Alkaline Prehydrolysis Prolongs Resin Life and Enhances the Adsorption of Phenolic Compounds

Abstract

Phenolic compounds in oil wastewater are highly toxic and refractory. Hydrolysis at pH 12 for 12 h makes these compounds more vulnerable to attack and destruction. Under the binding and precipitation of polyaluminum chloride (PAC) at pH 8, the chemical oxygen demand (COD) was significantly reduced by 38%. The simulation found that hydrolysis + flocculation was a complex multistep process. The COD removal rate was mainly controlled by the prehydrolysis process. The metabolic pathway suggested that the m-cresol produced in the factory was oxidized to low water-soluble aldehyde. Alkaline hydrolysis converted the aldehyde into m-toluene-methanol, which was conducive to being captured by the PAC. Fourier transform infrared spectroscopy (FTIR) showed that the alkaline dehydrogenation of two m-methylphenyl carbinols produced a molecule that was removed by the resin. Generally, the particle size of the residue after alkaline hydrolysis was 6.4–8.3 nm, which was included in the pore size range of the resin. Therefore, the resin adsorption capacity for the hydrolyzed substances increased to 47,000 mg L−1, with 93% renewability. In short, hybrid technology reduces the concentration burden of the resin inflow and controls the molecular size of adsorbed substances for repurification. It strengthens the treatment effect of high COD wastewater and provides innovative ideas for extending the service life of resin.