Biobased Castor Oil-Based Polyurethane Foams Grafted with Octadecylsilane-Modified Diatomite for Use as Eco-Friendly and Low-Cost Sorbents for Crude Oil Clean-Up Applications.

Herein we report the synthesis and characterization of novel castor oil-based polyurethane (PU) foam functionalized with octadecyltrichlorosilane (C18)-modified diatomaceous earth (DE) particles, exhibiting superior hydrophobicity and oil adsorption, and poor water absorption, for use in effective clean-up of crude oil spillage in water bodies. High-performance and low-cost sorbents have a tremendous attraction in oil spill clean-up applications. Recent studies have focused on the use of castor oil as a significant polyol that can be used as a biodegradable and eco-friendly raw material for the synthesis of PU. However, biobased in-house synthesis of foam modified with C18-DE particles has not yet been reported. This study involves the synthesis of PU using castor oil, further modification of castor oil-based PU using C18 silane, characterization studies and elucidation of oil adsorption capacity. The FTIR analysis confirmed the fusion of C18 silane particles inside the PU skeleton by adding the new functional group, and the XRD study signified the inclusion of crystalline peaks in amorphous pristine PU foam owing to the silane cross-link structure. Thermogravimetric analysis indicated improvement in thermal stability and high residual content after chemical modification with alkyl chain moieties. The SEM and EDX analyses showed the surface's roughness and the incorporation of inorganic and organic elements into pristine PU foam. The contact angle analysis showed increased hydrophobicity of the modified PU foams treated with C18-DE particles. The oil absorption studies showed that the C18-DE-modified PU foam, in comparison with the unmodified one, exhibited a 2.91-fold increase in the oil adsorption capacity and a 3.44-fold decrease in the water absorbing nature. From these studies, it is understood that this novel foam can be considered as a potential candidate for cleaning up oil spillage on water bodies.

Advances in the role of natural gums-based hydrogels in water purification, desalination and atmospheric-water harvesting.

Freshwater scarcity is one of the world's foremost environmental stress concerns. In the last few years, with sustainable industrial growth and rapidly growing population, the problem of freshwater shortage has encouraged researchers to conduct comprehensive research for the development of advanced water harvesting and wastewater treatment techniques. Natural gums-based hydrogels have been widely used in different water purification and harvesting applications because of their environment friendly nature, high water absorption, adsorption and retention capacities. In this article, we presented an entirely conceptual and critical review of literature mainly focused on the potential of different natural gums-based hydrogel in water harvesting and wastewater treatment applications. First, different categories of natural gums-based hydrogels including stimuli responsive hydrogels, physically and chemically crosslinked hydrogels, were introduced. Then, the emphasis was given on the role of natural gums-based hydrogels in different wastewater treatment applications like adsorption, photocatalysis and flocculation. After that, the latest research progress on the use of natural gums-based hydrogels in atmospheric water harvesting and seawater desalination was discussed. Finally, different challenges and main limitations associated with the use of natural gums-hydrogels in water purification and harvesting applications were discussed to understand the research gaps and drawbacks which need improvements.

Surface properties of alkylsilane treated date palm fiber.

The present work focuses on investigating the effect of non-fluoro short-chain alkylsilane treatment on the surface characteristic of date palm (Phoenix dactylifera) fiber. Raw date palm fiber (DPF) was treated with octylsilane and the surface properties of treated fiber was investigated using thermogravimetric analysis (TGA), fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), contact angle analysis and X-ray diffraction (XRD) on configuring the thermal stability, chemical structures and surface properties (morphology, hydrophobicity and crystallinity). The decomposition temperature of 75% mass loss raw and treated DPF, the onset of temperatures were increased from 464 to 560 °C with the introduction of alkylsilane. Hydrophobicity and crystallinity index of the DPF fibers were increased from 66.8° to 116° and 31 to 41, introducing octylsilane to raw DPF. The SEM and XRD experimental results showed that the octylsilane treatment could effectively increase the pore size and crystallinity index as an indication of the removal of non-crystalline cellulosic materials from DPFs. Thermal stability, hydrophobicity and crystallinity of the fibers increased on DFP after alkylsilane treatment. The results indicated that alkylsilane-treated DPFs were a suitable reinforcing substitute for hydrophobic polymer composite.

LAPONITE® nanodisk-"decorated" Fe3O4 nanoparticles: a biocompatible nano-hybrid with ultrafast magnetic hyperthermia and MRI contrast agent ability.

