Adsorptive removal of Cu(II) and Ni(II) from single-metal, binary-metal, and industrial wastewater systems by surfactant-modified alumina

Batch adsorption was carried out to investigate the possibility of utilizing surfactant-modified alumina (SMA) as an adsorbent for the removal of Cu(II) and Ni(II) from single-metal and binary-metal solutions. Scanning electron microscopic (SEM) images of SMA before and after metal removal from single-metal matrix, showed no significant changes, whereas energy dispersive X-ray (EDX) studies confirmed the incorporation of Cu(II) (similar to 0.74 atomic%) and Ni(II) (similar to 0.64 atomic%) on the adsorbent surface. The removal of Cu(II) and Ni(II), using SMA depends on contact time, adsorbent dose and medium pH. The sorption kinetics followed pseudo-second-order model for Cu(II). However, for Ni(II), either pseudo-first-order or pseudo-second-order model is applicable. The batch experimental data were fitted to Langmuir and Freundlich isotherm, and based on the correlation coefficient value (R-2), the adsorption could be described more precisely by the Freundlich isotherm. The maximum adsorption capacity from Langmuir isotherm of Cu(II) was 9.34mg g(-1) and for Ni(II) 6.87mg g(-1). In a synthetic binary mixture of Cu(II) and Ni(II), having a concentration of 10mg L-1 each, removal of Cu(II) was better. The treatment method was further applied to real wastewater from an electroplating industry. The batch experiment results showed that SMA was effective in the simultaneous removal of Cu(II) and Ni(II) to a significant extent, with additional improvement of water quality of the industrial effluent considered.