Effect of Temperature and Electrolyte Concentration on the Surface Charge Properties of Fe(OH)3

Amorphous iron hydroxide was fabricated in the laboratory by precipitation technique. Salt addition and fast titration methods were employed for the determination of zero point charge. The present study is mainly focused on the surface charge, PZC determination from the potentiometric titration data in the temperature range 293 – 323 K and to calculate the thermodynamic parameters during the exchange of surface H+/OH- ions. The PZC of the solid was decreased with increasing the temperature of electrolytic solution. The Standard thermodynamic parameters such as ΔHo and ΔSo were also determined from Berube and DeBruyn equation, which showed the endothermic nature of potential determining ion H+/OH- ions. Further, their freedom in the double layer has lost on account of the electrostatic force of interaction. The positive ΔGo values are suggesting the nonspontaneous transferring reactions of H+ and OH- from the bulk solution to the interfacial region.read more

Muhammad Irshad, Syed Mustafa, Muhammad Waseem, Khizar Hussain Shah and Umer Rashid

Kinetics, Equilibrium and Thermodynamic Studies of Mn (II) Biosorption from Aqueous Solution onto Pleurotus Ostreatus

Biosorption of Mn (II) from aqueous solution by P. ostreatus was investigated at different concentrations, pH and temperature. The close agreement between the experimental and theoretical biosorption capacity confirmed that Pseudo 2nd order equation is best fitted to the present experimental data. The biosorption capacity of P. ostreatus was observed to be dependent upon the pH and temperature of adsorption system. The values of biosorption maxima (Xm) and binding energy constant (Kb) were observed to decrease with rise in temperature in the range of 298 – 323K. The negative values of ΔG and ΔH showed the process of Mn (II) biosorpt ion onto P. ostreatus is spontaneous and exothermic respectively. Similarly, t he values of isosteric heat of biosorption ( ) were decreased with increase in surface coverage (ɵ) which indicated that the surface of the P. ost reatus is energetically heterogeneous in nature.read more

Abdul Naeem Afsar Khan, Tahira Mahmood, Mairman Muska, Salah Ud Din, Muhammad Saleem Khan1, Muhammad Hamayun and Muhammad Waseem

Experimental and Simulation Analysis of Hydrogen Production by Partial Oxidation of Methanol

Partial oxidation of methanol is the only self-sustaining process for onboard production of hydrogen. For this a fixed bed catalytic reactor is designed, based on heterogeneous catalytic reaction. To develop an optimized process, simulation is carried out using ASPEN HYSYS v 7.1. Reaction kinetics is developed on the basis of Langmuir Hinshelwood model. 45:55:5 of CuO: ZnO: Al2O3 is used as a catalyst. Simulation results are studied in detail to understand the phenomenon of partial oxidation of methanol inside the reactor. An experimental rig is developed for hydrogen production through partial oxidation of methanol. Results obtained from process simulation and experimental work; are compared with each other.read more

Umair Sikander and Arshad Hussain

Conductometric Studies of Dissociation Constants of Benzoic Acid in Water and 2-Propanol Mixtures at Different Temperatures

The molar conductance of dilute solutions of benzoic acid in binary mixtures of water and 2-propanol has been measured at temperatures ranging from 298.15 K to 313.15 K. The experimental data were analyzed by means of the Fuoss-Kraus equation (1933) for the derivation of the thermodynamic dissociation constants and limiting molar conductance. The results were compared with those available in literature pertaining to analogue media.read more

A. K. M. Atique Ullah, Shamim Akhtar, Mahmuda Akter and Muhammod Habibullah

Control of Particle Size and Morphology in Compatiblized Self-Catalyzed Co-Polyimide/SiO2 Nanocomposites

The size of the silica particles and morphology of hybrids were controlled in copolyimide based hybrids through amino-silane functionalization of silica particles prepared in situ through a self-catalyzed sol-gel process using atmospheric moisture. The particles were generated using tetraethoxysilane in the uncompatiblized (UPISH) system whereas a mixture of 3-aminopropyltrietoxysilane and tetraethoxysilane was used in the compatiblized Co-PI/silica hybrid (CPISH) system. The properties of resulting hybrid films were measured by Fourier Transform Infrared Spectroscopy, Scanning Electron Microscopy, Thermogravimetirc Analysis, Dynamic Mechanical Analysis and Universal Testing Machine. FTIR results confirmed the formation of silica particles and Co-PI matrix. FE-SEM images revealed spherical silica particles with sharp boundaries in UPISH; whereas nano-sized coupled silica network structures with totally different morphologies were observed in CPISH system. The CPISH system exhibited better thermal stability, higher modulus and Tg values than UPISH system. The improvement in thermal and mechanical properties has been discussed with reference to morphological changes due to incorporation of 3-aminopropyltrietoxysilane in aerobic condition and in a self-catalyzed sol-gel process.read more

Farman Ali, Shaukat Saeed, Khaled M. Saoud and Syed Sakhawat Shah

Ion Exchange Removal of Chromium (III) from Tannery Wastes by Using a Strong Acid Cation Exchange Resin Amberlite IR-120 H+ and its Hybrids

