Fabrication of carboxymethyl tamarind kernel gum-based hydrogel and its applicability in different types of soils for agronomy

An avant-garde agricultural hydrogel - Carboxymethyl tamarind kernel gum-poly sodium acrylate-polyacrylamide hydrogel was designed by free-radical polymerization of biopolymer: carboxy-methyl tamarind kernel gum and monomers: sodium acrylate, acrylamide, using N,N' methylene bisacrylamide as crosslinker and potassium persulphate as initiator, to explore its application as a soil conditioner. It was characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, and thermogravimetric techniques. Swelling was investigated at different pH and in saline solutions. The fabricated hydrogel absorbed 189 ml/g of distilled water. Minimal 0.1 % hydrogel-amended different soils unveiled an upswing in maximum water holding capacity: Sandy soil (43%), Clay soil (31 %), Silty soil (29 %) & Loamy soil (9 %).; decrease in porosity: Sandy (29 %) > Loamy (15.2 %) > Silty (6 %) > Clay (5.9 %), increase in available water content: Clay soil (17.52 %), Silty (13.45 %), Loamy soil (9.416 %), Sandy soil (10.375 %); increase in bulk density: Clay (1.7 %), Silty (5.3 %), Loamy (10 %) and Sandy (13%) as compared to control sample. These sequels were corroborated by water retention capacity in chickpea plants. The designed hydrogel, as a soil conditioner, was commendable in all types of soils but is worth applying in sandy and loamy soils. This hydrogel richly assists as a soil conditioner and boosts plant performance in a green eco-friendly way.

Urea intercalated encapsulated microalgae composite hydrogels for slow-release fertilizers

In agriculture, hydrogels can be addressed for effective operation of water and controlled-release fertilizers. Hydrogels have a significant ability for retaining water and improving nutrient availability in soil, enhancing plant growth while reducing water and fertilizer usage. This work aimed to prepare a hydrogel composite based on microalgae and biopolymers including chitosan and starch for use as a soil conditioner. The hydrogel composite was characterized by FTIR, XRD, and SEM. All hydrogel properties were studied including swelling degree, biodegradability, water-holding capacity, water retention, and re-swelling capacity in soil and water. The urea fertilizer loading and releasing behavior of the prepared hydrogels were investigated. The results revealed that the range of the maximal urea loading was between 99 and 440%, and the kinetics of loading was fitted with Freundlich model. The urea release % exhibited 78-95%, after 30 days, and the kinetics of release was fitted with zero-order, Higuchi, and Korsmeyer-Peppas models. Furthermore, the prepared hydrogels obtained a significant water-holding capacity, after blending soil (50 g) with small amount of hydrogels (1 g), the capacity increased in the range of 99.4-101.5%. In sum, the prepared hydrogels have the potential to be applied as a soil conditioner.

Natural gums and their derivatives based hydrogels: in biomedical, environment, agriculture, and food industry

The hydrogels based on natural gums and chemically derivatized natural gums have great interest in pharmaceutical, food, cosmetics, and environmental remediation, due to their: economic viability, sustainability, nontoxicity, biodegradability, and biocompatibility. Since these natural gems are from plants, microorganisms, and seaweeds, they offer a great opportunity to chemically derivatize and modify into novel, innovative biomaterials as scaffolds for tissue engineering and drug delivery. Derivatization improves swelling properties, thereby developing interest in agriculture and separating technologies. This review highlights the work done over the past three and a half decades and the possibility of developing novel materials and technologies in a cost-effective and sustainable manner. This review has compiled various natural gums, their source, chemical composition, and chemically derivatized gums, various methods to synthesize hydrogel, and their applications in biomedical, food and agriculture, textile, cosmetics, water purification, remediation, and separation fields.

Novel hydrogel poly (GG-co-acrylic acid) for the sorptive removal of the color Rhodamine-B from contaminated water

Textile effluent's treatment is highly desired due to the presence of hazardous, water-soluble and non-biodegradable dyes that not only have harmful effect on the environment but on living beings as well. Treatment of these pollutants by sorption through biosorbents is considered to be a best method of choice due to greener nature of the processes. In this connection hydrogel sorbents might be an intriguing option due to its straightforward application, great efficacy, easy synthesis, rapid turnaround, and potential of recycling. Herein, novel hydrogel was prepared using Gellan Gum and acrylic acid (GG-co-AAc) which were then characterized by instrumental techniques like UV/visible and FTIR spectroscopy, SEM, EDX and XRD. The anionic hydrogel's adsorption capacity, swelling behavior, and sorption potential were determined using Rhodamine-B as potential environmental pollutant. The hydrogel exhibited an impressive adsorption capacity of 1250 mg/g. Swelling experiments were performed in Milli-Q distilled water at different pH levels, reaching maximum swelling of 3230% after 23 h as determined through Fickian diffusion. At pH 7, the anionic hydrogel's sorption potential was thoroughly studied in the subsequent experiments. The adsorption process was found to follow the Langmuir isotherm, indicating a monolayer adsorption mechanism supported by higher R2 values compared to the Freundlich isotherm. Thermodynamic analysis revealed the exothermic nature of the adsorption process, with a negative enthalpy value of -11371 KJmol-1 and negative entropy value of -26.39 Jmol-1K-1, suggesting a less ordered system. These findings provide valuable insights into the adsorption characteristics and potential applications of the synthesized anionic hydrogel.

