One-pot preparation of amphoteric cellulose polymers for simultaneous recovery of ammonium and dihydrogen phosphate from wastewater and reutilizing as slow-release fertilizer

In this paper, a simple approach was developed to prepare amphoteric cellulose adsorbent (EAC) through etherification of cellulose with glycidyl trimethyl ammonium chloride (ETA) and glycidylsulfonoic acid sodium salt (SEP) in a one-pot reaction system. The effect of the molar ratio of cellulose to ETA and SEP on the contents of sulfur and nitrogen elements in the EAC was evaluated with the aim of deriving the adsorbents with amounts of ionic functional groups. The EAC was examined for adsorption to NH4+ and H2PO4- ions. Meanwhile, the effect of adsorption parameters, including dosage of EAC, pH value of solution, contact time and ionic strength, on its adsorption capacity was also analyzed. The EAC displayed excellent affinity to the targeted ions, with an adsorption capacity of 40.38 mg/g for NH4+ and 30.42 mg/g for H2PO4-. The adsorption of EAC for NH4+ and H2PO4- reached equilibrium within 30 min and was fitted by second-order and Langmuir models well. More importantly, the EAC after adsorption could be recovered and recycled as a slow-release fertilizer, which could release approximately 95.5% of NH4+ and 92.5% of H2PO4− within 30 days. The results demonstrated that the EAC after adsorption would be reutilized as a slow-release fertilizer, which would give highlights on cost-effective and eco-friendly development in agriculture.