Eco-friendly nano-hybrid superabsorbent composite from hydroxyethyl cellulose and diatomite

Abstract

The simultaneous introduction of green polysaccharides and low-cost inorganic clay into superabsorbent (SAP) polymeric networks has witnessed growing interest for developing eco-friendly and low-cost SAPs since the last decade. In this study, a high performance nano-hybrid SAP composite (HEC-g-PAA/diatomite) was prepared through the graft polymerization of acrylic acid into hydroxyethyl cellulose backbone chains under aqueous conditions in the presence of diatomite clay as an inorganic nano-filler, N,Nʹ-methylenebisacrylamide as the cross-linker and ammonium persulfate as the initiator. FTIR, XRD, and SEM investigations confirmed the successful synthesis of this HEC-g-PAA/diatomite nano-hybrid SAP composite with high porosity on the surface. The composite prepared under optimized conditions presented a significantly enhanced thermal stability according to the TGA and DSC analysis and remarkably improved water-retention properties at various temperatures compared with the clay-free counterpart. Our SAP showed the eminent maximum swelling ratio of 1174.85 g g⁻¹ in distilled H₂O and 99.55 g g⁻¹ in 0.9 wt% NaCl salt solutions. In addition, factors influencing various amounts of water absorbency of the prepared SAP were extensively determined and discussed. Therefore, this SAP, with a high content of biodegradable and low-cost material, could be a good candidate for hygienic products, waste-water treatment, agriculture, and horticulture uses.