The fabrication of monodisperse polypyrrole/SBA-15 composite for the selective removal of Cr(vi) from aqueous solutions

Abstract

Monodisperse polypyrrole/SBA-15 composite (PPy/SBA-15) was fabricated by in situ polymerization and used for Cr(VI) adsorption from aqueous solution. PPy/SBA-15 was characterized by numerous approaches. Factors affecting the Cr(VI) adsorption process, including the pH, the dose of adsorbent and contact time, were analyzed through batch experiments. The optimum experimental conditions were pH 2, dose of 4 g L⁻¹ and contact time of 300 min. Meanwhile, PPy/SBA-15 had strong selective adsorption of Cr(VI) in co-existing ionic solution, the adsorption kinetics matched a pseudo-second-order kinetic model, and the adsorption isotherm data followed Langmuir adsorption isotherm models with a maximum adsorption capacity of 194.17 mg g⁻¹ at 298 K, which is higher than that found in other reports of the same type of adsorbent. Regeneration evaluation demonstrated that the adsorbent can be recycled four times, retaining 92.58% of its removal rate. Moreover, EDX indicated that PPy/SBA-15 adsorbed Cr(VI) on its surface owing to ion exchange of chloride ions with either HCrO₄⁻ or Cr₂O₇²⁻. XPS further certified that part of Cr(VI) was reduced to Cr(III). Overall, PPy/SBA-15 possesses capability as an alternative adsorbent to remove Cr(VI) from aqueous solution.