Development Of A Combined Oxidation-resin Adsorption Process For Treatment And Recovery Of The Pickling Waste Liquor Of Hydrochloric Acid

With the development of steel industry and electroplating industry, increasing amount pickling liquid waste is thus generated. The widely used technique for disposal of the waste, i.e., neutralization by alkaline compounds, would result in high cost, possible secondary pollution, and waste of large amount of acids.In this paper, we developed a new technology for treatment and recovery of the waste acid by integrating efficient oxidation and selective resin adsorption. The process can be described as follow:firstly, we used H2O2to oxidize Fe(Ⅱ) into Fe(Ⅲ) in the waste hydrochloric acid,. Then, the waste acid flowed through a column packed with strong-base anion exchanger D201, where most of the iron species was preferably adsorbed. Finally, the exhausted exchanger was regenerated by water for repeated use without any significant capacity loss. Besides, the solution after desorption could be used as a flocculent to treat electroplating wastewater containing heavy metals and phosphate.The process parameters of laboratory study could be summarized as follows.(1) Oxidation. H2O2dosage,1.2times of the theoretic amount; oxidizing time,2hours; oxidation efficiency,>99.5%;(2) Column adsorption and regeneration. A double-bed continuous running, flow rate,1BV per hour; temperature25℃; height-to-diameter ratio,4:1; Fe(Ⅲ) in the first3BV effluent,<5mg/L with the removal efficiency higher than99.9%. Regenerant,2BV water and the flow rate,1BV per hour.Based on the results of laboratory study, we proposed an pilot-scale process for treatment and recovery of pickling liquid waste (1m3/d), and the economic benefit analysis was also considered. The overall investment was575,000RMB and the economic benefit was207RMB after treating1m3waste acid. All the above results indicated that the proposed process exhibits great potential for industrial application in both technical and economic terms.