Pretreatment and Resource Utilization of Industrial Effluent with Benzoic Acid
苯甲酸生产废水的处理与资源化

Extraction equilibrium of benzoic acid were studied using 20%, 30% and 50% tributyl phosphate (TBP) in kerosene, 1-octanol and toluene as the extractants, to investigate the efficient method of recovering benzoic and acetic acid in the industrial effluent and meeting the requirement of the terminal wastewater treatment. The CODCr value in residual phase and the recovery of benzoic acid in various extractants were measured. The results showed that the recovery of benzoic acid was closed to 100% with 50% TBP/kerosene system, and depended on the polarity of extractant for pure solvent system. The recovery with 1-octanol was equivalent to the one with 30% TBP. The CODCr value in the residual phase depended on the CODCr value from benzoic acid and the solubility of extractant, which does not depend on the benzoic acid concentration in the residue phase apparently, and shown 50% TBP approximately equal to 30% TBP > 1-octanol > 20% TBP > toluene. Meanwhile, the profitable diagram of pretreatment of industrial effluent with benzoic acid was suggested, i.e. firstly, extract benzoic acid with toluene and return the toluene to the benzoic acid reactor, then, extract acetic acid with trialkylphosphine oxide and back-extract the acetic acid with CaO or MgO to produce calcium magnesium acetate.