Removal of nickel through sulfide precipitation and characterization of electroplating wastewater sludge

Abstract

This work consists of the removal of nickel by sulfide precipitation from an industrial electroplating wastewater and characterization of the produced sludge. Tests are carried out in a perfectly stirred batch reactor on electroplating industrial solution and synthetic solution prepared in the laboratory. The aim is to evaluate the impact of complexing agents formed during precipitation of metal ions in the industrial effluent. The concentration of nickel in both solutions is 100 mg/L. The operating conditions for sulfide precipitation process are optimized: pH, molar ratio [S=]/[Ni2+] and dosage of S= ions. For an initial pH of 5 and an equimolar ratio of [S=]/[Ni2+]:1/1, the results show that the removal efficiency of Ni2+ ions is approaching 91 and 94% for industrial and synthetic solutions, respectively. Otherwise, for the same pH value in supersaturation conditions ([S=]/[Ni2+]:1.5/1), the removal efficiency is approaching 62 and 92% for industrial and synthetic solutions, respectively. For an effective metal removal, the optimal dosage of sulfide ions was evaluated. For 33 mg/L of S=, the removal efficiency of Ni2+ is approximately 90%. The resulting sludge has been characterized by x-ray diffractometry, scanning electron microscopy, infrared spectroscopy and thermal analysis. It consists essentially of millerite and nickel oxide.

Low-Energy Electrodeposition of Nickel in Electroplating Wastewater Using a Water Hyacinth Separated Double Chamber Electrodeposition Cell

“…However, it has both economic and environmental importance since nickel in wastewater may be recovered through a variety of techniques. 3 Many techniques, including adsorption, [9][10][11][12][13][14] microbial desalination cells, 4 biosorption, 9,15 electrolysis, 16 precipitation, 17,18 membrane filtration, 13,19 nanofiltration, 20 and reverse osmosis, 21 have been utilized in nickel and other metal removals. However, in most cases, these processes are inefficient or have prohibitively high costs.…”

The efficiency of removing heavy metal ions from industrial electropolishing wastewater using natural materials

“…[24][25][26] . Chemical precipitation is the process of forming insoluble metal deposits by reacting a precipitating agent, often hydroxides, with dissolved metal ions 27 . This technique is currently the most widely used of treatment methods in the electroplating industry where pH adjustment to an alkaline reaction is used to maximize the precipitation of metals in the form of hydroxides in wastewater.…”