Sangeeta Garg

Effect of cross linking of PVA/starch and reinforcement of modified barley husk on the properties of composite films.

Barley husk (BH) was graft copolymerized by palmitic acid. The crystalline behavior of BH decreased after grafting. Poly vinyl alcohol (PVA)/starch (St) blend film, urea formaldehyde cross linked PVA/St films and composite films containing natural BH, grafted BH were prepared separately. The effect of urea/starch ratio, content of BH and grafted BH on the mechanical properties, water uptake (%), and biodegradability of the composite films was observed. With increase in urea: starch ratio from 0 to 0.5 in the blend, tensile strength of cross linked film increased by 40.23% compared to the PVA/St film. However, in grafted BH composite film, the tensile strength increased by 72.4% than PVA/St film. The degradation rate of natural BH composite film was faster than PVA/St film. Various films were characterized by SEM, FT-IR and thermal analysis.

Synthesis of cross-linked starch based polymers for sorption of organic pollutants from aqueous solutions

Abstract Three cross-linked starch based polymers (1–3) were prepared by reaction between starch and hexamethylene diisocynate in the presence of dimethylformamide. The cross-linked adsorbents were used for the recovery of 4-nitrophenol (pNP) and 4-chlorophenol (pCIP) from aqueous solutions. Characterization of the polymers was performed by Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy thermogravimetric analysis (TG) and differential thermal analysis (DTA). It was observed that the X-ray diffraction patterns of native starch and cross-linked starch were similar. TG-DTA studies revealed that the decomposition temperature of cross-linked starch was higher than that of native starch. The influence of pH, adsorbent dose and contact time on the percentage sorption capacity was examined using batch study. Adsorption results revealed that the starch-based bio-adsorbents showed high sorption capacity towards pNP and pCIP. At optimized conditions the maximum sorption capacity observed for polymer 3 was 83% for pNP. Substitution of experimental data values in the Freundlich model showed favourable results as compared with the Langmuir model.

Catalytic Wet Peroxide Oxidation of 4-Nitrophenol Over Al–Fe, Al–Cu and Al–Cu–Fe Pillared Clays

Abstract Bentonite clay was modified with Al, Fe and Cu metal cations to form pillared interlayered catalysts (Al–Fe, Al–Cu and Al–Cu–Fe). These catalysts were synthesized, characterized and tested for their reactivity in the presence of hydrogen peroxide for the degradation of 4-Nitrophenol (NP). The X-ray diffraction studies and Brunauer Emmett Teller results showed increases in basal spacing d (0 0 1) and specific surface area of bentonite clay after pillaring with Al, Fe and Cu metal cations. The effect of various parameters, such as concentration of hydrogen peroxide, catalyst dose, temperature and initial pollutant concentration, for the degradation of 4-NP over Al–Fe pillared interlayered clay PILC catalyst has been studied. Samples were analysed to determine degradation (%) of 4-NP, total organic carbon (TOC) removal (%) and chemical oxygen demand (COD) removal (%). At optimized conditions, Al–Fe PILC showed higher catalytic activity compared to Al–Cu and Al–Cu–Fe PILCs. The degradation efficiency of 4-NP was 99.6% with TOC and COD removal of 83% and 75%, respectively using Al–Fe PILC at 20 mM H2O2, 3 g/L PILC and 50°C temperature in 5 h. Possible degradation pathways have been proposed for the catalytic oxidation of 4-NP.

Synthesis of Graft Copolymers for Green Composite Films and Optimization of Reaction Parameters using Taguchi (L16) Orthogonal Array

Abstract Oleic acid was graft copolymerized onto barley husk (BH) using a redox initiator. Samples of natural and grafted BH were characterized by fourier transform infrared spectroscopy, scanning electron microscopy (SEM), x-ray diffraction, thermal analysis, swelling (%) and moisture absorption (%). SEM analysis revealed that the surface of the BH became rough after grafting. Reaction time, temperature, amount of solvent, monomer concentration and initiator molar ratio were optimized using conventional as well as Taguchi L16 (orthogonal array) design to get maximum percentage graft yield. At optimized conditions, the maximum graft yield was 55.3% by conventional method, whereas it was 56.82% by Taguchi method. Analysis of variance revealed that the reaction temperature and reaction time were the most and the least influential factors, respectively. Swelling (%) and moisture absorption (%) decreased with the increase in percentage graft yield. Grafted BH showed more chemical and thermal resistance as compared to natural BH. Synthesized graft copolymers were used as reinforcing material in poly vinyl alcohol composite films and rendered higher mechanical properties.

Preparation of LDPE-acetylated/butyrylated starch blend blow films and characterization

Development of modified plastics has been studied through the LDPE-acylated starch blend films to examine the effect of different acyl groups and degrees of substitution (DS) on properties of films. Corn starch was modified with acetyl and butyryl groups and films were prepared by blending acylated starch with low density polyethylene (LDPE). Systematic studies were done to observe the effect of acyl groups, DS and starch concentration on the properties and biodegradability of the blend films. It was observed that blend films containing 5% acetylated and butyrylated starches of high DS (2.5, 1.7) maintained 75% and 83% of tensile strength of LDPE films. Thermal analysis results indicated that acetylated and butyrylated starch blend films decomposed at 370 °C and 389 °C which were higher than the decomposition temperature of native starch film (349 °C). Scanning electron micrographs of blend films containing high DS acylated starch showed well dispersed starch particles due to improvement in dispersion between starch and LDPE. Water absorption capacity of high DS acetylated and butyrylated starch blend films (4.18% and 3.76%, respectively) was lower than that of native starch films (5%). This study has an advantage because of blown films prepared can be integrated with the present manufacturing systems without any other requirement.

Catalytic wet peroxide oxidation of 4-Nitrophenol over Al–Fe PILC: Kinetic study using Fermi’s equation and mechanistic pathways based on TOC reduction

ABSTRACT The Al–Fe pillared interlayered clay catalyst (PILC) was synthesized by pillaring bentonite clay with Al and Fe metal cations. 4-Nitrophenol (4-NP) was oxidized over Al–Fe PILC using catalytic wet peroxide oxidation process. The catalyst was characterized using X-ray diffraction, BET, wavelength-dispersive X-ray fluorescence, FTIR, and thermogravimetric analysis/derivative thermogravimetric techniques. The Al–Fe PILC was thermally stable as compared to bentonite clay. Reaction kinetics for the catalytic oxidation of 4-NP onto Al–Fe PILC was described using Fermi’s equation. Fermi’s model was fitted well to the experimental data for the degradation of 4-NP and total organic carbon (TOC) removal histories and followed pseudo-first-order rate equation. The apparent activation energies for 4-NP degradation and TOC removal histories were 21.17 and 14.12 kJ/mol, respectively. In the present study, the mechanistic pathways for the catalytic oxidation of 4-NP based upon TOC reduction have been proposed. The toxicity of 4-NP after oxidation decreased as the zone of inhibition decreased to 5 mm from 12 mm.