Magnetic Fe3O4 nanoparticles "decorated" by LAPONITE® nanodisks have been materialized utilizing the Schikorr reaction following a facile approach and tested as mediators of heat for localized magnetic hyperthermia (MH) and as magnetic resonance imaging (MRI) agents. The synthetic protocol involves the interaction between two layered inorganic compounds, ferrous hydroxide, Fe(OH)2, and the synthetic smectite LAPONITE® clay Na0.7+[(Si8Mg5.5Li0.3)O20(OH)4]0.7-, towards the formation of superparamagnetic Fe3O4 nanoparticles, which are well decorated by the diamagnetic clay nanodisks. The latter imparts high negative ζ-potential values (up to -34.1 mV) to the particles, which provide stability against flocculation and precipitation, resulting in stable water dispersions. The obtained LAPONITE®-"decorated" Fe3O4 nanohybrids were characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), Mössbauer spectroscopy, dynamic light scattering (DLS) and vibrating sample magnetometry (VSM) at room temperature, revealing superior magnetic hyperthermia performance with specific absorption rate (SAR) values reaching 540 W gFe-1 (28 kA m-1, 150 kHz) for the hybrid material with a magnetic loading of 50 wt% Fe3O4/LAPONITE®. Toxicity studies were also performed with human glioblastoma (GBM) cells and human foreskin fibroblasts (HFF), which show negligible to no toxicity. Furthermore, T2-weighted MR imaging of rodent brain shows that the LAPONITE®-"decorated" Fe3O4 nanohybrids predominantly affected the transverse T2 relaxation time of tissue water, which resulted in a signal drop on the MRI T2-weighted imaging, allowing for imaging of the magnetic nanoparticles.

Capturing water vapors from atmospheric air using superporous gels.

Dehumidification performance of most polymer desiccant materials is unsatisfactory because of the complex adsorption mechanism on polymer surface and non-porous structure. A viable alternative of solid desiccants, especially existing polymer desiccants, for capturing water vapors from moist air is the super-porous gels (SPGs). The presence of interconnected channels of pores in its structure facilitates the transfer of water molecules to the internal structure of SPGs. Therefore, in this research work, we are proposing N-isopropylacrylamide (NIPAM) and acrylamide (AM) based thermoresponsive SPGs as a potential alternative to the existing conventional solid desiccants. To ensure the formation of interconnected capillary channels, the SPGs were synthesized via gas blowing and foaming technique. Surface morphology of the SPGs was studied using scanning electron microscopy (SEM) and the other physio-chemical characteristics were studied using different techniques like fourier Transform Infrared Spectroscopy (FTIR), X-ray diffraction (XRD) and thermo-gravimetric analysis (TGA). Water vapors adsorption properties of the SPGs were explored via adsorption isotherm and kinetics. The adsorption isotherm was found to be of type-III isotherm with a maximum adsorption capacity of 0.75 gw/gads at 25 °C and 90% relative humidity. Experimental isotherm data correlated well with BET, FHH and GAB isotherm models. Adsorption kinetics suggested that the water vapors diffusion followed intraparticle diffusion and liquid field driving mechanisms collectively. SPGs exhibited very good regeneration and reusability for ten continuous adsorption/desorption cycles. Therefore, the dehumidification efficiency of synthesized SPGs shows that they have potential to replace most of the conventional solid desiccant materials in use.

Synthesis of 2D Germanane (GeH): a New, Fast, and Facile Approach.

Germanane (GeH), a germanium analogue of graphane, has recently attracted considerable interest because its remarkable combination of properties makes it an extremely suitable candidate to be used as 2D material for field effect devices, photovoltaics, and photocatalysis. Up to now, the synthesis of GeH has been conducted by substituting Ca by H in a ß-CaGe2 layered Zintl phase through topochemical deintercalation in aqueous HCl. This reaction is generally slow and takes place over 6 to 14 days. The new and facile protocol presented here allows to synthesize GeH at room temperature in a significantly shorter time (a few minutes), which renders this method highly attractive for technological applications. The GeH produced with this method is highly pure and has a band gap (Eg ) close to 1.4 eV, a lower value than that reported for germanane synthesized using HCl, which is promising for incorporation of GeH in solar cells.

GO crosslinked hydrogel nanocomposites of chitosan/carboxymethyl cellulose - A versatile adsorbent for the treatment of dyes contaminated wastewater.

