pectins and acrylic-acid

The objective of this research was to devise a functional hydrogel was synthesized using pectin (PE), acrylic acid (AA), dimethyldiallyl ammonium chloride (DC), and polyvinyl alcohol (PVA), designed to adsorb both cationic and anionic dyes concurrently. The low methoxy pectin formed double network hydrogel through chemical and physical crosslinking with AA and PVA respectively. DC is combined into the hydrogel system through copolymerization reaction. Analysis of hydrogel's physicochemical properties was conducted using techniques such as infrared spectroscopy, texture analysis, thermogravimetry, and scanning electron microscopy. Dyes adsorption studies showed that the LP/AA/DC/PVA-2 hydrogel, prepared at the molar ratio of AA to DC of 1:2, exhibited higher adsorption efficiency for methylene blue (MB) and Congo red (CR). Kinetics and isotherms studies indicated that the adsorption behavior conformed to the pseudo-second-order kinetic model and Langmuir isotherm model. By the Langmuir isotherm fitting, the maximum adsorption capacities of MB and CR by LP/AA/DC/PVA-2 were recorded to be 222.65 mg/g and 316.46 mg/g, respectively. The adsorption mechanism is dominated by the hydrogen bonding and electrostatic interactions. Further, the adsorption and desorption experiments demonstrated that LP/AA/DC/PVA-2 hydrogel have excellent reusability.

Topics: Adsorption; Coloring Agents; Congo Red; Hydrogels; Hydrogen-Ion Concentration; Kinetics; Methylene Blue; Pectins; Water Pollutants, Chemical

In this study, an interpenetrating double-network hydrogel (LMP/AA/PVAH) was prepared based on low methoxy pectin (LMP), acrylic acid (AA) and polyvinyl alcohol (PVA). The first rigid network of chemical crosslinking was constructed via free radical polymerization of LMP and AA, and the second of ductile physical crosslinking network was constructed via cyclic freeze-thaw of PVA. The first cycle hardness and elasticity of the LMP/AA/PVAH significantly increased from 13.08 N and 0 to 24.28 N and 0.79, respectively, when the second network structure was constructed in the hydrogel by PVA. Besides, the PVA network might enhance the ductile and limit the swelling of hydrogel. In addition, the adsorption properties of LMP/AA/PVAH were evaluated by adsorption of methylene blue (MB). The adsorption behavior of MB by LMP/AA/PVAH conformed to the pseudo-second-order kinetic model. Besides, after 4 cycles of adsorption, there was no significant difference in adsorption capacity of LMP/AA/PVAH. The results showed that LMP/AA/PVAH had good reusability.

Topics: Hydrogels; Methylene Blue; Pectins; Polyvinyl Alcohol

The purpose of present study is to load Metformin HCl into pH-sensitive hydrogels to have sustained release over a period of time. The hydrogel was synthesized from naturally occurring polysaccharide pectin and monomer acrylic acid (AA) using ethylene glycol dimethacrylate (EGDMA) as cross-linker under controlled conditions for polymerization at 45°C for one hr, 50°C for two hrs, 55°C for three hrs, 60°C for four hrs and finally 65˚C for 12 hrs. Hydrogels were characterized for dynamic/equilibrium swelling, sol-gel fraction analysis, diffusion coefficient and percentage porosity. Hydrogels were tested by FTIR, XRD and SEM for structure and surface morphology respectively. Experimental in-vitro drug release data was applied to kinetic models. Formation of strong bonding between pectin and AA was supported by FTIR. The intensity of XRD peaks was reduced in non-loaded and loaded hydrogels compared to active drug substance. The non-loaded hydrogel showed discrete porous structure whereas loaded hydrogels were fibrous and smooth. Hydrogels showed higher swelling in the solutions of pH 6.5 and 7.5 as compared to in the solutions of pH 1.2 and 5.5. The diffusion coefficient decreases with the increase of AA and pectin concentrations. It was observed upon increasing the EGDMA concentration porosity decreases. The release of drug from all compositions of hydrogels took place through non-Fickian diffusion mechanism.

Topics: Acrylates; Acrylic Resins; Cross-Linking Reagents; Delayed-Action Preparations; Diffusion; Drug Carriers; Drug Liberation; Hydrogels; Hydrogen-Ion Concentration; Kinetics; Metformin; Methacrylates; Pectins; Porosity

This research aims to compare the ability of smart hydrogel in removing the methylene blue prepared by using two different radiation methods. The extracted pectin from the dragon fruit peel (Hylocereus polyrhizus) was used with acrylic acid (AA) to produce a polymerized hydrogel through gamma and microwave radiation. The optimum hydrogel swelling capacity was obtained by varying the dose of radiation, pectin to AA ratio and pH used. From the array of samples, the ideal hydrogel was obtained at pH 8 with a ratio of 2:3 (pectin: AA) using 10 kGy and 400 W radiated gamma and microwave respectively. The performance of both hydrogels namely as Pc/AA(G) (gamma) and Pc/AA(Mw) (microwave) were investigated using methylene blue (MB) adsorption studies. In this study, three variables were manipulated, pH and MB concentration and hydrogel mass in order to find the optimum condition for the adsorption. Results showed that 20 mg of Pc/AA(G) performed the highest MB removal which was about 45% of 20 mg/L MB at pH 8. While 30 mg of Pc/AA(Mw) able to remove up to 35% of 20 mg/L MB at the same pH condition. To describe the adsorption mechanism, both kinetic models pseudo-first-order, pseudo-second-order were employed. The results from kinetic data showed that it fitted the pseudo-first-order as compared to pseudo-second-order model equation. This study provides alternative of green, facile and affective biomaterial for dye absorbents that readily available.

Topics: Acrylates; Acrylic Resins; Adsorption; Fruit; Gamma Rays; Hydrogels; Hydrogen-Ion Concentration; Kinetics; Methylene Blue; Microwaves; Pectins; Polymerization; Tracheophyta; Water Pollutants, Chemical