Microwave activated and iron engineered biochar for arsenic adsorption: Life cycle assessment and cost analysis.

Humans are exposed to arsenic (As) from various sources such as food, drinking water, and air, thus, treatment of water matrices contaminated with As is a worldwide challenge. In this work, H 3 PO 4 and FeCl 3 treated canola straw biochar (CSB) was assessed for its adsorption efficiency for arsenite, As(III), and arsenate, As(V), in water. The main factors in determination of an optimal CSB (OCSB) included microwave (MW) power for the creation of the biochar and FeCl 3 modification. For both As(III) and As(V), the highest performing biochar was found to be at the highest MW power (1000 W) and lowest FeCl 3 concentration (0.1 M). It was found that biochar surface area was enhanced by biomass activation using FeCl 3 and no crystalline phases of FeCl 3 were identified, potentially a consequence of the low iron concentrations considered. Modification parameters were studied and showed that pH 7 was more favorable for As(V) adsorption, while pH 10 favored As(III) adsorption. Additionally, isotherm and kinetic analysis indicated that a physical adsorption mechanism took place for As(III) and As(V) which may have resulted from surface complexation. Life cycle assessment (LCA) results showed that OCSB production is environmentally friendly, generating − 0.298 kg CO 2 eq/kg of biochar. For an economic perspective, a life cycle cost analysis (LCCA) of OCSB found a cost of $5.14/kg (USD) of biochar that is mainly impacted by materials. Overall, OCSB shows potential for As adsorption and environmental evaluation shows promising results for consideration of this biochar as an adsorbent. [Display omitted] • Arsenic (As) contaminates waters worldwide and can be treated by adsorption. • Modified canola straw biochar (CSB) is an effective As adsorbent. • Optimal microwave power and iron chloride doses can improve CSB adsorption. • Life cycle assessment found − 0.298 kg CO 2 eq/kg of biochar. • Life cycle cost analysis found a cost of $5.14 kg/biochar (USD). [ABSTRACT FROM AUTHOR]