Graphene oxide (GO) crosslinked nanocomposites hydrogels (NCH) of chitosan (CS) and carboxymethyl cellulose (CMC) were synthesized and the feasibility of its application as a versatile adsorbent for the remediation of cationic (methylene blue, MB) as well as anionic (methyl orange, MO) dyes contaminated wastewater was explored. Initially, GO was functionalized with vinyltriethoxysilane which was subsequently used as a chemical crosslinker to synthesize the NCH of CS and CMC (CS/CMC-NCH) with the polymeric mixture of diallyldimethylammonium chloride and 2-acrylamido-2-methyl-1-propanesulfonic acid. About 99% dye was adsorbed from 50 mg/L dye solution of MB dye with 0.4 g/L of CS/CMC-NCH at pH 7, whereas, for MO about 82% dye was adsorbed with 0.6 g/L of CS/CMC-NCH at pH 3. The Adsorption of both dyes is well explained using pseudo-second-order and Langmuir models with the maximum adsorption capacities of 655.98 mgdye/gads for MB and 404.52 mgdye/gads for MO. Thermodynamics studies suggested spontaneous and exothermic nature of the adsorption process with values of ΔS < 0 and ΔH > 0. Furthermore, CS/CMC-NCH showed excellent regeneration capacity for continuous twenty cycles of adsorption-desorption. Therefore, the synthesized CS/CMC-NCH is a versatile adsorbent that can treat both anionic and cationic dyes contaminated wastewater.

The Role of Titanium Dioxide on the Hydration of Portland Cement: A Combined NMR and Ultrasonic Study.

Titanium dioxide (TiO2) is an excellent photocatalytic material that imparts biocidal, self-cleaning and smog-abating functionalities when added to cement-based materials. The presence of TiO2 influences the hydration process of cement and the development of its internal structure. In this article, the hydration process and development of a pore network of cement pastes containing different ratios of TiO2 were studied using two noninvasive techniques (ultrasonic and NMR). Ultrasonic results show that the addition of TiO2 enhances the mechanical properties of cement paste during early-age hydration, while an opposite behavior is observed at later hydration stages. Calorimetry and NMR spin-lattice relaxation time T1 results indicated an enhancement of the early hydration reaction. Two pore size distributions were identified to evolve separately from each other during hydration: small gel pores exhibiting short T1 values and large capillary pores with long T1 values. During early hydration times, TiO2 is shown to accelerate the formation of cement gel and reduce capillary porosity. At late hydration times, TiO2 appears to hamper hydration, presumably by hindering the transfer of water molecules to access unhydrated cement grains. The percolation thresholds were calculated from both NMR and ultrasonic data with a good agreement between both results.

Scalable High Refractive Index polystyrene-sulfur nanocomposites via in situ inverse vulcanization.

In this work, we demostrate the preparation of low cost High Refractive Index polystyrene-sulfur nanocomposites in one step by combining inverse vulcanization and melt extrusion method. Poly(sulfur-1,3-diisopropenylbenzene) (PS-SD) copolymer nanoparticles (5 to 10 wt%) were generated in the polystyrene matrix via in situ inverse vulcanization reaction during extrusion process. Formation of SD copolymer was confirmed by FTIR and Raman spectroscopy. SEM and TEM further confirms the presence of homogeneously dispersed SD nanoparticles in the size range of 5 nm. Thermal and mechanical properties of these nanocomposites are comparable with the pristine polystyrene. The transparent nanocomposites exhibits High Refractive Index n = 1.673 at 402.9 nm and Abbe'y number ~ 30 at 10 wt% of sulfur loading. The nanocomposites can be easily processed into mold, films and thin films by melt processing as well as solution casting techniques. Moreover, this one step preparation method is scalable and can be extend to the other polymers.

Enhanced Mechanical Toughness of Isotactic Polypropylene Using Bulk Molybdenum Disulfide.

Herein, we report the use of bulk molybdenum disulfide (MoS2) as the reinforcing agent to enhance the toughness of isotactic polypropylene (iPP). The iPP-MoS2 nanocomposites with varying amounts of MoS2 (0.1 to 5 wt %) were prepared by a one-step melt extrusion method, and the effects of MoS2 on the morphology, thermal, and mechanical properties were evaluated by different instrumental techniques such as Raman, ATR-FTIR, UTM, TEM, TGA, and DSC. TEM images showed the uniform dispersion of multilayer MoS2 in the polymer matrix, and XRD results suggested the formation of the ß phase when a low amount of MoS2 is loaded in the composites. Mechanical tests revealed a significant increase in the toughness and elongation at break (300-400%) in the composites containing low amounts of MoS2 (0.25 to 0.5 wt %). Enhanced toughness and elongation in iPP could be related to the combined effect of the ß phase and the exfoliation of bulk MoS2 under applied stress. The thermal stability of the composites was also improved with the increase in MoS2 loading. Direct utilization of bulk MoS2 and one-step melt extrusion process could be a cost-effective method to induce high elasticity and toughness in iPP.

