Removal of Chromium(VI) and Copper(II) from Aqueous Solutions Using Biochars Derived from Wheat Straw and Wood Dust.

Heavy metals found in water sources create dangerous environmental problems and health hazards that stem from industrial, agricultural and domestic activities. The objective of this study focused on examining biochar made from wheat straw (WSB) and wood dust (WDB) as an eco-friendly solution for extracting chromium Cr (VI) and copper Cu (II) from an aqueous solution. The biochar materials underwent pyrolysis at various temperatures between 500°C to 600°C, and their characteristics were evaluated. Freundlich, Langmuir, and Temkin isotherm were used to evaluate the WSB and WDB adsorption capacities. The results showed that WSB exhibited elevated carbon content (72%), cation exchange capacity (CEC) (44 cmol kg⁻¹), and nitrogen (N) levels (1.12%), whereas WDB demonstrated superior surface area (26.35 m² g⁻¹), pore radius (69.2 Å), and volatile matter (50%), highlighting the differing adsorption and nutrient characteristics of the biochars. Cr (VI) adsorption on WSB varied from 22.64 ± 0.93 to 113.37 ± 2.5 mg kg⁻¹, whereas adsorption onto WDB ranged from 21.68 ± 2.25 to 77.37 ± 0.5 mg kg⁻¹, indicating the lowest and greatest adsorption capabilities reported under the studied circumstances for each biochar. The WSB and WDB materials displayed Cu (II) adsorption variables between 47.95 ± 0.24 to 131.38 ± 0.7 mg kg -1 while WDB adsorbed from 48.38 ± 0.07 to 145.84 ± 0.08 mg kg -1 at 50 and 150 mg L-1 initial concentrations. The isotherm results showed that the Freundlich model is the best model for describing Cr (VI) adsorption across WSB (R² = 0.9771) and WDB (R² = 0.8439) and the Temkin model for Cu (II) adsorption in WSB (R² = 0.7673) but the Langmuir model for WDB (R² = 0.9781). WSB shows stronger adsorption for Cr (VI), while WDB is more effective for Cu (II) removal, indicating their potential for wastewater treatment applications.