Research Progress on Resource Utilization Technology of Surface Treatment Waste Liquid
Metal surface treatment processes often use strong acid solutions(such as nitric acid,hydrochloric acid,etc.)to remove oxides on the surface of metal workpieces to improve the strength of the electroplating layer and the corrosion resistance of the metal workpieces.Therefore,the surface treatment waste liquid contains a large amount of metals ions and spent acid.Technologies such as precipitation,evaporation,and ion exchange methods realize the resource utilization of surface treatment waste acid liquid by precipitating metal ions,separating acid liquid,and increasing the concentration of metal ions in the mother liquid.Various surface treatment waste acid liquid resource utilization methods have different mechanisms.The mechanism of resource utilization of all kinds of surface treatment waste acid solution is different.Precipitation method uses the principles of hydroxyl neutralization reaction and metal sulfide precipitation to separate metal ions from waste acid liquid.Evaporation method uses the characteristics of volatile part of acid solution and different solubility of metal salts to realize the resource utilization of acid and metal ions.Ion exchange resin achieves the recovery and reuse of target ions through the process of selective adsorption-elution.Dialysis method uses the selective permeability of membrane or electric field force to achieve the separation of acid and metal salts.Utilizing industrial waste heat,adding pretreatment processes,coupling other processes,reducing the output of secondary pollutants to reduce the resource utilization cost of surface treatment waste acid liquid,and improving resource utilization efficiency are the focus of future research in this field.
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