خرید و فروخت کے شرعی احکامات، عصرِ حاضر میں اطلاق کی صورتیں: سیرت طیبہ کی روشنی میں

Transactions are part of social life. Sale and purchase are important activities of human life. Islam gives guidance for sale and purchase transactions and the life. Jurists and ulma have addressed the varieties of such transactions as the world became increasingly complex place. This article discuss the basic type of sale and purchase and is being used in Islamic banking system.

Chemical Analysis of Arsenic and Mercury in Coal of Thar Coal Field and Their Interaction With Adjoining Aquifer Water and Solid Matrices: An Environmental Impact Study

The main focus of this work was to evaluate the quality parameters of coal, adjoining solid matrices (clay, sand and surface soil) and aquifer water collected from different depths of block III and V of Thar coal field, Sindh, Pakistan. Quality parameters such as elemental composition, proximate and ultimate parameters of coal samples were point out the physicochemical characteristics. Moisture contents in coal samples of Thar coalfield indicated that the direct use of coal is not suitable for power generation. Mineral composition has been determined by Scanning Electron Microscopy (SEM) and X-ray diffraction. The occurrence of arsenic (As) and mercury (Hg) in coal samples of Thar coal field and its behavior during the combustion were studied in detail. Extracted As and Hg contents in coal and laboratory made ash (LMA) samples were measured by MHS-15 hydride/Cold vapor generation atomic absorption spectrometry, respectively. Results of LMA indicated that during combustion of coal >75% and >90% of As and Hg, respectively can be released into the atmosphere. The contents of As and Hg in coal samples of block-III of Thar coalfield was found to be higher as compared to block-V, might be due to difference in geochemical mineral composition. The As bounded with different chemical fractions of coal and solid matrices was carried out by BCR sequential extraction scheme (BCR-SES) and single step, based on BCR scheme (BCR-SS). Meanwhile, the three step fractions of As in LMA have also been investigated. The extraction efficiency of As by BCR-SES and BCR-SS is found to be greater than 97%. The BCR-SS method is a time saving; it can reduce the extraction time from 51 to 36 h.For fractionation of Hg in coal samples by two alternative modified schemes (conventional and ultrasonic assisted single step extractions) were designed and applied on same operating conditions for each individual as BCR fractions. In both CSE and USE extractions, the time was reduced from 51 to 36 h and 2 h, respectively. The relative mobility of As and Hg in coal samples were found in the following decreasing order: oxidizable fraction >reducible fraction >acid soluble fraction. The developed methods for water soluble Hg in clay, sand and surface soil samples obtained from Thar coalfield, Pakistan, using liquid-liquid microextraction (EW-LLME), based on exchangeable water system, which was first time developed for Hg enrichment. Exchangeable water was made by the reaction of carbon dioxide with diethylenetriamine. The exchanging phenomena from low polarity to high polarity were confirmed by FT-IR Spectrometry. The complex formation of HgII with 1, 5-diphenylcarbazone was achieved under the optimized experimental conditions. Another method, supramolecular solvent-based dispersive liquid-liquid microextraction was also used. The HgII in acidic medium forms complex with dithizon in the presence of supramolecular solvent (Tetrahydrofuran and 1-Undecanol) that have been formed reverse micelles. Under optimized experimental conditions the LOD for both developed methods were found 0.5 ng L-1 and 5.61 ng L-1 respectively. Meanwhile the EF was obtained to be 45.2 and 77.8, respectively. Advance extraction methodologies were used to evaluate the physicochemical parameters, As and Hg in aquifer water from different seams of Thar coalfield. The polymer, polystyrene polydimethyl-siloxane was loaded into the micropipette tip of the syringe system as an adsorbent to developed miniaturized solid phase microextraction for speciation of arsenic. It was observed that AsV adsorbed on the polystyrene polydimethylsiloxane in the pH rang of 6-8, while AsIII was not reacted. The adsorbed AsV in micropipette tip of syringe system was eluted by 1.0 M hydrochloric acid. The total iAs contents were obtained by the addition of oxidizing agent (potassium permanganate) into the studied samples before passing to the micropipette tip of syringe system. Concentration of AsIII in water samples were measured by subtracting AsV from total iAs concentration. Different characteristics which effect the determination of AsV specie, such as amount of adsorbent, adsorption capacity, pH, pulling and pushing cycles for adsorption and desorption, volume of sample, eluent type and its volume were also studied in detail. The EF and LOD of AsV by desired method were 218 and 6.9 ng L−1 respectively. A simple and green preconcentration method of hydrophobic to hydrophilic switchable liquid-solid dispersive microextraction has been introduced first time for separation of As in the real water samples. Multiwall carbon nanotube was immobilized with diethylenetriamine and then used as solid phase adsorbent for the determination of trace level of arsenic. The reversibly hydrophobic-hydrophilic switchable phenomena of immobilized MWCNT in the liquid-solid dispersive microextraction were checked by using FT-IR Spectrometry and SEM. Optimized analytical conditions, EF and LOD were obtained as 83 and 3.05 ng L−1, respectively for arsenic. The innovative pressure induced ionic liquid based dispersive liquid-liquid microextraction method has been developed for determination of total As in water samples. The complexing reagent diethyldithiocarbamate was formed a strong hydrophobic complex with As at pH 4. Various experimental parameters like pH, complexing reagent, ionic liquid, induced pressure and centrifugation were optimized to achieve maximum recovery. Analytical parameters like LOD, LOQ and linear range were obtained 0.016 µg L-1, 0.055 µg L-1 and 0.062-1.25 µg L-1, respectively. The percentage RSD and EF were found 4.89% and 87.5, respectively. A novel matrix-less cloud point extraction procedure was developed for Hg determination in aquifer water samples. Complexing reagent, diethyldithiophosphate was selected for Hg extraction. Various parameters such as pH, complexing reagent, surfactant, temperature and time have been studied. Optimized parameters such as LOD and EF were found to be 7.5 ng L-1 and 22.8, respectively. The relative standard deviations was >5%, which indicates that the developed method is highly precise. Accuracy of all developed advance extraction methods were checked by performing the standard addition methods in real sample as well as matrixes matched certified reference materials. Aquifer water samples were collected from both selected blocks (III and V) different depths such as first aquifer (AQ1) 50-60 m, second aquifer (AQ2) 100-120 m and third aquifer (AQ3) 200-250 m of Thar coalfield, Pakistan. Different aquifers water were analysis for As, Hg using advance extraction methodologies as described above. The physicochemical parameters using different advance extraction methodologies. The results indicated that the As, Hg and physicochemical parameters were found to be higher than WHO recommended values for drinking water except pH and SO42-. The relative levels of As and Hg in aquifer water obtained from different depths was found in the following decreasing order: AQ2 <AQ1 <AQ3. Different statistical multivariate techniques (principal component and cluster analysis) were used for correlation of As and Hg with other metals in aquifers water at different depths. The positive correlation was observed between Hg, As and As species with other ions of aquifers water except F , K+ and HCO3-, which might be caused by geochemical minerals. The interpretation of determine values by the cluster technique to point out the variations within the water quality parameters as well as sampling location of Thar coalfield. Results of cluster analysis indicated that aquifer water of AQ2 was highly contaminated as compared to AQ1 and AQ3 it may be due to leaching from coal zone aquifer water.