A novel graphene oxide coated biochar composite: synthesis, characterization and application for Cr(vi) removal

Abstract

In the current work, a graphene oxide coated water hyacinth biochar composite (WHB-GO) was synthesized to remove Cr(vi) from aqueous solution.

The development of a ternary nanocomposite for the removal of Cr(vi) ions from aqueous solutions

“…The kinetic experiments show that the rate of Cr(VI) adsorption on the surface of PANI/Ag (AMPSA)/GO QDs NC increased as the temperature increased from 22 C to 60 C, which suggests that adsorption process is endothermic and spontaneous. 29,33,45,48 The enlargement of pore size and activation of the adsorbent surface at high temperature promote rate of adsorption. 45,49 The rate constant k 2 for each temperature (Table 2) was obtained by tting the data to the linear pseudo-second order kinetic model, as shown in Fig.…”

“…45 In addition, a further increase in NaCl concentration to 1000 mM led to a decline in R by 12.8% due to the reduction in the number of collisions between Cr(VI) ions and PANI/Ag (AMPSA)/GO QDs. 48 Industrial wastewater also contains other types of heavy metal cations and anions such as Cd(II), Cu(II), Pb(II), Al(III) and Mg(II). Therefore, it is essential to investigate the competitive inuence of these co-existing ions on the Cr(VI) removal percentage using the PANI/Ag (AMPSA)/GO QDs nanocomposite.…”

“…A dose of 1 g L À1 of each adsorbent was used to treat 25 mL solution of 60 mg L À1 Cr(VI) at pH 2 for 60 min at 30 C. Pure GO QDs exhibit small values of R% and q of 77.7% and 46.64 mg g À1 , respectively, for the adsorption of Cr(VI) through electrostatic interactions coupled with Cr(VI) reduction to Cr(III) and followed by Cr(III) complexation. 48,54 At a low pH value of 2, the removal of Cr(VI) in the aqueous phase is faster since the negatively charged Cr(VI) species migrate to the positive surface of the GO QDs (protonated hydroxyl groups and carbonyl groups) with the help of electrostatic driving forces. Cr(VI) reduction to Cr(III) by contact with the electron-donor groups of GO QDs (OH À groups) occurs during the adsorption process and the reduced Cr(III) remains in the aqueous solution.…”

“…Cr(VI) reduction to Cr(III) by contact with the electron-donor groups of GO QDs (OH À groups) occurs during the adsorption process and the reduced Cr(III) remains in the aqueous solution. 48 However, the low Cr(VI) R% and q of GO QDs are attributed to the aggregation resulting from the strong van der Waals interactions and p-p stacking of the graphene oxide, which reduce the availability of effective sorption area, hence decreasing the overall metal removal and capacity. 55 Ag (AMPSA) NPs produced small values of Cr(VI) R% and q of 70.6% and 42.37 mg g À1 , respectively at pH 2.…”

Peer Review #1 of "Recent advances in biochar application for water and wastewater treatment: a review (v0.2)"

“…Among various biochar-based composites, the biochar-graphene oxide composite material, which is obtained by impregnating the raw material in a graphene oxide suspension and then pyrolyzing, also displays more oxygen-containing functional groups after incorporating the graphene structure (Tang et al, 2015;Shang et al, 2016). The removal rate of Hg 2+ raised with the increase of the proportion of graphene oxide in the composite.…”