Sreedevi Upadhyayula

Hydrolysis of microcrystalline cellulose using functionalized Bronsted acidic ionic liquids – A comparative study

Cellulose conversion to platform chemicals is required to meet the demands of increasing population and modernization of the world. Hydrolysis of microcrystalline cellulose was studied with SO3H, COOH and OH functionalized imidazole based ionic liquid using 1-butyl-3-methylimidazolium chloride [BMIM]Cl as a solvent. The influence of temperature, time, acidity of ionic liquids and catalyst loading was studied on hydrolysis reaction. The maximum %TRS yield 85%, was obtained at 100°C and 90min with 0.2g of SO3H functionalized ionic liquid. UV-vis spectroscopy using 4-nitro aniline as an indicator was performed to find out the Hammett function of ionic liquid and acidity trends are as follows: SO3H>COOH>OH. Density functional theory (DFT) calculations were performed to optimize the ionic liquid and their conjugate bases at B3LYP 6-311G++ (d, p) level using Gaussian 09 program. Theoretical findings are in agreement with the experimental results.

Mesoporous SAPO-5 (MESO-SAPO-5): a potential catalyst for hydroisomerisation of 1-octene

Mesoporous silicoaluminophosphate was assembled from microporous SAPO-5 secondary building unit precursors. The resultant material possessed both mesoporous channel properties and microporous wall properties. The catalyst showed promising results for vapour phase isomerisation of 1-octene. The presence of strong acidic sites favoured the formation of considerable skeletal isomerised products at elevated temperatures (400–450 °C). However, the catalytic conversion remains constant and active for several hours.

An investigation on biosorption of nitrate from water by chitosan based organic-inorganic hybrid biocomposites.

In this study, three types of crosslinked organic-inorganic hybrid biocomposites, such as chitosan/bentonite, chitosan/titanium oxide, and chitosan/alumina (ChBT, ChTi, and ChAl respectively) were prepared and utilized for the removal of nitrate from water by batch biosorption experiments. Effects of crosslinker dose, initial nitrate concentration, contact time, initial pH of the nitrate solution, biosorbent dose, temperature, and the presence of competitive ions on adsorption capacities were investigated. Actual adsorption capacities of ChBT, ChTi, and ChAl at a crosslinker to chitosan solution ratio of 1:40 were 35.68 and 43.62, and 45.38mg/g as nitrate respectively. The actual adsorption capacities decreased with increase in crosslinker dose. Adsorption equilibrium isotherm models data were well fitted to the linear Freundlich isotherm model. Thermodynamic parameters indicate that adsorption process was spontaneous and endothermic. The adsorption process was better described by a pseudo-second-order equation. The results show that chitosan based organic-inorganic biocomposites were effective, low cost, and reusable for the removal of nitrate from water.

Synergistic effect of chloro and sulphonic acid groups on the hydrolysis of microcrystalline cellulose under benign conditions

The hydrolysis of cellulose catalysed by ionic liquid (IL) immobilized on chloromethyl vinyl benzene (CMVB) with different IL/CMVB ratio was carried out in water as a solvent. The influence of process variables like IL/CMVB ratio in catalyst, temperature and time were investigated in a batch reactor. It was found that 40% IL/CMVB catalyst afforded maximum%TRS and glucose yield 58.5 and 47.9% respectively at 160 °C in 6h reaction time. This can be attributed to the synergistic effect of chloro and sulfonic groups, to dissolve the cellulose by breaking the intra and inter molecular hydrogen bonds and cleave the β-1, 4 glycosidic bonds respectively. The catalysts synthesized in the laboratory were characterized by FTIR, CHNS and TGA. The catalyst can be recovered three times without any significant loss in activity and characterized by FTIR to show the peaks of chloro and sulfonic groups in the recovered catalyst.

A structure–activity relationship study using DFT analysis of Bronsted–Lewis acidic ionic liquids and synergistic effect of dual acidity in one-pot conversion of glucose to value-added chemicals

