负载型氯铬酸吡啶氧化后残渣的处理研究

Reprocessing of the residue from supported PCC after oxidation

载体氧化剂氯铬酸吡啶PCC/SiO2能有效地将醇氧化到相应的醛或酮,氧化后的残渣含有大量的SiO2、铬离子。用40 mL水回流浸取5 g残渣,滤液用KOH调pH至13～14后用H2O2氧化,反应完后用冰乙酸调pH至4～5,最后水浴蒸发结晶,得到纯度为88.9%的重铬酸钾晶体0.36 g。滤液进行铬的无害处理。最后用50%的硫酸再次回流4.5 g残渣2 h,得到SiO24.3 g。可达到循环利用的目的。

Supported oxidant PCC/SiO2 can be effectively used in the oxidation of alcohols,but the residue in this oxidation contains much SiO2 and chromium ion.First,the residue was leached with refluented water（40 mL）,the pH of the filtrate was adjusted to 13-14 with KOH,and then this solution was oxidized with H2O2,when the oxidation was ended,the pH of the remaining was adjusted to 4-5 with acetic acid,finally the remaining solution was evaporated with water bath to crystal K2Cr2O7（0.36 g） with the purity of 88.9%.At last the residue in the forementioned procedure was dipped in 50% sulfuric acid for 2 h to recover SiO2（4.3 g）,which can be reused.