Department of Chemistry

Palmyrahjaggery is a popular traditional sweetener in Jaffna. It is a nutrient rich crude sugar which is also used in the traditional medicine. The authenticity of the product in markets is questionable since there is no analytical methods exist to detect adulterations. Adulteration spoils the good recognition for the jaggery, which results in lessprofit for the industry, also, it affects the livelihood of those people who directly involved in the production of jaggery. Other than the economic aspects, since jiggery is used in traditional medicine, adulteration of jaggery has some health related consequences as well. In this study the NIR spectroscopyis used to study the principal component analysis for the authentication of jaggery and identification of the adulterant. A reasonable amount ofjaggery samples were used as data set for calibration-validation procedure. Jaggery was produced in a laboratory scale as pure, adulterated with sugar and rice bran at different concentrations. Aqueous solutions of these samples were prepared and NIR spectra of the samples were recorded via using the UV/VIS/NIR spectrophotometer (Jasco V570) with scanning range of 750-1300 nm wavelength. Principal component analysis of the spectra is useful for the identification of the adulterations and for the authentication of jaggery.

In the post-war context, Jaffna crab industry is developed, exporting live, fresh de-shelled and processed crabs all around the world. Human consumes only 40% of the crab’s weight as meat and the rest is thrown into the environment as waste shell. This unutilized waste crab shell contains large amount of chitin which can be extracted and utilized for different applications in cosmetics, agriculture, food, medicine and waste water treatment. The present study was carried out to find out the chitin content in selected, most abundant crabs such as Portunus pelagicus, Thalamita crenata and Portunus sanguinolentus available in Jaffna peninsula, during the period of July October, 2017. Crabs were deshelled and the shells were dried, ground and screened through < 0.5 mm sieve. Fine particles of the crab shells samples were deproteinized by treating with 3.5% (w/v) NaOH solution and demineralized by treating with 1 N HCl. The extracted chitin was confirmed via the functional group using ...

Salt is the maximum commonly spread inorganic chemical in all over the world. It is a part of human food, and life without salt is improbable. Salt is widely used for cooking, preserving and for preventing roads from icing up. The study was carried out from March 2010 to September 2010. The salt samples were collected from Araly, Thanuvil, Uppuveli, Chemmani and vallai in the Jaffna peninsula, Sri Lanka. To determine the standard value, salt samples were collected from Puttalam and Palavi salt producing areas. The water, salt and soil sample were collected from Araly, Thanuvil, Uppuveli, Vallai, Chemmani, Kalundaiveli, and Kaarainagar in the Jaffna peninsula Sri Lanka. In this study salt, water, and soil were analyzed for physical (pH, color, taste) and chemical (Cl-, SO42-, Ca2+, Mg2+, Na+, K+, PO43-, Fe3+, total alkalinity and total solids) characteristics. The salt quality in all the salt samples except Thanuvil, are chemically safe for human consumption. Even though there are so...

The present study was carried out to analyse the inorganic and organic contents in the leaf of Datura metel and to investigate the acute toxicity at varying concentrations on grasshoppers and red ants. We determined the calcium, magnesium and phosphorous in the ionic state quantitatively and carried out screening tests and solvent extraction using chloroform to find out the presence of organic groups such as alkaloids, flavanoids, saponins and steroids. The concentration of Ca 2+ , Mg 2+ , Fe 3+ and PO 4 3− were found to be (4.28 ± 0.05)×10 4 , (3.86 ± 0.009)×10 4 , (2.33 ± 0.007)×10 4 and (4.65 ± 0.06)×10 4 ppm respectively. The screening tests confirmed the presence of alkaloids and steroids and the absence of saponins and flavanoids. Increasing concentrations of the plant extracts (2500-15000 ppm) were added to grasshoppers (n = 10) and red ants (n = 10) in an experimental chamber. After 10 minutes of exposure, the numbers of live insects were counted. The results showed the EC 50 value was 12000 ppm for grasshoppers and 11600 ppm for red ants. Percentage mortality increased from 20-60% with increasing concentrations. Our results indicated that extract of Datura metel leaves at higher concentrations was more toxic and it can be used as an insecticide against grasshoppers and red ants.

