Sorption of halogenated phenols and pharmaceuticals to biochar: affecting factors and mechanisms

Abstract

The feasibility of using biochar as a sorbent to remove nine halogenated phenols (2,4-dichlorophenol, 2,4-dibromophenol, 2,4-difluorophenol, 2-chlorophenol, 4-chlorophenol, 2-bromophenol, 4-bromophenol, 2-fluorophenol, and 4-fluorophenol) and two pharmaceuticals (triclosan and ibuprofen) from water was examined through a series of batch experiments. Types of biochar, synthesized using various biomasses including fallen leaves, rice straw, corn stalk, used coffee grounds, and biosolids, were evaluated. Compared to granular activated carbon (GAC), most of the biochar samples did not effectively remove halogenated phenols or pharmaceuticals from water. The increase in pH and deprotonation of phenols in biochar systems may be responsible for its ineffectiveness at this task. When pH was maintained at 4 or 7, the sorption capacity of biochar was markedly increased. Considering maximum sorption capacity and properties of sorbents and sorbates, it appears that the sorption capacity of biochar for halogenated phenols is related to the surface area and carbon content of the biochar and the hydrophobicity of halogenated phenols. In the cases of triclosan and ibuprofen, the sorptive capacities of GAC, graphite, and biochars were also significantly affected by pH, according to the point of zero charge (PZC) of sorbents and deprotonation of the pharmaceuticals. Pyrolysis temperature did not affect the sorption capacity of halogenated phenols or pharmaceuticals. Based on the experimental observations, some biochars are good candidates for removal of halogenated phenols, triclosan, and ibuprofen from water and soil.

Adsorption of Scandium and Neodymium on Biochar Derived after Low-Temperature Pyrolysis of Sawdust

“…The most important factors that define the adsorption efficiency of a carbon-rich material are the pore structure, the pore size distribution and the presence of surface functional groups [73]. The degree to which each factor contributes to adsorption depends on the characteristics of the initial raw material and the type of treatment applied, namely chemical or thermal, that defines the physico-chemical properties of the produced biochar or a commercial adsorbent.…”

Morphology of Modified Biochar and Its Potential for Phenol Removal from Aqueous Solutions

“…surface which is also related to their increased carbon content and the number of oxygenated functional groups Oh and Seo, 2016). Also aromatic hydrocarbons present in phenols can be covalently bonded to surfaces of biochar (Cornelissen et al, 2005).…”

“…Rice straw biochar was used to decrease the concentration of pentachlorophenol in leachates produced from contaminated sediments which were then used to increase the germination rate of wheat seeds (Lou et al, 2011). Biochar produced after pyrolysis of municipal wastewater biosolids removed effectively halogenated phenols, while its sorption capacity was improved at lower solution pH (Oh and Seo, 2016). Sewage sludge biochar showed excellent adsorption capacity for sulfonated methyl phenol resins which are used as additive in drilling fluids (Liu et al, 2015).…”

Renewable Material-derived Biochars for the Efficient Removal of 2,4-Dichlorophen from Aqueous Solution: Adsorption/Desorption Mechanisms

“…The modified biochar simultaneously degraded PCP by dechlorination (Devi and Saroha 2015). Oh and Seo (2016) reported that bio-solid derived biochar had maximum adsorption capacity (34.4 mg g −1 ) for 2,4-DCP in an aqueous solution compared to other biochars (rice straw, oak tree leaves, corn stalks, and coffee grounds). However, very limited knowledge is available regarding the potential of plant biomass derived biochars with varying physico-chemical properties to remove the 2,4-DCP from an aqueous solution.…”