Swelling capacity of sugarcane bagasse-g-poly(acrylamide)/attapulgite superabsorbent composites and their application as slow release fertilizer

Abstract

In this work, sugarcane bagasse (SCB)-g-poly(acrylamide)/attapulgite superabsorbent composites (SBCs) were prepared by graft copolymerization of acrylamide (AM) onto SCBin presence of attapulgite (ATP) using N,N′-methylene-bis-acrylamide (MBA) as crosslinker and potassium persulfate (KPS) as initiator in aqueous solution. The composite structures were characterized by Fourier Transform Infrared spectroscopy (FT-IR), Thermal Gravimetric Analysis (TGA), X-ray powder diffraction (XRD) and Scanning Electron Microscopy (SEM). The effect of the initiator, crosslinker amounts and attapulgite/hydrogel weight ratio (0.0–14.4 wt%) on the swelling capacity was investigated. The results indicated that highest swelling capacity in distilled water was 920 g/g, obtained with the composite containing 1.3 wt% KPS, 0.08 wt% MBA, 79.9 wt% AM, 5.3 wt% ATP and 13.3 wt% SCB. Different SCBs were loaded with urea and its release was evaluated over time, showing that the urea release rate decreased by increasing ATP amount up to14.4 wt%. Therefore, the SCB-g-poly(AM)/ATP composites could have promising applications also as controlled urea release fertilizer.