The catalytic conversion of biomass-derived carbohydrates to value-added chemicals, such as 5-hydroxymethylfurfural, levulinic acid, and formic acid, is a commercially important reaction and requires the use of both Lewis and Bronsted acids. Multifunctional ionic liquids (ILs) with both types of acidity show promise as useful catalysts as well as solvents for one-pot glucose conversion to value-added chemicals. In this study, a series of chlorometallate ILs were synthesized and characterized, and their catalytic activity towards glucose conversion was investigated. The structure–activity relationship of chlorometallate ILs was investigated by qualitative comparison of their structural parameters obtained using density functional theory and catalytic activity studies. The acidity and basicity of these ILs were correlated with theoretically estimated parameters such as electrostatic surface potential maxima and minima, average local surface ionization energy, Fukui functions, and stabilization energy. Metal atoms showed a significant effect in controlling both the Lewis and Bronsted acidity of these ILs by withdrawing electron density from the cationic counterpart. Fukui function values showed the presence of significant amount of Lewis basicity in the metal halide-containing anionic part of the ILs. The ZnCl3-containing IL with highest electrostatic surface potential maxima, representing more electron-deficient region in the cationic part of the IL, was found to be highly Lewis acidic. Furthermore, it showed maximum catalytic activity in glucose conversion resulting in yields of 13.4%, 23.8%, and 67.1% of 5-hydroxymethyl furfural (HMF), levulinic acid (LA), and formic acid (FA), respectively. Hence, Lewis acidity was found to be the controlling parameter for glucose conversion to value-added chemicals. These multifunctional chlorometallate ILs were found to be recyclable with no loss of metal chloride from the anion of the ILs.

Hydrothermal conversion of glucose to levulinic acid using multifunctional ionic liquids: effects of metal ion co-catalysts on the product yield

Efficient conversion of glucose to levulinic acid (LA) was achieved with –SO3H functionalized ionic liquids in combination with a catalytic amount of metal salts under environmentally benign mild reaction conditions. Ionic liquids having different Bronsted acidic functional groups were prepared in the laboratory. The acidity of these ionic liquids was determined on the basis of the Hammett acidity function using UV-Visible spectroscopy. These catalysts were then screened in the conversion of glucose to LA using a batch autoclave under autogenous pressure at a temperature range of 140 to 175 °C. The structure–activity relationship of these multifunctional ionic liquids was correlated based on the Hammett function (Ho) and the catalytic activity results obtained in terms of glucose conversion and LA yield. The catalytic activity of the functionalized ionic liquids decreased in the order: IL-SO3H > IL-COOH > IL-OH, which is in good agreement with their Bronsted acidity trends. Furthermore, a metal salt based Lewis acidic co-catalyst, with metal ions (Fe, Co, Ni, Cu and Zn), was used in combination with the laboratory prepared Bronsted acidic functionalized ionic liquids in the efficient conversion of glucose to LA. Among all the investigated catalyst and co-catalyst systems, the –SO3H functionalized ionic liquid with nickel sulfate (NiSO4·6H2O) showed the highest LA yield (56.33%) and selectivity (56.37%). The synergistic effect of the metal ions helps in improving the LA yield by 10% as observed in our investigations. The co-catalytic effect of the transition metal chlorides and metal nitrates was not obvious as compared to transition metal sulfates. The catalyst could be recovered easily and reused three times without significant loss of activity.

Prediction of crude oil blends compatibility and blend optimization for increasing heavy oil processing

Abstract In the present study, prediction of crude oil blends compatibility and blend optimization for increasing heavy oil processing has been attempted. The crude oil blend compatibility (K model) is determined based on the physical parameter ratios of the crude oils. The physical parameter ratios of the crude oil include at least log (Sulphur)/Carbon Residue, API/Sulphur, and Kinematic Viscosity/API. The K model is developed by coefficients obtained by regression analysis between the ratios of physical parameters of known crude oils and composite compatibility measure determined from multiple compatibility test results of the known crude oils. Nine different tests conducted to estimate crude oils blend compatibility viz. colloidal instability index (CII), colloidal stability index (CSI), Stability Index (SI), Stankiewicz plot (SP), qualitative-qualitative analysis (QQA), Stability Cross Plot (SCP), Heithaus parameter (P value), Oil compatibility model (OCM) and Spot tests. 50 different crude oils have been participated in the development and tuning of the model. The compatibility criterion is proposed as if K ≥ 0; blend is compatible and if K  There is strong relationship of K model with intensity of spot color, desalting performance and fouling behaviour which further verified through experiments. If K is positive; Spot color is darker, desalting is better and fouling is minimum. But if K is negative; there is lighter Spot color with asphaltene flocculation or precipitation, poor desalting and high fouling is observed. K model accurately predicts the blend composition to minimize operational problems while increasing heavy oil processing.