A strong acid cation exchange resin Amberlite IR-120 H+ and its hybrids with Mn(OH)2, Cu(OH)2 and Fe(OH)3 are used for the removal of chromium (III) from spent tannery bath. The experimental data give good fits with the Langmuir sorption model. The thermodynamic parameters entropy (ΔS°), enthalpy (ΔH°) and free energy (ΔG°) changes are computed, which reveal that the chromium removal from tannery wastes by ion exchangers is an endothermic, physical sorption and entropically driven process. The rate of sorption is found to increase with the increase of resin dosage, stirring speed and temperature. Different kinetic models such as film diffusion, particle diffusion and Lagergren pseudo first order are used to evaluate the mechanism of the process. It is found that the hybrid ion exchange resins have better removal capacity as compared to the parent ion exchanger. The increase in the removal capacity is found to be in the order of the corresponding PZC values of the hybrid ion exchangers. Further, it is suggested that the higher exchange capacity is the result of Donnan effect and specific adsorption of chromium by the oxides / hydroxides present inside the matrix of the organic cation exchanger.read more

Tauqeer Ahmad, Syed Mustafa, Abdul Naeem, Farooq Anwar, Tahir Mehmood and Khizar Hussain Shah

Catalytic Thermal Decomposition of Polyethylene Determined by Thermogravimetric Treatment

In this study low density polyethylene (LDPE) has been studied by thermogravimetric analysis (TGA) using commercially available oxides as catalysts. TGA experiments were used to evaluate the activity of different catalysts on low density polyethylene (LDPE) degradation and to study the effect in terms of type and amount of catalyst used. All the catalysts used improved the pyrolysis of LDPE. The reaction rates were found to increase with increase in amount of catalyst. Among the catalysts used, alumina acidic active catalyst performed better at all four fractions. Moreover, alumina acidic active reduced weight loss temperature better than others tested catalysts. The effect of alumina neutral catalyst on the pyrolysis of LDPE is less pronounced due to its small surface area and pore size. The effect of these catalysts showed that surface area, number of acidic sites and pore size were found as the key factors for the energy efficient degradation of polymers.read more

Jan Nisar, Muhammad Sufaid Khan, Mudassir Iqbal and Muhammad Anas Khan

Treatability Study of Arsenic, Fluoride and Nitrate from Drinking Water by Adsorption Process

Natural contamination of nitrate, fluoride, arsenic and dissolved salts in ground water sources is the main health menace at present in different parts of Pakistan. The metalloids especially arsenic, fluoride and nitrate pose severe health hazards to human being. The present research work investigated the removal techniques for arsenic, fluoride and nitrate from drinking water by adsorption process. Ion exchange resins, activated carbon and activated alumina were used for removal of selected contaminants. These adsorbents were evaluated by comparing their removal efficiency as well as requisite operator skills. The result of activated alumina was found good as compared to activated carbon, mix bed resins and ion exchange resins (IRA-400) for maximum removal of arsenic, nitrate and fluoride. The removal efficiency of arsenic, fluoride and nitrate were found 96%, 99%, 98% respectively in case of activated alumina. The advantage of adsorption process is easy to use and relatively cheaper as compared to other treatment methodologies.read more

Naeem Abbas, Farah Deeba, Muhammad Irfan, Muhammad Tahir Butt, Nadia Jamil and Rauf Ahmad Khan

Removal of Copper Ions from Water Using Chemical Modified Multi-walled Carbon Nanotubes

Multi-walled carbon nanotubes (CNTs) were modified by oxidation with sodium hypochlorite (NaClO) solutions and were employed as adsorbents to study the adsorption characteristics of copper ions from water. The results show that adsorption capacity of CNTs treated by NaClO solution can be greatly enhanced. The adsorption capacity of Cu2+ on as received and modified CNTs increased with the increase of pH and CNTs mass, but it decreased with the temperature. Experimental data also indicated that the adsorption process could achieve equilibrium within 40 min. Both Langmuir and Freundlich isotherm models fitted the experimental data very well. According to the Langmuir model the maximum copper ions adsorption uptake onto modified CNTs was determined as 40.00 mg/g. Our results suggest that CNTs have profound potential application in environmental protection.read more

Yu-Jun Zhang, Jun Yang, Bo-Liang Liu and Yuan-Dong Xu

Preparation and Characterization of Hesperidin - PEG 6000 Complex

In this study, the preparation and characterization of hesperidin-PEG 6000 solid dispersion were investigated. The ultraviolet-visible spectrometry (UV), infrared spectrometry (IR), X-ray diffractometry (XRD) and Differential scanning calorimetry (DSC) were used to analyze the physicochemical properties of the complex. By forming the complex with polyethylene glycol 6000 (PEG 6000), the solubility of hesperidin in water could be significantly improved. UV spectra and IR spectrum showed that there was no obvious difference between hesperidin and the complex. The XRD pattern of the complex suggested that hesperidin in the matrix was either molecularly dispersed or in amorphous form. DSC analysis implied that hesperidin had been completely dispersed in PEG6000 and there were some interaction between hesperidin and PEG 6000. The results showed that hesperidin in the complex had been completely dispersed in the PEG 6000, not forming a new compound.read more

Haiyan Gao, Yuzhen Chen, Hanjun Ma, Jie Zeng and Guanglei Li