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挥发性有机物(VOCs)是一种有害气体污染物,是雾霾和臭氧污染的前驱物,会对环境和人群健康造成危害。因此,VOCs的控制技术已成为近年来的研究热点[1-2]。近年来,光催化氧化技术因其成本低、无二次污染等优点,得到了广泛的关注。催化剂是光催化技术的核心技术,由于TiO2具有成本低、安全、活性高、稳定性好等优点,目前已成为应用最广泛一种光催化剂[3-4]。然而,它也存在着一些缺点,如易失活、可见光利用率低等。因此,对光催化剂的改性研究成为了热点,目前主要的改性方法主要包括金属离子掺杂、非金属离子掺杂、贵金属表面沉积、表面光敏化和半导体复合材料等[5]。
有研究表明,复合半导体改性方法能有效提高TiO2的光催化活性,特别是ZnO和MnO2[6-8]。SIWINSKA等[9]采用溶胶-凝胶法研究了一系列不同摩尔比的二氧化钛-氧化锌体系。结果表明,与原来的TiO2相比,二氧化钛-氧化锌对3种有机染料具有更高的光催化活性。MA等[10]采用阳极氧化和电沉积方法合成了二氧化锰/二氧化钛纳米管阵列(MnO2/TiO2-NTAS)光电阴极,具有良好的稳定性和可重复利用性,在废水处理中具有很大的应用潜力。
Zn-MnO2干电池具有成本低、容量大等优点,是目前应用最广泛的消费型电池之一。全球锌锰电池的年消耗量约为6×107 t,且仍在增长[11]。废旧锌锰电池含有大量的锰和锌以及其他重金属元素,大量废弃的锌锰电池处理不当会造成土壤、水和大气污染[12-13]。因此,开发出一种经济可行的回收方法非常重要,将废旧电池回收制备功能材料已经逐渐成为研究热点[14-19]。GALLEGOS等[20]使用生物湿法冶金工艺从废电池中回收锌和锰,以制备去除VOCs的催化剂。ZHANG等[21]采用还原酸浸法从废旧锌锰电池中成功合成二氧化锰,并用其负载Cu作为一氧化碳氧化催化剂。将废旧锌锰电池制备成催化剂来处理环境问题是一种具有前景的技术。但截至目前,现有的回收方法过于复杂,成本过高,大部分都只针对废旧电池中的特定金属进行回收,并且回收过程中还存在二次污染问题,因而不利于在实际工程中推广应用。
废旧锌锰电池中含有大量的锰和锌,利用废旧锌锰电池来提高TiO2的光催化性能是一种较为可行的方法。因此,本研究以废旧锌锰电池和二氧化钛为原料,采用球磨法制备复合改性光催化剂,以实现废旧电池中的相关物质全部回收利用。
利用废旧锌锰电池制备光催化剂净化甲苯
Preparation of photocatalyst for toluene purification from waste zinc manganese battery
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摘要: 针对废旧锌锰电池回收利用难,以及光催化剂TiO2活性低的问题,以废旧锌锰电池和商业二氧化钛为原料,通过球磨法制备了新型复合光催化剂。在紫外光灯照射下,进行了废旧锌锰电池复合改性TiO2对甲苯的光催化氧化实验,并重点探究空速、光照强度、相对湿度和氧气体积分数等关键实验条件对甲苯净化效率的影响。结果表明,改性后的催化剂对甲苯的净化能力大幅提高;当TiO2与废电池芯粉的质量比为2∶1时,催化剂的催化效果最好,甲苯的净化效率提高了近45%;空速越大,催化剂对甲苯的净化效率越低;净化效率随光照强度的增加呈现先增加后保持不变的规律;催化剂在相对湿度为30%的条件下具有最佳的催化活性,氧气体积分数为15%时为净化效率达到最大。本研究结果可为废旧锌锰电池的回收利用提供新的思路。Abstract: In view of the difficult recycling of waste zinc manganese batteries and the low activity of photocatalyst TiO2, a new composite photocatalyst was prepared by ball milling with waste zinc manganese batteries and commercial titanium dioxide as raw materials. Under the irradiation of ultraviolet lamp, the photocatalytic oxidation of toluene by composite modified TiO2 of waste zinc manganese battery was studied, and the effects of key experimental conditions such as space velocity, light intensity, relative humidity and oxygen volume fraction on the purification efficiency of toluene were mainly explored. The results showed that the purification ability of the modified catalyst for toluene was greatly improved. When the mass ratio of TiO2 to waste battery core powder was 2∶1, the catalytic effect of the catalyst was the best, and the purification efficiency of toluene was increased by nearly 45%. It was found that the higher the space velocity, the lower the purification efficiency of the catalyst for toluene. The purification efficiency increased first and then remained unchanged with the increase of light intensity. The catalyst had the best catalytic activity when the relative humidity was 30%, and the purification efficiency reaches the maximum when the oxygen volume fraction was 15%. This study provided a new idea for the recycling of waste zinc manganese batteries.
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Key words:
- solid waste recycling /
- waste zinc manganese battery /
- TiO2 /
- photocatalysis /
- toluene
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表 1 样品的比表面积、孔容和孔径
Table 1. Specific surface area, pore volume, and pore size of the samples
样品名称 比表面积/(m2·g−1) 孔体积/(cm3·g−1) 平均孔径/nm TiO2 179.33 0.58 13.02 WBP 10.08 0.06 23.66 WBC1 54.64 0.24 17.32 WBC2 68.9 0.28 16.09 WBC3 89.61 0.35 15.91 WBC4 98.31 0.39 15.67 -
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