Biodegradable superabsorbent hydrogel for water holding in soil and controlled‐release fertilizer

Abstract

The bio‐based environment‐friendly functional polymers are the most desired materials for the society. Thus, a superabsorbent hydrogel (SAH) of starch‐modified poly(acrylic acid) was reported and the concentrations of reactants, initiators, and crosslinkers were optimized to achieve the highest water absorption (>700 g/g). The chemical structure of SAH was supported by solid‐state 13C nuclear magnetic resonance and Fourier‐transform infrared spectroscopic studies. The hydrogels were found to be biodegradable and possess high water absorption capacity. After the addition of 0.25% of the hydrogel, water‐holding capacity of the soil was enhanced by 120%. Significant effect was also observed on bulk density and porosity of the soil after the addition of SAH. Furthermore, urea‐encapsulated SAH can be used as a controlled release fertilizer for crops, as indicated by a preliminary study on the growth rate of chick pea (Cicer arietinum) plant. Thus, SAH has the potential to be used as a controlled‐release carrier and water‐conserving agent in different fields. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48495.

Hydrogels Based on Starch from Various Natural Sources: Synthesis and Characterization

“…Hydrogels with a slow release of nutrients prevent over-fertilization of the soil, thus avoiding salinization and subsequent contamination of groundwater. [16,28,29] In this work, hydrogels were synthesised by grafting AA and AAm on starches, obtained from different natural sources, using PSA as initiator and MBA as cross-linking agent. The aim of this study was to find conditions for preparation of hydrogels with properties suitable for agricultural applications; in particular, high swelling and low solubility.…”

Biopolymer Hydrogel Based on Acid Whey and Cellulose Derivatives for Enhancement Water Retention Capacity of Soil and Slow Release of Fertilizers

“…The biodegradability of the hydrogel was studied through burial in garden soil (pH ∼6.0) [ 14 ]. Hydrogel samples of defined size (2 × 20 mm 2 ) were placed approximately 10 cm beneath the surface of the soil in the pots.…”

Functional starch-based hydrogels: renewable material solutions for wastewater and agriculture industries

“…In addition to biological activities, biodegradation of agricultural polymers is often influenced by various environmental factors, including exposure to ultraviolet radiation, chemical oxidisers, fertiliser salts, mechanical abrasion, and freeze-thaw events, which result in the breakdown of the polymer into smaller fragments, leading to a decline and ultimately loss of functional properties in these materials (Mignon et al, 2019). In most previous studies, biodegradability has been highlighted as a unique advantage of starch-based polymeric materials as a better alternative to traditional petroleum-based polymers (Sarmah & Karak, 2019). This feature is particularly important in the design of polymeric materials for environmental applications (i.e.…”

“…starch) is only included in small quantities, which makes them unsuitable for agricultural applications (Chandrika et al, 2014;Helaly et al, 2005;Thombare et al, 2018;Zhu et al, 2012). A relatively small number of previous studies have investigated massloss of starch-based hydrogels in soil, over a short period of time (30-90 days), mainly focusing on estimating the rates of biodegradation based on mass-loss (Jin et al, 2013;Sarmah & Karak, 2019).…”

“…starch-based hydrogels) for environmental applications has been highlighted as an advantage, the kinetics and mechanisms of their biodegradation in soil has rarely been studied (Saha et al, 2020). A relatively small number of previous studies investigated mass-loss of these hydrogels in soil over a short period of time (30-90 days), mainly focusing on estimating the rates of biodegradation based on mass-loss (Sarmah & Karak, 2019). For example, Riyajan and Wongsa (2013) investigated the effects of addition of starch and natural rubber (0-15% relative to total feed), as well as chemical crosslinking on the weight loss rate of PAM hydrogels in soil, during a 90-day trial.…”