Impact of natural organic matter on arsenic removal by modified granular natural siderite: Evidence of ternary complex formation by HPSEC-UV-ICP-MS.
High arsenic (As) groundwater usually has high concentrations of natural organic matter (NOM). Effects of NOM on arsenic adsorption were investigated to evaluate the efficiency of modified granular natural siderite (MGNS) as an adsorbent for groundwater arsenic remediation. Humic and fulvic acids (HA/FA) were selected as model NOM compounds. In batch tests, HA or FA was either first adsorbed onto the MGNS, or applied together with dissolved arsenic to investigate effects of both adsorbed and dissolved NOM on arsenic removal. The kinetic data showed no significant effects of both adsorbed and dissolved HA/FA on As(III) adsorption. However, As(V) removal was inhibited, whereby the adsorbed NOM compounds had greater inhibitory effect. The inhibitory effect on As(V) removal increased with increasing NOM concentrations. FA exhibited higher inhibitory effect than HA at the same concentration. Steric Exclusion Chromatography-HPLC (SEC-HPLC), and High-Performance Size Exclusion Chromatography-UV-Inductively Coupled Plasma Mass Spectrometry (HPSEC-UV-ICP-MS) revealed that As(V) removal was mostly achieved by the oxyanion adsorption and adversely affected by dissolved FA via competitive adsorption for surface sites. In addition to oxyanion adsorption, removal of As(V) was related to scavenging of ternary HA-As-Fe complexes, which led to the less inhibitory effect of dissolved HA on As(V) removal than dissolved FA via competitive adsorption.
State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Beijing 100083, PR China; School of Water Resources and Environment, China University of Geosciences (Beijing), Beijing 100083, PR China.
Fulan
F
Li
State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Beijing 100083, PR China; School of Water Resources and Environment, China University of Geosciences (Beijing), Beijing 100083, PR China. Electronic address: hmguo@cugb.edu.cn.
Huaming
H
Guo
State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Beijing 100083, PR China; School of Water Resources and Environment, China University of Geosciences (Beijing), Beijing 100083, PR China.
Xiaoqian
X
Zhou
China Institute for Geo-environmental Monitoring, Beijing 100081, PR China.
Kai
K
Zhao
State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Beijing 100083, PR China; School of Water Resources and Environment, China University of Geosciences (Beijing), Beijing 100083, PR China.
Jiaxing
J
Shen
School of Water Resources and Environment, China University of Geosciences (Beijing), Beijing 100083, PR China.
Fei
F
Liu
National Institute of Metrology, Beijing 100013, PR China.
Chao
C
Wei
D000327:Adsorption; D001151:Arsenic / Q000032:analysis / Q000737:chemistry*; D001578:Benzopyrans / Q000737:chemistry*; D002254:Carbonates / Q000737:chemistry*; D002850:Chromatography, Gel; D002851:Chromatography, High Pressure Liquid; D052918:Environmental Restoration and Remediation / Q000379:methods*; D005290:Ferric Compounds / Q000737:chemistry*; D060587:Groundwater / Q000737:chemistry*; D006812:Humic Substances; D013058:Mass Spectrometry; D009930:Organic Chemicals / Q000737:chemistry; D013057:Spectrum Analysis; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000737:chemistry*
D001578:Benzopyrans; D002254:Carbonates; D005290:Ferric Compounds; D006812:Humic Substances; D009930:Organic Chemicals; D014874:Water Pollutants, Chemical; C486982:siderite; D001151:Arsenic; C005023:fulvic acid
Adsorbed organic matter; Aggregation; Competitive adsorption; Dissolved organic matter; Fulvic acid; Humic acid