The pH dependent surface charging and points of zero charge. VII. Update.

As an alternative to activated carbon, biochar has been considered for removal of organic micropollutants from water and wastewater via adsorption. This review elaborates on the fundamental basis of adsorption kinetics, mechanisms, and equilibrium with respect to biochar-based adsorption of micropollutants. The objectives include: 1) linking biochar surface properties with adsorption abilities, 2) categorizing the kinetics of adsorption of aqueous-phase organic compounds onto biochar, 3) categorizing the molecular-scale interactions between organic micropollutants and biochar, and 4) reviewing existing quantitative methods for characterizing adsorption equilibrium of organic micropollutants from water onto an adsorbent surface. To fulfill these goals, the relationships among biochar surface properties, adsorption kinetics, mechanisms, and equilibrium were clarified as current literature often lacks such discussion or may include conflicting descriptions. Due to its heterogeneous nature, research on biochar's adsorption potential for micropollutants is ambiguous. By adapting adsorption theories to biochar application specifically, this review helps to inform future research in terms of addressing knowledge gaps in characterizing and improving biochar adsorption.

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Adsorption of organic micropollutants onto biochar: a review of relevant kinetics, mechanisms and equilibrium

The increasing worldwide pollution of nature waters with endocrine disrupting chemicals (EDCs), heavy metals and dyes has highlighted the need for versatile and effective removal approaches. In this study, a citric acid-crosslinked β-cyclodextrin polymer (CA-β-CD) was applied for simultaneous adsorption of bisphenol A (BPA), methylene blue (MB) and Cu2+, typical pollutants of EDCs, dyes and heavy metals, respectively. In a monocomponent system, the adsorption behaviors exhibited a monolayer maximum adsorption capacity (qm) of 0.3636 mmol/g for BPA, and a heterogeneous qm of 0.9229 and 0.9155 mmol/g for MB and Cu2+, respectively. The multicomponent experiment indicated that BPA and MB adsorptions onto CA-β-CD were independent from each other, whereas MB and Cu2+ competed over the same sites. An adsorption mechanism was proposed: each component of CA-β-CD played an essential role, the cyclodextrin cavities contributed to entrapment of non-polar BPA, and the surface carboxyl groups provided binding sites for polar MB and Cu2+. Adsorption performance of the polymer was unaffected by humic acid, a major component of natural organic matter. Overall, due to its green synthetic procedure, versatile and good adsorption performance, excellent recyclability and anti-jamming capacity, CA-β-CD has great potentials for practical applications in water purification.

Citric acid-crosslinked β-cyclodextrin for simultaneous removal of bisphenol A, methylene blue and copper: The roles of cavity and surface functional groups

Current advances in treatment technologies for removal of emerging contaminants from water – A critical review

Sorption of hydrophobic organic contaminants on functionalized biochar: Protagonist role of π-π electron-donor-acceptor interactions and hydrogen bonds.

Fabio Engel

Papers

Adsorption of steroid micropollutants on polymer-based spherical activated carbon (PBSAC)