VOLUME 38, NO4, AUG-2016
123
 
Adsorption of Alizarin and Fluorescein Dyes onto Palm Seeds Activated Carbon: Kinetic and Thermodynamic Studies

Nasiru Abdus-Salam and Magaji Buhari

Activated carbon was prepared from date palm seed using one step procedure with 56.54 % efficiency, 2.89 % ash content, 781.40 m2 g-1 surface area, 711.2 mg g-1 iodine number and the CHN analysis gave 69.25 % C, 3.91% H and 1.56% N. The FTIR spectroscopy revealed O-H, C-H, C≡C, C=C and C-O stretching; XRF revealed P, Ca, Si, S and K as major elements. The influences of agitation time, initial dye concentration, adsorbent dose and temperature were studied in batch experiments. A 57.78% Alizarin and 68.40% Fluorescein removal were attained within the first 15 min of agitation. Kinetic studies showed good correlation coefficient for pseudo-first and pseudo-second order kinetic models. The adsorption data fitted well into Langmuir isotherm than Freundlich isotherms with correlation coefficient (R2) very close to unity and Langmuir maximum adsorption constant, qm 1000. The Freundlich coefficients relating to overall adsorption capacity, Kf (mg g-1) is 197.65 and 396.28 and surface heterogeneity, n is 3.34 and 3.18 for Alizarin and Fluorescein respectively. The activation energy (Ea) of the adsorption process of alizarin and fluorescein on DPA were found to be -8.19 and +21.43 Kj mol-1 respectively. The evaluation of the thermodynamic quantities showed that the adsorption process was spontaneous and endothermic.
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Nickel Oxide Photocathodes Prepared Using Rapid Discharge Sintering for p-Type Dye-Sensitized Solar Cells

Muhammad Awais, Danilo Dini, Johannes G. Vos and Denis P. Dowling

This paper compares the photoelectrochemical performances of nickel oxide (NiO) thin films processed using two different sintering procedures: rapid discharge sintering (RDS) and conventional furnace sintering (CS). Prior to sintering, NiO nanoparticles were sprayed onto substrates to form loosely adherent nanoparticulate coatings. After RDS and furnace sintering the resultant NiO coatings were sensitized with erythrosine B dye and corresponding p-type dye-sensitized solar cells were fabricated and characterized. NiO electrodes fabricated using the RDS technique exhibited a fourfold enhancement in electroactivity compared to CS electrodes. A possible explanation is the smaller sintered grain size and more open mesoporous structure achieved using the microwave plasma treatments.
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Thermal and Morphological Analysis of TNT and RDX Recovered From Unserviceable Composition B Explosive for Re-Utilization

Muhammad Farooq Ahmed, Abdul Qadeer Malik and Arshad Hussain

Energetic materials being sensitive in nature require careful handling during manufacture, storage, transportation and field utilization. Special care is required when these materials are declared Unserviceable (US), degraded or deteriorated. Original high explosive seldom initiates under ordinary circumstances unless appropriate explosive train is provided. But US explosive materials possess high risk of inadvertent initiation. The present study is aimed at finding out thermal behavior and possible degradation mechanism of US Composition B (Comp B) explosive containing RDX and Tri-nitrotoluene (TNT), so that viable means for reutilization of these unwanted energetic materials can be sorted out. Solvent based technique has been used for the successful recovery of US Comp B explosive ingredients. Various analytical techniques such as Thermo gravimetric/ Differential Thermal Analysis, Scanning Electron Microscopy, X-Ray Diffraction and Fourier Transform Infra Red have been used for the analysis of five types of explosive samples to provide insight into thermal behaviour and structure of each explosive sample. Finally, analytical results of both recovered TNT and RDX have been compared with original TNT and RDX samples to find out any possible changes in their thermal behaviour. It has been noticed that the purity and other characteristics like melting point, decomposition temperatures of the recovered versions are almost comparable with original TNT and RDX.
Pages(623)
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Effect of Rosemary Extract and TBHQ on the Stability of Radish Seed Oil

