Recovery of Copper (Ii) and Chromium (Iii,vi) From Electroplating-Industry Wastewater by Ion Exchange

Abstract

Two laboratory-scale separation processes have been developed for the recovery of copper (II) from acidic and cyanide-containing alkaline wastewater of electroplating industries. Acidic bath wastes were treated with Dowex 50X8, a strongly acidic cation-exchange resin, and the retained copper was eluted with H 2 SO 4 . The cyanide-containing alkaline bath waste was first oxidized with excessive hypochlorite, then neutralized, and recovered by the use of Amberlite IRC-718 chelating resin. Copper was eluted with H 2 SO 4 .The two different valencies of chromium have been recovered from electroplating-industry wastewater by different separation processes: The predominant valency, Cr(VI), was retained on a strongly basic Dowex 1X8 resin and eluted with a NaCl and ORDER REPRINTS NaOH solution. Alternatively, Cr(III), either existing originally in electroplating-industry waste-rinse mixtures or converted from Cr(VI) by reduction with Na 2 SO 3 , could be recovered by a weakly acidic Amberlite IRC-50 resin and eluted with a solution containing H 2 O 2 and NaOH. Where plating industry wastes contain high levels of organic contamination, Cr(VI) would be naturally reduced to Cr(III) upon acidification, and it may be more economical to recover all chromium as Cr(III).

Simultaneous Adsorption of Chromium (VI) and Phosphate by Calcined Mg-Al-CO3Layered Double Hydroxides

“…29,34 (12) where K b and n are the Freundlich constants incorporating all parameters affecting the adsorption process. It is reported that 1 ≤ n ≤ 10 represent favourable adsorption conditions.…”

“…2 9,10 Methods for the removal of Cr (VI) involve chemical precipitation, electrolysis, biochemical process, and adsorption. 11,12 Phosphorus is one of the major nutrients for plant growth and it comes from agricultural fertilisers, soaps, and detergents with formulations containing sodium tripolyphosphates, atmospheric nitrogen, erosion of soils containing nutrients, and discharge from sewage treatment plants. 7,13 Though it is an essential macronutrient responsible for healthy plant growth, concentration in an excess of the described limit can result in the eutrophication of lakes, rivers, and seas.…”

Speciation analysis of chromium by separation on a 5-palmitoyl oxine-functionalized XAD-2 resin and spectrophotometric determination with diphenylcarbazide

“…the hydrolysis products held by the resin may be resistant to dilute acids [24], and since stronger acid eluents would not be selective for Cr(III) among other metals, Cr(III) was preferentially eluted with an alkaline solution (ammonia buffer) containing H 2 O 2 so that the oxidation product (CrO 4 2-) would be rejected by the XAD-POx chelating cation exchanger column. Thus selectivity was achieved for Cr(III).…”

Evaluation of a low-cost adsorbent for removal of toxic metal ions from wastewater of an electroplating factory

“…Next, a sample was treated by alkaline chlorination for cyanide destruction. The method involved overnight treatment with 2.0 mol L À1 NaOCl for total oxidation of cyanide to inorganic carbon (Yalçin et al, 2000). The precipitate was dissolved in 1.0 mol L À1 H 2 SO 4 to yield a final solution with metal concentrations of 200 mg L À1 , 14.4 mg L À1 , and 65.5 mg L À1 of Cu 2þ , Ni 2þ and Zn 2þ ions, respectively.…”