Kashif Gul

Functionalization of magnetic chitosan with graphene oxide for removal of cationic and anionic dyes from aqueous solution.

In the present study, we decorated chitosan (©) with Fe3O4 nanoparticles followed by cross-linking with GO to prepare Fe3O4 supported chitosan-graphene oxide composite (Fe3O4©-GO). Different properties of synthesized material were investigated by SEM, XRD, FTIR, TGA and EDX. Batch adsorption experiments were performed to remove toxic cationic and anionic dyes from industrial wastewater. To maximize removal efficiency of composite material, effect of pH (4-12), time (0-80min), Fe3O4©-GO dosage (2-10mg), initial dye concentration (2-30μgmL̄ (1)) and temperature (303, 313, and 323K) were studied. The uptake of dyes presented relatively fast adsorption kinetics with pseudo-second-order equation as the best fitting model. To understand the interaction of dye with adsorbent, Langmuir and Freundlich isotherm were applied. Thermodynamic studies were conducted to calculate the changes in free energy (ΔG(0)), enthalpy (ΔH(0)) and entropy (ΔS(0)). In view of practical application, the influence of ionic strength, recycling as well as investigations based on percent recoveries from spiked real water samples were also taken into account.

DDT residue in soil and water in and around abandoned DDT manufacturing factory.

Dichlorodiphenyltrichloroethane (DDT) belongs to one of the most hazardous groups of chemicals called persistent organic pollutants. Many organochlorine pesticides including p,p′-DDT are long lasting due to their non-degradability can travel to distant places and being fat soluble can accumulate in animals and human bodies. Due to the persistent nature of p,p′-DDT, its adverse environmental and health impacts, the present study was undertaken to examine the residual p,p′-DDT in and around abandoned p,p′-DDT manufacturing factory in Amman Gharh, Nowshera, NWFP. Samples of soil, sediments and water were collected in and around the factory area, nearby p,p′-DDT stores, main factory drain leading to river Kabul and nearby villages. Standard procedures were used for the collection, transportation and storage of samples for analyses. Extraction of each sample for p,p′-DDT analyses was carried out in triplicates using Soxhelt extraction. p,p′-DDT contents in the samples were analyzed by capillary GC with electron capture detector. Most of the samples collected up to half kilometer distance from the site of the DDT factory were found contaminated. Further the level of p,p′-DDT decreased with increasing depth from top to bottom and with distance from the site. The results indicate that there is no immediate threat to underground water reservoirs.

Synthesis of Diorganyl Selenides Mediated by Zinc in Ionic Liquid

A new approach for the synthesis of diorganyl selenides is described. By using economically attractive zinc dust in BMIM-BF(4), a series of diorganyl selenides were efficiently achieved in excellent yields, under neutral reaction conditions. Compared to the usual organic solvents, BMIM-BF(4) exhibited higher performance with the advantage to be reused up to five successive runs.

Pyrolysis Study of Polypropylene and Polyethylene Into Premium Oil Products

Pyrolysis of polypropylene (PP) and high density polyethylene (HDPE) into fuel like products was investigated over temperature range of 250– 400°C. The product yields as a function of temperature were studied. Total conversion as high as 98.66% (liquid; 69.82%, gas; 28.84%, and residue; 1.34%) was achieved at 300°C in case of PP and 98.12% (liquid; 80.88%, gas; 17.24%, and residue; 1.88%) in case of HDPE at 350°C. The liquid fractions were analyzed by FTIR and GC-MS. The results showed that the liquid fractions consisted of a wide range of hydrocarbons mainly distributed within the C6–C16. The liquid product obtained in case of PP is enriched in the naphtha range hydrocarbons. Similarly, the liquid product obtained in case of HDPE is also enriched in naphtha range hydrocarbons with preponderance in gasoline and diesel range hydrocarbons. The% distribution of paraffinic, olefinic, and naphthenic hydrocarbons in liquid product derived from PP is 66.55, 25.7, and 7.58%, respectively, whereas in case HDPE, the% distribution is 59.70, 31.90, and 8.40%, respectively. Upon comparing the hydrocarbon group type yields, PP gave high yield of paraffinic hydrocarbons while HDPE gave high yields of olefins and naphthenes. The whole liquid fractions and their corresponding distillates fractions were also analyzed for fuel properties. The results indicated that the derived liquid fractions were fuel-like meeting the fuel grade criteria.

