Uptake and desorption of copper ion using functionalized polymer coated silica gel in aqueous environment

A resinous functionalized polymer, aniline formaldehyde condensate (AFC) coated on silica gel was used as an adsorbent to remove copper (Cu2+) from aqueous solution under conditions of different initial Cu2+ concentration, adsorbent loading, pH and adsorption time. Coordination bond formation between amine group and Cu2+ ion was the main mechanism of copper removal. Adsorption increased from 20% at pH 4 to 71% at pH 6 due to less competition from proton. Adsorption equilibrium was achieved within 120–150 min. The kinetics of adsorption followed second order model with rate constant of 0.0021 g/mg min. The adsorption data gave good fit with Langmuir isotherm and yielded Langmuir monolayer isotherm uptake of 76.33 mg/g and adsorption equilibrium parameter of 0.022 L/mg at solution pH of 5.4–5.7 and temperature of 22–25 °C. During desorption studies 97–100% of adsorbed copper ion released in solution in presence of 1N strength of mineral acids HCl, H2SO4 and HNO3. Dynamic study shows that column breakthrough was achieved at 264 bed volume at initial Cu2+ of 25 mg/L. Further studies are recommended on regeneration and reuse of AFC coated silica gel after desorption of copper ion.