摘要
浸出液pH是影响城市生活垃圾焚烧飞灰金属浸出的主要因素.通过比较pH变化浸出测试和Visual MINTEQ模拟结果,研究了浸出液pH对飞灰金属浸出特性的影响机制.结果发现,酸性条件下(Cd、Zn、Ni:pH<8;Pb、Cu、Cr:pH<6;Al:pH<4),金属会随pH降低而大量溶出;两性金属Pb和Zn,在强碱性条件时浸出浓度亦会增加,pH=12.5时可分别达42和2.4 mg.L-1.飞灰中金属的pH相关浸出行为可通过Visual MINTEQ模型很好地模拟.模拟计算结果表明,浸出液pH的变化会改变金属在浸出体系中的化学形态,从而影响金属的浸出浓度;不同pH下Pb、Zn、Cu、Ca和Al的化学形态和浸出行为主要由溶解/沉淀平衡决定,吸附作用对其影响不大;在酸性至中性pH条件下,飞灰中HFO会吸附Cd、Cr和Ni而降低其溶解度,但在碱性条件下这些重金属的浸出又转而由溶解/沉淀平衡控制.
Metals leaching behavior of air pollution control residues （APC residues） from municipal solid waste incinerator （MSWI） is greatly dependent on the leaehate pH. pH-varying leaching tests and Visual MINTEQ modeling were conducted to investigate the mechanism of pH effect on the metals leaching characteristics from MSWI APC residues. Results show that, under acidic environment （for Cd, Zn, and Ni, pH 〈 8; for Pb, Cu, and Cr, pH〈6; for Al, pH〈4）, leaching concentrations of metals increase greatly with the decrease of pH. Release of amphoterie metals, Pb and Zn, can be induced in strong alkaline leaehate, reaching to 42 and 2.4 mg·L^-1 at pH 12.5 respectively. The equilibrium modeling results are well in agreement with the analyzed leaching concentrations. Variation of leaehate pH changes the metals speeiation in the leaching system, thus influencing their leaching concentrations. Speeiation and leaching behavior of Pb, Zn, Cu, Ca, and Al mainly depend on their dissolution/precipitation reactions under different leaehate pH. Leachability of Cd, Cr, and Ni can be lowered under acidic and neutral leachate pH due to HFO adsorption, while under alkaline conditions, the effect of adsorption is not significant and dissolution/precipitation becomes the major reactions controlling the leaching toxicity of these heavy metals.
出处
《环境科学》
EI
CAS
CSCD
北大核心
2008年第1期268-272,共5页
Environmental Science
基金
上海市重点科技攻关项目(032312043)
关键词
垃圾焚烧
飞灰
PH
金属
浸出
VISUAL
MINTEQ
municipal solid waste incinerator
air pollution control residues
pH
metals
leaching
Visual MINTEQ
