Anila Sarwar - Academia.edu (original) (raw)

Papers by Anila Sarwar

Physicochemical Analysis of Thar Coal And Its Chemical Interpretation

TURKISH JOURNAL OF CHEMISTRY, 2001

The kinetics of the oxidation of L-ascorbic acid (H2 A) by methylene blue was investigated in str... more The kinetics of the oxidation of L-ascorbic acid (H2 A) by methylene blue was investigated in strongly acidic media over the temperature range 22-40 • C. The kinetic studies were carried out as a function of different variables like concentration, pH, ionic strength and temperature. The rate was found to be a linear relation with [H2 A], [M.B.] and [H + ]. Ionic strength dependence formation indicated complex formation by monocationic and anionic species in solution. The reaction rate was greatly catalyzed by the presence of trace amounts of copper (II) ion. Possible mechanisms for the catalyzed and uncatalyzed reactions are proposed. Kinetic evidence for a specific catalytic effect by binding of alkali metal ions to oxidant is also reported. The derived rate equations are in good agreement with the experimental observations.

Chemical composition of wet precipitation of air pollutants: A case study in Karachi, Pakistan

Atmósfera, 2014

Analytical Sciences, 2001

A sensitive and selective kinetic-spectrophotometric method is proposed for the determination of ... more A sensitive and selective kinetic-spectrophotometric method is proposed for the determination of µg mL-1 amounts of Cu 2+ based on its catalytic effect on the oxidation of L-ascorbic acid by Methylene Blue in a strongly acidic medium. The reaction is monitored spectrophotometrically by measuring the decrease in color intensity of Methylene Blue at 665 nm. The analysis of Cu 2+ ion is performed by a fixed-time method. At a given time of 2 min at pH 2.20 and 32˚C, the detection limit is 10 ng mL-1 and the relative standard deviation for 0.4 µg mL-1 Cu 2+ is 3.60% (n = 6). The method is free from most of the interferences and the effect of diverse ions on the determination of Cu 2+ is also reported. The proposed method is virtually specific to copper and has been satisfactorily applied to its determination in electric copper wire samples and pharmaceutical products. Results were also verified by the atomic absorption spectrometry technique (AAS).

Pakistan Journal of Scientific & Industrial Research Series A: Physical Sciences, 2012

Laboratory scale process of underground gasification of Pakistani lignite has been performed to c... more Laboratory scale process of underground gasification of Pakistani lignite has been performed to check the potential of the Pakistani coal for gasification. High permeability and low swelling index of coal are desirable properties for UCG. In Pakistani lignite both properties are found and in case of lignite and brown coal, natural permeability provides adequate linkage. The proximate and ultimate compositions of the samples show that it is of low quality coal with high volatile matter. Coal has been converted into syngas and utilized as the substitute of natural gas and for power generation.

Kinetics of Iodination of Dipentene by Iodine in Different Polar and Nonpolar Solvent Systems

Oriental journal of chemistry, 2017

Asthma is a complex, chronic inflammatory lung disease that may result in alterations in various ... more Asthma is a complex, chronic inflammatory lung disease that may result in alterations in various anti oxidants.In this study superoxide dismutase (SOD), Vitamins C and E, Zinc, Copper and Magnesium were estimated using standard procedures in spirometry proven asthmatics selected at random. Ninety two (n=92) asthmatics, forty nine (n=49) females with mean age 33.98 ±11.52 standard deviation and forty three (n=43) males with mean age 35.91±12.88 between the ages of 16-70 years were enrolled and thirty healthy subjects (n=30), out of which nine (9) females with mean age 31.25±10.77 and twenty one (21) males with mean age 31.05±12.95 were taken as controls. Significant differences have been observed between the control and patient data for FEV1, FVC, FEV/FVC, PEF and Zn. Higher SOD value (19.92%) and lower Vit-C value (13.59%) have been observed in patients compared to control. The value of Vit-E has been increased to 2.06 times in patient data when compared to control. No significant d...

The exposure to nicotine, sugar and trace elements in tobacco are associated with health risks in... more The exposure to nicotine, sugar and trace elements in tobacco are associated with health risks including inflammation, sensitization and carcinogenesis. The aim of this study was to investigate the physicochemical properties of tobacco used in the cigarette brands available in Pakistan. Physical properties such as moisture, volatile matters, ash, pH, conductivity, and total reducing sugar were measured using standard procedures. Heavy metals, toxic metals, and nicotine were determined using atomic absorption spectrophotometer, flame photometry, and liquid chromatography, respectively. Local, and local branded samples were found to be rich with iron and magnesium and safe in terms of lower copper content when compared with the branded samples and other reported data of different countries of the world. Significant differences (p < 0.05) have been observed in the values of ash, conductivity, iron, zinc, copper, nickel, cobalt, magnesium, lithium, sodium, and potassium in local, loc...

