Arsenic removal by Spherical Agglomeration Technique in groundwater using vegetable oil instead of n-heptane

Abstract

Arsenic present in groundwater is a global problem that requires innovative remediation, this study used the Spherical Agglomeration Technique (SAT) using Fe(OH)₃ as adsorbent, Agave extract as biosurfactant, and olive oil as humectant. The primary objective was to evaluate the olive oil versus n-heptane efficacy in arsenic removal within the SAT methodology while assessing the synergistic effects of varying adsorbent (AD) and humectant (HD) dosages. Experiments evaluated arsenic-contaminated water models and groundwater with adsorbent concentrations ranging from 30 to 150 g _Fe(OH)₃/L and humectant dosages from 3.0 to 9.0 mL _Hum/g _TMC. Initial arsenic levels in aqueous models were established at 100 µg/L, maintaining pH at 7.0, 300 rpm stirring speed, and 0.5 g _Ext/g _TMC surfactant dosage. The SAT process efficiency was evaluated under optimized conditions for aqueous models and groundwater samples. In aqueous models, optimal arsenic removal was achieved with a AD of 150 g _Fe(OH)₃/L and HD of 6 mL _Hum/g_TMC, resulting in final arsenic concentrations of 3.2 µg/L, with iron and calcium levels compliant with regulatory limits. For groundwater, reduced dosage of 30 g _Fe(OH)₃/L and higher humectant dosage of 9.0 mL _Hum/g _TMC enabled arsenic reduction to 3.5 µg/L while maintaining minimal final concentrations of iron (0.01 mg/L) and calcium; the results highlight olive oil's superior performance over n-heptane, demonstrating the importance of precise dosage optimization for maximum efficacy, this study positions olive oil as a viable and sustainable solution for treating arsenic in water via SAT, which can be tailored to specific circumstances.