Detoxification of Cr(VI) using biochar-supported Cu/Fe bimetallic nanoparticles

Abstract

Nanoscale zero-valent iron (nZVI) has been proven to be more effective for the treatment of hexavalent chromium(Cr(VI)) when modified with the transition metal Cu. In this study, biochar-supported Cu/Fe bimetallic nanoparticles (Cu-nZVI/BC) were prepared and used for Cr(VI) removal from aqueous solution. The effects of the pH value, the initial concentration of Cr(VI), coexisting ions and humic acids (HA) were investigated. The compositional structures of Cu-nZVI/BC were analyzed by transmission electron microscopy, scanning electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy. The maximum removal efficiency of Cr(VI) was 50.57% (126.41 ± 3.75 mg g-1) for Cu-nZVI/BC at pH 2. The adsorption kinetic data were in agreement with the pseudo-second-order model, which confirmed that the adsorption step was a chemical adsorption and reduction process. The presence of Ca 2+ and NO 3 had an inhibitory effect on Cr(VI) removal, while dHA increased the removal efficiency at high concentrations. This study proves that Cu-nZVI/BC removal of solution Cr(VI) is feasible and shows significant potential in practical applications.

Removal of hexavalent chromium from wastewater by Cu/Fe bimetallic nanoparticles

“…A diffraction peak at 50.4° was observed in the pattern of Cu/Fe bimetallic nanoparticles, which indicated that (200) facet of fcc copper (JCPDS no. 04–0836) was loaded on the surface of the particles 27 . In addition, the bimetallic nanoparticles after reaction with Cr(VI) was analyzed by XRD patterns (Fig.…”

“…On the one hand, the presence of these ions could compete for the reaction sites on the surface of the iron particles 47 . On the other hand, certain ions (such as Ca 2+ ) could result in nZVI aggregation and reduce the removal efficiency 27 . Moreover, the solution pH was alkaline (pH = 8.32 ± 0.10), which inhibited the reaction of Cu/Fe nanoparticles with Cr(VI) under high pH conditions 48 .…”

“…Compared with other catalytic metals, Cu is an essential trace element for human health, and its cost is also lower. Therefore, Cu/Fe bimetallic nanoparticles show a strong application prospect in water treatment 27 , 28 . Recent studies have pointed out that (1) catalytic metals can enhance the oxidation of nZVI during the interaction with pollutants through the formation of galvanic cells; (2) catalytic metals can facilitate the generation of activated atomic hydrogens which lead to the enhancement of reduction of pollutants and corrosion of nZVI 29 – 31 .…”

Preparation and characterization of nano-galvanic bimetallic Fe/Sn nanoparticles deposited on talc and its enhanced performance in Cr(VI) removal

“…Furthermore, the modified Langmuir isotherm model assumes that each site can bind a single adsorbate molecule, and there is no interaction between two adsorbed pollutant molecules. Also, the modified Langmuir model implies that adsorption processes are controlled by chemical reactions 29 , 70 .…”

Preparation and Characterization of Nano-galvanic Bimetallic Fe/Sn Nanoparticles Deposited on Talc and its Enhanced Performance in Cr(VI) Removal

“…Furthermore, the Langmuir isotherm model assumes that each site can bind a single adsorbate molecule, and there is no interaction between two adsorbed pollutant molecules. Also, the Langmuir model indicates that adsorption processes are controlled by chemical reactions 16,49 . The changes in Cr concentration (total Cr, Cr(VI), and Cr(III)) in aqueous solution during reaction time using Talc-nZVI/6Sn was illustrated in Fig.…”