近年来,环境污染特别是水的严重污染使其治理成为一个极具挑战性的课题.各种污染物复杂的化学成分和催化剂在处理过程中的浸出、寿命及成本等问题是导致众多氧化催化剂难以实际应用的主要原因.相对而言, H2O2是一种活性氧含量高、清洁并可在温和条件下使用的氧化剂,在各种高级氧化技术中受到广泛关注.而碳酸氢盐是一种弱碱性物质,在自然界及水体系中广泛存在,且无明显毒害.它可活化 H2O2,加快其氧化各种有机物,并在废水处理领域开始受到关注.该体系的明显优势在于处理体系始终处于微碱性环境,可以有效避免金属氧化物催化剂在处理过程中由于体系酸化而带来的催化剂流失,从而延长催化剂寿命,降低催化剂成本.
本文采用浸渍法制备了一种双金属铜、钴氧化物催化剂及相关的对照催化剂体系,利用碳酸氢盐活化 H2O2用于降解苯酚模拟废水.通过各种空白实验发现,负载于γ-Al2O3表面的钴、铜氧化物催化剂 CuO?Co3O4@γ-Al2O3具有最好的催化降解活性,而 CuO@γ-Al2O3, Co3O4@γ-Al2O3, CuO?Co3O4及 CuO和 Co3O4的物理混合物均表现出较差的催化性能.由此可见,在 CuO?Co3O4@γ-Al2O3催化剂中,铜、钴离子在苯酚降解过程中存在协同效应,这可能与催化剂中钴、铜金属离子的相互作用相关. X射线衍射和 X射线光电子能谱结果表明,反应前后 CuO?Co3O4@γ-Al2O3催化剂中金属的氧化状态并未发生改变,在使用过程中钴离子的浸出率可以忽略,铜离子的浸岀率也仅有0.6 ppm.荧光分析实验和自由基捕获实验表明,只有添加?O2-和?OH的捕获剂能明显抑制降解反应,因而推测该反应体系对有机物的降解是一个自由基氧化过程,起关键作用的可能是?O2-和?OH.
The development of new catalytic techniques for wastewater treatment has long attracted much attention from industrial and academic communities. However, because of catalyst leaching during degradation, catalysts can be short lived, and therefore expensive, and unsuitable for use in wastewater treatment. In this work, we developed a bimetallic CuO–Co3O4@γ‐Al2O3 catalyst for phenol degradation with bicarbonate‐activated H2O2. The weakly basic environment provided by the bicarbonate buffer greatly suppresses leaching of active Cu and Co metal ions from the catalyst. X‐ray diffraction and X‐ray photoelectron spectroscopy results showed interactions between Cu and Co ions in the CuO–Co3O4@γ‐Al2O3 catalyst, and these improve the catalytic activity in phenol deg‐radation. Mechanistic studies using different radical scavengers showed that superoxide and hy‐droxyl radicals both played significant roles in phenol degradation, whereas singlet oxygen was less important.
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