Composite Materials
Fiza Simran; Prathiksha Karumbaiah; Pratik Roy; R.R.N. Sailaja
Abstract
The present study is aimed to remove toxic crystal violet dye from aqueous solutions. In this study guar gum (GG) has been grafted with acrylic acid (AA) by following microwave assisted grafting method. Two different nanomaterials i.e., nanoclay (NC) and multiwalled carbon nanotubes (MWCNT) has been ...
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The present study is aimed to remove toxic crystal violet dye from aqueous solutions. In this study guar gum (GG) has been grafted with acrylic acid (AA) by following microwave assisted grafting method. Two different nanomaterials i.e., nanoclay (NC) and multiwalled carbon nanotubes (MWCNT) has been incorporated either alone or in combination during the grafting reaction. The synthesized nanocomposites have been used for removal of crystal violet dye from aqueous solutions. Study showed higher dye adsorption capacity of the synthesized composites after addition of nanomaterials. The adsorption isotherm followed both Langmuir and Freundlich model. It was found that GG grafted AA composite with MWCNT showed highest crystal violet dye adsorption compared to others. Swelling behaviour of the synthesized composites in acidic, neutral and alkaline medium has been studied. The swelling kinetics in acidic, neutral and alkaline medium was found to follow pseudo second order kinetic model with <R2> value more than 0.98. Fourier transform infrared spectroscopy (FTIR) showed efficient grafting of AA on GG. X-ray diffraction (XRD) and morphological characteristics depicted enhanced dispersion of nanomaterials in GG matrix.
Abstract
Guar gum-graft-poly(vinylacetate) (GG-g-PVA) has been synthesized and evaluated for Hg(II) removal from synthetic Hg(II) solution. The optimum performance GG-g-PVA sample (G1) was synthesized using 0.25 g guar gum, 1.0 × 10 -2 M K2S2O8, 2.3 × 10-2 M ascorbic acid, 0.46 M vinyl acetate (VA), ...
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Guar gum-graft-poly(vinylacetate) (GG-g-PVA) has been synthesized and evaluated for Hg(II) removal from synthetic Hg(II) solution. The optimum performance GG-g-PVA sample (G1) was synthesized using 0.25 g guar gum, 1.0 × 10 -2 M K2S2O8, 2.3 × 10-2 M ascorbic acid, 0.46 M vinyl acetate (VA), total reaction volume 25 mL, grafting time 1 h, and reaction temperature 35±0.5 °C. G1 has been extensively characterized using FTIR, SEM, TGA, and DSC studies. pH drift experiments have shown that G1 has pHzpc of 2.8 and it was most efficient in removing Hg(II) at pH 6. The kinetic studies indicated that the removal involved chemisorption in the rate determining step and the sorption equilibrium was attained in 4 h. High Qmax (100 mg g -1 ) of the copolymer indicated its suitability as a versatile and sustainable adsorbent for exceptionally high mercury recovery.
Vandana Singh; Somit Kumar Singh
Abstract
In present communication we report on Cd(II) adsorption using our recently reported material, the guar gum-silica nanocomposite. The equilibrium, thermodynamics and kinetics of Cd(II) adsorption onto composite from aqueous solution were investigated. Optimum experimental parameters were determined to ...
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In present communication we report on Cd(II) adsorption using our recently reported material, the guar gum-silica nanocomposite. The equilibrium, thermodynamics and kinetics of Cd(II) adsorption onto composite from aqueous solution were investigated. Optimum experimental parameters were determined to be pH 8, contact time 2 hours, Cd(II) concentration 100 mg/L, temperature 30 o C and adsorbent dose 10 mg. The sorption equilibrium data were modeled using the Langmuir and Freundlich isotherms where the data fitted better to Langmuir model indicating unilayer sorption, the Qmax being 666 mg/g. The kinetic data indicated chemisorption in the rate-controlling step as the pseudo-second-order model was best suited (rate constant of 2.79 × 10-4 gmg -1 min -1 at 100 mg/L Cd 2+ ). The calculated thermodynamic parameters (ΔG°, ΔS°, ΔH°) showed the adsorption to be exothermic and spontaneous with decreased randomness at the solid–solution interface. The adsorbent could be recycled for six successive cycles with 31% loss in its efficiency.
Vandana Singh; Devendra Singh
Abstract
In the present communication, we report on diastase alpha amylase immobilization at guar gum-silica nanohybrid material (H5). The immobilized amylase (H5-Amyl) showed significantly higher bioactivity (21.62 U mg -1 ) as compared to free amylase (15.59 U mg -1 ) in solution at pH 5 and temperature 40°C. ...
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In the present communication, we report on diastase alpha amylase immobilization at guar gum-silica nanohybrid material (H5). The immobilized amylase (H5-Amyl) showed significantly higher bioactivity (21.62 U mg -1 ) as compared to free amylase (15.59 U mg -1 ) in solution at pH 5 and temperature 40°C. The kinetic parameters of the free (Km = 10.66 mg L -1 ; Vmax = 1.36 µmolemL -1 .min -1 ) and the immobilized enzyme (Km = 6.11 mg mL -1 ; Vmax = 1.45 µmolemL -1 .min -1 ) revealed that the immobilization has increased the overall catalytic property of the enzyme. The immobilized enzyme on recycling could show 87% of initial activity even in the sixth cycle. Since immobilization did not hamper the enzymatic reaction rate, the biocatalyst may be suitably exploited in food and pharmaceutical industries.
Hisatoshi Kobayashi
Abstract
Guar gum is a non-ionic carbohydrate polymer derived from the endosperm of two annual leguminous plants Cyanaposis teragonalobus and Cyanaposis psoraloides. Chemically, it is galactomannan consisting straight chain of mannose units attached by β-D-(1→4) linkages, having α-D-galactopyranosyl ...
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Guar gum is a non-ionic carbohydrate polymer derived from the endosperm of two annual leguminous plants Cyanaposis teragonalobus and Cyanaposis psoraloides. Chemically, it is galactomannan consisting straight chain of mannose units attached by β-D-(1→4) linkages, having α-D-galactopyranosyl unit bonded to poly(mannose) chain through (1→6) glycosidic links. Molecular weight of galactomannan varies ranging from 50 to 8000 kDa depending on the seeds and origin of plants; however polymer usually contains a definite ratio of building blocks, i.e., 1: 2 ratio of galactose to mannose. It is used in wide range of industries including cosmetics, paper, pharmacy, textile, adhesive, inks, lithography, paints, explosive and smoking products. In general, seed gums are non-toxic and applicable as emulsion stabilizer, thickening and gelling agents. Although, they nearly indigestible but consum in many food and pharmaceutical products as valuable additives to improve product qualities.