Tan X1, Gao W1, Duan Z1,2, Zhu N1, Wu X3, Ali I1, Ruan Y4
1 Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, College of Environment, Hohai University, Nanjing 210098, China, 2 College of Hydrology and Water Resources, Hohai University, Nanjing 210098, China, 3 College of Environmental Science and Engineering, Yangzhou University, Yangzhou, Jiangsu, 225009, China, 4 Institute for Photonics and Advanced Sensing, The University of Adelaide, SA 5005, Australia
Correspondence: Duan Zhipeng, hhualgae@163.com
Adsorption is assumed as an effective and reliable method to recover phosphorus (P) from sewages. Extracellular polymeric substances (EPS) and agarose are common polysaccharides bio-resources. Their carboxylic and phenolic hydroxyl groups directly adsorbed P by ion exchange and hydrogen bonds. Here, we designed EPS-based and Fe-modified hydrogels (agarose (AG) and agarose-humic (AH) based hydrogels) for P recovery. The effects of coexisting anions (i.e., SO42-, NO3–, and CO32-) and pH (pH=3-10) on adsorption were tested. AG and AH hydrogels adsorbed 33.9 and 67.7 mg P g-1, respectively. Both as-developed hydrogels showed >75% of the maximal adsorption capacity in the tested pH conditions. Coexisting anions did not significantly affect the adsorption performance, except for CO32-which inhibited the process. Intra-particle diffusion controlled the adsorption process. After adsorption, large amounts of FePO4 and Fe2(HPO4)3 were generated in the hydrogels, confirming that ligand exchange was the major driving force. Overall, the developed EPS-based hydrogels can be used to remove and recover P from water efficiently.