title: Electro-regeneration of Ce(IV) in real spent Cr-etching solutions.
abstract: This paper presents the electro-regeneration of Ce(IV) in real (hazardous) spent thin-film transistor liquid-crystal display (TFT-LCD) Cr-etching solutions. In addition to Ce(III)>Ce(IV) in diffusivity, a quasi-reversible behavior of Ce(III)/Ce(IV) was observed at both boron-doped diamond (BDD) and Pt disk electrodes. The Ce(IV) yield on Pt increased with increasing current density, and the best current efficiency (CE) was obtained at 2A/2.25 cm(2). The performance in terms of Ce(IV) yield and CE of tested anodes was in order BDD>Pt>dimensional stable anode (DSA). At 2A/2.25 cm(2) on Pt and 40 °C for 90 min, the Ce(IV) yield, CE and apparent rate constant (k) for Ce(III) oxidation were 81.4%, 21.8% and 3.17 × 10(-4) s(-1), respectively. With the increase of temperature, the Ce(IV) yield, CE, and k increased (activation energy = 10.7 kJ/mol), but the specific electricity consumption decreased. The Neosepta CMX membrane was more suitable than Nafion-117 and Nafion-212 to be used as the separator of the Ce(IV) regeneration process. The obtained parameters are useful to design divided batch reactors for the Ce(IV) electro-regeneration in real spent Cr-etching solutions.
authors.affiliation: Department of Environmental Engineering and Science, National Pingtung University of Science and Technology, Pingtung 91201, Taiwan.
authors.forename: Te-San
authors.initials: TS
authors.lastname: Chen
authors.forename: Kuo-Lin
authors.initials: KL
authors.lastname: Huang
mesh_terms: D002563:Cerium / Q000737:chemistry*; D002857:Chromium; D055615:Electrical Equipment and Supplies; D004563:Electrochemistry; D007220:Industrial Waste; D050866:Liquid Crystals; D059027:Recycling / Q000379:methods; D012996:Solutions; D014865:Waste Disposal, Fluid / Q000379:methods; D014874:Water Pollutants, Chemical / Q000737:chemistry*
chemical_list: D007220:Industrial Waste; D012996:Solutions; D014874:Water Pollutants, Chemical; D002857:Chromium; D002563:Cerium
keywords: Anode; Ce(IV) yield; Electro-regeneration; Real spent TFT-LCD Cr-etching solution; Separator