VOLUME 32, NO6, DEC 2010
Adsorption of Azo Dye on Activated Carbon Prepared from Waste Wood: 2. Equilibrium


The present study was designed to investigate the effect of activation temperature on carbon prepared from the wood of Salvadora oleoides. The samples were characterized. Activation at 800 ºC is higher due to the decrease in polarity of the carbon surface, resulted from the decomposition of some of the acidic oxygen surface functionalities. Increase in adsorption rate was observed for higher temperature activated sample due to the increase in the surface area and opening of the blind pores and the increase in pore volume. Lower rate of dye adsorption on sample activated at 400 ºC may be due to the fact that polar functional groups situated at the pore opening have adsorbed water strongly through hydrogen bonds that in turn has resulted in the pores constriction or blockage. Freundlich, Langmuir, DR isotherm, and distribution coefficient models were used to compare the efficiency of the carbon activated at different temperature (400, 800 ºC). The data generated from all isotherms, show that 800 ºC activated sample has greater dye adsorption capacity.
Synthesis and Spectral Characterization of Mono- and Homodinuclear Complexes of Co(II), Ni(II), and Cu(II) with a Compartmental Hexadentate Schiff Base Ligand Derived from 3-Formylsalicylic Acid


Reaction between 3-formylsalicylic acid and 4,5-dichloro-1,2-phenylenediamine gave a compartmental hexadentate Schiff base (H4fsacph) with an N2O4 donor frame involving an inner N2O2 set of donors and an outer set of O2O2 donors. Three mononuclear complexes of the form M(H2fsacph)(H2O)2 (M = Co(II), Ni(II), Cu(II), and three homodinuclear complexes M'2(fsacph)(H2O)2 (M' = Co(II), Ni(II)) and Cu2(fsacph) were isolated and analyzed by physico-chemical techniques. The metal ions have been found to occupy the outer coordination site in the mononuclear complexes and occupy both sites in the dinuclear complexes.
Chemical Oxygen Demand (COD) Fractions Characterization of Karachi Metropolitan Wastewater


To prove the hypothesis that the inert products are given to environment due to biological degradation of substrate in activated sludge operations. This study was design to investigate the inert fractions of chemical oxygen demand (COD) in metropolitan effluent. An aerobic batch reactor system was experimentally setup and maintained up to 480 hours. At the end of operations, COD compositions of metropolitan wastewater were found to be STO = 131 mg/L, XSO = 63 mg/L, CSO = 178 mg/L, SSO = 115 mg/L, SI = 16 mg/L, XI = 218 mg/L, respectively. At the end of operations, COD compositions of metropolitan wastewater were found to be STO = 131 mg/L, XSO = 63 mg/L, CSO = 178 mg/L, SSO = 115 mg/L, SI = 16 mg/L, XI = 218 mg/L respectively.This study is focused on inert COD fractions of metropolitan wastewater which consist of domestic as well as local industrial effluent. Soluble inert COD (SI) must be determined for discharge standards since it did not give any reaction in activated sludge system and was given with wastewater discharge. However particulate inert COD (XI) accumulated in system depending on sludge retention time due to it is only wasted from system by wasted sludge. Experimental techniques were used attained Zohu X. et al. [1, 2] in order to determine directly influent particulate and soluble inert fractions. The experimental study was carried out until COD profile reached to steady state or depletion of degradable substrate.The conventional parameters of municipal characterization were as follows: total COD (CTO) = 412 mg/L, total soluble COD (STO) = 131 mg/L, biochemical oxygen demand (BOD5) = 197 mg/L, total biochemical oxygen demand (BODt) = 351 mg/L, total suspended solids (TSS) = 264 mg/L, ammonia nitrogen (NH3-N) = 26.6 mg/L, grease & oil (G & O) = 17.5 mg/L and pH were 7.4 SU, respectively.
Coatings of Poly-p-Aminophenol at Carbon Electrodes: Electrochemical Behavior


Polymer coated carbon electrodes were prepared by reductive electro-polymerization of p-aminophenol in 1.0 M nitric acid. Polymer films thus formed were then investigated by voltammetric and electrochemical impedance spectroscopy. Impedance studies in 1.0 M nitric acid revealed that these coatings showed mixed behavior both resistive and capacitive.
Effect of L-Ascorbic Acid on the Formulation and Characterization of a Multiple Emulsion from Paraffin Oil


Multiple emulsions contain at least three phases. The material entrapped in internal phase is released slowly and thus its effects can be prolonged. The other benefit of multiple emulsions is protection of material entrapped in internal phase. The purpose of the study was to prepare a stable multiple emulsion containing a skin antiaging agent L-Ascorbic acid (vitamin C) using paraffin oil. L-Ascorbic acid, which is a very unstable ingredient and is decomposed in the presence of oxygen, in a concentration of 2% was entrapped in the inner most aqueous phase of w/o/w multiple emulsion. Formulation of multiple emulsion was stored at different accelrated conditions i.e. 8 ºC, 25 ºC, 40 ºC and 40 ºC+75% RH (Relativ Humidity) for 28 days to predict the stability of formulation. Formulation was found to be stable at lower temperatures for a given period of time and no phase sepration was observed in any sample. Different parameters like pH, globule size, electrical conductivity and effects of centrifugation were studied for a period of 28 days to confirm the stability of multiple emulsion. It was found that there was no significant change in globule sizes in any sample kept at most of the conditions. Significant changes in both pH and conductivity were observed in the samples of formulation kept at 8 ºC. Insignificant changes both in pH and electrical conductivity were observed in samples of formulation kept at 40 ºC and 40 ºC + 75%RH conditions throughout study period. The data obtained was evaluated statistically using two way ANOVA (Analysis of Variance) and LSD (Least Significant Difference) tests.
Mass Spectral Studies of Tetraorganotin (IV) Compounds Containing Long Chain Alkyl and Aryl Groups


