Electro-oxidation and characterization of nickel foam electrode for removing boron. (January 2017)

• Record Type: Journal Article
• Authors: Kartikaningsih, Danis; Huang, Yao-Hui; Shih, Yu-Jen
• Is Part Of: Chemosphere. Volume 166(2017)
• Page Start: 184
• Page End: 191
• Publication Date: 2017-01
• Subjects: Ni(OH)2 -- NiOOH -- Electrocoagulation -- Cyclic voltammetry -- Zeta-potential; Pollution -- Periodicals; Pollution -- Physiological effect -- Periodicals; Environmental sciences -- Periodicals; Atmospheric chemistry -- Periodicals; 551.511
• DOI: 10.1016/j.chemosphere.2016.09.091
• Languages: English
• ISSNs: 0045-6535

Abstract

Abstract: The electrocoagulation (EC) using metallic Ni foam as electrodes was studied for the removal of boron from solution. The electrolytic parameters were pH (4–12), current density (0.6–2.5 mA cm −2 ), and initial concentration of boron (10–100 mg L −1 ). Experimental results revealed that removal efficiency was maximized at pH 8–9, and decreased as the pH increased beyond that range. At particular onset potentials (0.5–0.8 V vs. Hg/HgO), the micro-granular nickel oxide that was created on the surface of the nickel metal substrate depended on pH, as determined by cyclic voltammetry. Most of the crystallites of the precipitates comprised a mixed phase of β-Ni(OH)2, a theophrastite phase, and NiOOH, as revealed by XRD and SEM analyses. A current density of 1.25 mA cm −2 was effective in the EC of boron, and increasing the concentration of boric acid from 10 to 100 mg L −1 did not greatly impair removal efficiency. A kinetic investigation revealed that the reaction followed a pseudo-second order rate model. The optimal conditions under which 99.2% of boron was removed from treated wastewater with 10 mg L −1 -B, leaving less than 0.1 mg L −1 -B in the electrolyte, were pH 8 and 1.25 mA cm −2 for 120 min. Graphical abstract: Highlights: Metallic nickel foam is used as sacrificial anode for coagulation of boron. Cyclic voltammetry defines the pH-dependent formation of nickel oxide flocs. Ni sludge is mainly composed of Ni(OH)2 and NiO/NiOOH. Electrostatic force influences the efficiency of boron adsorbing onto the coagulant. Energy consumption of using Ni is comparable to Al and Fe electrodes.