Environmentally friendly superabsorbent polymers for water conservation in agricultural lands

Abstract

Polymer complexes of crosslinked carboxymethyl cellulose (CMC) and starch were synthesized to form superabsorbent polymers (SAP) and their performances as a water retaining aid for irrigation were assessed. The SAP was crosslinked with aluminum sulfate octadecahydrate for optimum water retention. Starch from vegetables and chemically modified cellulose fibers were used as the basis for the polymer structure because of their biodegradability and the sustainability of their sources. The starch vegetables include potatoes, yam, cassava, and corn. Radish seeds were planted in pots that contained soil amended with the SAPs (as well as soils control with no amendment). For the first two weeks the plants were given a healthy amount of water, then watering was reduced to observe how the plants responded to drought. The plants with no amendment to the soil stopped growing after the first two weeks and showed signs of dehydration. All the plants in the amended soil continued to grow after the first two weeks and they looked much healthier. Performance evaluation of the response to the four starch types suggests that potato based SAP performed the best with 73% water retention, while corn gave 56%. The study also suggests that lower dosage of 0.12% by weight of the potato based SAP performed better than 0.24% when used for soil amendment.   Key words: Carboxymethyl cellulose, starch, superabsorbent polymer, water retention, biodegradable.