Microwave-assisted spent black tea leaves as cost-effective and powerful green adsorbent for the efficient removal of Eriochrome black T from aqueous solutions

Abstract In this work, microwave-assisted spent black tea leaves (MASTL) were used as effective low-cost green adsorbents for the removal of Eriochrome Black T (EBT) from aqueous solutions and adequately characterized. The pHpzc of MASTL was found to be 4.6. The experimental conditions, such as pH, contact time, temperature, adsorbent dose and EBT concentration, were optimized to evaluate the interaction of EBT with MASTL. The adsorption isotherms were simulated by Langmuir, Freundlich, Temkin and Dubinin-Radushkevich models. The results showed that the Langmuir model best fitted the adsorption data. The monolayer adsorption capacity was calculated to be 242.72 mg/g at 25 °C. The thermodynamic data calculated from the temperature-dependent adsorption isotherms indicated that the adsorption process was spontaneous, endothermic and physicochemical in nature. The results revealed that the MASTL could be used as low-cost green adsorbents for the efficient removal of EBT from aqueous solutions in environmental pollution clean-up.

Self-assembled three-dimensional reduced graphene oxide-based hydrogel for highly efficient and facile removal of pharmaceutical compounds from aqueous solution

Herein, self-assembled three-dimensional reduced graphene oxide (RGO)-based hydrogels were synthesized and characterized in detail. A thorough investigation on the uptake of three widely used pharmaceutical drugs, viz. Naproxen (NPX), Ibuprofen (IBP) and Diclofenac (DFC) was carried out from aqueous solutions. To ensure the sustainability of developed hydrogel assembly, practically important parameters such as desorption, recyclability and applicability to real samples were also evaluated. Using the developed 3D hydrogels as adsorptive platforms, excellent decontamination for the above mentioned persistent pharmaceutical drugs was achieved in acidic pH with a removal efficiency in the range of 70-80%. These hydrogels showed fast adsorption kinetics and experimental findings were fitted to different kinetic models, such as pseudo-first order, pseudo-second order, intra-particle and the Elovich models in an attempt to better understand the adsorption kinetics. Furthermore, equilibrium adsorption data was fitted to the Langmuir and Freundlich models, where relatively higher R2 values obtained in case of former one suggested that monolayer adsorption played an important part in drug uptake. Thermodynamic aspects were also studied and negative ΔG0 values obtained indicated the spontaneous nature of adsorption process. The study was also extended to check practical utility of as-prepared hydrogels by spiking real aqueous samples with drug solution, where high % recoveries obtained for NPX, IBP and DFC were of particular importance with regard to prospective application in wastewater treatment systems. We advocate RGO-based hydrogels as environmentally benign, readily recoverable/recyclable material with excellent adsorption capacity for application in wastewater purification.

DDT residue in soil and water in and around the abounded area of DDT manufacturing factory

Due to the persistent nature of DDT, a persistent organic pollutant and its adverse environmental and health impacts, the present study was undertaken to examine the residual DDT in and around DDT manufacturing factory in Amman Gharh, Nowshera, NWFP. The factory was established in 1963 and remained in operation till 1994. Composite samples of soil, sediments and water were collected in and around the factory area, nearby DDT stores, main factory drain leading to river and nearby villages. Standard procedures were used for the collection, transportation and storage of samples for analysis. Physical parameters for the collected water samples measured were temperature, pH and conductance. Extraction of each sample for DDT analyses was carried out in triplicates using soxhlet extraction apparatus. The extract was transferred to well washed, clean; dry glass vial, sealed and put in the refrigerator. Gas Chromatograph with electron capture detector and capillary column was used for analysis. DDT in the samples was identified on the basis of their retention time and quantified on the basis of peak areas. It is evident from the analytical data obtained in the present study that both water and soil in and around the factory area are still contaminated with DDT, despite the closure of the factory since the past few years. In the well established and known persistency, transportation, accumulative characteristics, environmental and health impacts of DDT, its contamination in and around the factory area pose threat to public health and environment and may cause most serious consequences for ecosystem function, food safety and other aspects of human health, very specially in Amman Gharh, Nowshera.

