High water absorbents from lignocelluloses. I. Effect of reaction variables on the water absorbency of polymerized lignocelluloses

Hydrogels of 350 water-absorbency (g H2O2/g sample) and 900 water-keeping c apacity (mL H2O2/g sample) were prepared from local lignocellulosic wastes. The wastes used are rice straw, sugar-cane bagasse, and cotton stalks. The se hydrogels were prepared via graft-polymerization reaction using some vin yl monomers, followed by alkali hydrolysis. The effects of grafting paramet ers (concentration of both initiator and monomer, temperature, and time), p urity of lignocellulose sample, type of monomer, pretreatment of lignocellu lose, and manner of saponification reaction were examined. The application of such polymeric materials as soil conditioners, by follow ing the pore size distribution of sand soil, in comparison with conventiona l soil conditioners (e.g., natural organic fertilizer and clay), were also evaluated.