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<p>Indonesia’s extensive laterite nickel reserves drive substantial nickel mining activities yet pose environmental risks due to the wastewater’s hexavalent chromium (Cr(VI)) contamination. This study evaluates a continuous-flow electrocoagulation reactor, using aluminum and iron electrodes to remove Cr(VI) from nickel mining wastewater. Optimization via a Box-Behnken design examined current intensity, flow rate, and reactor flow distance. Results revealed that iron electrodes achieved superior Cr(VI) removal efficiency of up to 99% at a flow rate of 0.99 L/min, current intensity of 2 A, and reactor flow distance of 165,6&#xa0;cm, whereas aluminum electrodes attained a maximum removal efficiency of 83% under optimal conditions of 2.9 A, 0.93 L/min, and 338&#xa0;cm. Iron electrodes also demonstrated lower specific electrical energy consumption (0.48 kWh/g Cr(VI)) than aluminum (1.39 kWh/g Cr(VI)). Kinetic studies indicated that Cr(VI) removal on aluminum electrodes aligns with a pseudo-first-order model, while iron electrodes follow a second-order model, highlighting a shift from physical to chemical adsorption mechanisms. Adsorption isotherms further supported these findings, with Freundlich isotherms fitting the aluminum electrodes (R<sup>2</sup> = 0.998), suggesting heterogeneous, multilayer adsorption, and Langmuir isotherms fitting the iron electrodes (R<sup>2</sup> = 0.988), indicating homogeneous, monolayer adsorption. This study underscores electrocoagulation’s potential as an energy-efficient and sustainable solution for Cr(VI) removal in mining wastewater treatment.</p>

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Continuous-Flow Electrocoagulation for Hexavalent Chromium Reduction in Nickel Mining Wastewater: Insights into Optimization and Mechanisms

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2025年12月17日

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  • Muhammad Risal Rusman,
  • Muhammad Sonny Abfertiawan,
  • Faiz Hasan,
  • Mindriany Syafila,
  • Marisa Handajani

摘要

Indonesia’s extensive laterite nickel reserves drive substantial nickel mining activities yet pose environmental risks due to the wastewater’s hexavalent chromium (Cr(VI)) contamination. This study evaluates a continuous-flow electrocoagulation reactor, using aluminum and iron electrodes to remove Cr(VI) from nickel mining wastewater. Optimization via a Box-Behnken design examined current intensity, flow rate, and reactor flow distance. Results revealed that iron electrodes achieved superior Cr(VI) removal efficiency of up to 99% at a flow rate of 0.99 L/min, current intensity of 2 A, and reactor flow distance of 165,6 cm, whereas aluminum electrodes attained a maximum removal efficiency of 83% under optimal conditions of 2.9 A, 0.93 L/min, and 338 cm. Iron electrodes also demonstrated lower specific electrical energy consumption (0.48 kWh/g Cr(VI)) than aluminum (1.39 kWh/g Cr(VI)). Kinetic studies indicated that Cr(VI) removal on aluminum electrodes aligns with a pseudo-first-order model, while iron electrodes follow a second-order model, highlighting a shift from physical to chemical adsorption mechanisms. Adsorption isotherms further supported these findings, with Freundlich isotherms fitting the aluminum electrodes (R2 = 0.998), suggesting heterogeneous, multilayer adsorption, and Langmuir isotherms fitting the iron electrodes (R2 = 0.988), indicating homogeneous, monolayer adsorption. This study underscores electrocoagulation’s potential as an energy-efficient and sustainable solution for Cr(VI) removal in mining wastewater treatment.