Environmental monitoring and assessment, 2015

The fluoride level in drinking water is an important parameter and has to be controlled in order ... more The fluoride level in drinking water is an important parameter and has to be controlled in order to prevent dental and skeletal fluorosis. The objective of this study is to assess fluoride content and other water quality parameters in the samples taken from open wells, tube wells, and karezes of Mastung, Mangochar, and Pringabad areas of Balochistan province. A total number of 96 drinking water samples out of 150 were found unfit for human consumption. Area-wise analysis show that the samples from 39 sites from Mastung, 12 from Mangochar, and 13 from Pringabad were found in the risk of dental fluorosis of mild to severe nature. However, 12 sampling sites from Mastung, 8 from Mangochar, and 2 from Pringabad were identified as the risks of mottling and skeletal fluorosis or other bone abnormalities. The highest concentration of F(-) has been observed as 14 mg L(-1) in Mastung. Correlation analysis show that fluoride solubility in drinking water is pH dependent; and the salts of Ca(2+)...

Journal of Minerals and Materials Characterization and Engineering, 2012

The surface of Thar coal has been characterized by spectroscopic, microscopic and chemical method... more The surface of Thar coal has been characterized by spectroscopic, microscopic and chemical methods using atomic absorption spectroscopy, fourier transform infrared analysis, X-ray diffraction, scanned electron microscopy and pH titration. The samples contained high moisture, low volatile and low to moderate sulfur content and ranked as lignite (heating value 2541-4289 kcal/kg on moist, mineral-matter-free basis). Scanned electron micrographs show porous matrix with calcium, potassium or sodium minerals. Fourier transform infrared analysis also confirmed the presence of aluminum, silica and hydrate mineral constituents. The spectra showed C=C aromatic groups at 1604-1609 cm-1. Phenolic ester and carboxylic acid are identified by C=O stretching vibration peaks at 1702 cm-1. The peaks of quartz and kaolinite were observed at 900-1100 cm-1. Point of zero charge of Thar coal has been estimated as 6.00 to 6.27 through adsorption of H + and OHions by suspending coal particles in aqueous electrolyte solution. Oxygen containing functional groups, mineral matter, and metal oxides are found to have a remarkable impact on point of zero charge. The surface characterization study will be helpful in the separation of hydrophilic impurities during coal preparation processes considering pzc as the controlling factor.

Asia-Pacific Journal of Chemical Engineering, 2015

Thermochemical decomposition of 16 samples of low-rank Thar coal has been investigated using noni... more Thermochemical decomposition of 16 samples of low-rank Thar coal has been investigated using nonisothermal thermogravimetric data under an inert environment. Rapid weight loss of volatiles was found in the regions of 164-233 and 473-503°C. Kinetics of pyrolysis reaction showed that the volatiles released in three consecutive steps follow first-order reaction. The kinetic evaluation focuses on all the steps to estimate activation energy, pre-exponential factor and the contribution of each step to the overall reaction. The results showed that evaporation of moisture and low-temperature volatile compounds require 3.17-4.81 kJ mol À1 activation energy. The combustion of char required a higher amount of energy (10.86-36.11 kJ mol À1). The formation of secondary char required 10.34-24.00 kJ mol À1 energy. The results suggested that Thar coal has a substantial potential for gasification due to high volatile content and low activation energy.

Determination of Points of Zero Charge of Natural and Treated Adsorbents

Surface Review and Letters, 2007

Although particle size and its measurement are intuitively familiar to particle technologists, th... more Although particle size and its measurement are intuitively familiar to particle technologists, the concept of point of zero charge (pzc) is less widely understood and applied. This is unfortunate since it is at least as fundamentally important as particle size in determining the behavior of particulate materials, especially those with sizes in the colloidal range below a micrometer. pzc is related to the charge on the surface of the particle and strongly depends on the pH of the material; so it influences a wide range of properties of colloidal materials, such as their stability, interaction with electrolytes, suspension rheology, and ion exchange capacity. The pH dependence of surface charges was quantified for four different adsorbent–aqueous solution interfaces. The points of zero charge were determined for activated charcoal, granite sand, lakhra coal, and ground corn cob materials using three methods: (1) the pH drift method, measuring pH where the adsorbent behaves as a neutra...

Journal of Thermal Analysis and Calorimetry, 2011

The concept of weighted mean activation energy has been used to assess the reactivity of Thar coa... more The concept of weighted mean activation energy has been used to assess the reactivity of Thar coal in terms of pyrolytic and combustion behavior using nonisothermal thermogravimetry. The samples were characterized as low sulfur and high volatile lignite to subbituminous coal. Modified Coats-Redfern method was applied to analyze the kinetic data of both processes. Thermal degradation of the samples studied was explained by three independent first-order kinetic steps. The good correlation coefficients for the independent first-order reaction models show the complexity of the overall process. The activation energy for pyrolysis reaction ranges from 19.20-63.55 to 23.68-54.49 kJ mol-1 for combustion profile. The samples of different rank were classified applying chemometric approach on the reactivity parameters. Principal component analysis was found as a statistical tool to organize the coal samples in accordance to ASTM classification. This study broadens the scope of thermal analysis in the field of coal utilization by assessing coal reactivity.

