Abstract
This study aims to clarify the removal mechanism and to calculate the effective current of electrocoagulation (i.e., EC) for treating wastewater containing Ni(II), Cu(II), and Cr(VI). The adsorption behavior of various heavy metals onto Al(OH)3 coagulant generated by the EC process was investigated and the estimating method of the corresponding current was established. Results indicate that adsorption of single Ni(II) and Cu(II) by Al(OH)3 coagulant can be simulated by the Langmuir isotherm, while Cr(VI) adsorption fits the Freundlich isotherm better. As treating single heavy metal of wastewater, the removal mechanism of the EC process is the adsorption reaction. Under the coexisting condition, the Ni(II) and Cu(II) will compete for the same active sites on the Al(OH)3 surface and Cu(II) suppresses Ni(II) adsorption. As treating the coexisting heavy metals, Ni(II) removal not only associates with adsorption but also with the coprecipitation. In contrast, Cr(VI) does not compete with other metal ions for the same type of adsorption sites. Whether single or coexisting conditions, the adsorption capacity of heavy metals onto Al(OH)3 coagulants can be used to compute the necessary current to effectively remove heavy metals in the EC system.
Highlights
Wastewater from metal-finishing facilities is troublesome for bio-treatment due to its complexity and toxicity
Adsorption is the to remove heavy metal ions in the EC system, which agrees with the literature research
The coagulant adsorption is the major mechanism to remove heavy metal ions in the EC system, which agrees with the literature research [20,27,28]
Summary
Wastewater from metal-finishing facilities is troublesome for bio-treatment due to its complexity and toxicity. A typically waste stream from metal-finishing facilities usually contains different kinds of metal ions such as copper, nickel, cadmium, and chromium ions, along with chelating agents, oil and grease, organic solvents, and suspended solid particulates [1]. Among the methods reviewed are chemical precipitation, coagulation/flocculation, adsorption, electro-coagulation, flotation, ion exchange, and membrane filtration. Especially hydroxide precipitation, was adapted early and is still recommended by US EPA for metal ion removal [1,4]. Coagulation is employed for the removal of contaminants in suspended or colloidal forms. Adsorption is the binding mechanism between soluble contaminants and solids that can provide a significant amount of active surface.The electro-coagulation (i.e., EC)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.