Zhao Gongling, Li Bing and Guo Yancheng

The effects of rosemary extract (RE) and tert-Butylhydroquinone (TBHQ) on the storage stability of radish seed oil were studied according to the change of the acid value, peroxide value, tocopherol and sulforaphene in radish seed oil. The results showed that under conditions of accelerated oxidation by (60±1) ℃, the storage stability of the radish seed oil with antioxidants could be significantly improved, among which TBHQ was better than RE. Besides, RE and TBHQ had a synergistic effect on antioxidation. The compound of 0.01% RE and 0.01% TBHQ had a better antioxidation effect than 0.07% RE and 0.02% TBHQ respectively, which recommended it can be a suitable antioxidant of radish seed oil.
Pages(631)
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Decomposition of Clofibric Acid in Aqueous Media by Advance Oxidation Techniques: Kinetics Study and Degradation Pathway

Murtaza Sayed, Luqman Ali Shah, Asad Muhammad Khan, Rafaqat Ali Khan, Abdur Rahman Khan and Hasan Mahmood Khan

This study investigates the decomposition of clofibric acid (CLF) by different advanced oxidation processes (AOPs), such as UV (254nm), VUV (185 nm), UV / TiO2 and VUV / TiO2. The removal efficiencies of applied AOPs were compared in the presence and absence of dissolved oxygen. The removal efficiency of the studied AOPs towards degradation of CLF were found in the order of VUV / TiO2 + O2 > VUV/TiO2 + N2 > VUV alone > UV / TiO2 + O2 > UV / TiO2 +N2 > UV alone. The decomposition kinetics of CLF was found to follow pseudo-first order rate law. VUV / TiO2 process was found to be most cheap and effective one for decomposition of CLF as compared to other applied AOPs in terms of electrical energy per order. Degradation products resulting from the degradation processes were also investigated using UPLC-MS /MS, accordingly degradation pathway was proposed.
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Radiation Induced Degradation of an Azo Dye Solution for Use in Dosimetric Applications

Sayeda Elewa Eid

The radiation induced color degradation of 4-(p-nitrophenyl-azo)-1-naphthol dye solution was studied in N,N- dimethylfomamide. The solutions were readout using absorption spectrophotometry technique at λmax 625 nm and 472 nm, respectively. The dose range was affected by dye concentration, where the useful dose range was found to be 0.5- 3.5kGy, depending on dye concentration .Magnesium chloride was then added in different concentrations, and the dose range was found to decrease to be 900Gy.The decoloration percent was calculated and found to increase proportionally with the absorbed dose. The radiation chemical yield ''G (-Dye)'' was calculated for both azo dye alone and in combination with MgCl2 solutions. In brief, Azo dye solutions in DMF exhibit good stability during the storage time period, while Azo dye with magnesium chloride solutions shows decoloration process over the storage time period of 21 days.
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Adsorption Mechanism of Microcrystalline Cellulose as Green Adsorbent for the Removal of Cationic Methylene Blue Dye

