隐钾锰型水合MnO_2的合成及其离子交换选择性

以硫酸锰和高锰酸钾为原料 ,合成了离子记忆无机离子交换剂—隐钾锰型水合二氧化锰 (CRYMO)。通过粉末X射线衍射以及热重分析确证了其晶体结构为α MnO2 ,化学式为MnO2 ·0 .4H2 O。考察了其对Na ,K ,Rb 的表观离子交换容量随溶液pH值的变化情况 ;离子交换等温线及分配系数曲线均表明隐钾锰型水合二氧化锰对K 和Rb 具有高选择性     

Effect of Crown Ethers on Sr2+, Ba2+, and Ra2+ Uptake by Tunnel‐Structure Ion Exchangers

Abstract

The effect of 15‐crown‐5 and 18‐crown‐6 ethers on the uptake of alkaline earth cations by tunnel‐structure ion exchangers polyantimonic acid (PAA) and cryptomelane manganese dioxide (CMD) was examined. In the case of PAA, 15‐crown‐5 and especially 18‐crown‐6 strongly influence the uptake of Sr²⁺ vs Ba²⁺ and Ra²⁺. For separation of the Ra²⁺‐Ba²⁺ pair, the effect of the crown ethers is insignificant. In CMD a small difference in complex formation between crown ethers and Ba²⁺ and Ra²⁺ gives an increase of separation. This effect is observed especially in 15‐crown‐5 solutions.     

物理方法从锌阳极泥中分离锰与铅银矿物工艺研究

针对株冶锌电解阳极泥, 开展了用浮选、重选和磁选等物理方法实现锰与铅银矿物分离的工艺试验研究。研究结果表明, 在锌电解阳极泥中, 锰的主要存在形式为锰钾矿(KMn₈O₁₆), 铅的主要存在形式为铅矾(PbSO₄), 银的存在形式为氯银矿(AgCl)、氧银矿(Ag₂O₃)和含氧硝酸银(Ag₇NO₁₁)。浮选可以较好地回收氯银矿等含银矿物, 但难以分离该体系中的锰钾矿和铅矾, 高梯度磁选和摇床重选可以较好的分离铅和锰, 但对含银矿物的分选效果差。采用 “浮选-高梯度磁选-摇床重选”联合流程方案, 获得了含银48 515 g/t的高品位银精矿、含铅60.89%的铅矾精矿和含锰50.17%的锰精矿, 银和铅在铅银精矿中的回收率分别达到74.71%和84.78%, 锰的回收率达到91.86%。     

The oxidative degradation of sulfadiazine at the interface of α‐MnO2 and water

BACKGROUND: Sulfadiazine (SD), a widely used antibiotic chemical, has been detected in contaminated water and soils. Manganese dioxides are common minerals with a high redox potential and can act as active oxidants for SD degradation in wastewater treatment. RESULTS: α‐MnO₂ was used to promote SD oxidative degradation. At pH 4.6 and 25 °C, 92.7% of SD (0.02 mmol L^?1) was degraded by 1.0 g L^?1α‐MnO₂. SO₄^2? was detected as the inorganic end product from the mineralization of SD. The ecological toxicity index of average well color development (AWCD) in SD solution was 2.01 after the solution was degraded by α‐MnO₂ for 2 h, while the AWCD was 0.48 for the solution without α‐MnO₂ treatment. The degradation rate of SD can be improved by increasing the dosages of α‐MnO₂ and the reaction temperature, but the rate was limited by increased initial SD concentration and reaction pH. CONCLUSION: SD can be effectively degraded and mineralized with α‐MnO₂. These results are helpful for removing antibiotics by manganese dioxides in the environment, and also for exploring new technology for wastewater treatment. Copyright © 2009 Society of Chemical Industry