Mohammad Sadiq

Investigating the Catalytic Activity of Monoclinic Zirconia; Oxidation of Benzyl Alcohol in Aqueous Medium at Mild Conditions

Abstract The oxidation/degradation of benzyl alcohol in artificially contaminated water under atmospheric pressure by molecular oxygen/air over ZrO2(m) catalyst was investigated. Monoclinic phase ZrO2 was synthesized and characterized by modern techniques. Oxidation of benzyl alcohol in aqueous medium was carried out in a typical three necked double walled batch reactor equipped with thermometer and condenser. The rate of oxidation was affected by different reaction parameters such as speed of agitation, catalyst loading, temperature, concentration of substrate solution (46.3 – 185 mmol/L) and partial pressure of oxygen. Major products were detected with GC and UV spectrophotometer. Optimal conditions were setup for better catalytic activity of ZrO2(m). To sum up, catalytic oxidation of benzyl alcohol in aqueous medium by ZrO2(m) is a useful and cheaper method for the conversion of benzyl alcohol to valuable products as well as for the removal of benzyl alcohol from industrial waste water.

Mixed-valence manganese oxide catalysed oxidation of benzyl alcohol and cyclohexanol in the liquid phase

Two types of mixed-valence manganese oxides were synthesised by a mechano-chemical process in the solid phase by chemical reaction of manganese(II) chloride and potassium permanganate at room temperature. The prepared catalysts were characterised by surface area and pore size, particle size, XRD analyses, SEM analyses and oxygen content measurements. These oxides were used as catalysts for oxidation of benzyl alcohol and cyclohexanol in the presence of solvent and also in solvent-free conditions using molecular oxygen as oxidant. The oxidation reactions were heterogeneous in nature where the catalysts were separated from the reaction mixture by simple filtration. Reaction took place in two steps according to the Langmuir–Hinshelwood mechanism. Benzyl alcohol/cyclohexanol and oxygen adsorb at the surface of the catalyst in the first step followed by reaction between adsorbed benzyl alcohol/cyclohexanol in second step. 69.8 kJ mol−1 and 140.8 kJ mol−1 were calculated as the activation energy for benzyl alcohol and cyclohexanol in n-octane as the solvent respectively, with values of 65.1 and 76 kJ mol−1 for benzyl alcohol and cyclohexanol in solvent-free conditions respectively.

Removal of Lead from Aqueous Solution by an Efficient Low Cost Biosorbent

Abstract Removal of Pb(II) ion from aqueous solution on modified sawdust obtained from Morus alba was investigated. The sample was characterized by BET surface area, EDX, FTIR and Zeta potential technique. The surface contains carbonyl and hydroxyl functional groups which act as binding sites for Pb(II) ion. Adsorption kinetics of Pb(II) on sawdust was tested by pseudo first order, Elovich and parabolic diffusion kinetic equations. The adsorption data were found to fit to Freundlich, Langmuir and Tempkin isotherms. The rate of adsorption was high at high temperature. Thermodynamic parameters like ΔH, ΔS and ΔG were calculated from the kinetic data. The positive values of ΔS reflect some structural exchange among the active site of the adsorbent and metal ion. The negative values of Gibbs free energy (ΔG) show the spontaneous nature of the process.

Tuning of Activated Carbon for Solvent-Free Oxidation of Cyclohexane

Activated carbon (AC) was prepared from carbonization of phosphoric acid soaked peanut shell at 380°C under inert atmosphere followed by activation with hydrogen peroxide. The AC was characterized by SEM, EDX, FTIR, TGA, and BET surface area and pore size analyzer. The potential of AC as a catalyst for solvent-free oxidation of cyclohexane to cyclohexanol and cyclohexanone (the mixture is known as KA oil) in the presence of molecular oxygen at moderate temperature was investigated in a self-designed double-walled three-necked batch reactor. The effect of different reaction parameters/additive was optimized. The maximum productivity value (2.14 mmolg−1 h−1, without base, and 4.85 mmolg−1 h−1, with 0.2 mmol NaOH) of the desired product was achieved under optimal reaction parameters: vol 12.5 mL, cat 0.4 g, time 14 h, oxygen flow 40 mL/min (pO2 760 Torr), stirring 1100 rpm, and temp 75°C. The AC shows recyclability for multiple runs without any significant loss in activity. Thus, the AC can be an efficient catalyst, due to low cost, ease of synthesis, easy recovery, nonleaching, and recyclability for multiple uses for the solvent-free oxidation of cyclohexane.

Photooxidation of Toluene: Correlation of Noble Metal Loading on Titania and Activation Energy

A series of platinum and palladium supported on titania catalysts were prepared by wet impregnation method with the Pt or Pd loading varying in the range of 0.1–1.2 weight percent. The catalysts were characterized by SEM, EDX, XRF, XRD, FT-IR, and BET surface area analysis. The catalysts were tested for their efficiency in the liquid phase solvent-free photooxidation of toluene to benzyl alcohol and benzaldehyde in the presence of molecular oxygen. The effect of noble metal contents on the activation energy was studied. Activation energy was found to be in a reciprocal relation to the platinum or palladium content of the catalyst. The percent conversion of toluene was observed to increase in response to an increase in the metal loading on titania. The apparent quantum yield, however, was independent of the platinum or palladium content of the catalyst.

