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•Water absorbency of the physically cross-linked SAP was investigated.•SAP was endowed with a flexible polymeric network under the support of physical nanoparticle ...cross-linker.•As-obtained SAP showed a remarkably increased water-absorbing capacity in distilled water, salt solution and urea solution.
Flexible polymeric network plays a crucial role for the water-absorbing capability of super absorbent polymers (SAPs). However, most of the chemical cross-linked SAPs show poor water absorbency due to their rigid networks. In the present work, by creating a high elastic framework for SAP under the support of nanoparticles as physical cross-linker, one novel potassiumion-based SAP (K-SAP) with a remarkably increased wateruptake was achieved via in-situ copolymerization of acrylic acid and (3-acrylamidopropyl)trimethylammonium chloride. The water-absorbing capacity can reach 3600 g/g in distilled water, 150 g/g in 0.9 wt% KCl solution, 130 g/g in 0.9 wt% NaCl solution and 2250 g/g in 10 wt% urea solution. Furthermore, an improved water-retention performance and recyclability were also achieved due to the firm network structure created by chelation between nanoparticles and polymeric chains. This work opens a new path to endow K-SAP with a super-high water absorbency by constructing a flexible polymeric network for K-SAP under the help of physical cross-linker, which may have promising applications in waste-water treatment, hygienic products, drug delivery system and agriculture.
Agriculture is an important sector of the economy, but this industry consumes significant amounts of water, which is a precious and limited natural resource. Irrigation techniques and efforts to ...mitigate water usage influence the growth, survival, and yield of crops. However, superabsorbent polymers in combination with fertilizers can be employed to obtain sustained release of nutrients and improved water retention capacity of the soil. Despite significant recent progress in this area involving synthetic polyacrylate hydrogels, there are no industrially applicable solutions exhibiting similar performance using natural biopolymers or synthetic polymers enriched with natural components. This review focuses on biodegradable chitosan-based hydrogels (both natural and semi-synthetic), and discusses their potential agricultural and horticultural applications. The methods for synthesizing hydrogels via physical or chemical crosslinking, and the resulting functional properties of recently reported hydrogels, such as water retention and release of active ingredients, are presented herein.
Magnesium/aluminum layered double hydroxide (LDH) nanoparticles were synthesized by hydrolyzing urea and used to remove metronidazole (MN) from aqueous solution. The surface morphology images of the ...LDH nanoparticles showed that the adsorbent surface consisted of hexagonal nanosheets with a diameter of 200–1000nm. The MN removal efficiency was strongly dependent on the solution pH ranging from 3 to 9. The addition of nitrate, sulfate, and carbonate did not remarkably affect MN adsorption, while hardness slightly improved MN removal efficiency. The adsorption isotherm data could be well described using the Sips equation. The analysis of kinetic data showed that the adsorption of MN onto LDH closely followed the Avrami model and that several kinetic processes may control the rate of sorption. The adsorption process was non-spontaneous and exothermic in nature. The maximum Langmuir adsorption capacity was 62.804mg/g, demonstrating that LDH is an efficient adsorbent that can be used for the removal of MN compounds.
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► Kapok fiber treated with various solvents can change the oil absorption capability. ► NaClO2-treated kapok fiber shows the highest oil absorbency. ► The removal of waxy on kapok ...fiber surface can not reduce the oil absorption capacity. ► The variation of surface morphology and crystallinity of kapok fiber is related to its oil absorbency. ► The HCl, NaClO2 and water-treated kapok fiber exhibits better reusability.
Kapok fiber is a naturally renewable material with large lumen and hydrophobic characteristics, which enables it to show good oil sorption capacity. To further improve the efficiency for oil absorbency, in this study, kapok fiber was treated with various solvents, including water, HCl, NaOH, NaClO2 and chloroform. The structure of untreated and treated kapok fibers was investigated and compared using Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The effects of treatment concentration, temperature and time on oil absorbency of kapok fiber were assessed with toluene, chloroform, n-hexane and xylene as the model oils. The results indicate that except for chloroform, kapok fibers treated with other solvents show enhanced oil absorbency. Compared with raw kapok fiber, NaClO2-treated kapok fiber shows the highest oil absorbency, with the increase percentage is found to be 19.8%, 30.0%, 21.5% and 24.1% for toluene, chloroform, n-hexane and xylene, respectively. In addition, the solvent-treated kapok fiber exhibits better reusability, suggesting its great potential for oil recovery.
Nearly 1.3 billion tons of food are discarded annually in the production process. In this study, a novel slow-release nitrogen fertilizer with water absorbency was developed using leftover rice and ...crosslinking methods. Urea was incorporated as the nitrogen source in a leftover rice-g-poly(acrylic acid)/montmorillonite (LR-g-PAA/MMT) network, and then the leftover rice-g-poly(acrylic acid)/montmorillonite/Urea (LR-g-PAA/MMT/Urea) retained in the soil, and used as the loss control agent for water and nutrients. Variables including concentrations of acrylic acid, montmorillonite, N,N´-methylenebis acrylamide (MBA), and potassium persulfate (KPS) were investigated. Samples were with a water absorbency of 102.6g/g in distilled water and 25.1g/g in 1.0wt% NaCl solution under optimized conditions. Swelling measurements and water-retention indicated that higher-covalent cations would aggregate the hydrogels and decrease swelling. Investigating leaching behavior showed that these samples have the potential to carry the necessary nitrogen (N). The results demonstrated that the LR-g-PAA/MMT/Urea had a low leaching losses of N (19.7%) compared with pure urea (52.3%). Therefore, the developed fertilizer may be widely applicable in agriculture and horticulture, and could provide a new platform for reusing leftover rice.
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•A novel slow-release nitrogen fertilizer was developed based on leftover rice.•The sample had the potential to carry the necessary N.•Mechanism of LR-AA/MMT/Urea formation was elucidated.•The developed fertilizer could be applicable in agriculture and horticulture.
Organic livestock farming requires all resource input to be organic as well. Competition for raw materials as bedding increases the demand for alternative bedding materials. The production of ...absorbent fibre pellets from underutilized lignocellulosic plant material is therefore a research area that needs further attention. Precise research on processing methods and absorbent quantity is essential for the development of sustainable, high-quality absorbent bedding pellets. Twin-screw extruded fibre from eight different raw materials were processed into absorbent pellets. These pellets were investigated for physical properties including absorbency, mechanical durability, particle-size distribution and bulk density in accordance with relevant standards. Due to the absence of a standardised method for assessing absorbency, a testing method was devised. This involved submerging the produced pellets in deionized water for durations of 30 s, 300 s, and 1200 s. This research analysed various raw materials for suitability in absorbent pellet production. Poplar pellets performed good in absorbency (130 %, 172 %, 194 % respectively) and mechanical durability (95 %). As a result, larger quantities of absorbent pellets could be produced from poplar if needed since poplar wood chips are of higher availability due to existing short rotation coppices. This article emphasised producing absorbent bedding pellets, prioritising, using twin-screw extruded lignocellulosic fibre, revealing significant raw material influence on absorption properties.
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•Various lignocellulosic residues can be processed into water absorbent fibre pellets.•Highest water absorbency was determined for thyme pellets at 320 % during a 1200 s submersion.•Poplar fibre pellets can absorb almost 200 % their dry mass in water and have a mechanical durability of 95 %.•Water absorbency of poplar pellets is comparable to commonly used straw bedding pellets.
•Chondroitin sulfate (CS) is functionalized by crosslinking with monomers.•Grafting of CS yield macromolecule with excellent swelling and drug loading.•An optimized feed ratio is developed in this ...study to prepare CS hydrogels.•Structural analysis confirmed the new polymeric network formation.•Newly synthesized functionalized CS hydrogels have capacity to absorb various drugs.
Mixtures of polymer (chondroitin sulfate) and monomer (AMPS) in the presence of co-monomer (MBA) were employed for the production of hydrogels, with adjustable properties, following free radical copolymerization. The hydrogel’s structural properties were assessed by FTIR, DSC, TGA, SEM and XRD which confirmed the development and stability of synthesized structure. The results from FTIR analysis showed that CS react with the AMPS monomer during the polymerization process and confirmed the grafting of AMPS chains onto CS backbone. The surface morphology of CS-co-poly(AMPS) hydrogels, as evident by SEM, corresponds to their improved swelling ability due to high porosity. Thermal analysis showed that crosslinking formed a stable hydrogel network which is thermally more stable than its basic ingredients. The effects of pH revealed an increasing trend in swelling with increasing concentration of either CS or AMPS. In addition, different modalities for drug loading were studied with respect to drug homogeneous distribution; loxoprofen sodium was employed as model drug and was loaded by swelling-diffusion method. In vitro drug release profiles and kinetics were assessed to confirm their reproducibility and reliability. Higuchi model is the best fit model to explain drug release from formed gels indicating diffusion-controlled release. Similarly, Korsmeyer–Peppas model yields remarkably good adjustments where release kinetics involves a combination of diffusion in hydrated matrix and polymer relaxation. Conclusively, CS-co-poly(AMPS) hydrogels could be a potential alternate to conventional dosage forms for controlled delivery of loxoprofen sodium for extended period of time.
•Properties of RCC containing conventional and RAP materials and rice husk ash was studied.•Substituting 3% RHA had beneficial effects on the material’s flexibility.•RCC mix containing 3% RHA had ...comparable fatigue life to conventional RCC.•Increasing the RHA content to 5% had contrary effects on the fatigue behavior of mixes.•There was a reverse relationship between the fatigue life and porosity of material.
This study focused on the effects of rice husk ash (RHA) on the mechanical properties of roller compacted concrete (RCC) designed with original and reclaimed asphalt pavement (RAP) materials. The RCC mixes were produced by partial substitution of cement with RHA at varying amounts of 3% and 5%. Four aggregate combinations including the mix with original aggregate, coarse RAP+fine original aggregate, coarse original aggregate+fine RAP and total RAP were considered. The main experimental design consisted of the compressive strength and three points bending tests. Bending test was used to measure the modulus of rupture, material’s energy absorbency and analyse the fatigue response of RCC mixes. All tests were performed after 7, 28 and 120days curing except the fatigue test that performed on 120days specimens. Adding RHA resulted in higher optimum moisture content (OMC) and lower maximum dry density. Furthermore, adding RAP with different dimensions reduced the OMC and maximum dry density. The material’s flexibility improved upon replacing 3% cement by RHA. However, the energy absorbency reduced by increasing the RHA content to 5%. The fatigue life of RCC mixes containing RAP material was lower than the conventional one. Furthermore, replacing the coarse aggregate by RAP led to higher fatigue life than the fine aggregate. There was a strong relationship (R2>0.90) between the energy absorbency and fatigue response of RCC mixes. At higher stress ratios of 0.72, the mix with higher energy absorbency behaved better under repeated loadings. Besides, a reverse relationship was found between the fatigue life and material porosity. Adding 3% RHA reduced the porosity especially after 120days curing and improved the fatigue resistance. However, the addition of RHA to 5% resulted in higher porosities and lower fatigue lives.
•Semi-IPNs SAR with slow release nitrogen and phosphorus fertilizer (WSC-g-PAA/PVA/NP) was prepared by wheat straw cellulose.•WSC-g-PAA/PVA/NP used in agriculture that can improve the water ...retentivity of soil and provide plants with fertilizer sustainably.•The effects of synthesis conditions, pH and salt solutions on water absorbency of WSC-g-PAA/PVA/NP were studied.•The fertilizer release behavior of WSC-g-PAA/PVA/NP, the dynamic simulating experiment of fertilizer leaching loss, and water-retention behaviors of soil with WSC-g-PAA/PVA/NP were studied.
A novel semi-interpenetrating polymer networks (semi-IPNs) superabsorbent resin with slow-release nitrogen and phosphorus fertilizer (WSC-g-PAA/PVA/NP), based on wheat straw cellulose-g-poly poly (acrylic acid) (WSC-g-PAA) network and linear polyvinyl alcohol (PVA) was prepared by solution polymerization. Urea and dipotassium hydrogen phosphate were introduced to supply nitrogen and phosphorus nutrients, respectively. The novel semi-IPNs SAR was characterized by methods of FTIR, SEM and TGA. The water absorbency under different conditions and the slow-release behavior of WSC-g-PAA/PVA/NP were studied. The semi-IPNs SAR synthesized under optimized condition not only showed excellent water absorbency of 198.5 g/g in distilled water and 26.3 g/g in 0.9 wt% NaCl solution, but also could significantly lessen the leaching losses of fertilizers and enhance the water-retention capacity of soil. It could be concluded that the product with water holding and slow-release property, being economical and friendly to environment, had great potential to be used in agriculture and horticultural.
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The present article describes guar-gum (GG) polysaccharide-based eco-friendly highly water absorbable polymer network with itaconic acid (IA) and acrylamide (AAm) as monomers, prepared due to ...characteristic features such as natural abundance, biocompatibilities, and biodegradability as well as biological and physicochemical properties. The solution polymerization technique was used successfully to synthesize the GG-g-PIA-co-AAm co-polymer. In this method, IA and AAm monomer polymerize onto polysaccharides GG in an aqueous medium at 70 °C with potassium persulfate (KPS) acting as a chemical initiator and N, N′-methylene-bisacrylamide (N-MBA) acting as a cross-linker. The maximum allowed time to complete the reaction was 1 hour and 20 minutes. The consequence of the neutralization degree of itaconic acid, GG, AAm, N-MBA, and KPS was optimized. Surface morphology and binding behavior of prepared GG-g-PIA-co-AAm were characterized by FTIR and SEM microscopy. The grafting (between GG and IA and AAm and crosslinking reactions were produced by a solid chemical empathy between the NH2 groups in the guar gum and the carboxylic groups in the poly itaconic acid, leading to the formation of amide bonds. Various parameters like free-absorbency capacity (FAC) as high as possible and (AUL) were also studied for efficient absorbent polymers. A hypothetical mechanism for polymeric reaction during polymerization has been proposed.
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