摘要
中和沉淀Cr3 + 的 pH范围较窄 (6 .3～ 9.5 )决定了采用NaOH或CaO时投药量必须严格控制 .MgCO3 在溶液中的少量溶解导致体系具备pH缓冲性质 ,且该缓冲 pH值 (pH =8.4)能够满足中和沉淀Cr3 + 的条件 ;Cr3 + 在MgCO3 表面生成Cr(OH) 3 沉淀的界面溶度积 (KSSP=10 -3 3 .50 )小于在溶液中的溶度积 (KSP=10 -3 0 .2 7) ,Cr3 + 在界面区域比在溶液中更易形成氢氧化物沉淀 ;表面沉淀生成之后 ,MgCO3 表现出类似Cr(OH) 3 的动电行为 .采用含MgCO3 矿物菱镁石为净化剂 ,在较低用量下能够净化极高浓度含铬废水 ,不仅净化效果好而且具有沉降速度快、污泥体积小等优点 .
The pH scope for neutralization sedimentation of chromium ion is comparatively narrow (6.3～9.5) and the dosage must be controlled strictly when NaOH or CaO was used. A little dissolution of MgCO 3 makes it possible that the solution has buffer pH (pH=8.4)which accord with the condition of neutralization sedimentation of chromium ion. It is easier to form hydroxide sediment for Cr 3+ in interface area than in solution because the interfacial solubility product of Cr(OH) 3 formed on the surface of MgCO 3 is less than the solubility product in solution ( K S SP =10 -33.50 and K SP =10 -30.27 ). After surface sediment is formed, the dynamic electricity behavior of MgCO 3 is similar to Cr(OH) 3. Using magnesite as purifier, the waste water with high concentration of chromium ion is purified, and some advantages, such as good purifying effect, fast subside speed and little sediment volume are manifested. [
出处
《中南工业大学学报》
CSCD
北大核心
2000年第5期429-432,共4页
Journal of Central South University of Technology(Natural Science)
关键词
废水处理
铬离子
溶液化学
碳酸镁
净化
MgCO 3
wastewater treatment
chromium ion
solution chemistry
