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<p>This study focuses on the optimization of acid activation of Sabga clay, a locally available natural resource from Cameroon, for the removal of nickel (Ni<sup>2+</sup>) ions from aqueous solutions. Sulfuric acid (H<sub>2</sub>SO<sub>4</sub>) was employed as the activating agent to enhance the clay’s porosity and surface functionality. A Central Composite Design (CCD) was applied to evaluate and optimize the effects of three key parameters: contact time, acid concentration, and activation temperature on the textural and adsorption properties of the material. The optimization results yielded a quadratic model with a high predictive accuracy for the methylene blue and iodine indices. Optimal activation conditions were determined to be a contact time of 52&#xa0;min, an acid concentration of 3&#xa0;M H<sub>2</sub>SO<sub>4</sub>, and an activation temperature of 70&#xa0;°C, leading to methylene blue and iodine indices of 8.4 and 248.25&#xa0;mg/g, respectively. The raw and activated clays were characterized using Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), and Brunauer–Emmett–Teller (BET) surface area analysis. Acid activation increased the specific surface area from 16.88 m<sup>2</sup>/g to 17.89 m<sup>2</sup>/g (≈ 6% increase) and improved porosity, confirming successful structural modification. Batch adsorption experiments revealed that the adsorption of Ni<sup>2+</sup> ions was strongly influenced by pH, initial concentration, and contact time, with maximum removal occurring at pH 8. Kinetic analysis showed that the process followed a pseudo-second-order model, indicating chemisorption as the dominant mechanism. The equilibrium data were best described by the Langmuir isotherm, suggesting monolayer adsorption with a maximum adsorption capacity (q<sub>m</sub>) of 13.87&#xa0;mg/g. These results demonstrate that acid-activated Sabga clay is an efficient, low-cost, and eco-friendly adsorbent for the removal of nickel ions from contaminated water. The study provides a statistically optimized activation procedure that can be extended to other heavy metal pollutants and scaled up for sustainable wastewater treatment applications.</p>

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Optimization of Preparation of Acid-Activated Sabga Clay for Adsorption of Nickel Ions from Aqueous Solution

  • 期刊论文

  • 发表日期：

    2025年11月18日

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  • Thamer Alomayri,
  • Armand Tchakounte,
  • Joseph Dika,
  • Charles Kede

摘要

This study focuses on the optimization of acid activation of Sabga clay, a locally available natural resource from Cameroon, for the removal of nickel (Ni2+) ions from aqueous solutions. Sulfuric acid (H2SO4) was employed as the activating agent to enhance the clay’s porosity and surface functionality. A Central Composite Design (CCD) was applied to evaluate and optimize the effects of three key parameters: contact time, acid concentration, and activation temperature on the textural and adsorption properties of the material. The optimization results yielded a quadratic model with a high predictive accuracy for the methylene blue and iodine indices. Optimal activation conditions were determined to be a contact time of 52 min, an acid concentration of 3 M H2SO4, and an activation temperature of 70 °C, leading to methylene blue and iodine indices of 8.4 and 248.25 mg/g, respectively. The raw and activated clays were characterized using Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), and Brunauer–Emmett–Teller (BET) surface area analysis. Acid activation increased the specific surface area from 16.88 m2/g to 17.89 m2/g (≈ 6% increase) and improved porosity, confirming successful structural modification. Batch adsorption experiments revealed that the adsorption of Ni2+ ions was strongly influenced by pH, initial concentration, and contact time, with maximum removal occurring at pH 8. Kinetic analysis showed that the process followed a pseudo-second-order model, indicating chemisorption as the dominant mechanism. The equilibrium data were best described by the Langmuir isotherm, suggesting monolayer adsorption with a maximum adsorption capacity (qm) of 13.87 mg/g. These results demonstrate that acid-activated Sabga clay is an efficient, low-cost, and eco-friendly adsorbent for the removal of nickel ions from contaminated water. The study provides a statistically optimized activation procedure that can be extended to other heavy metal pollutants and scaled up for sustainable wastewater treatment applications.