Adsorption and coadsorption mechanisms of Cr(VI) and organic contaminants on H3PO4 treated biochar

Abstract

The study of simultaneous removal of heavy metals and organic contaminants has practical applications due to the coexistence of complex pollutants in the wastewater or soil. In this work, biochar was prepared to study the removal efficiencies of Cr(VI), naphthalene (NAP) and bisphenol A (BPA) in the single or mixed systems. HPO-treated biochar presented a much higher adsorption capacity of the pollutants than the untreated biochar and also showed a high resistance to coexisting salts. The maximum adsorption capacities for Cr(VI) and BPA were 116.28 mg g and 476.19 mg g, respectively. Coadsorption experiments revealed that the presence of organic pollutants caused a limited decrease (∼10%) of removal efficiency of Cr(VI) and no further decrease was observed with higher concentrations of organic pollutants, while the presence of Cr(VI) had little impact on the removal of NAP. Infrared spectra and molecular simulation demonstrated that Cr(VI) was mainly adsorbed on the biochar via chemical complexation, while the organic pollutants through π-π interaction. Unexpectedly, the addition of Cr(VI) increased the removal efficiency of BPA, probably due to the increased H-bond interactions between BPA and the biochar through bridge bonds of oxygenic groups from CrO.

Efficient elimination of organic and inorganic pollutants by biochar and biochar-based materials

“…Adsorption capacity of biochar for metal endocrine disruptors (Hg 2+ , Pb 2+ , Cd 2+ ) was compared through DFT calculations, and the effect of oxygen-containing groups has been suggested for the high binding energy (Zhang et al 2019d). Besides, quantum chemistry calculations turned out that inner-sphere chemical complexation with functional groups was responsible for the adsorption of Cr(VI), Pb 2+ , and Zn 2+ (Zhao et al 2017(Zhao et al , 2020. On the other hand, a significant amount of theoretical research has gone into addressing the organic pollutants such as antibiotics, ionizable organic pollutants (IOPs), drugs, dyes, pesticide and so on (Peng et al 2016;Zhang et al 2018b;Jung et al 2015b;Wang et al 2016).…”

Mechanism of Cr(VI) removal by magnetic greigite/biochar composites

“…However, the pristine biochars, acquired from direct biomass pyrolysis, often have relatively low adsorptive and reductive ability for Cr(VI), but these properties are dependent on biomass feedstock and pyrolysis temperature (Dong et al, 2011;Jin et al, 2016;Zhang et al, 2018). Thus, specific activation processes, such as surface functionalization, molecular grafting, ultraviolet irradiation and ball milling, have been used to enhance the Cr(VI) removal performance of biochars (Peng et al, 2018;Zhang et al, 2019b;Zhao et al, 2017;Zhu et al, 2018b). These modifications not only increase surface adsorption sites, but also change surface charge and functional group characteristics that regulate Cr(VI) adsorption and reduction dynamics.…”

Carbon Nano-Sphere Derived From Crop Residues by Acidic Lithium Bromide Treatment and as an Excellent Adsorbent to Both Heavy Ions and Methyl Orange

“…3.5 the removal ability of biochar to heavy ions and methyl orange Currently, biochar as the adsorbent was usually used in the removal of heavy ions and organic chemicals in environmental remediation (Bai et al, 2018;Dai et al, 2020;Kazakis et al, 2018;Zhao et al, 2017). The Cr(VI), as one of the most toxic metal ion, could cause many diseases, such as dermatitis and lung cancer, highly threating human health (Gao & Xia, 2011;Kazakis et al, 2018).…”