Adsorption equilibrium and kinetic study of removal of nitrate from drinking water supplies by chitosan composite

H activities have become a major source of environmental pollution especially on the issue of water pollution which includes surface and ground water. This research was aimed at studying the effect of human activities such as indiscriminate defecation, fermentation of cassava tubers etc on the water quality of Onuakpaka stream and selected ground water in Ogwuama community of Ahiazu, Imo State, Nigeria. Water samples were collected in triplicates each with sterile containers from upstream, downstream and ground water. All the samples were analyzed using standard method. The result showed that the pH of samples collected from the upstream and downstream were more acidic (5.70 and 5.90 respectively) than the ground water (6.06). Also, the upstream and downstream have high turbidity of 14.76 and 15.40 respectively. More also, dissolved oxygen in the stream samples were below the World Health Organization and Federal Ministry of Environment standards while the ground water samples were within the standard. Also there were presence of fecal counts and Escherichia coli in all the samples collected (8.00 in ground water, 13.00 in the upstream and 23.00 downstream) this may be due to indiscriminate defecation. Furthermore, the temperature, conductivity, total dissolved oxygen etc. were within the standard in all the samples collected. Conclusively, the presence of fecal contaminant and Escherichia coli signifies that the water is highly polluted and unfit for drinking and domestic work. This leads to great danger to human health in this community.M successful methods are required to mineralize the expanding number of contaminants at low focuses on the water environment utilizing advanced oxidation process. Phenols, pesticides, fertilizers, cleansers, and other synthetic items are disposed off straightforwardly into nature, without being treated, by means of releasing, controlled or uncontrolled. The degradation of 2,4 dichlorophenoxyaceticacid, a herbicide has been carried out at room temperature by varying the pH. The ozonation of 2,4 dichlorophenoxyaceticacid(2,4D) in aqueous solution as a function of pH-value(pH-4.5,7,9.2)was investigated. Ozonation is a straight forward for all intents and purposes suitable procedure which can be utilized for the evacuation of the herbicide at the contaminant destinations or even purification of contaminated water sample collected post disposal. Thus this experimental work provide a solution for pre as well as post disposal removal of the contaminant 2,4 dichlorophenoxyaceticacid. The analysis work was completed in a constantly stirred reactor. Uniform flow of ozone gas and uniform stirring was ensured using a polymeric diffuser. The initial pH of the solution was adjusted and ozonation carried out. A sharp decrease in concentration of the substrate was found .The results show that the elimination rate of the initial compound increases with the pH value. The conductivity studies confirm the formation of acidic byproducts. The removal of 2,4-D followed second order at pH 4.5 , first order pH 7 and zero order at 9.2. In order to reach useful conclusion about the process the COD of the process was measured. Maximum reduction in concentration takes place at pH 9.2(87%).This study determined concentrations of toxic pollutants, volatile organic compounds and meteorological parameters in three sampling locations (SL1, SL2 and SL3) at Ilupeju industrial Estate. Average concentrations of toxic pollutants; CO (14.70 ppm), NO2 (0.88 ppm), and SO2 (0.55 ppm) and O3 (17.67 ppb) were determined. These had high correlation with temperature, wind speed, pressure and relative humidity. In terms of air quality, unhealthy air quality was obtained for CO, NO2 and SO2 while O3 gave a good air quality. Seventeen VOCs species belonging to alkane, alkene, aromatic and chlorinated hydrocarbons were determined. m/p - xylene was the most abundant species accounting for 16.28%, 11.66% and 14.06% at SL1, SL2 and SL3 respectively. Different ratios such as toluene/m,p – xylene, Σ Xylene/CO, trichloroethene/CO and tetrachloroethene/CO indicated solvent related emissions from these locations while Benzene/Toluene ratio indicated a traffic related emission. m/p - xylene and propene were the major contributors to O3 formation at SL1, SL2 and SL3 respectively. Ozone determined was VOC sensitive at all locations. Factor analysis using principal component analysis suggested traffic, industrial related emission sources solvent evaporation as sources for toxic pollutants and VOCs.

A Functionalized, Supported Ionic Liquid for Alkylation of p-Cresol withTert-Butyl Alcohol

SO3-H functionalized ionic liquid was prepared using 1-vinyl imidazole and 1,4 -butanesultone as source materials and then supported on mesoporous silica material (SBA-15). This supported ionic liquid catalyst was characterized using XRD, SEM, FT-IR, solid state NMR, TGA. Their catalytic activity in Tert-butylation of p-cresol with tert-butyl alcohol (TBA) was investigated in a batch autoclave. The effects of reaction time, reaction temperature, catalyst amount and reactant mole ratio on the conversion of p-cresol and 2-tert-butyl-p-cresol (TBC) and 2, 6-di-tert-butyl-p- cresol (DTBC) selectivities were investigated. Lower alcohol to p-cresol mole ratios, lower catalyst loading at 110°C gave a 65% maximum conversion of p-cresol. The recoverability and recyclability of the catalyst was also investigated. The catalyst could be completely recovered and its activity was found to be almost completely retained even after 5 recycles. The experimental data was found to satisfy a second order rate equation. The activation energy was calculated to be 5.2 kcal/mol.