Treatment of purified terephthalic acid wastewater using a bio-waste-adsorbent bagasse fly ash (BFA)

• Published in: Environmental science and pollution research international Vol. 24; no. 2; pp. 1953 - 1966
• Main Authors: Verma, Shilpi, Prasad, Basheshwar, Mishra, Indra Mani
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 2017; Springer Nature B.V
• Subjects: Acids; Adsorbents; Adsorption; Adsorptivity; Aquatic Pollution; Atmospheric Protection/Air Quality Control/Air Pollution; Bagasse; Benzoic acid; Cellulose - chemistry; Chemical oxygen demand; Chemical precipitation; Coal Ash - chemistry; Earth and Environmental Science; Ecotoxicology; Environment; Environmental Chemistry; Environmental Health; Environmental science; Fly ash; Free energy; Gibbs free energy; Hydrogen-Ion Concentration; Industrial Waste - analysis; Kinetics; Petrochemicals; Petrochemicals industry; pH effects; Phthalic Acids - isolation & purification; Pollution load; Research Article; Sedimentation; Terephthalic acid; Thermodynamics; Waste Water - analysis; Waste Water Technology; Wastewater; Wastewater treatment; Water Management; Water Pollutants, Chemical - isolation & purification; Water Pollution Control; Water Purification; Kinetics; BFA; Isotherms; Petrochemical wastewater; Adsorption thermodynamics
• ISSN: 0944-1344; 1614-7499
• DOI: 10.1007/s11356-016-7986-1

Purified terephthalic acid (PTA) plant of a petrochemical unit generates wastewater having high pollution load. Acid treatment of this wastewater reduces the chemical oxygen demand (COD) load by more than 50%, still leaving substantial COD load (>1500 mg/L) which should be removed. The present study reports on the use of a bio-waste-adsorbent bagasse fly ash (BFA) for the reduction of COD and other recalcitrant acids from this wastewater. The BFA showed basic character and was mesoporous with a BET specific surface area of 82.4 m 2 /g. Optimum conditions for the adsorptive treatment of acid-pretreated PTA wastewater were found to be as follows: initial pH (pH i ) = 4, BFA dosage = 15 g/L, and contact time = 3 h. Adsorption treatment resulted in 58.2% removal of COD, 96.3% removal of terephthalic acid (TA), and 99.9% removal of benzoic acid (BA). TA and BA were removed from the pretreated PTA wastewater through precipitation and sedimentation of un-dissociated acid molecules inside the mesopores of the BFA. The results showed that the COD removed by the BFA followed pseudo-second-order kinetics. Equilibrium sorption data were best correlated by the Freundlich isotherm. The process of adsorptive removal of COD was found to be exothermic. The change in the Gibbs free energy was found to be negative, suggesting that the adsorption process is spontaneous and feasible for the treatment of PTA wastewater.