Development and evaluation of pH sensitive semi-interpenetrating networks: assessing the impact of itaconic acid and aloe vera on network swelling and cetirizine release

Hydrogels are crosslinked three-dimensional networks, and their properties can be easily tuned to target the various segments of the gastrointestinal tract (GIT). Cetirizine HCl (CTZ HCl) is an antihistaminic drug, which when given orally can upset the stomach. Moreover, this molecule has shown maximum absorption in the intestine. To address these issues, we developed a pH-responsive semi-interpenetrating polymer network (semi-IPN) for the delivery of CTZ HCl to the lower part of the GIT. Initially, 10 different formulations of itaconic acid-grafted-poly (acrylamide)/aloe vera [IA-g-poly (AAm)/aloe vera] semi-IPN were developed by varying the concentration of IA and aloe vera using the free radical polymerization technique. Based on swelling and sol-gel analysis, formulation F5 containing 0.3%w/w aloe vera and 6%w/w IA was chosen as the optimum formulation. The solid-state characterization of the optimized formulation (F5) revealed a successful incorporation of CTZ HCl in semi-IPN without any drug-destabilizing interaction. The in vitro drug release from F5 showed limited release in acidic media followed by a controlled release in the intestinal environment for over 72 h. Furthermore, during the in vivo evaluation, formulation F5 did not affect the hematological parameters, kidney, and liver functions. Clinical observations did not reveal any signs of illness in rabbits treated with hydrogels. Histopathological images of vital organs of treated animals showed normal cellular architecture. Thus, the results suggest a non-toxic nature and overall potential of the developed formulation as a targeted drug carrier.

Facile synthesis of biopolymer decorated magnetic coreshells for enhanced removal of xenobiotic azo dyes through experimental modelling

Since contamination of xenobiotics in water bodies has become a global issue, their removal is gaining ample attention lately. In the present study, nZVI was synthesized using chitosan for removal of two such xenobitic dyes, Bromocresol green and (BCG) and Brilliant blue (BB), which have high prevalence in freshwater and wastewater matrices. nZVI functionalization prevents nanoparticle aggregation and oxidation, enhancing the removal of BCG and BB with an efficiency of 84.96% and 86.21%, respectively. XRD, FESEM, EDS, and FTIR have been employed to investigate the morphology, elemental composition, and functional groups of chitosan-modified nanoscale-zerovalent iron (CS@nZVI). RSM-CCD model was utilized to assess the combined effect of five independent variables and determine the best condition for maximum dye removal. The interactions between adsorbent dose (2-4 mg), pH (4-8), time (20-40 min), temperature (35-65 0C), and initial dye concentration (40-60 mg/L) was modeled to study the response, i.e., dye removal percentage. The reaction fitted well with Langmuir isotherm and pseudo-first-order kinetics, with a maximum qe value of 426.97 and 452.4 mg/g for BCG and BB, respectively. Thermodynamic analysis revealed the adsorption was spontaneous, and endothermic in nature. Moreover, CS@nZVI could be used up to five cycles of dye removal with remarkable potential for real water samples.

DOE-based synthesis of gellan gum-acrylic acid-based biodegradable hydrogels: screening of significant process variables and in situ field studies

