Development of a Xanthan Gum Based Superabsorbent and Water Retaining Composites for Agricultural and Forestry Applications

Abstract

In this work, bio-based hydrogel composites of xanthan gum and cellulose fibers were developed to be used both as soil conditioners and topsoil covers, to promote plant growth and forest protection. The rheological, morphological, and water absorption properties of produced hydrogels were comprehensively investigated, together with the analysis of the effect of hydrogel addition to the soil. Specifically, the moisture absorption capability of these hydrogels was above 1000%, even after multiple dewatering/rehydration cycles. Moreover, the soil treated with 1.8 wt% of these materials increased the water absorption capacity by approximately 60% and reduced the water evaporation rate, due to the formation of a physical network between the soil, xanthan gum and cellulose fibers. Practical experiments on the growth of herbaceous and tomato plants were also performed, showing that the addition of less than 2 wt% of hydrogels into the soil resulted in higher growth rate values than untreated soil. Furthermore, it has been demonstrated that the use of the produced topsoil covers helped promote plant growth. The exceptional water-regulating properties of the investigated materials could allow for the development of a simple, inexpensive and scalable technology to be extensively applied in forestry and/or agricultural applications, to improve plant resilience and face the challenges related to climate change.

Superabsorbent Hydrogels in the Agriculture and Reclamation of Degraded Areas

“…Superabsorbents, depending on their chemical composition, can be divided into two groups. The raw materials for production of acrylic SAP are mostly petroleum-based, relatively cheap synthetic copolymers produced from vinyl monomers and chemically modified natural polymers [25,26] based on starch [27][28][29], cellulose [30][31][32][33][34], chitosan [13,[35][36][37], humic acid [38], proteins [39][40][41], alginate [42][43][44][45] agar [46], curdlan [47][48][49], gellan [50], xanthan [51,52] or arabic gum [46,53,54]. It is also possible to produce SAPs as a result of alkaline hydrolysis of polyacrylonitrile waste used for the production of fibres and fabrics [55] or a combination of several processes [56].…”

“…Many materials have also been created consisting of acrylic and/or natural polymers, both chemically modified and grafted polymers additionally containing other functional ingredients (Figure 1). Additions of mineral substances such as silica [57,58], attapulgite [59], bentonite [51][52][53][54][55][56][57][58][59][60][61] or kaolin [62] are often used.…”

Exopolysaccharides Producing Bacteria: A Review

“…Xanthomonas genomes comprise different mobile genetic elements, such as transposons, insertion sequence, plasmids, and genomic islands associated with virulence factors, genetic variations, and genome structure [311]. Xanthan is synthesized through a Wzy-dependent pathway, which comprises several steps including the synthesis of exopolysaccharide precursors (nucleotide sugars GDP-mannose, UDP-glucose, and UDP-glucuronic acid), repeat-unit assembly on a lipid Xanthan is a biopolymer that has found application in food, petroleum, pharmaceutical, mining, textile, cosmetics, and other industries [3,[294][295][296][297][298][315][316][317][318][319]. This polymer is environmentally friendly and non-toxic and, therefore, used in the food industry for the last 50 years as a stabilizer and thickener.…”

“…Xanthan is a biopolymer that has found application in food, petroleum, pharmaceutical, mining, textile, cosmetics, and other industries [ 3 , 294 , 295 , 296 , 297 , 298 , 315 , 316 , 317 , 318 , 319 ]. This polymer is environmentally friendly and non-toxic and, therefore, used in the food industry for the last 50 years as a stabilizer and thickener.…”

“…Xanthan can be used as a new green-based material to produce superabsorbents and for the remediation of contaminated waters. Sorze et al (2023) developed novel biodegradable hydrogel composites of xanthan gum and cellulose fibers to be used both as soil conditioners and topsoil covers to promote plant growth and forest protection [ 318 ]. The rheological, morphological, and water absorption properties of produced hydrogels were comprehensively investigated.…”