酸和氧化还原剂对二氧化锰溶解度的影响
作者:
作者单位:

作者简介:

通讯作者:

中图分类号:

基金项目:


EFFECT OF ACIDS AND REDUCTANTS ON SOLUBILITY OF MANGANESE DIOXIDE
Author:
Affiliation:

Fund Project:

  • 摘要
  • |
  • 图/表
  • |
  • 访问统计
  • |
  • 参考文献
  • |
  • 相似文献
  • |
  • 引证文献
  • |
  • 资源附件
  • |
  • 文章评论
    摘要:

    由于土壤中锰的有效性随pH和Eh的变化而变化,利用土壤测试方法得到的锰素营养丰缺指标,通常难以代表田间锰素营养的实际状况.然而,在应用土壤pH和氧化锰溶解度的关系时,某些文献的不确切解释,引起一些误解.本实验研究了在浓HCl、HNO3和H2SO4及其稀溶液的不同浓度情况下对二氧化锰水钠锰矿(MnO2)的溶解能力和机理,以及三种卤素还原剂(KCl、KBr和KI)在两种pH值条件下对MnO2的还原能力,从实验上和理论上进一步阐明了pH和Eh对MnO2溶解度的影响.实验结果表明,在浓HCl中,MnO2能被Cl-迅速还原而溶解.而在浓HNO3和H2SO4溶液中,MnO2不能被酸所直接溶解,只能被酸中的H2O缓慢还原,放置两年后反应仍未到达终点.在稀酸溶液中,当H+强度小于05molL-1(pH>10)时,三种强酸对MnO2都无明显的溶解能力;当H+强度>10molL-1时,HCl对MnO2的溶解能力显著地高于HNO3和H2SO4.三种卤盐溶液对MnO2的还原能力为KI>KBr>KCl,并随pH的降低和浓度的升高而增强.当pH>3时,KCl对MnO2的还原能力极弱;而无论pH高低(pH3或pH5),KI在很低浓度(0.001molL-1)时都能有效地还原MnO2.上述结果说明,如果二氧化锰不被还原,仅改变pH则很难被溶解.然而,在较高pH条件下,如有强还原剂存在,也有相当量的MnO2被还原.低Eh和pH条件下最有利于MnO2的还原.

    Abstract:

    Owing to the fact that Mn availability in soils varying in pH and Eh,the values of available Mn determined through soil tests tend to be an irreliable indicator for the actual Mn availability to crops in the field In literature,however,there is some incorrect interpretation and confusion in discussion of the relationships between soil pH and Mn availability This study examined the solubility of manganese dioxide,in the form of birnessite(MnO2),in three acids(HCl,HNO3 and H2SO4) varying in concentration and its mechanism,and the reduction powers of three halides(KCl,KBr and KI) under two different pH conditions The effect of pH on the solubility of MnO2 was elucidated in theory and experiment Results showed that MnO2 could be dissolved instantly by HCl high in concentration In concentrated HNO3 and H2SO4,however,this was not observed A process of reduction by water took place slowly in the two acids and the reaction was still not completed in a two-year standing When the three acids were low in concentration,none noticeably dissolved the MnO2 with the H+ ion strength <0.5 mol L-1 HCl significantly dissolved much more MnO2 than HNO3 or H2SO4 when the H+ ion strength reached>1.0 mol L-1 The reduction powers of the three halides were observed as KI>KBr>KCl and further enhanced by a decrease in pH and an increase in concentration KCl had a very weak reducing power at pH>3,while KI showed a very strong reducing power even at the very low concentration(0.001 mol L-1) regardless of pHs under the test The above results further indicate that H+ perse,regardless of its concentration,cannot reduce MnO2 in the absence of reductant or e--donor On the contrary,MnO2 can be reduced in large quantity in the presence of strong reductant even at a higher pH Low Eh and pH are most favorable to reduction of MnO2 to Mn2+.

    参考文献
    相似文献
    引证文献
引用本文

涂仕华.酸和氧化还原剂对二氧化锰溶解度的影响[J].土壤学报,2004,41(4):530-535. DOI:10.11766/trxb200307230406 Tu Shihua. EFFECT OF ACIDS AND REDUCTANTS ON SOLUBILITY OF MANGANESE DIOXIDE[J]. Acta Pedologica Sinica,2004,41(4):530-535.

复制
分享
文章指标
  • 点击次数:
  • 下载次数:
  • HTML阅读次数:
  • 引用次数:
历史
  • 收稿日期:2003-07-23
  • 最后修改日期:2003-12-16
  • 录用日期:
  • 在线发布日期: 2013-02-25
  • 出版日期: