Superabsorbent Composite Research Articles

Organic Capillary Barriers for Soil Water Accumulation in Agriculture: Design, Efficiency and Stability

Acute shortage of water resources and high unproductive water losses are the key problems of irrigated agriculture in arid regions. One of the possible solutions is to optimize soil water retention using natural and synthetic polymer water absorbers. Our approach uses the HYDRUS-1D design to optimize the placement of organic water absorbents such as peat and composite hydrogels in the soil profile in the form of water-storing capillary barriers. Field testing of the approach used a water balance greenhouse experiment with the cultivation of butternut squash (butternut squash (Cucurbita moschata (Duchesne, 1786)) under sprinkler irrigation with measurement of the soil moisture profile and unproductive water losses in the form of lysimetric water outflow. In addition, the biodegradation rate of organic water absorbents was studied at the soil surface and at a depth of 20 cm. Organic capillary barriers reduced unproductive water losses by 40–70%, retaining water in the topsoil and increasing evapotranspiration by 70–130% with a corresponding increase in plant biomass and fruit yield. The deepening of organic soil modifiers to the calculated depth not only allowed capillary barriers to form, but also prevented their biodegradation. The best results in soil water retention, plant growth and yield according to the “dose-effect” criterion were obtained for a composite superabsorbent with peat filling of an acrylic polymer matrix. The study showed good compliance between the HYDRUS design and the actual efficiency of capillary barriers as an innovative technology for irrigated agriculture using natural and synthetic water absorbents.

Synthesization and characterizations of coal fly ash-coffee grounds-based composite as super-absorbent for application in soil

To recycle and utilize two types of harmful solid waste, coffee grounds (CG) and coal fly ash (CFA), a novel and low-cost superabsorbent composite (MCG-PAA/CFA) was synthesized by aqueous solution polymerization with modified coffee grounds (MCG), acrylic acid (AA) and CFA as raw materials, and it was applied to soil to improve its drought resistance. Various reaction conditions were comprehensively investigated and analyzed to assess their influence on the water absorbency of the superabsorbent composite (SAC). After optimization, the MCG-PAA/CFA exhibited water absorbency capacities of 1260(±10.6) g/g and 82(±1.4) g/g in deionized water and physiological saline, respectively. After adding 3 wt% MCG, the water absorption of SAC was improved from 415 to 746 g/g. After further introduction of 2 wt% CFA, the water absorption of SAC increased from 746 to 1260 g/g. Fourier Transform Infrared (FTIR) analysis confirmed that the grafting reaction was successful and that CFA participated in the reaction, while scanning electron microscope (SEM) and thermogravimetric analysis (TGA) results revealed that the grafting reaction and the introduction of CFA improved the surface morphology and thermal stability of the SAC. Kinetic analysis was conducted to investigate how the grafting reaction and the introduction of CFA affected the swelling and water retention kinetics of the superabsorbent composite. In the soil experiment, adding only 0.1 wt% MCG-PAA/CFA can improve the water holding capacity of sandy soil, loam soil and clay soil by 6.65%, 4.42%, and 3.76% respectively This SAC composite has great potential in soil drought resistance.

Coal gasification slag for preparation of environmentally friendly superabsorbent composites with rapid water absorption and salt tolerance

It is crucial to design the novel low-cost and salt-tolerant superabsorbent for safeguarding food security and achieving sustainable agriculture. Herein, the porous superabsorbent composites with excellent salt tolerance were fabricated by redox-initiated grafting polymerization using water-based Pickering foam template co-stabilized with solid waste of coal gasification slag and plant particles Sapindus mukorossi pericarp. The stabilization mechanism of Pickering foams, swelling performance and salt-resistance of porous superabsorbent composites were studied in detail. Due to the abundant porous structure and the presence of coal gasification slag, the obtained superabsorbent composites exhibited rapid swelling rate and excellent water absorption capability, and the maximum water absorption in distilled water and 0.9 wt% NaCl solution reached 910 g/g and 126 g/g after 30 min, respectively. As 1.5 wt% the optimal superabsorbent composites was added into the saline-alkali soil, the growth of cabbages was significantly improved, and the plant height and chlorophyll content increased by 45.0% and 12.5%, respectively. This work served as a significant reference for preparing novel environmentally friendly water-saving materials for arid saline-alkali soil improvement.

HYDROGEL BASED ON STARCH, ACRYLAMIDE AND KAOLINE

The reduction of water resources in Central Asia forces agriculture to switch to water-saving technologies in the future. One of the ways of rational use of water resources is the use of highly swelling polymer hydrogels (HSP). A hydrogel based on starch, acrylamide, and kaolin was obtained based on a radical copolymerization reaction. In these studies, a superabsorbent composite was synthesized, obtained by the reaction of grafted copolymerization of acrylamide and potato starch in a ratio of 2:1, based on starch, acrylamide, and kaolin. Studies have shown that a superabsorbent composite with the best properties was obtained using 1 wt. % potassium persulfate, 0.8 wt. % methylene bisacrylamide and 2 wt. % aqueous kaolin solution. The rate of swelling of the hydrogel was determined, and it was shown that the moisture absorption of the hydrogel reached 890 g. This proposed method of producing super absorbent composites using natural resources such as starch, and kaolin, of course, reduces the cost of production and also makes the material environmentally friendly.

Swelling behaviors of superabsorbent composites based on acrylic acid/acrylamide copolymer and acid-modified attapulgite.

The swelling behaviors and water retention of superabsorbent materials prepared from acrylic acid/acrylamide copolymer and acid-modified attapulgite under ultrasonic treatment and different pH conditions were investigated. The results demonstrated that a suitable amount of attapulgite can effectively improve the absorption capacity. The superabsorbent achieved the highest absorptions of 1257.54 g g-1 and 209.45 g g-1 in distilled water and a 0.9 wt% NaCl solution, and a higher water absorbency occurred over a wide pH range of 5-9 when the ultrasonic power was 200 W, and the attapulgite content was 10%. Addition of attapulgite could significantly increase the water absorption and retention of this kind of material, which can be applied as a sand-fixing material.

Porous superabsorbent composites prepared from aqueous foam template and application evaluation.

Rapid water absorption is very important for the application of superabsorbent polymers under dry or semi-dry conditions, but there are currently few relevant studies. In this context, a novel porous superabsorbent of chitosan-grafted acrylic copolymer-2-acrylamido-2-methylpropanesulfonic acid/sapindus mukorossi pericarp/calcined oil shale semi-coke (CS-g-P(AA-co-AMPS)/SMP/COSSC) was prepared by a green and convenient foam template method, which was triggered by redox polymerization. The rich pore structure of the porous superabsorbent was conducive to accelerating the water absorption rate. It only took 15 min to reach a swelling capacity of 650 g g-1 in distilled water. Soil experiments show that even with the addition of 0.5 wt% porous superabsorbent, the soil water retention time can be extended to 7 days. Finally, it was applied to the growth of cabbage seeds and it was found that the growth was significantly improved. Based on these excellent properties, we expect to provide a valuable reference for the preparation of fast-absorbing materials through the green water-based foam template method, contributing to sustainable agriculture.

The influence of dibutyl sebacate on the sorption properties of a composite superabsorbent based on chitosan

Composite superabsorbents, combining both acrylate and biodegradable units, are more environmentally friendly products compared to fully synthetic analogues, however, their equilibrium degree of swelling Qe, usually, lower than the latter. Therefore, the search for new approaches to increase this parameter is an urgent task of modern chemistry. A promising way to solve this problem seems to be the use of plasticizers - low-molecular compounds that increase the segmental and molecular mobility of macromolecules. The purpose of this study was investigation of the effect of the presence of dibutyl sebacate on the sorption properties of composite superabsorbents containing chitosan. Dibutyl sebacate is known as a plasticizer for many industrially important polymers, including cellulose derivatives, and is also less toxic than commonly used phthalates. Superabsorbents based on acrylic acid and acrylamide containing 10 wt.% chitosan with different molecular weights: 20, 200, and 600 kDa were obtained by radical precipitation polymerization with substance initiation. The structure of the resulting superabsorbents was confirmed by FTIR spectroscopy, and the morphology of their surfaces was studied by scanning electron microscopy. With an increase in the molecular weight of the polysaccharide used, a decrease in the equilibrium degree of swelling of the resulting composite superabsorbent in distilled water was observed. In the case of swelling in a 0.15 M NaCl solution, a sharp decrease in Qe values occurred. The presence of dibutyl sebacate increased the equilibrium degree of swelling in distilled water of superabsorbents obtained based on chitosan with molecular weights of 200 and 600 kDa. The increase in Qe values correlated with the molecular weight of the polysaccharide: the higher it was, the more pronounced was the effect of the presence of dibutyl sebacate. A study of the swelling kinetics of superabsorbents showed that, regardless of the presence of dibutyl sebacate, the process is two-stage: a stage of fast and slow water sorption was observed. Using mathematical kinetic models, it was shown that swelling was controlled by chemisorption, and at the slow stage of swelling, the diffusion of water molecules inside the superabsorbent phase played a significant role. Thus, the use of dibutyl sebacate is a promising approach to increasing the equilibrium degree of swelling of composite superabsorbents based on chitosan with a molecular weight of more than 200 kDa.

Kinetic Assessment of the Biodegradability of Gel-Forming Soil Conditioners in Incubation Experiments with Instrumental Monitoring of Carbon Dioxide

A quantitative study of the biodegradability of polymer soil conditioners is necessary for a reasonable prediction of their stability and functioning in soils. For this purpose, a new methodological approach based on PASCO (USA) equipment was proposed. This approach allows recording continuous kinetic curves of CO2 emission in laboratory experiments based on incubation of composite gel-forming soil conditioners. Several characteristic types of respiration curves have been identified, and new physically based models have been proposed for their description with subsequent calculation of the half-lives of composite hydrogels. For the traditionally considered non-biodegradable acrylic superabsorbents of soil water, the possibility of rapid biodegradation was shown for the first time in the case of the addition of a biologically active compost extract into their liquid phase. With this treatment, which brings laboratory experiments closer to real soil conditions, the half-lives of both the well-known European Aquasorb and Zeba superabsorbents and the Russian Aquapastus hydrogel decreased by an order of magnitude from the initial values of 2–6 years to 0.1–0.3 years. In practice, this can negatively affect the profitability of using such materials for soil conditioning due to their rapid destruction and loss of functionality. The addition of silver ions into innovative Aquapastus composite superabsorbents at a dose of 0.1% or 10 ppm in swollen gel structures effectively reduces their biodegradability, prolonging the half-life to 10 years or more, which is twice the German standard DüMV 05.12.12 of the stability of polymer ameliorants.

Kinetic Assessment of the Biodegradability of Gel-Forming Soil Conditioners in Incubation Experiments with Instrumental Monitoring of Carbon Dioxide

A quantitative study of the biodegradability of polymer soil conditioners is necessary for a reasonable prediction of their stability and functioning in soils. For this purpose, we proposed a new methodological approach based on PASCO (USA) equipment, which allows recording continuous kinetic curves of CO2 emission in laboratory experiments on incubation of composite gel-forming soil conditioners. Several characteristic types of respiratory curves have been identified and new physically based models have been proposed for their description with subsequent calculation of the half-lives of composite hydrogels. For the traditionally considered non-biodegradable acrylic superabsorbents of soil water, the possibility of rapid biodegradation was shown for the first time in the case of the introduction of a biologically active compost extract into their liquid phase. With this treatment, which brings laboratory experiments closer to real soil conditions, the half-lives of both the well-known Western superabsorbents Aquasorb and Zeba and the Russian hydrogels Aquapastus decreased by an order of magnitude from the initial values of 2–6 years to 0.1–0.3 years. In practice, this can negatively affect the profitability of using such materials for soil conditioning due to their rapid destruction and loss of functionality. The introduction of silver ions into innovative Aquapastus composite superabsorbents at a dose of 0.1% or 10 ppm in swollen gel structures effectively reduces their biodegradability, prolonging the half-life to 10 years or more, which is twice the German standard DüMV 05.12.12 for the stability of polymer meliorants.

Microwave‐Assisted Soft Method for Synthesis of Poly (Acrylic Acid)/Organo‐clay Composites: Application As Superabsorbent For Phenol and Cr (VI)

AbstractA series of superabsorbent composites (PAA/HDTMA‐MMT) based on poly (acrylic acid) (PAA) and different content of organo‐modified natural clay HDTMA‐MMT (1,3 and 5 wt.%) were synthesized via in‐situ radical polymerization using microwave method. This eco‐friendly route was chosen to avoid the use of toxic solvents and reduce polymerization time. In addition, it can be considered an efficient approach for industrial‐scale polymer synthesis. The microstructure of the obtained hydrogels was evidenced by Fourier transformation infrared spectroscopy (FTIR), X‐ray diffraction (XRD), and scanning electron microscopy (SEM). Thermal stability was examined according to nano‐filler content on the matrix. The composite (PAA/HDTMA‐MMT) at 3 wt % exhibits an important swelling capacity value (833.33 g g−1). The efficiency of the synthesized hydrogel composites for phenol and Cr (VI) uptakes from aqueous solutions was studied in batch experiments. The main reason for their selection is their remarkable industrial use, despite their high toxicity and persistence in the environment. In order to underline the mechanism of the phenol and Cr (VI) adsorptions on the (PAA/HDTMA‐MMT), respectively, the zeta potential of the hydrogel was evaluated. Maximum adsorption capacity values of 170.7 mg g−1 and 197.3 mg g−1 were screened for phenol and Cr(VI), respectively. The adsorption process concurs with pseudo‐second‐order kinetics and with the Langmuir isotherm equation. A very high adsorption capacity (qmax=225.2 mg g−1) and a correlation coefficient of 0.998 calculated from isotherm equations show the high efficiency of the adsorbent and thus expected to be a good adsorbent candidate for wastewater treatment. The thermodynamic studies evidenced the exothermic character of the adsorption reactions of the studied pollutants.

KINETIC ASSESSMENT OF BIODEGRADABILITY IN GEL-FORMING SOIL CONDITIONERS BASED ON BOD ANALYSIS

Biodegradation is one of the main factors limiting the efficiency and service life of gel-forming soil conditioners. The study quantifies this process using laboratory analysis of biological oxygen uptake (BOD) in innovative composite superabsorbents with an acrylic polymer matrix, amphiphilic agents (humates, peat) and silver ions as an inhibitor of biological activity. A simple kinetic model of BOD is proposed to standardize the analysis and calculation of the half-life of polymers after their incubation in precision VELP respirometers (Italy). The half-life of hydrogels swollen in distilled water (1:100) at a temperature of 30°C varied in the range from 0,8±0,2 to 2,4±1,6 years. The addition of an aqueous extract from compost sharply enhances biodegradation and reduces the half-life of hydrogels up to 40–60 days. Doses of 0,1–1% silver in a polymer matrix or 10-100 ppm in swollen hydrogels increase their half-life by 5–20 times. The new methodological approach makes it possible to fully automatically evaluate the biodegradation of gel–forming polymers in laboratory conditions, however, for stable materials with a half-life of more than 2,5–3 years, the accuracy of manometric BOD analyzers is insufficient for a statistically reliable assessment of the kinetics of biodegradation even in long (120 days) incubation experiments.

Synthesis of superabsorbent composite based on chitosan-g-poly(acrylamide)/attapulgite

The production of environmentally friendly SAP using biodegradable natural resources such as chitosan was synthesized for water saving and controlled-released fertilizer. Chitosan-g-poly(acrylamide)/attapulgite superabsorbent composites (CTS) were created by crosslinking N,N'-methylene-bis-acrylamide (MBA) with chitosan (Ch), acrylamide, and attapulgite (ATP) and initiating the reaction with potassium persulfate (KPS). Spectroscopic techniques such as Fourier transform infrared spectroscopy, thermal gravimetric analysis (TGA), and scanning electron microscope were used to characterize the composite structures. It was done to determine how certain characteristics, such as the initiator percentage, crosslinker ratio, and clay content, affected the composite's ability to swell. The results confirmed that the thermal stability of the composite was improved by the addition of ATP. The maximum swelling was attained when the KPS concentration was 0.1 g. However, the addition of 0.2 g of KPS created a composite with a lower swelling capacity. When the amount of ATP was increased by up to 0.4 g, the swelling increased from 210 to 319 g/g. However, as the clay amount was increased further to 1.2 g, the swelling capacity decreased to 170 g/g. As pH increased to 3.0, the swelling of ATP2 grew larger; nevertheless, it shrank between pH values of 3 and 6. As the pH climbed to 8, the swelling sharply grew. The chosen composition was evaluated as a controlled-release method for urea fertilizer and swelled to 319 g/g in water (CTS2). The findings demonstrated that when the formulation's ATP content was increased from 0 to 1.2 g, the release rate was delayed, and the release length increased from 5 to 21 h.Graphical abstract

Fabrication and swelling properties of a novel superabsorbent composite derived from waste coal gangue

In this work, novel superabsorbent composites made of starch-grafted-polyacrylic acid/coal gangue were prepared via aqueous solution polymerization. The starch-g-polyacrylic acid/coal gangue (St-g-PAA/CG) composite with 10 wt.% CG showed the maximum water absorbency in distilled water (560 g·g−1) and a 0.9 wt.% NaCl solution (102 g·g−1). Moreover, this superabsorbent composite exhibited fine thermal stability and its swelling behavior was dependent on pH. In general, the swelling kinetics of the superabsorbent composites fitted with the Scott’s kinetic model. These composites not only showed excellent water absorption reversibility after five absorption/drying cycles, but also exhibited considerable environmental responsiveness after the swelling medium was changed from distilled water to the 0.9 wt.% NaCl solution. Based on these results, the prepared superabsorbent composites can be applied in several fields such as horticulture, agriculture, health care, and controlled drug delivery, while ensuring comprehensive utilization of solid wastes.

Biodegradation of Aqueous Superabsorbents: Kinetic Assessment Using Biological Oxygen Demand Analysis

Biodegradation is an important environmental factor controlling the effectiveness of aqueous superabsorbents for soil conditioning. The purpose of the study is to quantify this process using biological oxygen demand (BOD) analysis of composite superabsorbents with an acrylic polymer matrix, amphiphilic fillers (humates, peat) and silver ions as an inhibitor of biological activity. A simple kinetic model of BOD is proposed for standardization of the analysis and calculation of polymer half-life after their long-term (60–120 days) incubation in the VELP BOD analyzer (Italy) with automatic control. The half-life of pure hydrogels pre-swollen in distilled water (1:100) at 30 °C varied from 0.8 ± 0.2 to 2.4 ± 1.6 years. The addition of water extract from compost sharply enhances the biodegradation, lowering the half-life up to 40–60 days. Doses of 0.1–1% silver in a polymer matrix or 10–100 ppm in swollen hydrogels increase their half-life by 5–20 times. The discussion part questions the traditional division of aqua superabsorbents into “biodegradable” and “non-biodegradable”, and also analyzes the main advantages and disadvantages of the new methodology for their BOD analysis. The results may be of interest to a wide range of specialists from chemical technologists and biochemists to environmental engineers.

Synthesis, Characterization and Application of Karak Bentonite Clay-Graft-Poly (Acrylamide/Co- Acrylic Acid) Superabsorbent Composite and its Adsorption Study for Selected Heavy Metals

A novel superabsorbent composite (SAC) based on bentonite, acrylamide and acrylic acid was synthesized. The effects of bentonite quantity, initiator content on the grafting degree and on the water absorbency for the samples were studied. Synthesis mechanism, morphology and thermal properties of the SAC were characterized. FTIR results confirmed the presence of acrylamide/ acrylic acid onto bentonite backbone while TGA showed that introduction of 70 % bentonite to polymer increases thermal stability. The SAC was also tested in the removal of heavy metal in aqueous solution where kinetics analyses were performed using Langmuir adsorption isotherm. The optimum adsorption capability of heavy metal ions onto bentonite-based SAC from solution was 92, 48 and 91 % for Pb++, Ni++, and Cu++ respectively. The unique characteristics of these SAC such as its slow-release and water-retention capability, nontoxicity in soil, environmentally friendly and high capacity for the removal of heavy metals might be very valuable in agriculture and environmental studies

Fenton-like redox-initiated synthesis of superabsorbent composites with excellent water retention and swelling properties based on green tea and oil shale semi-coke

Much increasing attention recently has been paid for the design of superabsorbent composites with superior adsorption/retention performances by economic and efficient preparation process. Herein, a facile and economic preparation strategy were employed for preparation of high-performance superabsorbent composites based on the redox-reaction between the components derived from natural green tea (GT) and calcined oil shale semi-coke (COSSC). The as-prepared chitosan-grafting-polyacrylic acid/green tea/calcined oil semi-coke (CS-g-PAA/GT/COSSC) superabsorbent composites showed the favorable water absorption capability and water uptake rate of 404 g/g in distilled water and 62 g/g in 0.9 wt% NaCl solution in 30 mins. After being buried for 90 days in soil, the superabsorbent composites indicated a 57 % biodegradation rate due to the presence of natural polymer of CS and GT residues. The superabsorbent composites also exhibited the perfect water retention capacity in soil, the total seed biomass and stem length of cabbage increased by 27.20 % and 30 %, after incorporation of 0.5 % of superabsorbent composites in soil, respectively. Based on the excellent water absorption, water retention and growth-promoting properties, the high efficient and economic superabsorbent composites prepared via low temperature-initiated polymerization presented a great potential in the charge of arid and semi-arid agriculture.

Preparation and properties of multifunctional polyaspartic acid/waste paper fiber-based superabsorbent composites

Superabsorbent composites (SACs) are widely used for agricultural applications acts as a “miniature soil moisture reservoir” for plants. While these substrates have excellent water retention properties, they often suffer from production costs and a variety of environmental challenges. Herein, polyaspartic acid (PASP), waste paper fibers (WPF) and 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS) graft copolymerize acrylic acid (AA) to prepare a novel multifunctional PASP-g-P(AA-co-AMPS)/WPF SACs. The synthesis conditions use to prepare the PASP-g-P(AA-co-AMPS)/WPF SACs are optimized, including PASP content, mass ratio of AMPS and AA, initiator content and cross-linker content. In addition, the water retention, salt and acid resistance, reversible swelling and temperature sensitivity of SACs are also investigated and analyzed in detail. Due to the uniform distribution and the rich pore structure, it has a maximum equilibrium adsorption capacity of optimal SACs in distilled water, tap water and NaCl solution (0.9 wt%) are determined to be 731.0 g g−1, 189.2 g g−1 and 81.4 g g−1, respectively. Thus, PASP-g-P(AA-co-AMPS)/WPF SACs exhibit excellent environmental tolerance and provide a promising strategy for sustainable agriculture and desertification control.

Eco-friendly superabsorbent composites based on calcined semicoke and polydimethylourea phosphate: Synthesis, swelling behavior, degradability and their impact on cabbage growth

In this work, novel eco-friendly superabsorbent composites of chitosan-grafted-polyacrylic acid/polydimethylourea phosphate/calcined semicoke (CS-g-PAA/PDUP/CSC) with the semi-interpenetrating network (semi-IPN) were developed via a convenient redox polymerization at room temperature. The redox polymerization was triggered by the calcined oil shale semicoke (CSC) under air atmosphere, in which the iron-compounds of CSC and Na2S2O3 were employed as oxidizing agent and reducing agent, respectively. The CS-g-PAA/PDUP/CSC composites prepared at the optimal conditions exhibited the maximum water absorption capacity of 412.89 and 51.30 g/g in deionized water and 0.9 wt% NaCl solution within 60 min, respectively. The excellent water absorption and retention performance were related to the introduction of CSC, which could be served as an inorganic component weakening the hydrogen-bond interaction between the functional groups in the polymer matrix and the semi-IPN. The superabsorbent composites also showed the favorable degradability, and 42.35 % of superabsorbent was degraded at 90 days. Interestingly, the nitrogen element provided by urea and chitosan could be released during degradation and directly absorbed by the plant to promote the growth. Integration of the above performance, the prepared composites may be used for better water resources management in agriculture taken into account of the corresponding environmental benefits.

Synthesis and characterization of superabsorbent composite based on natural polysaccharide

In this work, Superabsorbent composite was synthesized based on guar gum and acrylic acid by free radicalgraft copolymerization reaction using N,N-methylene bisacrylamide as a cross linking agent and potassiumpersulphate as an initiator in complete aqueous solution to make it environmental friendly. The compositewas synthesized to be used as superabsorbent for the purpose of water absorption. Fourier transforminfrared analysis was carried out to confirm grafting of acrylic acid onto guar gum. The Thermal gravimetricanalysis confirms the stability of composite. The composite was characterized by X-ray diffraction to studyits crystalline nature. The Scanning electron microscopy analysis was used to study the morphology ofcomposite. The water absorption capacity of superabsorbent was measured in distilled water by free swellingmethod as a function of percentage swelling and found to be 4600%. The effect of reaction parameters suchas guar gum concentration, monomer concentration, initiator concentration, cross-linker concentration andpH on percentage swelling was also studied.

Bagasse Cellulose Composite Superabsorbent Material with Double-Crosslinking Network Using Chemical Modified Nano-CaCO3 Reinforcing Strategy.

To improve the salt resistance of superabsorbent materials and the gel strength of superabsorbent materials after water absorption, a bagasse cellulose-based network structure composite superabsorbent (CAAMC) was prepared via graft copolymerization of acrylamide/acrylic acid (AM/AA) onto bagasse cellulose using silane coupling agent modified nano-CaCO3 (MNC) and N,N′-methylene bisacrylamide (MBA) as a double crosslinker. The acrylamide/acrylic acid was chemically crosslinked with modified nano-CaCO3 by C-N, and a stable double crosslinked (DC) network CAAMC was formed under the joint crosslinking of N,N′-methylene bisacrylamide and modified nano-CaCO3. Modified nano-CaCO3 plays a dual role of crosslinking agent and the filler, and the gel strength of composite superabsorbent is two times higher than that of N,N′-methylene bisacrylamide single crosslinking. The maximum absorbency of CAAMC reached 712 g/g for deionized water and 72 g/g for 0.9 wt% NaCl solution. The adsorption process of CAAMC was simulated by materials studio, and the maximum adsorption energy of amino and carboxyl groups for water molecules is −2.413 kJ/mol and −2.240 kJ/mol, respectively. According to the results of CAAMC soil water retention, a small amount of CAAMC can greatly improve the soil water retention effect.