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• 基金项目：

• 吴瑜端
• 厦门大学海洋系

• 蔡卫君
• 厦门大学海洋系

• 摘要：工厂排放的含Cr(Ⅵ)废水注入河口之后,受水体中溶解有机物的还原,转化为低毒的Cr(Ⅲ).在天然水体中Cr(Ⅵ)被溶解有机物还原的反应动力学表明:该过程对Cr(Ⅵ)和H⁺均为一级反应.还原过程由两个反应组成,反应Ⅰ是Cr(Ⅵ)对酚羟基(φ-OH)的氧化,反应速度常数k₁^18℃=0.036min^-1.反应Ⅱ是Cr(Ⅵ)对醇羟基(R-OH)的氧化,反应速度常数k₁^18℃=1.5×10^-3min^-1。反应的活化能E₁=26kcal/mol,E₁^＇=40kcal/mol(18-28℃).利用正交设计实验测定该还原反应热力学的有关参数得出:溶解有机物对Cr(Ⅵ)的还原作用体系的反应物浓度和pH对反应平衡点有显著影响河口水域的水化学条件有利于Cr(Ⅵ)的还原.在反应平衡时六价铬的浓度(C_Cr^eq_VI)与溶解有机物含量(DOC)之间的相关关系的基础上,外推得出不同环境功能水质要求的排放标准的计算通式:C_Cr^d_VI=α(Q/q)C_Cr⁸_VI+kDOC

• Abstract：During sewage discharge into estuary Cr(Ⅵ) in industrial waste water is reduced by dissolved organics into low-toxic Cr(Ⅲ). In natural water body, kinetics of Cr(Ⅵ) reduction by dissolved organics is of a first order reaction for both Cr(Ⅵ) and H⁺. Reduction process consists of two reactions, of which reaction I is the oxidation of hydroxyl of phenol (φ-OH) by Cr(Ⅵ), k₁^18℃ =0.036 min^-l and reaction Ⅱ is for hydroxyl of alcohol (R-OH) k₁^18℃=1.6×10^-3min^-l. Activation energy is E₁ = 26kcal and E₂ = 40kcal respectively (18-28℃).Based on relevant thermodynamic data of reduction which are determined by orthogonal design, conclusion [may be drawn in a way that reactant concentration and pH have significant influence on the equilibrium point of Cr(Ⅵ) reduction by dissolved organics.

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