Palmyrahjaggery is a popular traditional sweetener in Jaffna. It is a nutrient rich crude sugar which is also used in the traditional medicine. The authenticity of the product in markets is questionable since there is no analytical methods exist to detect adulterations. Adulteration spoils the good recognition for the jaggery, which results in lessprofit for the industry, also, it affects the livelihood of those people who directly involved in the production of jaggery. Other than the economic aspects, since jiggery is used in traditional medicine, adulteration of jaggery has some health related consequences as well. In this study the NIR spectroscopyis used to study the principal component analysis for the authentication of jaggery and identification of the adulterant. A reasonable amount ofjaggery samples were used as data set for calibration-validation procedure. Jaggery was produced in a laboratory scale as pure, adulterated with sugar and rice bran at different concentrations. Aqueous solutions of these samples were prepared and NIR spectra of the samples were recorded via using the UV/VIS/NIR spectrophotometer (Jasco V570) with scanning range of 750-1300 nm wavelength. Principal component analysis of the spectra is useful for the identification of the adulterations and for the authentication of jaggery.

The present study was carried out to analyse the inorganic and organic contents in the leaf of Datura metel and to investigate the acute toxicity at varying concentrations on grasshoppers and red ants. We determined the calcium, magnesium and phosphorous in the ionic state quantitatively and carried out screening tests and solvent extraction using chloroform to find out the presence of organic groups such as alkaloids, flavanoids, saponins and steroids. The concentration of Ca 2+ , Mg 2+ , Fe 3+ and PO 4 3− were found to be (4.28 ± 0.05)×10 4 , (3.86 ± 0.009)×10 4 , (2.33 ± 0.007)×10 4 and (4.65 ± 0.06)×10 4 ppm respectively. The screening tests confirmed the presence of alkaloids and steroids and the absence of saponins and flavanoids. Increasing concentrations of the plant extracts (2500-15000 ppm) were added to grasshoppers (n = 10) and red ants (n = 10) in an experimental chamber. After 10 minutes of exposure, the numbers of live insects were counted. The results showed the EC 50 value was 12000 ppm for grasshoppers and 11600 ppm for red ants. Percentage mortality increased from 20-60% with increasing concentrations. Our results indicated that extract of Datura metel leaves at higher concentrations was more toxic and it can be used as an insecticide against grasshoppers and red ants.

Palmyrah palm (Sweet Toddy) to a thick consistency. The palmyrah jaggery made in household level has bitter taste due to the presence of excess amount of lime with low purity. During the period of May 2013 to June 2013 four field experiments were carried out to optimize the amount of quick lime (CaO) for a suitable Palmyrah sweet sap collection in the areas of Jaffna district, using Randomized Complete Block design. This experiment was carried out with four different concentrations of quick lime such as 5.0, 3.0, 2.5 and 2.0 grams of CaO in liter of sap. The quick lime used in this study was produced from sea shells with 96% of purity at Palmyrah Research Institute laboratory. Existing palmyrah jaggery available in the market is inferior in its quality as liquefaction and deterioration of color. Through this research attention to be made to eradicate its hydroscopic nature in the existing jaggery to upgrade it. Physicochemical quality parameters of commercially available samples and produced jaggery samples were studied according to Sri Lankan standards for jaggery. Quality of jaggery was enhanced using sweet sap with acceptable lime with higher degree of purity. For suitable jaggery production, 2.508 ± 0.411 grams of lime (96 % purity) per one liter of sweet sap were optimized and this jaggery was scored high score than jaggery from other field experiments. _____________________________________________________________________________________________

The present study focuses on the interaction of H 2 Rydberg molecules with doped silicon semiconductor surfaces. Para-H 2 Rydberg states with principal quantum numbers n = 17-21 and core rotational quantum number N + = 2 are populated via resonant two-colour two-photon (vacuum ultraviolet-ultraviolet) excitation and collide at grazing incidence with a surface. For small Rydbergsurface separation, the Rydberg states are ionized due to the attractive surface potential experienced by the Rydberg electron and the remaining ion-core is detectable by applying a sufficiently strong external electric field. It is found that the surface ionization profiles (ion signal vs applied field) of H 2 on p-type doped Si surfaces show a higher detected ion signal than for n-type Si surfaces, while an Au surface shows lower detected ion signal than either type of Si surface. It is shown that ion detectability decreases with increasing dopant density for both types of Si surfaces. Higher-n Rydberg states show higher ion detectability than lower-n Rydberg states but this variation becomes smaller when increasing the dopant density for both p-and n-type surfaces. Theoretical trajectory simulations were developed with a 2D surface potential model and using the over-the-barrier model for the ionization distance; the results help to explain the observed variations of the experimental surface ionization profiles with dopant density and type.

The detection of ions or electrons from the surface ionisation of molecular H 2 and atomic H Rydberg states incident at doped Si surfaces is investigated experimentally to analyse the effect of the dopant charge distribution on the surface-ionisation processes. In both experimental studies, the molecular H 2 and atomic H Rydberg states are generated via two-colour vacuum ultraviolet-ultraviolet (VUV-UV) resonant excitation. For H 2 , various Stark states of the N + = 2, n = 17 manifold are populated in the presence of an electric field. The variation of the observed surface-ionisation signal with surface dopant concentration and type, shows similar characteristics for all the Stark states. A comparison is made between these ion-detected surface-ionisation profiles and those obtained via electron detection. Different trends as a function of dopant concentration and type are observed for the two cases, explained by the greater effect of surface charges on the post-ionisation ion trajectory compared to the electron trajectory. For the atomic-H Rydberg states with principal quantum number n = 29-34 populated in the absence of a Stark field, the observed behaviour is similar to the interaction of molecular H 2 Rydberg states at the same surfaces, and these measurements confirm that the observed effects are attributable to the nature of the target surface rather than the specific atomic or molecular Rydberg species.

The adsorption capability of activated carbon is applied to remove large variety of compound from contaminated water through carbon adsorption. The scope of this study was to investigate the water purification capabilities of prepared activated charcoalfrom dried Palmyrah (Borassus flabellifer) kernel shell. 18 types of different activated charcoal samples were prepared through the following steps as carbonization, chemical activation and pyrolysis. Carbonized kernel shells which were prepared at 400⁰C, 500⁰C and 600 ⁰C for 10minutes and 20 minutes, were chemically activated by base (Potassium hydroxide), acid (Phosphoric acid) and water. Finally activated kernel shells were pyrolyzed at 800⁰C for 30 minutes.Physico-chemical analysis of collected pond water before and after filtration using prepared activated charcoal was carried out.The pH and conductivity were measured by electrometric method. The calcium and magnesium were determined by ethylene diamine tetra acetic acid complexiometric titration method. Mohr's argentometric method was used to determine chloride. Nitrate and ammonia were determined by Kjeldhal method. The phosphate content determination was carried out by spectrophotometric (Vanadomolybdate colour development) method.All results were analyzed in SAS software and the mean separation was done by LSD at p=0.05. Results of analyzedwater quality parameters revealed that the best thermal condition to carbonize the kernel shell was at 600 ⁰C for 20 minutes and basechemical activation was the best than acid or water activation.41.7 % of nitrate, 54.5 % of ammonia, 58.3 % of calcium, 57.8 % of phosphate and 42.3 % of chloride were removed from collected pond water during water treatment by using activated charcoal produced at best carbonization and activation conditions. The physical characteristics such as colour, odur and taste were analyzed by organoleptic method and these characteristics were also superior in treated pond water than untreated pond water for all the activated charcoal treatments. This study will be a positive sign to prepare activated charcoal by applying different pyrolysis conditionsand which is applied to treat water from natural contaminated water bodies and industries.

