title: Electro-oxidation and characterization of nickel foam electrode for removing boron.
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-2was effective in the EC of boron, and increasing the concentration of boric acid from 10 to 100 mg L-1did 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-2for 120 min.
authors.affiliation: Department of Chemical Engineering, National Cheng-Kung University, Tainan 701, Taiwan.
authors.forename: Danis
authors.initials: D
authors.lastname: Kartikaningsih
authors.affiliation: Department of Chemical Engineering, National Cheng-Kung University, Tainan 701, Taiwan.
authors.forename: Yao-Hui
authors.initials: YH
authors.lastname: Huang
authors.affiliation: Department of Chemical Engineering, National Cheng-Kung University, Tainan 701, Taiwan. Electronic address: mcdyessjin@gmail.com.
authors.forename: Yu-Jen
authors.initials: YJ
authors.lastname: Shih
mesh_terms: D001895:Boron / Q000737:chemistry* / Q000302:isolation & purification*; D004563:Electrochemistry / Q000295:instrumentation*; D004566:Electrodes; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D009532:Nickel / Q000737:chemistry*; D010084:Oxidation-Reduction; D062065:Wastewater / Q000737:chemistry; D014874:Water Pollutants, Chemical / Q000737:chemistry* / Q000302:isolation & purification*
chemical_list: D001895:Boron; D009532:Nickel; D062065:Wastewater; D014874:Water Pollutants, Chemical
keywords: Cyclic voltammetry; Electrocoagulation; Ni(OH)(2); NiOOH; Zeta-potential