The current study uses the free radical graft copolymerization of acrylic acid as a monomer, N,N-methylene-bis-(acrylamide) as a crosslinker and ammonium persulfate as an initiator to synthesise GG-cl-poly(AA) hydrogels based on gellan gum utilising response surface methodology (RSM). A full factorial design was used to obtain the greatest percent swelling (P_s), and key process variables were determined using the Pareto chart. To make the procedure cost-effective, a multiple regression model employing ANOVA projected a linear model with a maximum percentage swelling of 556 at the lowest concentration of all three studied factors. As a result, the sequential experimental design was successful in obtaining two-fold increases in the percentage swelling in a systematic way. An RSM-based central composite design was used to optimize the percentage swelling of the three most important synthesis parameters: initiator concentration, monomer concentration, and crosslinker concentration. The best process conditions are 7.3 mM L⁻¹ initiator, 44 μM L⁻¹ monomer, and 21.6 mM L⁻¹ crosslinker. The effective synthesis of GG-cl-poly(AA) was validated by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction, field emission scanning electron microscopy (FE-SEM), and ¹H-nuclear magnetic resonance. The swelling behavior of GG-cl-poly(AA) in water and saline solutions, as well as its water retention capability, was investigated. In comparison to distilled water, the swelling potential of optimized hydrogel was shown to be significantly reduced in saline solutions. The addition of GG-cl-poly(AA) significantly improved the moisture properties of plant growth media (clay, sandy, and clay–soil combination), implying that it has great potential in moisture stress agriculture. GG-cl-poly(AA) biodegradation was studied by soil burial and vermicomposting methods. The composting approach showed 89.95% deterioration after 22 days, while the soil burial method showed 86.71% degradation after 22 days. The synthesized hydrogel may be beneficial for agricultural applications because of its considerable degradation behaviour, strong water retention capacity, low cost, and environmental friendliness.

We use free radical graft copolymerization of acrylic acid as a monomer, N,N-methylene-bis-(acrylamide) as a crosslinker and ammonium persulfate as an initiator to synthesise GG-cl-poly(AA) hydrogels based on gellan gum utilising response surface methodology.

Conducting polymer hydrogels as a sustainable platform for advanced energy, biomedical and environmental applications

Environmentally friendly polymeric materials and derivative technologies play increasingly important roles in the sustainable development of our modern society. Conducting polymer hydrogels (CPHs) synergizing the advantageous characteristics of conventional hydrogels and conducting polymers are promising to satisfy the requirements of environmental sustainability. Beyond their use in energy and biomedical applications that require exceptional mechanical and electrical properties, CPHs are emerging as promising contaminant adsorbents owing to their porous network structure and regulable functional groups. Here, we review the currently available strategies for synthesizing CPHs, focusing primarily on multifunctional applications in energy storage/conversion, biomedical engineering and environmental remediation, and discuss future perspectives and challenges for CPHs in terms of their synthesis and applications. It is envisioned to stimulate new thinking and innovation in the development of next-generation sustainable materials.

Preparation and Applications of Salt-Resistant Superabsorbent Poly (Acrylic Acid-Acrylamide/Fly Ash) Composite

Solution polymerization synthesized alt-resistant superabsorbent poly (acrylic acid-acrylamide/fly ash) composites. The mass ratio of acrylic acid (AA) to acrylamide (AM), the concentration of crosslinker, the neutralization degree (ND) of AA, and the polymerization temperature were investigated by single-factor method. Optimized conditions for the synthesis of poly (acrylic acid-acrylamide/fly ash) (PAA-AM/FA) are, as following: m (AA)/m (AM) is 1.5, the content of crosslinker N, N-methylenebisacrylamide. (MBA) is 0.7%, neutralization degree of AA is 70%, polymerization temperature is 70 °C, and fly ash (FA) content is 50%. The prepared PAA-AM/FA demonstrated superior water absorption performance. The absorption capacities of PAA-AM/FA for pure water and 0.9% NaCl solution were found to be 976 g·g-1 and 81 g·g-1, respectively. Furthermore, PAA-AM/FA was found to have excellent adsorption capacity (148 mg·g-1) for Rhodamine B in water. Fourier Transform-Infrared Spectroscopy (FT-IR), Thermogravimetric Analysis (TGA), and Scanning Electron Microscopy (SEM) characterized the prepared materials. Results showed that fly ash was incorporated into the macromolecular polymer matrix and played a key role in improving the performance of the polymer composites.

Slow release fertilizer hydrogels: a review

Slow release fertilizer hydrogels combine fertilizer and hydrogel into one system.

Tree gum-based renewable materials: Sustainable applications in nanotechnology, biomedical and environmental fields

The prospective uses of tree gum polysaccharides and their nanostructures in various aspects of food, water, energy, biotechnology, environment and medicine industries, have garnered a great deal of attention recently. In addition to extensive applications of tree gums in food, there are substantial non-food applications of these commercial gums, which have gained widespread attention due to their availability, structural diversity and remarkable properties as 'green' bio-based renewable materials. Tree gums are obtainable as natural polysaccharides from various tree genera possessing exceptional properties, including their renewable, biocompatible, biodegradable, and non-toxic nature and their ability to undergo easy chemical modifications. This review focuses on non-food applications of several important commercially available gums (arabic, karaya, tragacanth, ghatti and kondagogu) for the greener synthesis and stabilization of metal/metal oxide NPs, production of electrospun fibers, environmental bioremediation, bio-catalysis, biosensors, coordination complexes of metal-hydrogels, and for antimicrobial and biomedical applications. Furthermore, polysaccharides acquired from botanical, seaweed, animal, and microbial origins are briefly compared with the characteristics of tree gum exudates.

