Fabrication and properties of a novel superabsorbent composite based on coco peat and poly (acrylic acid) cross-linked trimethylolpropane trimaleate under ultraviolet irradiation

Abstract

A series of novel poly(acrylic acid)/coco peat (PAA/CP) superabsorbent composites were prepared via the ultraviolet irradiation copolymerization of acrylic acid monomer (PAA) and coco peat cellulose (CP) in the presence of the cross-linker trimethylolpropane trimaleate. The physico-chemical structures of obtained PAA/CP were characterized by Fourier transform infrared spectroscopy, thermogravimetry/derivative thermogravimetry, X-ray diffraction, and scanning electron microscopy, respectively. The critical parameters of affecting the water absorbency of PAA/CP, including the cross-linker level, amount of CP and reaction time, were studied in detailed. The experimental results showed that the PAA/CP samples exhibited the maximum swelling value of 523.09 g/g in distilled water and 40.52 g/ g in 0.9 wt % NaCl solution. The swelling behaviors of PAA/CP were significantly relied on the concentration of salt solution and the pH of external solution. The effect of ions species on the swelling performance was in the order: Na + > Ca 2+ > Fe 3+ , and in pH 2.2 and 7.2 aqueous solutions PAA/CP composites displayed better pH-responsiveness and reversible on-off switching characteristics. Urea, as an agrochemical model, was loaded into PAA/CP substrate to supply with nitrogen nutrient. The test of their loading and releasing diffusion performance of urea suggested that the urea loading percentage of PAA/CP was remarkably dependent on the concentration of aqueous urea solutions and the release of urea from loaded PAA/CP samples in water followed a non-Fickian mechanism. Owing to their considerable good water absorption capacity, slow urea release, economical and environment-friendly merits, PAA/CP composites could be exploited for the agriculture applications.

Fine tuning of SAP properties via epoxy-silane surface modification

“…Since their first introduction, these polymers have gone through series of structural modifications in order to meet the needs in hygiene and other industries . For instance, superabsorbents with improved gel strength in their swollen state have been designed utilizing composite and nanocomposite polymer hydrogels, hybrid physical and chemical cross‐linking, slide ring polymer gels, interpenetrating polymer networks (IPNs) and double networks . Clays and silica have also been investigated as multifunctional cross‐linkers in order to improve gel strength by adding crystallinity to an amorphous medium .…”

“…To the best of our knowledge based on two decades of research on SAPs, despite pervasive use of epoxy silanes (EPSs) in latex and coating applications, they have not been used in surface treatment of SAPs. Accordingly, the present work is the first original report on organic–inorganic surface treatment of SAP particles by 3‐[(2, 3‐epoxy propoxy)‐propyl]‐trimethoxysilane (EPS).…”

Preparation of an Attapulgite-Modified Composite Hydrogel and Application in an Environmentally Responsive Green Fertilizer

“…Zhang et al 12 created a highly absorbent hydrogel by grafting a copolymer of acrylic acid and acrylamide (AA-co-AM) on a mulberry branch, which was subsequently loaded with urea to create an environmentally friendly slow-release urea fertilizer. Through ultraviolet irradiation copolymerization of acrylic acid monomer and coco peat cellulose in the presence of the cross- linker trimethylolpropane trimaleate, Su et al 13 created a novel poly(acrylic acid)/coco peat (PAA/CP) superabsorbent composite hydrogel. Additionally, urea can be added to the PAA/CP hydrogel at a high loading.…”