Three-Dimensional MoS2 Nanodot-Impregnated Nickel Foam Electrodes for High-Performance Supercapacitor Applications.

An economical and binder-free electrode was fabricated by impregnation of sub-5 nm MoS2 nanodots (MoS2 NDs) onto a three-dimensional (3D) nickel substrate using the facile dip-coating method. The MoS2 NDs were successfully synthesized by controlled bath sonication of highly crystalline MoS2 nanosheets. The as-fabricated high-surface area electrode demonstrated promising electrochemical properties. It was observed that the as-synthesized NDs outperformed the layered MoS2 peers as the electrode for supercapacitors. MoS2 NDs exhibited an excellent specific capacitance (C sp) of 395 F/g at a current load of 1.5 A/g in a three-electrode configuration. In addition, the fabricated symmetric supercapacitor demonstrated a C sp value of 122 F/g at 1 A/g and a cyclic performance of 86% over 1000 cycles with a gravimetric power and energy density of 10,000 W/kg and 22 W h/kg, respectively. Owing to its simple and efficient fabrication and high surface area, such 3D electrodes show high promise for various energy storage devices.

Low-Temperature Synthesis of Magnetic Carbonaceous Materials Coated with Nanosilica for Rapid Adsorption of Methylene Blue.

This work reports the synthesis of nanosilica-coated magnetic carbonaceous adsorbents (MCA@SiO2) using low-temperature hydrothermal carbonization technique (HCT) and the feasibility to utilize it for methylene blue (MB) adsorption. Initially, a carbon precursor (CP) was synthesized from corn starch under saline conditions at 453 K via HCT followed by the magnetization of CP again via HCT at 453 K. Subsequently, MCA was coated with silica nanoparticles. MCA and MCA@SiO2 were characterized using X-ray diffraction, Fourier transform infrared, scanning electron microscopy/energy-dispersive spectroscopy, transmission electron microscopy, and Brunauer-Emmett-Teller (BET) N2 adsorption-desorption isotherms. The BET surface area of MCA and MCA@SiO2 were found to be 118 and 276 m2 g-1, respectively. Adsorption of MB onto MCA@SiO2 was performed using batch adsorption studies and in the optimum condition, MCA@SiO2 showed 99% adsorption efficiency with 0.5 g L-1 of MCA@SiO2 at pH 7. Adsorption isotherm studies predicted that MB adsorption onto MCA@SiO2 was homogeneous monolayer adsorption, which was best described using a Langmuir model with the maximum adsorption capacity of 516.9 mg g-1 at 25 °C. During adsorption kinetics, a rapid dye removal was observed which followed pseudo-first- as well as pseudo-second-order models, which suggested that MB dye molecules were adsorbed onto MCA@SiO2 via both ion exchange as well as the chemisorption process. The endothermic and spontaneous nature of the adsorption of MB onto MCA@SiO2 was established by thermodynamics studies. Mechanism of dye diffusion was collectively governed by intraparticle diffusion and film diffusion processes. Furthermore, MB was also selectively adsorbed from its mixture with an anionic dye, that is, methyl orange. Column adsorption studies showed that approximately 500 mL of MB having 50 mg L-1 concentration can be treated with 0.5 g L-1 of MCA@SiO2. Furthermore, MCA@SiO2 was repeatedly used for 20 cycles of adsorption-desorption of MB. Therefore, MCA@SiO2 can be effectively utilized in cationic dye-contaminated wastewater remediation applications.

Template-Free, Solid-State Synthesis of Hierarchically Macroporous S-Doped TiO2 Nano-Photocatalysts for Efficient Water Remediation.