Investigating the Activity of Zirconia as a Catalyst and a Support for Noble Metals, in Green Oxidation of Cyclohexane

Abstract Green oxidation of cyclohexane by molecular oxygen was carried out over ZrO2 and noble metals (Pd and Pt) supported on zirconia in solvent free conditions. Studies have been carried out in a typical three-necked batch reactor. Reaction products were identified by GC and UV spectrophotometer. Reaction rates were determined as a function of temperature, partial pressure of oxygen, amount of catalyst, volume of reactants, agitation and reaction duration. The agitation effect and activation energy revealed the absence of mass transfer resistance. Experimental results unveiled the effect of morphology of ZrO2 on catalysis. 1.0 wt.% noble metal/ZrO2(m) was found more selective for cyclohexanol production at low temperature, agitation 900rpm and partial pressure of 101.325 KPa while at high temperature cyclohexanol was further oxidized to cyclohexanone. Comparison of Pt/ZrO2 and Pd/ZrO2 catalysts was made on the basis of reactivity and selectivity. Catalysts were characterized by using BET surface area and pore size analyzer, XRD and SEM. To conclude shortly, for the oxidation of cyclohexane, platinum or palladium supported on zirconia are selective, recyclable and could behave as truly heterogeneous catalysts.

Thermodynamic and kinetic studies of adsorptive removal of toluidine blue by activated carbon from olive pit

aDepartment of Chemistry, University of Malakand, Chakdara 18800, Pakistan, emails: sadiq@uom.edu.pk, mohammad_sadiq26@yahoo.com (M. Sadiq), razia.aman@yahoo.com (R. Aman), sohail850@gmail.com (M. Sohail Ahmad), muhammadali041988@yahoo.com (M. Ali) bDepartment of Chemistry, Beijing Key Laboratory of Microanalytical Methods and Instrumentation, Tsinghua University, Beijing 100084, China, emails: mashooq_khan@yahoo.com, khan1985@mail.tsinghua.edu.cn cSchool of Applied Chemical Engineering, Kyungpook National University, Daegu, Korea, email: saimasadiq1978@yahoo.com dDepartment of Chemistry, National Center of Excellence in Physical Chemistry, University of Peshawar, Peshawar, Pakistan, email: rahmat_chemistpk@yahoo.com

Synthesis and Pharmacological Properties of 1,3-Bis[(S)Phenylethyl]Imidazolidine-2-Thione

Enantiomerically and diastereomerically pure thiourea derivative (compound I) has been synthesized in two steps starting from (S)-1-phenylethanamine and 1,2-dibromoethane. Compound I was screened for various biochemical parameters including blood glucose level, serum total cholesterol level, serum bilirubin and triglyceride levels, serum glutamate pyruvate transaminase (SGPT) and alkaline phosphatase (ALP) activity in New Zealand White (NZW) rabbits. Compound I was also screened for brine shrimp cytotoxicity, antileishmanial and antioxidant activity. Acute toxicity tests in NZW rabbits were performed and the results showed that compound I was safe up to 2 mg/mL/kg rabbit body weight. For the blood parameters, it was found that compound I caused slightly reduced blood glucose level, increased blood serum bilirubin, ALP and SGPT levels, and caused no changes in cholesterol and triglyceride levels. Thus, results show that compound I possesses good cytotoxic, poor antileishmanial activity, and no prominent antioxidant activity.

Potent Heterogeneous Catalyst for Low Temperature Selective Oxidation of Cyclohexanol by Molecular Oxygen

Platinum supported on zirconium dioxide catalyst was prepared by standard method and characterized by SEM, EDX, XRD, BET surface area and pore size analyzer, and FT-IR. The catalyst was screened for its catalytic activity in a model reaction, selective oxidation of cyclohexanol. The only one major product, cyclohexanone 31%, with 99.8% selectivity was obtained. Experimental data was analyzed through different kinetic models and we deduced that the reaction follows Langmuir-Hinshelwood mechanism. The apparent activation energy for the model reaction was calculated as 45 kJ/mole. The catalyst was regenerated several times with same efficiency.

KINETIC STUDY OF SELECTIVE GAS-PHASE OXIDATION OF ISOPROPANOL TO ACETONE USING MONOCLINIC ZRO2 AS A CATALYST

Zirconia was prepared by a precipitation method and calcined at 723 K, 1023 K, and 1253 K in order to obtain monoclinic zirconia. The prepared zirconia was characterized by XRD, SEM, EDX, surface area and pore size analyzer, and particle size analyzer. Monoclinic ZrO2 as a catalyst was used for the gas-phase oxidation of isopropanol to acetone in a Pyrex-glass-flow-type reactor with a temperature range of 443 K - 473 K. It was found that monoclinic ZrO2 shows remarkable catalytic activity (68%) and selectivity (100%) for the oxidation of isopropanol to acetone. This kinetic study reveals that the oxidation of isopropanol to acetone follows the L-H mechanism.