Abstract
A low-cost and eco-friendly superabsorbent composite is prepared through the free-radical graft co-polymerization of wheat bran (WB), acrylic acid (AA) and laterite (LA) in an aqueous solution. Elemental map, scanning electron microscopy and Fourier transform infrared spectra revealed that the LA evenly distributed in the superabsorbent composite and wheat bran-g-poly(acrylic acid)/laterite (WB-g-PAA/LA) formed successfully. Thermogravimetric analysis confirmed that the WB-g-PAA/LA had high thermal stability. Furthermore, the properties of the WB-g-PAA/LA, such as swelling in saline solutions and degradation, are also assessed. The final WB-g-PAA/LA (5 wt%) superabsorbent composite attained an optimum water absorbency of 1425 g g−1 in distilled water and 72 g g−1 in 0.9 wt% NaCl solution. The water absorbency of WB-g-PAA/LA (10 wt%) is even greater than that of the WB-g-PAA. Moreover, the water-retention capacity of WB-g-PAA/LA (5 wt%) is high, and the water-retention process followed a zero-order reaction. The reaction rate constant is 8.2428 × 105 exp(−Ea/RT) and the apparent activation energy (Ea) is 35.11 kJ mol−1. Furthermore, WB-g-PAA/LA (5 wt%) may regulate the release of urea, indicating that the superabsorbent composite could provide a promising application as a urea fertilizer carrier. Additionally, it increased the germination and growth rates of Glycyrrhiza uralensis Fisch, suggesting it could influence the growth of Chinese herbal medicine.
Highlights
Fertilizer and water play critical roles in increasing crop yields [1]
Compared with the FTIR spectrum of wheat bran (WB), the absorption band at 1656 cm−1 can be assigned to the stretching vibration of the −C=O in −COOH groups of the polysaccharide structure in the WB [28], but it almost disappears in the FTIR of WB-g-PAA/LA (5 wt%)
Two new absorption bands at 1558 and 1418 cm−1 appear in the FTIR of WB-g-PAA/LA (5 wt%), [29] which are ascribed to the asymmetric and symmetric stretching vibrations of –COO− groups, respectively
Summary
Fertilizer and water play critical roles in increasing crop yields [1]. application of large amounts of fertilizer has already caused serious environmental contamination and economic loss [2]. As the petrochemical products are costly, poorly degradable, non-renewable and environmentally unfriendly, the practical application of the petroleum-based superabsorbents has been severely restricted [6] To overcome these drawbacks, renewable natural resources, especially agricultural wastes, such as pineapple peel [7], peanut hull [8], wheat straw [9] and corn straw, [10] have attracted considerable research attention owing to their economic efficiency and environmental friendliness. While many reports regarding agricultural waste-based superabsorbent composites have mainly focused on their properties, including swelling and de-swelling behaviours, a few reports provided systematical research on their application as fertilizer carriers or their effects on the growth of Chinese herbal medicine [17,18]. Specific objectives included: (a) optimization of conditions to prepare the WB-g-PAA/LA superabsorbent composite; (b) studying the properties of the WB-gPAA/LA and (c) investigating its applications as a urea fertilizer carrier and in the growth of a Chinese herb
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
