College of Resource&Environment;
Hunan Agricultural University;
Changsha 410128;
China;
Hunan Engineering&Technology Research Center for Irrigation Water Purification;
Changsha 410128;
China;
Key Laboratory of Southern Farmland Pollution Prevention and Control;
Ministry of Agriculture;
Changsha 410128;
China;
Ferrihydrite; 2D-COS; Surface complexation; Electrostatic interaction; Roxarsone;