Layered Li 9 V 3 (P 2 O 7) 3 (PO 4) 2 has attracted considerable interest as a novel cathode material for potential use in rechargeable lithium batteries. The defect chemistry, doping behavior and lithium diffusion paths in Li 9 V 3 (P 2 O 7) 3 (PO 4) 2 are investigated using atomistic scale simulations. Here we show that the activation energy for Li migration via the vacancy mechanism is 0.72 eV along the c-axis. Additionally, the most favourable intrinsic defect type is Li Frenkel (0.44 eV/defect) ensuring the formation of Li vacancies that are required for Li diffusion via the vacancy mechanism. The only other intrinsic defect mechanism that is close in energy is the formation of anti-site defect, in which Li and V ions exchange their positions (1.02 eV/defect) and this can play a role at higher temperatures. Considering the solution of tetravalent dopants it is calculated that they require considerable solution energies, however, the solution of GeO 2 will reduce the activation energy of migration to 0.66 eV. Lithium ion batteries are widely used as a dominant power source in consumer electronics and electric vehicles 1-5. Batteries with high-power density needed for large scale applications require new class of electrode materials providing large quantities of Li ions together with low cost, environmentally benign and constituent elements being high abundance. Several promising cathode materials for Li ion batteries [e.

In this study, force field-based simulations are employed to examine the defects in Li-ion diffusion pathways together with activation energies and a solution of dopants in Li2Ti6O13. The lowest defect energy process is found to be the Li Frenkel (0.66 eV/defect), inferring that this defect process is most likely to occur. This study further identifies that cation exchange (Li–Ti) disorder is the second lowest defect energy process. Long-range diffusion of Li-ion is observed in the bc-plane with activation energy of 0.25 eV, inferring that Li ions move fast in this material. The most promising trivalent dopant at the Ti site is Co3+, which would create more Li interstitials in the lattice required for high capacity. The favorable isovalent dopant is the Ge4+ at the Ti site, which may alter the mechanical property of this material. The electronic structures of the favorable dopants are analyzed using density functional theory (DFT) calculations.

Lithium zinc silicate, Li2ZnSiO4, is a promising ceramic solid electrolyte material for Li-ion batteries. In this study, atomistic simulation techniques were employed to examine intrinsic defect processes; long range Li-ion migration paths, together with activation energies; and candidate substitutional dopants at the Zn and the Si sites in both monoclinic and orthorhombic Li2ZnSiO4 phases. The Li-Zn anti-site defect is the most energetically favourable defect in both phases, suggesting that a small amount of cation mixing would be observed. The Li Frenkel is the second lowest energy process. Long range Li-ion migration is observed in the ac plane in the monoclinic phase and the bc plane in the orthorhombic phase with activation energies of 0.88 eV and 0.90 eV, respectively, suggesting that Li-ion diffusivities in both phases are moderate. Furthermore, we show that Fe3+ is a promising dopant to increase Li vacancies required for vacancy-mediated Li-ion migration, and that Al3+ is th...

Wollastonite (CaSiO3) is an important mineral that is widely used in ceramics and polymer industries. Defect energetics, diffusion of Ca ions and a solution of dopants are studied using atomistic-scale simulation based on the classical pair potentials. The energetically favourable defect process is calculated to be the Ca-Si anti-site defect cluster in which both Ca and Si swap their atomic positions simultaneously. It is calculated that the Ca ion migrates in the ab plane with an activation energy of 1.59 eV, inferring its slow diffusion. Favourable isovalent dopants on the Ca and Si sites are Sr2+ and Ge4+, respectively. Subvalent doping by Al on the Si site is a favourable process to incorporate additional Ca in the form of interstitials in CaSiO3. This engineering strategy would increase the capacity of this material.