Design and development of guar gum based novel, superabsorbent and moisture retaining hydrogels for agricultural applications

The novel hydrogels were synthesized by grafting guar gum with acrylic acid and cross-linking with ethylene glycol di methacrylic acid (EGDMA). The synthesis of hydrogel was confirmed by characterization through ¹³C NMR, FTIR spectroscopy, SEM micrography, thermo-gravimetric analysis and water absorption studies under different solutions. Synthesized hydrogel (GG-AA-EGDMA) was confirmed to be biodegradable with half-life period of 77 days through soil burial biodegradation studies. The effects of hydrogel treatment on soil were evaluated by studying various physico-chemical properties of soil like bulk density, porosity, water absorption and retention capacity etc. The hydrogel which could absorb up to 800 ml water per gram, after addition to soil, improved its porosity, moisture absorption and retention capacity significantly. Water holding capacity of water increased up to 54% of its original and porosity also increased up to 9% of its original. The synthesized hydrogel revealed tremendous potential as soil conditioning material for agricultural applications.

Sequestration of dyes from artificially prepared textile effluent using RSM-CCD optimized hybrid backbone based adsorbent-kinetic and equilibrium studies

Present work reports the synthesis of semi-Interpenetrating Network Polymer (semi-IPN) using Gelatin-Gum xanthan hybrid backbone and polyvinyl alcohol in presence of l-tartaric acid and ammonium persulphate as the crosslinker-initiator system. Reaction parameters were optimized with Response Surface Methodology (RSM) in order to maximize the percent gel fraction of the synthesized sample. Polyvinyl alcohol, l-Tartaric acid, ammonium persulphate, reaction temperature, time and pH of the reaction medium were found to make an impact on the percentage gel fraction obtained. Incorporation of polyvinyl alcohol chains onto hybrid backbone and crosslinking between the different polymer chains were confirmed through techniques like FTIR, SEM-EDX and XRD. Semi-IPN was found to be very efficient in the removal of cationic dyes rhodamine-B (70%) and auramine-O (63%) from a mixture with an adsorbent dose of 700 mg, initial concentration of rhodamine-B 6 mgL^-1 and auramine-O 26 mgL^-1, at an time interval of 22-25 h and 30 °C temp. Further to determine the nature of adsorption Langmuir and Freundlich adsorption isotherm models were studied and it was found that Langmuir adsorption isotherm was the best fit model for the removal of mixture of dyes. Kinetic studies for the sorption of dyes favored the reaction mechanism to occur via a pseudo second order pathway with R² value about 0.99.

Synthesis, characterization, and anti-microbial activity of superabsorbents based on agar–poly(methacrylic acid-glycine)

In this study, poly(methacrylic acid-glycine)-grafted agar-based hydrogels with optimized process parameters were synthesized via a two-step green-radiation induced grafting process using microwave heating. Poly(methacrylic acid) chains were graft copolymerized onto an agar backbone using ammonium persulfate as a free radical initiator and N,N′-methylene-bis-acrylamide as a cross-linking means using microwave heating. The influence of different reaction parameters was investigated on the percentage swelling behavior of the cross-linked hydrogel networks. The prepared hydrogel networks with optimum percentage swelling were characterized by Fourier transform infrared spectroscopy, time-of-flight secondary ion mass spectrometry, scanning electron microscopy, X-ray diffraction, and thermogravimetric analysis, using agar as a reference. The anti-bacterial activities of the prepared hydrogels against Gram-positive Staphylococcus aureus bacteria and Gram-negative Escherichia coli bacteria were investigated. Staphylococcus aureus was found to be more susceptible to the compounds compared to Escherichia coli. These results indicate that the prepared hydrogels have the potential to be applied as anti-bacterial agents.

Preparation and characterization of a novel superabsorbent of konjac glucomannan-poly(acrylic acid) with trimethylolpropane trimethacrylate cross-linker

A novel superabsorbent was prepared by the solution polymerization of partially neutralized acrylic acid onto konjac glucomannan using potassium persulfate as a free radical initiator and trimethylolpropane trimethacrylate as a crosslinking agent.

Evaluation of a conducting interpenetrating network based on gum ghatti-g-poly(acrylic acid-aniline) as a colon-specific delivery system for amoxicillin trihydrate and paracetamol

Development of colon-specific drug delivery systems for amoxicillin trihydrate and paracetamol using gum ghatti based crosslinked hydrogels.