A novel magnetite nanorod-decorated Si-Schiff base complex for efficient immobilization of U(VI) and Pb(II) from water solutions

A novel silicon Schiff base complex (Si-SBC) and magnetite nanorod-decorated Si-SBC (M/SiO2-Si-SBC) were synthesized and well characterized in detail. The synthesized materials were applied for the removal of U(vi) and Pb(ii) from water solutions under various experimental conditions. The monolayer maximum adsorption capacities of M/SiO2-Si-SBC (6.45 × 10-4 mol g-1 for Pb(ii) and 4.82 × 10-4 mol g-1 for U(vi)) obtained from the Langmuir model at 25 °C and pH = 5.00 ± 0.05 were higher than those of Si-SBC (5.18 × 10-4 mol g-1 for Pb(ii) and 3.70 × 10-4 mol g-1 for U(vi)). Moreover, DFT calculations showed that the high adsorption energies (Ead) of 7.61 kcal mol-1 for Pb2+-(Si-SBC) and 2.72 kcal mol-1 for UO22+-(Si-SBC) are mainly attributed to stronger electrostatic interactions. The results revealed that the Si-SBC and M/SiO2-Si-SBC could be used as efficient adsorbents for the effective elimination of U(vi) and Pb(ii) from contaminated wastewater. High sorption capacity and reusability indicated the practical applications of the synthesized materials in environmental pollution cleanup.

Monitoring of oxidation behavior in mineral base oil additized with biomass derived antioxidants using FT-IR spectroscopy

This paper reports the artificial oxidation of original and additized mineral base oil (MBO) samples. The additives used were methanolic extracts from rice husk (RHE) and saw dust (SDE). The oxidation was performed at 100 and 200 °C, separately for a time duration of six hours according to the modified IP method. A Fourier Transform Infra Red (FTIR) spectroscopic study was carried out to identify the oxidation products like carboxylic acids/carboxylates, esters, olefins, naphthenes and aromatics in the residual samples. The level of degradation was quantified by measuring the area under carbonyl (CO) or double bond (CC) bands in order to determine the concentration of these compounds using Peak Area Increase (PAI) and Peak Height (PH) methods [ASTM 7214-07]. The results indicate that the MBO withstood oxidation in the presence of the RHE as well as the SDE. Among the two antioxidants used, the antioxidant potential of the RHE was more efficient while that of the SDE was better at 100 as well as at 200 °C.

Catalytic Performance of Metal Impregnated Carbon (Darco) in Conversion of Polypropylene and High-Density Polyethylene into Useful Products

Catalytic pyrolysis is considered as the promising route for getting valuable chemicals from plastics. Pyrolysis reactions of polypropylene (PP) and high-density polyethylene (HDPE) were carried out in a fixed bed reactor in the presence of carbon-based catalysts under optimized conditions. The catalysts used were original (Darco (20-40 mesh) and transition metal salts impregnated activated carbons (AC, Fe/AC, Ni/AC, Zn/AC, Mn/AC, and Co/AC). The performance of each catalyst and its concentration in terms of overall yields of pyrolysates and yields of liquid, gas, and coke/solid residue was evaluated by comparing the results with the non catalyzed run. The results indicated that the catalysts used greatly affected the liquid yields in case of PP, however in case of HDPE, the yields were comparable with the thermal run. The catalysts used also altered the hydrocarbon group type distributions in the liquid pyrolysates. In case of PP, the Fe/AC catalyzed run caused the yield of olefins to increase by 16% while in case of HDPE, the Zn/AC catalyzed run, caused the yield of paraffins to increase from 59% to 64% as compared to thermal run.