Removal of Nickel and Cobalt from Aqueous Solutions by Na-Activated Bentonite

Abstract

Abstract--The ability of Na-activated bentonite to remove Ni 2+ and Co 2+ from aqueous solutions at room temperature (22 _+ I~ was studied under various experimental conditions. The parameters studied were solid-to-liquid ratios and initial cation concentrations. Experiments involved the behavior of bentonite vs. Ni and Co separately and where Ni and Co were present in solution at different concentrations and ratios. Bentonite retained substantial amounts of both metals readily, but it showed a higher affinity for Ni.Over-exchange appears when initial metal concentration exceeds the concentration corresponding to the cation exchange capacity (CEC) of bentonite. The presence of both metals in solution may be either synergistic or antagonistic sorption, depending on the initial ion concentrations.

Nickel removal from waste water by electrocoagulation with aluminum electrodes

“…Several treatment processes have been suggested for the removal of nickel ions from aqueous waste streams: adsorption [2,3], biosorption [4,5], ion exchange [6], chemical precipitation [7,8] and electrochemical methods: electrowinning [9.10], electrodialysis [11], electrodeionization [12,13], membrane-less electrostatic shielding based electrodialysis/electrodeionization [14][15][16] and electrocoagulation.…”

“…The best solution to solid formation and separation problem is the use of inorganic and organic coagulants. For this purpose, FeCl 3 coagulant aid agents in the hydroxide precipitation application.…”

Geomaterials: their application to environmental remediation

“…In the octahedral sheet, each octahedron (e.g. AlO 6 or MgO 6 ) is connected to neighboring octahedra by sharing edges. The edge-shared octahedra form a sheet of hexagonal or pseudo-hexagonal symmetry.…”

“…In the smectite structure, the cations in the interlayer space are easily exchanged, and this high cation-exchange capacity can be used to absorb metals from wastewater [5][6][7]. Therefore, the interactions between smectite and various metals in solutions have been investigated for evaluating environmental impact.…”

“…Their structure consists of positively charged brucite-like layers sharing edges with M 2+ (OH) 6 and M 3+ (OH) 6 octahedra. Partial M 2+ to M 3+ substitution imparts the layers with a positive charge, which is compensated by the exchangeable interlayer anions, which are usually hydrated.…”