Study On Synergistic Degradation Of Aqueous Organic Contaminants By Adsorption-catalytic Ozonation System

Adsorption-catalytic ozonation process is a novel alternative to Advanced Oxidation Technologies (AOTs). It is composed of adsorption, ozonation and catalytic oxidation. In our work, Activated Carbon (AC) and Bentonite are selected as adsorbents in this process to degrade nitrophenol wastewater and slightly-polluted potable water. This paper investigates operation parameters; reaction mechanism; carbon modification and reaction kinetic model.Firstly, the process is utilized in degrading p-nitrophenol (PNP) wastewater by using AC as adsorbent. Treating efficiency and effect of operation parameters are investigated. PH is found to be the key parameter. Based on the optimized condition, comparison among adsorption, ozonation and adsorption-catalytic ozonation process is comprehensively investigated, and synergistic effects between ozone and AC are found, and the synergistic factor is increased from 0.8 at pH 4.0 to 1.3 at pH 10.0. The reaction mechanism of the adsorption-catalytic ozonation process is clarified. At acidic conditions, adsorption predominated in organics removal. The pollutants are congregated from aqueous to AC surface, and AC experiences an oxidation regeneration process. The reactions mainly take place on AC surface. At basic conditions, catalytic oxidation contributed primarily, and the reactions take place in aqueous phase. A corresponding adsorption-oxidation-regeneration kinetic model for the process is established. The model can acceptably simulate and predict the way of containment removal for further industrial applications.To improve adsorbility of AC and removal of organics in the adsorption-catalytic ozonation process, modification of AC by pulsed high-voltage electrohydraulic discharge non-thermal plasma is investigated. The modification process extends AC's pore structure and redistributes its surface functional groups. Specially, the modification process in absence of gas introduces phenolic groups on AC surface, resulting in a considerable increase of the adsorbility of nitrophenol. The maximum adsorption capacity is increased from 254.9 mg/g to 304.0 mg/g. The modified AC enhances the adsorption effect in the adsorption-catalytic ozonation process, resulting in a promoted nitrophenol removal.Bentonite adsorption-catalytic ozonation process is investigated as a method of concurrent remove natural organic matters (NOM) and synthetic organic compounds (SOCs) from slightly-polluted potable water. Bentonite adsorbs or enmeshes NOM, which lowers its HO·scavenger effect. On the other hand, Fe³⁺ addition in this process promotes HO·generation, resulting in an enhancement in SOCs removal. The Bentonite adsorption-catalytic ozonation process remedies the drawbacks of AOTs in slightly-polluted water treatment, and realizes concurrent removal of NOM and aromatic containment.