Co-precipitation Phenomena in Wastewater Treatment of Dilute Toxic Anions
Co-precipitation of dilute toxic anions with ferrihydrite is an important removal mechanism in wastewater treatment system.Although,numerous qualitative studies have been published on removal characteristic from wastewater of dilute anions by co-precipitation treatment,detail mechanism or quantitative characteristic is not well understood.This paper discussed the co-precipitation mechanism of As(Ⅴ) and Cr(Ⅵ) with ferrihydrite by comparative experiments between co-recipitation and simple adsorption.In this study,co-precipitation experiments and simple adsorption ones were distinguished closely.In the former,precipitation of hydroxides and adsorption of anions develop simultaneously,but in the latter,anions adsorb onto prepared hydroxides.Although high affinity anions for hydroxides (e.g.As(Ⅴ) for ferrihydrite) showed quantitative difference of removal ratio between co-precipitation experiments and simple adsorption ones,low affinity anions (e.g.Cr(Ⅵ) for ferrihydrite) showed quantitative agreement in spite of deferent forms of ferrihydrites between them,that is,amorphous ferrihydrite was formed in co-precipitation experiments,but goethite was formed in simple adsorption ones.In order to discuss the mechanism of co-precipitation phenomena,three experimental studies have been carried out:(ⅰ) adsorption isotherm measurement in the co-precipitation experiments of As(Ⅴ) or Cr(Ⅵ) with ferrihydrite,(ⅱ) zeta potential measurement of co-precipitated or simple adsorbed ferrihydrite with As(Ⅴ) or Cr(Ⅵ),and (ⅲ) XRD analysis of co-precipitated As(Ⅴ) for ferrihydrite. All experimental results suggested the main mechanism in co-precipitation phenomena of As(Ⅴ) was not only a surface complexation (simple adsorption) but also a surface precipitation.
Wastewater treatment Co-precipitation Surface complexation Adsorption Toxic anions
C.Tokoro Y.Yatsugi A.Otsuki S.Owada H.Sasaki
Faculty of Science and Engineering,Waseda University,Tokyo,Japan
国际会议
XXIV International Mineral Processing Congress(第24届国际矿物加工大会)
北京
英文
3809-3814
2008-09-24（万方平台首次上网日期，不代表论文的发表时间）