Tetraorganotin (IV) compounds having general formula R4-xSnR¢x where R = CH3, n-C4H9, C6H5, C6H5CH2, R¢ = n-C6H13 and x = 1 or 2, have been synthesized by the reaction of R2SnCl2 and R3SnCl with appropriate amount of n-hexylmagnesium bromide, prepared in situ in dry ether. All the products were distilled under vacuum and thoroughly studied by mass spectrometric analysis to confirm their formation and fragmentation behavior. Molecular ion peaks were observed for some compounds with low relative abundance. The possible fragmentation pattern and data for all compounds have been discussed in detail.
Heavy Metal Levels in Commonly used Traditional Medicinal Plants


In the present study a survey of 24 commonly used medicinal plants of Indian subcontinent origin was carried out to evaluate their levels of heavy metals by electrothermal atomic absorption spectroscopy. The results showed that the highest mean value for Cd (12.06 µg.g-1), Cr (24.50 µg.g-1), Cu (15.27 µg.g-1), Pb (1.30 µg.g-1), Fe (885.60 µg.g-1), Mn (90.60 µg.g-1), Ni (9.99 µg.g-1) and Zn (77.15 µg.g-1) were found in Lawsonia inermis, Murraya koenigii, Mentha spicata, Beta vulgaris Linn, Mentha spicata, Lagenaria sicerana standl, Lawsonia inermis, Emblica officinalis, respectively. The mean and maximum levels of Cd in plant samples were found higher than the recommended values of the Joint Expert Committee on Food Additives of the Food and Agriculture Organization of the United Nations and the World Health Organization and may constitute a health hazard for consumers. All other heavy metals in medicinal plants were found below the recommended tolerable limits.
Quality Assessment of Surface and Groundwater of Taluka Daur, District Nawabshah, Sindh, Pakistan.


In present work groundwater and surface water samples are analyzed from taluka Daur, district Nawabshah, Sindh. 38 water samples of the study area were examined. The physico-chemical parameters of the water samples were found in the following ranges pH 6.64-8.18, total dissolved salts (TDS) 188-26752 mg/L, HCO3 27-5011 mg/L, total hardness (TH) 62-13200 mg/L, chloride 41-13953 mg/L, SO4 23-5122 mg/L, ortho-phosphate (P) 0.09-0.144 mg/L, total phosphate (P) 0.097-0.925 mg/L, NO2-N 0-0.662 mg/L, NO3-N 0.02-1.993 mg/L and dissolved oxygen 1.1-10.0 mg/L. The concentration of essential metal ions (Na, Ca, Mg, and K) was found in the ranges of 18-4600 mg/L, 12-3610 mg/L, 4-1308 mg/L and 3-570 mg/L, respectively. Only ten samples were found suitable and rest of the samples were unsuitable for human consumption. The study shows that the groundwater of the major portion of study area is not suitable for drinking purpose.
Recovery of Gold from Electroplating Waste Water Effluents by using Orange Peel


A method for the recovery of gold from the electroplating waste water effluents has been developed based on its adsorption on orange peel. Adsorption of gold(III) from dilute solutions of hydrochloric acid on orange peel has been studied under various experimental conditions by using batch technique. Distribution coefficients, Kd and % extraction were determined for the orange peel-gold solution system as a function of contact time, pH, sorbent, sorbate concentrations and temperature. The uptake of gold by raw orange peel is time, pH, initial metal concentration, sorbate dose, and temperature dependent. Adsorption data have been interpreted in terms of Langmuir and the Freundlich equations. Thermodynamic parameters for adsorption of gold on raw orange peel have been determined at three different temperatures. The positive value of heat of adsorption; ΔH° = 61.85 kJ/mol shows that the adsorption of gold on orange peel is endothermic whereas the negative value of ΔG° = -35.85 kJ/mol at 308 K shows the spontaneity of the process. ΔG° becomes more negative with increase in temperature which shows that the adsorption is more favorable at higher temperatures. Under the optimal adsorption conditions the adsorption capacity of gold is 5.79 mg/g of the raw orange peel out of which 5.37 mg of gold gets desorbed with 0.1 % thiourea solution.
Microstructural Development of Superconducting Phases in Pb-BSCCO System Derived from Sol-Gel Technique


Sol-gel processing technique has been utilized to produce the gel of Pb-BSCCO system (Bi2-xPbxSr2Ca2Cu3O10±y, where x = 0.2, 0.4, and 0.8, are the mole fraction of Pb substituted against Bi). The gel samples were subsequently heated to 800 °C for 2 h to obtain the powders which were then pressed and sintered at 845 °C for 60 h. The morphologies in the Pb-BSCCO gel, powder and sintered products were observed with scanning electron microscope (SEM) and optical microscope. The plate-like growths of the superconducting phases are evident from the SEM micrographs. The optical micrographs of sintered samples showed that the samples containing 0.2 and 0.8 mole fraction of Pb mainly consisted of dark grey and white regions, while sample having 0.4 mole fraction of Pb comprised of dark grey, light grey, and white regions. The different regions were analyzed by using energy dispersive X-rays (EDX) analyzer attached with SEM. The results revealed that the dark grey regions in all the samples represented the Bi2Sr2CaCu2O8±y (2212) phase whereas, light grey regions in sample (x = 0.4) constituted the Bi2Sr2Ca2Cu3O10±y (2223) phase. The white regions in all samples depicted the presence of CuO. The best result in term of larger fraction of superconducting phase (2223) has been observed in sample containing 0.4 mole fraction of Pb.


Browse By Issue