Adsorption of Phosphates onto Mg/Al-Oxide/Hydroxide/Sulfate-Impregnated Douglas Fir Biochar

Nitrates and phosphates, found in fertilizers, are the most common eutrophication-causing agents. Douglas fir biochar (BC), a syngas byproduct, was treated with different Al/Mg ratios of sulfate (5% w/w metal loading) followed by an NaOH treatment. The greatest phosphate uptake at 25 °C pH 7 attributed to composite Mg/Al 2:1 ratio prepared 13 (AMBC). Batch AMBC optimized for initial pH, equilibrium time, temperature, concentration. Phosphate removal following pseudo-2nd-order kinetics increases gradually before reaching max 11, 95% 15 mins. Sips isotherm model provided best sorption data fit resulting 42.1 mg/g capacity 11. Endothermic spontaneous adsorption were determined using van ’t Hoff’s plots. BET, XRD, XPS, SEM, TEM, EDS used characterize after sorption. Used has potential be exploited as fertilizer key part environmentally friendly agricultural management plan.