非过滤法共沉淀富集—火焰原子吸收测定饮水中镉铜铅

在中性或弱碱性条件下，向被没水样中加入适量Ｂｉ＾３＋和硫化钠，使水样中Ｃｄ＾２＋，Ｃｕ＾２＋，Ｐｂ＾２＋与Ｂｉ＾３＋一起硫化物（ＣｄＳ，ＣｕＳ，ＰｂＳ）和Ｂｉ２Ｓ３的共沉淀，加入明矾加速硫化物的沉淀，凝结，然后用虹吸法吸去上层清液（无须过滤），将沉淀物用热稀硝酸溶液，以火焰原子吸收法测定这三个元素的含量。方法简便，实用，且具有较高的准确率和精密度，尤其适于对大体积水样的沉淀富集。     

SELECTIVE PHOTOOXIDATION OF THIOLS SENSITIZED BY AQUEOUS SUSPENSIONS OF CADMIUM SULFIDE

-Finely powdered cadmium sulfide in aqueous, air-saturated, phosphate buffered suspension sensitizes the photooxidation of cysteine to cystine with good efficiency; several additional thiols and inorganic sulfides are also photooxidized. The other amino acids (histidine, methionine, tryptophan, tyrosine) known to be rapidly photooxidized with typical organic photosensitizers are photooxidized only very slowly. The quantum yield of oxygen uptake during cysteine photooxidation is pH dependent with a maximum (0.021) at pH 9.5; the yield is not increased in D₂O and is not decreased appreciably by sodium azide, suggesting that singlet oxygen is not involved in the photooxidation process. The slow rate of photooxidation of histidine, which is known to react efficiently with singlet oxygen, also suggests that little if any singlet oxygen is produced by illuminated cadmium sulfide. Superoxide dismutase inhibits the yield of cysteine photooxidation to a maximum of approximately 50%, suggesting the partial involvement of superoxide in the reaction mechanism. The quantum yields of the photooxidation of cysteine, ethylenediaminetetraacetate and inorganic sulfides decrease as the wavelength of the exciting light is increased. Yeast alcohol dehydrogenase, a sulfhydryl enzyme, is inactivated by photodynamic treatment with cadmium sulfide; lysozyme, which has no free sulfhydryl groups, is not.     

二氧化硫水溶液在修饰硫化镉粉末上的光催化反应

本文从应用意图出发,采用CdS、混Pt/CdS和镀Pt/CdS三种光催化剂,研究(1)反应温度,(2)催化剂表面含Pt量,(3)修饰方法和催化剂表面结构形貌对光催化SO₂水溶液生成H₂SO₄同时放H₂反应的活性和选择性的影响。结果表明:(1)本反应有明显温度效应,利用太阳能中约占50％的红外段辐射来提高反应温度到70℃可使活性增至7倍,但选择性下降,(2)估算了反应活化能为21kJ·mol^-1,(3)得出60℃为反应较佳温度,(4)表面含Pt量在5％左右活性最高,(5)混Pt/CdS体系形成高分散、细颗粒分布,其催化活性比镀Pt/CdS体系为高。根据实验结果对反应机理进行了一些讨论。     

CdS-Ag2S混晶膜电极对络合剂的响应

本文选择了八种典型的有代表性的络合剂,分别观察了它们在CdS-Ag₂S混晶膜电极上的响应,并根据实验值和计算值的比较,探讨了与镉电极响应有关的络合平衡以及应用镉电极测定某些络合物常数的问题,指出了所研究的络合剂在镉电极测试中的实用意义.     

HETEROGENEOUS PHOTO CATALYSIS–VII. THE INFLUENCE OF ZINC IONS ON THE PHOTOCATALYTIC PROPERTIES OF PLATINIZED CADMIUM SULFIDE

Abstract— The reaction rate of the CdS/Pt-catalyzed hydrogen evolution and photodehydro-dimerization from aqueous 2,5-dihydrofuran depends strongly on the reaction conditions in the preparation of CdS/Pt by photoplatinization. Highest rates, 12 ml H₂/h, are obtained when the photocatalyst was prepared with a low-intensity lamp in the presence of 4.3 mol% of platinate (sample I) while lower rates are observed with 1.07, 2.15, 3.23 and 6.45 mol% Pt. At higher intensity and 4.3 or 2.15 mol% Pt the produced samples II and III induce rates of 5 or 2.5 ml H₂/h. Addition of zinc sulfate to the 2,5-dihydrofuran solution results in a maximum rate increase to 7.5 and 12.5 ml H₂/h in the case of II and III , respectively. Similarly, zinc sulfate improves the catalytic properties also when it is present during photoplatinization. In this case only half the amount of platinum, 2.15 mol%, is necessary to obtain the highest rates of 12 ml H₂/h.