Ni removal from aqueous solutions by chemical reduction: Impact of pH and pe in the presence of citrate
| Autor: | Hyung-June Park, Shiao-Shing Chen, Jui-Hsuan Yu, Yi-Hsuan Chou, Yang-Min Liang, Chi-Wang Li, Kwang-Ho Choo |
|---|---|
| Rok vydání: | 2016 |
| Předmět: |
Environmental Engineering
Aqueous solution Chemistry Health Toxicology and Mutagenesis Inorganic chemistry chemistry.chemical_element 02 engineering and technology 010501 environmental sciences 021001 nanoscience & nanotechnology Dithionite 01 natural sciences Pollution Redox Industrial wastewater treatment chemistry.chemical_compound Nickel X-ray photoelectron spectroscopy Environmental Chemistry Chelation 0210 nano-technology Citric acid Waste Management and Disposal 0105 earth and related environmental sciences |
| Zdroj: | Journal of hazardous materials. 320 |
| ISSN: | 1873-3336 |
| Popis: | The chemical precipitation of Ni ions from industrial wastewater at alkaline pH values creates waste chemical sludge (e.g., Ni(OH) 2 ). We herein focused on Ni removal via chemical reduction using dithionite, by converting Ni(II) to its elemental or other valuable forms. Without the presence of a chelator (e.g., citrate), the nickel reduction efficiency increased with increasing dithionite:Ni molar ratio, reaching ⿼99% at ratios above 3:1. The effect of pH on Ni reduction was in agreement with the standard redox potentials (pe 0 ) of dithionite, which became more negative with an increase in pH leading to greater Ni reduction efficiencies. With the formation of Ni-citrate chelates, however, the Ni reduction deteriorated. Elevated pH and temperature improved nickel reduction, due to the greater reducing power of dithionite. The optimal pH value for Ni(II) reduction was found to be ⿼8. Injecting Cu seed particles enhanced the rate and amount of Ni reduced. NiS and Ni 3 S 2 were identified in the crystal of the resulting solids by X-ray crystallography, and the presence of elemental Ni was explained by X-ray photoelectron spectroscopy. The chemical reduction of actual printed circuit board wastewater with the dithionite:Ni(II) molar ratio dose of 12:1 retrieved ⿼99% nickel after 30-min reaction at 40 °C. |
| Databáze: | OpenAIRE |
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