Journal of Thermal Analysis and Calorimetry, 2010

The effect of microwave heating was studied in six varieties of edible oil. Variations in physico... more The effect of microwave heating was studied in six varieties of edible oil. Variations in physicochemical properties were observed and compared with the data obtained by hot plate heating. Fourier-transform infrared spectra of the oils showed substantial variations after both types of heating in the region of hydrogen's stretching (C-H) vibration, region of double bond's stretching (C=O), and fingerprint region. The visible spectra of mustard and olive oil showed the reduction in carotenoid, flavonoid, and chlorophyll pigments after heating. The oil samples were discriminated as saturated, monounsaturated, and polyunsaturated fats using chemometric techniques on physical and spectroscopic measurements.

International Journal of Food Properties, 2010

Six strawberry samples, commercially grown in Pakistan, were studied for physicochemical properti... more Six strawberry samples, commercially grown in Pakistan, were studied for physicochemical properties. All samples have high level of water and low contents of ash and volatile compounds. The berry was found to be a good source of potassium (1.14-1.93 g/kg), magnesium (0.12-0.15 g/kg), calcium (79.59-124.11 mg/kg) and sodium (23.51-36.03 mg/kg). The lead and cadmium contents were below the detection limits (1.0 ± 0.1 µg/l for lead and 0.1 ± 0.01 µg/l for cadmium). Principal component analysis and cluster analysis were found to be good statistical tools for the evaluation of the compositional variations with respect to geographical origin.

Study of dye–surfactant interaction: Aggregation and dissolution of yellowish in N-dodecyl pyridinum chloride

Fluid Phase Equilibria, 2006

Among several known technique for investigating dyesurfactant interactions, the conductivity mea... more Among several known technique for investigating dyesurfactant interactions, the conductivity measurement and spectroscopy are simple and accessible methods for determining the degree of interaction between dye and surfactant. An abrupt change in measured specific ...

Environmental Monitoring and Assessment, 2011

The anthropogenic and natural emissions of heavy metal pollutants in the atmospheric environment ... more The anthropogenic and natural emissions of heavy metal pollutants in the atmospheric environment adversely affect the health of people exposed to the pollutants in different parts of the world. The concentration values of the heavy elements in suspended dust, trapped in Air conditioner's filters, along the Murree Highway were measured using Flame Atomic Absorption Spectrometer (FAAS). Health risk assessments for non-carcinogenic and carcinogenic effects, due to the heavy element contaminants, have been calculated for both children and adults. The risk assessments in case of children for non-carcinogenic effects showed that As has values greater than the safe level of Hazard Index (HI=1), the threshold value, however in case of adults the value of risk for As is also higher in comparison to the rest of the elements but lies within the safe range of Hazard Index (HI<1). The carcinogenic effects lie within the range of threshold values for all the investigated elements in case of children as well as adults.

The Physicochemical Characterization of a Newly Explored Thar Coal Resource

Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2014

ABSTRACT The samples of Thar coalfield were characterized using a thermogravimetric analyzer, ato... more ABSTRACT The samples of Thar coalfield were characterized using a thermogravimetric analyzer, atomic absorption spectrophotometer, X-ray diffractometer, Fourier transform infrared spectra, and scanning electron microscopy-energy dispersive x-ray spectroscopy analysis. The samples were ranked as lignite and subbituminous according to American Society for Testing and Materials standard classification. Differential thermogravimetric analysis results specified chemical reactivity of coal at the primary devolatilization region (257–412°C) and secondary devolatilization region (741–900°C). The minerals identified were quartz, kaolinite, dikite, halloysite, gold copper indium, graphite hydrogen nitrate, and magnesium vanadium molybdenum oxide. X-ray diffraction study confirmed the presence of mineral constituents as indicated by microscopic investigation. Fourier transform infrared spectra identified C=C aromatic groups at 1,500–1,700 cm−1 as maturity indicator and 2,800–3,000 cm−1 and 2,300 cm−1 as aliphatic stretching regions. The peaks of quartz and kaolinite were observed at 900–1,100 cm−1. Strong correlations between mineral matter-SiO2 (r 2 = 0.808) and Al2O3-SiO2 (r 2 = 0.957) indicates Al and Si as the dominant inorganic components. Cluster analysis appeared as an additional tool for coal ranking based on their physicochemical properties.

Physico-chemical characterization of date varieties using multivariate analysis

Journal of the Science of Food and Agriculture, 2008

... How to Cite. Khan, MN, Sarwar, A., Wahab, MF and Haleem, R. (2008), Physico-chemical characte... more ... How to Cite. Khan, MN, Sarwar, A., Wahab, MF and Haleem, R. (2008), Physico-chemical characterization of date varieties using multivariate analysis. ... In Proceedings of the First International Symposium on Date Palm, King Faisal University, Saudi Arabia, 2325 March (1982). ...