Adsorbtion And Degradation Of Nitro-aromatic Toxic Substance Using Modified Chloromethylated Polystyrene Microspheres Supported Nanoscale Zero-valent Iron

Nitro aromatic(NACs) belong to the toxic and harmful substances, Because of its stable chemical properties, hard biodegradable, they are easy to accumulating residue in environmental water or soil, once enter into the food chain, they are stored in organism and lead to amplfication phenomenon easily, which constitute a great threat to the ecological safety and public health.This study intends to establish a highly efficient, economic, and harmlessly method or technology of degrading NACs.Preparation of the load-type nano iron by the liquid reduction method with the quaterisation modified chloromethylated polystyrene microspheres as the supporter,which was prepared by the method of soap-free emulsion polymerization. Based on the good adsorption capacity of polystyrene carrier microspheres and strong reducing zero-valent iron nanoparticles, treat the toxic refractory nitrobenzene(NB) as the main study object, determine the optimal technological conditions and mechanism by conducting experiments of degrading the nitrobenzene with the home-made load-type nano zero-valent iron material. By using the method of orthogonal experiment and the single-factor analysis, explore the impact of six kinds of factors: the variety of microsphere, the materials consumption, ionic strength, pH and temperature.Successfully designed a compound degradation method integrating the two advantages of both physical adsorption and chemical reduction.NZVI-PS was applied to degrade the target material nitrobenzene. The experiment results show that under the optimal conditions, the degradation rate of250 ml, initial 123.1mg/L nitrobenzene solution is 99.5%. Fnially NB is degraded into aniline, which is a kind of easily biodegradable low toxic substances. According to the results of detecting ferrous iron which can cause secondary pollution, under the optimum condition,there is no ferrous iron in the filtrate. This paper also studied the reusable performance of the carrier, the results shows that the degradation rate of the nitrobenzene is still very high after repeated regeneration using four times, whichreflect the environmental and economic side of the load-type nano-iron material.NZVI-PS was applied to degrade the other four kinds of NACs. The performance of the material is excellent. Under the optimum condition, the degradation rate of other four kinds of NACs which are 4-NP, 4-CNB, DNB and TNT, are 99.94%?99.70%?86.76% and 84.80%, Reflecting the NZVI-PS material excellent degradation ability. The reaction kinetics study shows that the degradation reaction follows the first-order kinetics model. NACs degradation reaction rate constant k values are-0.722 min-1?-0.388 min-1?-0.064 min-1?-0.040 min-1 respectively. Compared with the reaction rate constant k of NB(-0.197 min-1), we can found that the variety and number of substituents on benzene have a great influence on the ease of its degradation.