THE SYNTHESIS OF BIODEGRADABLE CROSS-LINKED POLYMER HYDROGELS BASED ON COTTON LINT, THE STUDY OF THEIR PROPERTIES AND THEIR APPLICATION IN AGRICULTURE

Abstract

Water scarcity and the instability of the irrigation regime, especially in arid and semi-arid regions, are among the main factors limiting the sustainable development of agricultural production. In this study, biodegradable hydrogels based on cotton lint were synthesized as cross-linked polymer hydrogels via a free-radical mechanism on the basis of partially neutralized acrylic acid. Ammonium persulfate was used as the initiator and N,N′-methylenebisacrylamide as the cross-linking agent, so that a three-dimensional polymer network was formed. The physico-chemical properties of the synthesized hydrogels were studied comprehensively. The results of the study showed that the hydrogels possess a water absorption capacity of 450–800 g/g in distilled water and of 120–250 g/g in a saline medium. The gel fraction and the degree of cross-linking confirmed the formation of a stable polymer network. Biodegradation tests carried out under soil conditions established that the hydrogels degraded by 70–85 % over 180 days. Vegetation experiments conducted under agricultural conditions showed that applying the hydrogels to the soil at a rate of 1.0–2.0 g/kg significantly increases the level of soil moisture retention and improves plant biomass formation by 25–30 % under reduced irrigation. The results obtained confirm that biodegradable hydrogels based on cotton lint are an environmentally safe, economically expedient and promising material for the efficient use of water and for increasing yield.