Ferrihydrite transformation impacted by coprecipitation of lignin:Inhibition or facilitation?  

作　　者：Lin Liu Zhihui Yang Weichun Yang Wen Jiang Qi Liao Mengying Si Feiping Zhao 

机构地区：[1]School of Metallurgy and Environment,Central South University,Changsha 410083,China [2]Chinese National Engineering Research Center for Control&Treatment of Heavy Metal Pollution(CNERC-CTHMP),Changsha 410083,China

出　　处：《Journal of Environmental Sciences》2024年第5期23-33,共11页环境科学学报（英文版）

基　　金：supported by the National Key Research and Development Program of China(No.2020YFC1808002);the National Natural Science Foundation of China(Nos.52104406,and U20A20267);the Natural Science Foundation of Hunan Province(Nos.2022JJ20074,and 2020JJ4740)。

摘　　要：Lignin is a common soil organic matter that is present in soils,but its effect on the transformation of ferrihydrite(Fh)remains unclear.Organic matter is generally assumed to inhibit Fh transformation.However,lignin can reduce Fh to Fe(Ⅱ),in which Fe(Ⅱ)-catalyzed Fh transformation occurs.Herein,the effects of lignin on Fh transformation were investigated at 75℃ as a function of the lignin/Fh mass ratio(0-0.2),pH(4-8)and aging time(0-96 hr).The results of Fh-lignin samples(mass ratios=0.1)aged at different pH values showed that for Fh-lignin the time of Fh transformation into secondary crystalline minerals was significantly shortened at pH 6 when compared with pure Fh,and the Fe(Ⅱ)-accelerated transformation of Fh was strongly dependent on pH.Under pH 6,at low lignin/Fh mass ratios(0.05-0.1),the time of secondary mineral formation decreased with increasing lignin content.For high lignosulfonate-content material(lignin:Fh=0.2),Fh did not transform into secondary minerals,indicating that lignin content plays a major role in Fh transformation.In addition,lignin affected the pathway of Fh transformation by inhibiting goethite formation and facilitating hematite formation.The effect of coprecipitation of lignin on Fh transformation should be useful in understanding the complex iron and carbon cycles in a soil environment.

关 键 词：Ferrihydrite transformation LIGNIN HEMATITE GOETHITE Fe(Ⅱ)-catalyzed Reactive Fe(Ⅲ)species 

分 类 号：X144[环境科学与工程—环境科学]