Kok Bing Tan, Ahmad Zuhairi Abdullah, Bahman Amini Horri and Babak Salamatinia

The adsorption mechanism of pure cellulose is yet to be explored. Thus, in this study, the adsorption mechanism of Microcrystalline Cellulose (MCC), a polysaccharide which is renewable, low cost and non-toxic, was studied on the adsorption of model dye Methylene blue (MB). It was found that the main adsorption mechanism of MB on MCC was due to the electrostatic attraction between the positively charged MB dye and negatively charged MCC. Thus, physical adsorption was the dominant effect, since electrostatic attraction is categorized as physical adsorption. This was verified by Dubinin-Radushkevich isotherm, whereby mean free energy adsorption value was found to be less than 8 kJ/mol. The values of Gibbs free energy for thermodynamics studies were found to be within the range of -20 kJ/mol and 0 kJ/mol, which also indicated physical adsorption. It was due to the electrostatic attraction as adsorption mechanism of this adsorption process which resulted rapid adsorption of MB dye. It was found that equilibrium dye concentration was achieved between 1-3 minutes, depending on the adsorption temperature. The rapid adsorption, as compared to a lot of materials, showed the potential of MCC as the future of green adsorbent. The adsorption of Methylene Blue on MCC fitted well in Langmuir Isotherm, with R2 values of higher than 0.99, while fitted moderately in Freundlich Isotherm, with R2 values between 0.9224 and 0.9223. Comparatively, the adsorption of MB on MCC fitted best Langmuir Isotherm as compared to Freundlich Isotherm which monolayer adsorption occurred at the homogenous surface of MCC. This also indicated adsorbed MB molecules do not interact with each other at neighboring adsorption sites. The maximum adsorption capacity calculated from Langmuir Isotherm was found to be 4.95 mg/g. Despite the potential of MCC as green adsorbent, the challenge of low adsorption capacity has to be addressed in the future.
Pages(651)
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Biogenic Synthesis, Characterization of Silver Nanoparticles Using Multani mitti (Fullers Earth), Tomato (Solanum lycopersicum) seeds, Rice Husk (Oryza sativa) and Evaluation of their Potential Antimicrobial Activity

Parsa Dar, Usama Waqas, Aysha Hina, Jamil Anwar, Amara Dar, Zaman Khan and Tauseef Shafqat

The synthesis of silver nanoparticles of three different biogenic materials Multani mitti (Fullers earth), Tomato (Solanum lycopersicum) seeds, Rice Husk (Oryza sativa) was carried out. The possible presence and variability of comprehensive biomolecules in these materials turned as capping and reducing agents which optimize the reduction rate and stabilization of silver nanoparticles. Characterizations were determined by using ultraviolet-visible (UV-Vis) spectroscopy, Scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). Stable silver nanoparticles of average size 4.6, 41.1 and 10.6 nm were obtained for Multani mitti, tomato seeds and rice husk respectively. Phenolic and carboxylic biomolecules were identified as active reducing agents of Ag+2 to Ag0. The antimicrobial activity was carried out against Klebsiella pneumonia, Salmonella enterica, Escherichia coliand Staphylococcus aureus strains by using well diffusion method. Maximum zone of inhibition (ZOI) was found against Staphylococcus aureus by all of the three biogenic materials.
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Synthesis and Application of a Benzotriazole Mannich Base as Effective Corrosion Inhibitor for N80 Steel in High Concentrated HCl

Ya Wu, Hongjiang Yu, Shijun Chen, Jiao Yan and Xuefan Gu, Yan Li and Gang Chen

A benzotriazole Mannich base, N-(N-diethylethanamine)-methyl benzotriazole (DEAMB), was synthesized and analyzed by NMR and MS. The corrosion inhibition of DEAMB and the inhibition mechanism in 2M and 3M HCl solution were investigated and discussed. The research results showed that DEAMB can inhibit the acidic corrosion with moderate to high inhibition efficiency in kinds of conditions, and the inhibition mechanism should be mainly contributed to the molecules adsorption on the steel surface, which is further confirmed by potentiodynamic polarization studies.
Pages(675)
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Fast and Efficient Protocol for Solvent-Free Reduction of Nitro Compounds to Amines with NaBH4 in the Presence of Bis-Thiourea Complexes of Bivalent Cobalt Nickel, Copper and Zinc Chlorides

Behzad Zeynizadeh and Serve Sorkhabi

Reduction of nitro compounds to the corresponding amines has been carried out efficiently with NaBH4 in the presence of bis-thiourea complexes of bivalent cobalt, nickel, copper and zinc chlorides, [MII(tu)2Cl2]. The reactions were carried out under solvent-free conditions at room temperature to afford amines in high to excellent yields. Comparison of the results showed that the reducing capability of NaBH4 was influenced with bis-thiourea complexes as: Co(tu)2Cl2> Ni(tu)2Cl2> Cu(tu)2Cl2> Zn(tu)2Cl2.
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