There is growing interest to discover suitable calcium containing oxides that can be used as electrode materials in calcium ion batteries. A comprehensive computational investigation of ionic defects and Ca-ion diffusion in Ca-bearing oxide materials at the atomic level is important so as to predict their suitability for use in Ca-ion batteries. In this study, we apply atomistic simulation techniques to examine the energetics of defects, dopants, and Ca-ion diffusion in Ca3Fe2Si3O12. The calculations suggest that the Ca/Fe anti-site defect is the most favorable intrinsic defect causing such significant disorder, which would be sensitive to synthesis conditions. Diffusion of Ca2+ ions within Ca3Fe2Si3O12 is three-dimensional, with the activation energy of migration of 2.63 eV inferring slow ionic conductivity. The most favorable isovalent defects are Mn2+, Sc3+, and Ge4+ on Ca, Fe, and Si, respectively, for this process. The formation of extra calcium was considered to increase the c...

Some physicochemical parameters related to groundwater quality obtained from Yola Area of Northeastern Nigeria was investigated for the purpose of drinking and irrigation. An attempt was also made to develop linear regression equations to predict the concentration of water quality having significant correlation coefficients with electrical conductivity (EC). The TDS and EC has perfect correlation coefficients whereas Na + and Cl-, are highly correlated in all the water sources. Furthermore while Ca 2+ and HCO3are highly correlated in both the shallow and deep groundwater they have relatively lower correlation coefficients in the surface water samples. It was equally observed that Mg 2+ , Ca 2+ , NO3-, Cland Fe are highly correlated with EC in surface water samples. The data also indicated that apart from surface water bodies Ca 2+ , NO3-, Cland HCO3are poorly related with electrical conductivity at 5% level of significance. These data has shown that linear regression equations can be applied in predicting groundwater quality in any location @ JASEM

Palmyrah (borrasusflabellifer) jaggery industry is one of the ancient and large cottage industries in palmyrah society and it is produced by concentrating the inflorescence sap of Palmyrah palm (Sweet Toddy) to a thick consistency. The palmyrah jaggery made in household level has bitter taste due to the presence of excess amount of lime with low purity. During the period of May 2013 to June 2013 four field experiments were carried out to optimize the amount of quick lime (CaO) for a suitable Palmyrah sweet sap collection in the areas of Jaffna district, using Randomized Complete Block design. This experiment was carried out with four different concentrations of quick lime such as 5.0, 3.0, 2.5 and 2.0 grams of CaO in liter of sap. The quick lime used in this study was produced from sea shells with 96% of purity at Palmyrah Research Institute laboratory. Existing palmyrah jaggery available in the market is inferior in its quality as liquefaction and deterioration of color. Through this research attention to be made to eradicate its hydroscopic nature in the existing jaggery to upgrade it. Physicochemical quality parameters of commercially available samples and produced jaggery samples were studied according to Sri Lankan standards for jaggery. Quality of jaggery was enhanced using sweet sap with acceptable lime with higher degree of purity. For suitable jaggery production, 2.508 ± 0.411 grams of lime (96 % purity) per one liter of sweet sap were optimized and this jaggery was scored high score than jaggery from other field experiments.

Palmyrahjaggery is a popular traditional sweetener in Jaffna. It is a nutrient rich crude sugar which is also used in the traditional medicine. The authenticity of the product in markets is questionable since there is no analytical methods exist to detect adulterations. Adulteration spoils the good recognition for the jaggery, which results in lessprofit for the industry, also, it affects the livelihood of those people who directly involved in the production of jaggery. Other than the economic aspects, since jiggery is used in traditional medicine, adulteration of jaggery has some health related consequences as well. In this study the NIR spectroscopyis used to study the principal component analysis for the authentication of jaggery and identification of the adulterant. A reasonable amount ofjaggery samples were used as data set for calibration-validation procedure. Jaggery was produced in a laboratory scale as pure, adulterated with sugar and rice bran at different concentrations. Aqueous solutions of these samples were prepared and NIR spectra of the samples were recorded via using the UV/VIS/NIR spectrophotometer (Jasco V570) with scanning range of 750-1300 nm wavelength. Principal component analysis of the spectra is useful for the identification of the adulterations and for the authentication of jaggery.