Comparative evaluation of alkali precipitation and electrodeposition for copper removal in artisanal gold smelting wastewater in the Philippines

Abstract

© 2019 Desalination Publications. All rights reserved. Alkali precipitation and electrodeposition for copper removal in artisanal gold smelting wastewater were evaluated. Alkali precipitation was done by dosing the wastewater with sodium hydroxide solution. Electrodeposition was conducted at operating current of 4 A for 3 and 6 h. Alkali treatment exhibited 99.83% removal efficiency, albeit residual copper concentration was still above effluent standards. Lead was no longer detected at pH ≥ 6 while 87.82% of cadmium was removed at maximum precipitation. Generation of metal hydroxide sludge implied the need for a post-treatment. Electrodeposition demonstrated superior copper removal efficiency (99.98%). With appropriate selection of electrolysis time, it could achieve complete copper removal. It had low energy consumption and indicative treatment cost, and no sludge generation. Electrodeposition current efficiency was relatively low due to other wastewater components which could have consumed a fraction of applied current. Kinetics evaluation showed a three-step electrodeposition process, each stage having a different reaction rate order. Lead was not detected after 3 h while 50.00% of cadmium was removed after 6-h electrolysis. Considering removal efficiency without sludge generation, indicative treatment cost, and value recovery of deposited copper, results revealed that electrodeposition has some advantage over alkali precipitation for the remediation of artisanal gold smelting wastewater.

Source or Periodical Title

Desalination and Water Treatment

ISSN

19443994

Page

396-405

Document Type

Article

Subject

Artisanal gold smelting, Chemical precipitation, Copper removal, Current efficiency, Electrochemical treatment, Electrodeposition, Heavy metals

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