Fenton-like redox-initiated synthesis of superabsorbent composites with excellent water retention and swelling properties based on green tea and oil shale semi-coke

Abstract

Much increasing attention recently has been paid for the design of superabsorbent composites with superior adsorption/retention performances by economic and efficient preparation process. Herein, a facile and economic preparation strategy were employed for preparation of high-performance superabsorbent composites based on the redox-reaction between the components derived from natural green tea (GT) and calcined oil shale semi-coke (COSSC). The as-prepared chitosan-grafting-polyacrylic acid/green tea/calcined oil semi-coke (CS-g-PAA/GT/COSSC) superabsorbent composites showed the favorable water absorption capability and water uptake rate of 404 g/g in distilled water and 62 g/g in 0.9 wt% NaCl solution in 30 mins. After being buried for 90 days in soil, the superabsorbent composites indicated a 57 % biodegradation rate due to the presence of natural polymer of CS and GT residues. The superabsorbent composites also exhibited the perfect water retention capacity in soil, the total seed biomass and stem length of cabbage increased by 27.20 % and 30 %, after incorporation of 0.5 % of superabsorbent composites in soil, respectively. Based on the excellent water absorption, water retention and growth-promoting properties, the high efficient and economic superabsorbent composites prepared via low temperature-initiated polymerization presented a great potential in the charge of arid and semi-arid agriculture.