Terephthalic acid removal from aqueous solution by electrocoagulation and electro-Fenton methods: Process optimization through response surface methodology

• Published in: Process safety and environmental protection Vol. 107; pp. 269 - 280
• Main Authors: Sandhwar, Vishal Kumar, Prasad, Basheshwar
• Format: Journal Article
• Language: English
• Published: Rugby Elsevier B.V 01.04.2017; Elsevier Science Ltd
• Subjects: Aqueous solutions; Chemical oxygen demand; Chemical plants; Chemical precipitation; Coagulation; Current density; Electro-Fenton; Electrochemistry; Electrocoagulation; Energy consumption; Graphite; Graphite cathode; Hydrogen peroxide; Optimization; Organic chemistry; pH effects; Response surface methodology; Sludge; Sludge analysis; Sodium sulfate; Terephthalic acid; Sludge analysis; Electro-Fenton; Electrocoagulation; Optimization; Terephthalic acid; Graphite cathode
• ISSN: 0957-5820; 1744-3598
• DOI: 10.1016/j.psep.2017.02.014

[Display omitted] •Removal of terephthalic acid was found maximum in EF treatment.•Closeness of experimental and CCD predicted results indicates good model adequacy.•Energy consumption was minimum in case of EF treatment at optimum conditions.•Operating cost during EF treatment was lower than EC treatment at optimum conditions.•Amount of generated sludge was higher in EC treatment. The present work deals with the treatment of terephthalic acid (TPA) and chemical oxygen demand (COD) from synthetic aqueous solution. Initially the aqueous solution was treated by acid precipitation at different pH (2–5) and temperature (15–60°C). Approximately 87.1% of TPA and 68.85% of COD were removed by acid precipitation treatment at optimum conditions. After acid precipitation, the filtered supernatant was further treated by electrocoagulation (EC) and electro-Fenton (EF) techniques separately. Operating parameters viz. pH—(4–12), current density (A/m2)—(15.24–45.72), Na2SO4 concentration (mol/L)—(0.02–0.04) and time (min)—(10–70) for EC treatment and pH—(1–5), current density (A/m2)—(15.24–45.72), H2O2 concentration (mg/L)—(50–250) and time (min)—(10–70) for EF treatment were optimized and modeled by Central Composite Design (CCD) in response surface methodology (RSM). Maximum removal of TPA—82.76%, 91.87% COD—79.56%, 89.68% with electrical energy consumption (kWh/kg COD removed)—22.65, 18.11 were obtained through EC and EF treatment respectively at optimum conditions. Sludge generated at optimum conditions via electrochemical treatments was characterized by FTIR, XRD, SEM/EDX and TGA/DTA techniques.