Cosorption of Phenanthrene and Mercury(II) from Aqueous Solution by Soybean Stalk-Based Biochar

Abstract

Soybean [Glycine max (L.) Merr.] stalk-based biochar was prepared using oxygen-limited pyrolysis. We evaluated phenanthrene (PHE) and Hg(II) sorption, from single and binary component solutions, onto prepared biochar. We found that the prepared biochar efficiently removed PHE and Hg(II) from aqueous solutions. The isotherms for PHE and Hg(II) sorption could be described using linear and Tóth models, respectively, both with high regression coefficients (R(2) > 0.995). When PHE and Hg(II) coexisted in an aqueous solution, we observed direct competitive sorption, each one suppressing another. Our results provide insight into the recycling of agricultural residues, and also a new application for removal of polycyclic aromatic hydrocarbons and heavy metals from contaminated water utilizing biochar from agricultural residue.

Review of Eco-Friendly Biochar Used in the Removal of Trace Metals on Aqueous Phases

“…This include metal exchange with K + and Na + due to the electrostatic outer-sphere complexation, inner-sphere complexation with free hydroxyl groups and surface complexation both carboxyl and hydroxyl functional groups being free. Similar mechanisms was observed in Hg (II) and Cd (II) adsorption onto biochar produced from soybean stalk [71] and corn straw [72], respectively. Also oxygen functional groups are noted to have stabilised trace metals in a biochar surface, mostly for softer acids like Cu 2+ and Pb 2+ [67,70].…”

“…A study conducted on the adsorption ability of biochar for co-existed atrazine and simazine revealed the adsorption of the two contaminants decreased as they co-existed in the aqueous environment [58]. Similarly, phenanthrene (PHE) and Hg (II) co-existed in aqueous solution, resulted in direct competition in adsorption as each one suppressed another, leading to reduction in adsorption [71].…”

Preparation and characterization of a novel graphene/biochar composite for aqueous phenanthrene and mercury removal

“…PAHs are persistent, carcinogenic, mutagenic, and mainly responsible for the toxicity of oil to organisms . Phenanthrene is a common PAH, which is ubiquitous in the environment and is difficult to remove (Kong et al, 2011). Mercury is one of the most harmful heavy metals to humans, and it is pervasive, cumulative, and persistent in both the human body and the environment.…”

Specific detection of bioavailable phenanthrene and mercury by bacterium reporters in the red soil

“…This result may due to the acute toxicity of Hg 2? , and may also indicate that the total bioavailability of multiple contaminants was dominated by the pollutant which is more soluble and more available to the bacterial cells (Kong et al 2011). …”