锌浸出液水热法制备纳米ZnO

Hydrothermal method to prepare nano-ZnO from zinc leachate with different precipitants

纳米ZnO是一种新型的高功能精细纳米材料,用途广泛,采用水热法制备的纳米ZnO颗粒纯度高、晶形好且操作简便;含锌二次资源的锌浸出液中杂质元素较多,对后期产品纯素的影响较大,其中除铜、镉较为关键。本文以含锌二次资源的锌浸出液为原料,采用锌粉置换除铜、镉,然后以净化后的硫酸锌溶液为锌源,分别采用氨水、碳酸钠、氢氧化钠作为沉淀剂通过水热法制备纳米ZnO,并考察不同工艺参数对纳米ZnO物相和形貌的影响,结果表明:在合适条件下,锌粉置换后浸出液中铜、镉离子浓度分别为0.039 9 mg·L^(-1)、6.416 2 mg·L^(-1),可用于制备纳米ZnO;采用氨水和碳酸钠作为沉淀剂制得的产物均为ZnO和其他晶体的混合物,属于非纯相的不规则晶体;采用氢氧化钠作为沉淀剂可制得纯相纳米ZnO,最佳制备条件为锌碱摩尔比1∶2、反应时间1 h、反应温度120℃,制得的纳米ZnO呈现棱柱结构,粒径在50~100 nm之间,颗粒尺寸分布均匀。

Nano-ZnO is a new type of high-function fine nano-material with wide application.The nano-ZnO particles prepared by hydrothermal method have high purity,good crystal shape and simple operation.There are many impurity elements in the zinc leaching solution containing zinc secondary resources,which has a great influence on the purity of the later products,among which the removal of copper and cadmium is more critical.In this paper,the zinc leaching solution containing zinc secondary resources was used as raw material,and copper and cadmium were removed by zinc powder replacement.Then,the purified zinc sulfate solution was used as zinc source,and ammonia water,sodium carbonate and sodium hydroxide were used as precipitants to prepare nano-ZnO by hydrothermal method.The effects of different process parameters on morphology of nano-ZnO were investigated.The results show that under the appropriate conditions,the concentrations of copper and cadmium ions in the leaching solution after zinc powder replacement are 0.0399 mg·L^(-1 )and 6.4162 mg·L^(-1 )respectively,which can be used to prepare nano-ZnO.The products prepared by using ammonia and sodium carbonate as precipitants are a mixture of ZnO and other crystals,which are irregular crystals of non-pure phase.Pure nano-ZnO can be prepared by using sodium hydroxide as precipitant.The optimum preparation conditions are as follows:the molar ratio of zinc to alkali is 1:2,the reaction time is 1 h,and the reaction temperature is 120℃.The prepared nano-ZnO presents a prism structure,the particle size is between 50~100 nm,and the particle size distribution is uniform.