Carboxylated nanocellulose superabsorbent: Biodegradation and soil water retention properties

Abstract

Carboxylated nanocellulose superabsorbent polymers (SAP) can be used to increase soil water retention in agriculture. The benefits investigated are influenced by the superabsorbent structure, composition and application rate.In this study, TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl)-oxidised nanocellulose superabsorbents were prepared using three different drying techniques: freeze-dried, and oven-dried at low and high temperatures. The swelling capacity in soil water extracts was measured and compared to deionised water. Soil was amended with different application rates of these superabsorbents to evaluate the effects on water retention, microbial community and their biodegradation.The absorption performance of nanocellulose superabsorbents is affected by the concentration and type of salts in the soil water extracts. Oven-dried at 50 °C SAP presents the highest ionic sensitivity attributed to its large number of accessible carboxylate groups. The water retention of the soil treatments increases with increasing application rate. Soil treated with the freeze-dried superabsorbent shows the highest water retention, whereas those amended with the 50°C oven-dried SAP remain moist the longest. The biodegradation rate of these materials depends on the application rate and nutrient availability. Carboxylated nanocellulose superabsorbents emerge as highperformance biodegradable materials for agricultural use, able to replace the current nonbiodegradable petrochemical-based superabsorbents. INTRODUCTIONWater is critical for agricultural production and food security. Irrigated agriculture uses about 70% of the water available for human consumption worldwide and accounts for 59% of the total fresh water in Australia (Organisation for Economic Co-operation and Development; Department of Agriculture 2020). Water availability has been impacted by climate change, drought and water shortage; its decrease has affected world agricultural development in recent years. According to Müller C. (2010), agricultural yields will decline between 2 -15% over the next 30 years due to climate change. Hence, the efficient use of water resources is crucial for the long-term sustainability of the agricultural industry.One strategy to optimise water retention in soils and hence making it more available to crops, is the use of superabsorbent polymers (SAPs) (Zohuriaan-Mehr et al. 2008). SAPs are three-dimensional (3D) networks of linear or branched hydrophilic polymers physically or chemically cross-linked (Guilherme et al. 2015). SAPs can absorb and hold water at hundreds of times their own weight and remain stable in their swollen state (Ahmed 2015;Ghorbani et al. 2019;Shen et al. 2016;Gross JR 1990). They have been extensively used in many applications including biomedicine (Curvello et al. 2019), food and beverages (Shewan and Stokes 2013), personal care and hygiene products (Bashari et al. 2018). In the agricultural and horticultural industries, SAPs have a range of applications which includes seed coatings, seed additives and root dips (Zoh...

Advanced applications of sustainable and biological nano-polymers in agricultural production

“…Cellulose nanofibers (CNF) derived from (2,2,6,6-Tetramethylpiperidin-1-yl)oxyl (TEMPO) mediated oxidation have been shown to increase water retention for a longer time compared to control soils. Soils remedied with a 1.0 wt% superabsorbent exhibited slower water evaporation than control, delaying wilting up to 20 days, suggesting that CNF superabsorbents may have use in soil conditioning and prolonging water retention in dry soils (Barajas-Ledesma et al, 2022). Cellulosic NP may also be used in conjunction with inorganic NP such as iron to improve the loading efficiency of hydrogels and provide prolonged, consistent release of fertilizers.…”

“…This demand for increased productivity without expanding agricultural lands could be achieved with the use of nanotechnology. Nanotechnology can address several agricultural issues such as the controlled release of active compounds (Singh et al, 2021), selective targeting of pests (Hao et al, 2020;Monteiro et al, 2021), efficient delivery of fertilizers (Guilherme et al, 2010;Ekanayake and Godakumbura, 2021), photoprotection of light-sensitive herbicides (Nguyen et al, 2012), and a way to remediate depleted or dry soils (Kathi et al, 2021;Barajas-Ledesma et al, 2022), but have yet to see widespread practical use. The hesitation surrounding nano-enabled agriculture stems from the many "unknowns" concerning nanomaterials in the environment: what is their fate in soil (Singh and Gurjar, 2022)?…”

Screening Additives for Amending Compacted Clay Covers to Enhance Diffusion Barrier Properties and Moisture Retention Performance

“…The dosage and ratio of dual-additives were determined through the orthogonal test. The test was conducted according to the following procedure: (1) placing the specimens in a 70 × 55 mm perforated aluminum box after sealing for 14 d; (2) placing the specimens in the oven, the temperature was targeted to be 60 • C, recording the mass change per three hours, and calculating the moisture retention percent of the specimens according to Equation (1) [35][36][37][38].…”

Biodegradation of a Nanocellulose Superabsorbent and Its Effect on the Growth of Spinach (Spinacea oleracea)

“…These studies reported cellulose-based SAPs to be effective in slowing the release of fertilizers in water and soil. However, few studies have measured the effect of nanocellulose-based SAPs on plant growth in a controlled soil environment not their biodegradability . Limited information relating the impact of these SAPs to plant yield and soil microbial activity is available using different types of soils.…”

“…However, few studies have measured the effect of nanocellulose-based SAPs on plant growth in a controlled soil environment not their biodegradability. 27 Limited information relating the impact of these SAPs to plant yield and soil microbial activity is available using different types of soils. Singh et al recently reviewed a range of materials with their applications in soil and effects on plant growth including cellulosic-based SAPs.…”