Quantitative structure-property relationship(QSPR)models were developed for prediction of photolysis half-life(t_(1/2))of polychlorinated biphenyls(PCBs)in water under ultraviolet(UV)radiation.Quantum chemical descriptors computed by the PM3 Hamiltonian software were used as independent variables.The cross-validated Q^(2)_(cum)value for the optimal QSPR model is 0.966,indicating good prediction capability for lg t_(1/2)values of PCBs in water.The QSPR results show that the largest negative atomic charge on a carbon atom(Q-C)and the standard heat of formation(ΔH_(f))have a dominant effect on t_(1/2)values of PCBs.Higher Q_(C)^(-)values or lowerΔHf values of the PCBs leads to higher lg t_(1/2)values.In addition,the lg t_(1/2)values of PCBs increase with the increase in the energy of the highest occupied molecular orbital values.Increasing the largest positive atomic charge on a chlorine atom and the most positive net atomic charge on a hydrogen atom in PCBs leads to the decrease of lg t_(1/2)values.
The electrochemical treatment of COD contained in biologically pretreated coking wastewater treated by a three-dimensional electrode system with modified coke as the particle electrode was investigated. And the electrochemical perromance of the coke modified with various active components was studied. The results show that the coke modified with Fe（NO3）2 has the lowest energy consumption and higher COD removal rate under the same condition, and the modified coke has better surface characteristics for the purpose of this study. In addition, the kinetic constant was also calculated. The study shows that the three-dimensional electrode system with Fe （NO3）z-modified coke can give a satisfactory solution in biologically pretreated coking wastewater.
HE Xu-wen LIU Li-yuan GONG Jing-wen WANG Jian-bing QIN Qiang WANG Hao