Nanosized sulfur-doped titanium dioxide emerged as an attractive photocatalyst in various environmental remediation applications, yet most synthesis methods require hazardous sulfurizing agents and intricate synthesis procedures. Herein, we present a facile, sustainable, and environmentally friendly preparation process for the production of visible-light-active meso-macroporous sulfur-doped anatase TiO2 (S-TiO2) nanoparticles for the first time. This strategy encompasses solventless mixing of titanium salt and surfeit yet nontoxic abundant elemental sulfur under continuous ball milling and moderate thermoannealing. The characterizations of as-obtained S-TiO2 nanoparticles showed enhanced physicochemical properties including distinctive surface features composed of hierarchical hollow macroporous channels having nanostructured mesoporous core walls. The annealing temperature was observed to control the structure and extent of sulfur doping in TiO2. Upon insertion of a sulfur atom into the TiO2 lattice, the band gap energy of S-TiO2 was significantly lowered, facilitating the enhanced photochemical activity. Owing to the effective S doping (1.7-2.8 atom %), and the interconnected hollow meso-macroporous nanostructure, the resulting nanosized S-TiO2 exhibited unique adsorption properties and superior photocatalytic efficiency for the rapid degradation of hazardous organic dyes and phenols for water remediation. The presented strategy holds high potential to provide rapid production of a hierarchical and highly porous S-TiO2 photocatalyst on a large scale for various environmental remediation and other myriad photochemical applications.

Resolving Dirac electrons with broadband high-resolution NMR.

Detecting the metallic Dirac electronic states on the surface of Topological Insulators (TIs) is critical for the study of important surface quantum properties (SQPs), such as Majorana zero modes, where simultaneous probing of the bulk and edge electron states is required. However, there is a particular shortage of experimental methods, showing at atomic resolution how Dirac electrons extend and interact with the bulk interior of nanoscaled TI systems. Herein, by applying advanced broadband solid-state 125Te nuclear magnetic resonance (NMR) methods on Bi2Te3 nanoplatelets, we succeeded in uncovering the hitherto invisible NMR signals with magnetic shielding that is influenced by the Dirac electrons, and we subsequently showed how the Dirac electrons spread inside the nanoplatelets. In this way, the spin and orbital magnetic susceptibilities induced by the bulk and edge electron states were simultaneously measured at atomic scale resolution, providing a pertinent experimental approach in the study of SQPs.

Steam-Induced Coarsening of Single-Unit-Cell MFI Zeolite Nanosheets and Its Effect on External Surface Brønsted Acid Catalysis.

Commonly used methods to assess crystallinity, micro-/mesoporosity, Brønsted acid site density and distribution (in micro- vs. mesopores), and catalytic activity suggest nearly invariant structure and function for aluminosilicate zeolite MFI two-dimensional nanosheets before and after superheated steam treatment. Yet, pronounced reaction rate decrease for benzyl alcohol alkylation with mesitylene, a reaction that cannot take place in the zeolite micropores, is observed. Transmission electron microscopy images reveal pronounced changes in nanosheet thickness, aspect ratio and roughness indicating that nanosheet coarsening and the associated changes in the external (mesoporous) surface structure are responsible for the changes in the external surface catalytic activity. Superheated steam treatment of hierarchical zeolites can be used to alter nanosheet morphology and regulate external surface catalytic activity while preserving micro- and mesoporosity, and micropore reaction rates.

Super porous TiO2 photocatalyst: Tailoring the agglomerate porosity into robust structural mesoporosity with enhanced surface area for efficient remediation of azo dye polluted waste water.

The low surface area of TiO2 (50 m2g-1 - Degussa P25) due to randomly oriented, agglomerated nanostructures and charge carrier recombination tendency, has till date been its major limitation for photocatalytic remediation of polluted wastewater. This study presents an innovative process to design super porous TiO2 nanostructures with high effective surface area (238 m2g-1), robust, structurally ordered mesoporosity via a simple sol-gel assisted reflux method. Detailed material characterization studies suggest that the higher degree of intermolecular ligation in novel templates such as butanetetracarboxylic or tricarballylic acid modified titanium hydroxide gels resulted in retainment of the porous structure during the urea assisted combustion synthesis. The induction of robust structural porosity is accompanied by a reduction in pore size distribution, an increase in pore volume leading to significantly higher total surface area of the synthesized TiO2. Detailed investigation of dye adsorption kinetics and photocatalytic degradation kinetics, complemented by kinetic modeling analysis confirmed that the super porous TiO2 with robust mesoporous structure outperforms the rest of synthesized TiO2 catalyst (having only agglomerate porosity) in terms of its superior adsorption capacity, faster diffusion kinetics and photocatalytic activity for degradation of Amaranth dye. Thus, the super porous TiO2 shows promising potential for application in sustainable photocatalytic technology for remediation of wastewater contaminated with azo dyes.

Utilization of gum xanthan based superporous hydrogels for the effective removal of methyl violet from aqueous solution.

