNZVI. Further, electroplating wastewater was used to demonstrate the practical applications of MNZVI. The removal capacity is up to 330 mg g À1 in the electroplating wastewater with a 556 ppm initial Cr(VI) content, which is more than 3 times higher than that of CZVI and also much higher than the previously reported results. This study has demonstrated that the ball milling-induced plate-like MNZVI is a good candidate material for efficient treatment of Cr(VI)-containing wastewater.

Reclamation of hexavalent chromium using catalytic activity of highly recyclable biogenic Pd(0) nanoparticles

“…The biosynthesised PdNPs were used for the catalytic reduction of Cr (VI) to Cr (III) in the presence of formic acid. Conversely, previous studies involved methods to maintain the pH of the solution 32,36,39 , which resulted in difficulty while applying these methods for large-scale wastewater treatment. Table 1 lists the comparative information of previous studies on the catalytic reduction of Cr (VI) [31][32][33][34][35][36][37][38][39] .…”

“…Conversely, previous studies involved methods to maintain the pH of the solution 32,36,39 , which resulted in difficulty while applying these methods for large-scale wastewater treatment. Table 1 lists the comparative information of previous studies on the catalytic reduction of Cr (VI) [31][32][33][34][35][36][37][38][39] . In the proposed method, a 250 ppm Cr (VI) aqueous solution was used for catalytic reduction, which is the highest concentration among the studies listed in Table 1.…”

Comparative analysis of biological versus chemical synthesis of palladium nanoparticles for catalysis of chromium (VI) reduction

“…The above argument implies that Cr(VI) reduction can be achieved physical-chemically 9 or biologically 10 , 11 . Chemically induced Cr(VI) reduction produces several unwanted side effects such utilization of a chemically toxic reactant feedstream and production of toxic sludge 12 .…”

Immobilization of Cr(VI) in Soil Using a Montmorillonite-Supported Carboxymethyl Cellulose-Stabilized Iron Sulfide Composite: Effectiveness and Biotoxicity Assessment

“…Chemical reduction is widely used owing to its high efficiency and low cost [ 21 ]. Inorganic or organic electron donors can reduce Cr(VI) to Cr(III) and form insoluble Cr(III) hydroxides in the reduction process [ 22 , 23 , 24 ]. Iron minerals, such as goethite, hematite, mackinawite, and pyrite, in soil and subsurface sediment have been shown to reduce Cr(VI) to Cr(III) [ 25 , 26 , 27 , 28 ].…”