Wastewater generated during gold recovery from its mined ores usually contains mercury causing water pollution when discharged into rivers disrupting the ecosystem. In this study, magnetized and functionalized 2-mercaptobenzothiazole nanosilica from rice husk (MnS@MBT) was applied to eliminate Hg 2+ from local gold mining wastewater (GMW). The influence of reaction time ( t : 30 – 90 min), dosage ( d : 1 – 3 g), temperature ( T : 30 – 50 o C) and mixing rate ( m : 110 – 130 rpm) was investigated on the removal efficiency of nanosilica from rice husk (nS), its magnetized form (MnS) and MnS@MBT for Hg 2+ removal from GMW. Adsorbents were characterized using BET, SEM, FTIR, XRD, EDX, TGA, pH PZC and saturation magnetization evaluation. At optimum predicted point (where t = 90 min, d = 3 g, T = 50 o C and m = 120 rpm), 81.09 ± 1.03%, 90.77 ± 0.43% and 99.78 ± 0.81% of Hg 2+ was removed from GMW using nS, MnS and MnS@MBT respectively. ANOVA test revealed developed mathematical models are significant. MnS@MBT possessed excellent attributes for Hg 2+ removal having adsorption capacity of 77.30 ± 1.20 mg/g. Experimental data conformed to Freundlich and pseudo-second order kinetic models. Adsorption was spontaneous and exothermic. After five adsorption-desorption cycles, nS, MnS and MnS@MBT could remove 50.27 ± 1.85%, 65.00 ± 1.42% and 91.09 ± 1.91% of Hg 2+ from GMW respectively. The synthesized MnS@MBT was a highly effective, cheap and reusable adsorbent that could be applied in the water treatment plant of a gold mining industry to eliminate Hg 2+ from wastewater.
Badi et al. (2026) studied this question.