In this research work the superporous hydrogels (SPHs) of acrylic acid (AA) and acrylamide (AM) with gum xanthan (GX) were synthesized using glass blowing and foaming technique and tested the feasibility of synthesized SPHs to remove removal of methyl violet dye (MV) by the process of adsorption from aqueous solution. Swelling properties of synthesized SPHs with different concentrations of GX were studied in deionized water and the swelling kinetics followed first-order model. The adsorption of MV using SPHs was highly influenced by the solution pH. Adsorption kinetics followed non-linear pseudo-second-order rate equation, whereas, isotherm of adsorption followed monolayer Langmuir model. Diffusion mechanism of dye molecules was controlled by the combination of two mechanisms i.e. intraparticle and liquid film diffusion mechanisms. Furthermore, during desorption studies, SPHs were efficiently used for the five continuous adsorption-desorption cycles. Hence, the removal of cationic dyes could be done using SPHs of GX as effective adsorbents.

Glucose isomerization in dioxane/water with Sn-ß catalyst: improved catalyst stability and use for HMF production.

The stability of zeolite Sn-beta (Sn-ß) was greatly improved for glucose isomerization to fructose and fructose yield of 41.5% has been obtained when dioxane/water was used as solvent. The effect of dioxane/water solvent mixtures for fructose dehydration on Amberlyst-131 was also studied and it was found that small amounts of water in dioxane increase the yield of HMF (up to 74%) by limiting the formation of oligomers like difructose anhydride (III). 56% yield of HMF from glucose, maltose, trehalose or cellobiose and 60% from sucrose were produced when hydrolysis of disaccharides, glucose isomerization and fructose dehydration were coupled in a mixture of dioxane/water (5 wt%).

Advanced TiO2-SiO2-Sulfur (Ti-Si-S) Nanohybrid Materials: Potential Adsorbent for the Remediation of Contaminated Wastewater.

In this present work, TiO2-SiO2-sulfur (Ti-Si-S) nanohybrid material was successfully prepared using TiO2 nano powder, TEOS sol-gel precursor, and elemental sulfur as raw material by sol-gel process and hydrothermal method at 120 °C temperature. Raman spectroscopy, XRD, SEM, TEM, and N2 absorption-desorption characterized the synthesized nanohybrid material. The characterization results confirmed the homogeneous distribution of sulfur in the nanohybrid material. The size of the Ti-Si-S nanohybrid material is vary between 20 and 40 nm and the surface areas of the nanohybrid material was measured using N2 absorption-desorption, which showed value of 57.2 m2 g-1. The potential of Ti-Si-S nanohybrid material as an adsorbent was further tested to adsorb methylene blue (MB) from aqueous solution. Adsorption performance of hybrid material was highly influenced by the solution pH and mass of adsorbent. The adsorption of MB using Ti-Si-S nanohybrid material was homogeneous monolayer adsorption, which followed the Langmuir adsorption isotherm with a qe,max value of 804.80 mg g-1 and pseudo-second-order rate equation. The dye diffusion mechanism partially followed both intraparticle and liquid film diffusion mechanisms. Thermodynamics studies predicted the spontaneous and endothermic nature of the whole adsorption process. The Ti-Si-S nanohybrid material was used for six repeated cycles of MB dye adsorption-desorption.

Biodegradable hydrogels of tragacanth gum polysaccharide to improve water retention capacity of soil and environment-friendly controlled release of agrochemicals.

This work reports the synthesis of lipase enzyme catalyzed biodegradable hydrogel interpenetrating polymer network (hydrogel-IPN) of natural gum polysaccharide i.e. gum tragacanth (GT) with acrylamide (AAm) and methacrylic acid (MAA) and their potential application in the delivery of agrochemicals. Biodegradation experiments were performed using composting and soil burial methods of biodegradation. Complete degradation of synthesized hydrogel-IPN occurred within 77 days using composting method, while using soil burial method 81.26% degradation occurred after 77 days. Furthermore, effect hydrogel-IPN degradation on the fertility of soil was also studied through macro-analysis of soil. Water retention capacity of clay soil and sandy loam soil was improved after mixing swelled sample of hydrogel-IPN with these soil samples. The potential of hydrogel-IPN was also tested for sustained and slow release of two agrochemicals i.e. urea and calcium nitrate. Kinetics of agrochemicals release revealed that the release rate of both the fertilizers was initially higher which kept on decreasing with time. Diffusion mechanism of agrochemicals followed Case-II diffusion type behavior. Therefore, synthesized hydrogel-IPN is important from agriculture view point and can be used for sustained and controlled release of agrochemicals.