量子点ZnS的制备及其光催化降解有毒有机污染物

Preparation of ZnS Quantum Dots and Photo-degradation of Toxic Organic Pollutants

分别以硫化钠(Na2S)和硫脲(CH3CSCH3)为硫源与醋酸锌(Zn(CH3COO)2.2 H2O)通过水热法反应制备了ZnS量子点,通过透射电子显微镜(TEM)及X-射线衍射(XRD)对ZnS进行了初步表征,结果表明:两类硫源制备的ZnS量子点均为颗粒状立方闪锌矿结构,量子尺寸分别为19.6 nm,25.1nm.在紫外光(λ≤387)照射下以有机染料罗丹明B(Rhodamine B,RhB)及无色小分子2,4-二氯苯酚(2,4-Dichlorophenol,DCP)的光催化降解为探针反应,研究了介质pH条件和光催化剂ZnS用量对光催化反应的影响,表明pH=10、光催化剂用量为50 mg条件下以Na2S为硫源制得的ZnS活性较好,能使RhB在70 min内褪色完全,呈现出ZnS量子点的量子尺寸效应.同时,此实验条件下11 h对2,4-二氯苯酚(2,4-Dichlorophenol,DCP)的深度氧化矿化率为90%.用酶催化分光光度法和苯甲酸荧光光度法分别跟踪测定了催化反应过程中产生的H2O2和.OH,表明量子点ZnS对有毒有机物的光催化氧化过程涉及H2O2和.OH的氧化历程.

The ZnS quantum dots were prepared by the hydrothermal method with zinc acetate（Zn（CH3COO）2·2H2O） and using sodium sulfide（Na2S） and thiocarbamide（CH3CSCH3） as sulfur sources.They were characterized by TEM and XRD.The results showed that the structure of ZnS was granular cubic sphalerite and the quantum sizes of ZnS prepared using Na2S and CH3CSCH3 as sulfur sources were 19.6nm and 25.1 nm,respectively.The photocatalytic degradation of organic dye Rhodamine B（RhB） and 2,4-Dichlorophenol（DCP） under UV light（λ≤387 nm） was used as the probe reaction to evaluate the catalytic activity of ZnS.The effects of pH and catalyst dosage on the catalytic efficiency were explored.It was found that under the conditions of pH 10 and catalyst dosage 50 mg,the ZnS prepared with the sulfur source Na2S had a better activity which faded RhB completely in 70 min under UV irradiation.Quantum size effect was showed on ZnS prepared.Under the same reaction conditions,2,4-dichlorophenol（DCP） was degraded effectively with the mineralization rate higher than 90% after 11h.Hydrogen peroxide（H2O2） and hydrogen radicals（·OH） were detected by Spectro-photometry and benzoic acid spectro-fluorescence analysis method.The results indicated that H2O2 and ·OH existed in the photocatalytic process,and ZnS photocatalytic degradation referred to the oxidation of H2O2 and ·OH radical oxidation.