Adsorbing colloidal flotation removing metals ions in a modified jet cell

Abstract

The removal of Cu 2+, Zn 2+ and Ni 2+ ions from synthetic wastewater with a modified Jameson cell (MJC) was studied using adsorption colloidal flotation (ACF). A colloidal dispersion of Fe (OH) 3 (formed in situ from FeCl 3) at pH 11 was used as an adsorbent colloid to ensure full adsorption and precipitation. The precipitates were flocculated with polyacrylamide and hydrophobised with sodium oleate and pine oil as a frother during the flotation stage. In the modified jet cell, the downcomer was sealed at the bottom with a diffuser, and the re-flotation of detached flocs and the probability of bubbles/particles capture was enhanced, which improved the recovery rate. As a result, the modified Jameson cell was more efficient (higher loaded carrier recoveries) than the conventional jet cell (CJC) in removing heavy metals ions. The physico-chemical characteristics, cell design and operating parameters were studied, and the removal efficiency was evaluated by monitoring the final concentration of ions in the treated effluent. The results indicated that the removal efficiencies of the MJC were approximately 95% and 98% for dilute (Cu 2+, Zn 2+ and Ni 2+ concentration of 2 mg/L) and concentrated wastewater (25 mg/L of each ion), respectively. The optimal parameters included a Fe +3/ion ratio of 0.5 and a minimum air flow-rate/feed flow-rate ratio of 0.18. The results are discussed in terms of the physical and physico-chemical parameters, and the findings suggested that the proposed flotation technique has great potential for the treatment of wastewater.