Removal Of Paes In Water By High Energy Irradiation

Phthalic Acid Esters (PAEs) is one of environmental endocrine disruptors, with low water solubility, high bioaccumulation and sever reproductive toxicity. There are more than20PAEs substances, which are ubiquitous in the soil, sediment, water, plants, animals, air and atmospheric deposition. They are chosen as one of the environmental pollutants to be firstly controlled by the United States, Japan, Europe and China. This research used the DMP, DEP and DBP as research objects to remove PAEs in water by high-energy radiation method. It contains four aspects:the removal efficiency, the influencing factor, the degradation mechanism of PAEs, and the change of bio-toxicity for PAEs solution. The experimental results are shown as follows:DMP, DEP and DBP can be efficiently degraded by high energy irradiation. The removal efficacy of irradiation (GD) were positively correlated with the concentration of PAEs, but dropped exponentially with the increase of dose; the energy utilization rate of gamma irradiation was higher than that of EB irradiation; the efficiency of irradiation degradation in DMP solution aerated with different atmosphere, were O2> saturated air> N2; the degradation reaction constants in the middle value of pH (5-8) was the highest, there was a downward trend in higher pH (8-10), while decreased rapidly in the lower pH (2-4); the irradiation removal efficiency of different types of PAEs were DMP>DEP> DBP> DOP>; DMP degradation reaction was followed a first-order kinetic relationship (In[Co/C]= kD,0-375mg/L, r>0.99); the OH· radical oxidation reaction was the major radiation degradation reaction, eaq-radical was the second one and H·radical was the last one.Using UV, HLCP, radical-scavenging, LC-MS and the method of radiation degradation standard substance, the results were confirmed: the degradation products of DMP were mainly DMP-(OH) n, phenols and p-hydroxybenzoic acids etc. It was suggested that the radiation degradation reaction can be divided into two stages: low dose addition reaction and high dose ring-opening reaction. Hydroxyl radicals as main active species was first added to a DMP phenyl ring and formed the DMP hydroxylated products, the hydroxylated products continue to be derivatisation, followed by hydrolysis reaction, ring opening broken down into small molecules, the products were finally completed mineralization.Three kinds of biological toxicity tests (bioluminescent bacteria, algae and zebra fish acute toxicity) had shown that: irradiation reduced bio-toxicity in DMP solution. Experiments showed that the toxicity of DMP solution irradiated on low doses was enhanced. The reason is that the bio-toxicity of DMP-(OH) n was greater than DMP.In short, removal of PAEs in water by high energy radiation was feasible. This research has important guiding significance in the disposal of micro-polluted drinking water and high PAEs concentration wastewater.