Moonis Ali Khan

Biosorption and desorption of Nickel on oil cake: Batch and column studies

Biosorption potential of mustard oil cake (MOC) for Ni(II) from aqueous medium was studied. Spectroscopic studies showed possible involvement of acidic (hydroxyl, carbonyl and carboxyl) groups in biosorption. Optimum biosorption was observed at pH 8. Contact time, reaction temperature, biosorbent dose and adsorbate concentration showed significant influence. Linear and non-linear isotherms comparison suggests applicability of Temkin model at 303 and 313 K and Freundlich model at 323K. Kinetics studies revealed applicability of Pseudo-second-order model. The process was endothermic and spontaneous. Freundlich constant (n) and activation energy (Ea) values confirm physical nature of the process. The breakthrough and exhaustive capacities for 5 mg/L initial Ni(II) concentration were 0.25 and 4.5 mg/g, while for 10 mg/L initial Ni(II) concentration were 4.5 and 9.5 mg/g, respectively. Batch desorption studies showed maximum Ni(II) recovery in acidic medium. Regeneration studies by batch and column process confirmed reutilization of biomass without appreciable loss in biosorption.

Aerodynamics of formation flight

Reported are the results of wind-tunnel tests conducted to evaluate aerodynamics characteristics of aircraft in formation flight. A vortex-lattice numerical scheme was used to investigate the effect of spatial offset (horizontal and vertical) between the leading and trailing wings. The wind-tunnel test configurations consisted of echelon, chevron, and in-line formations. Analysis of the data revealed that the spatial offset and the angle of attack of the leading wing had significant impact on the trailing aircraft. For some test conditions an increase in lift-to-drag ratio of the trailing aircraft was measured. Variation in C Lmax and/or α stall was observed as well. At higher angles of attack of the leading wing, the C L-α curve of the trailing aircraft was significantly altered.

Top-cited articles in environmental sciences: merits and demerits of citation analysis.

The purpose of this study was to identify the top-cited articles published in environmental science journals listed in Journal Citation Reports (JCR). The Web of Science database was used to retrieve the top-cited articles having 500 or more total citations from their publication to 2010. The articles were analyzed with regard to institution and country of origin with five indicators including total number of top-cited articles, as well as independent, collaborative, first author, and corresponding author articles. Article life was also investigated for history of impact of articles. Results showed that 88 articles were cited more than 500 times. These articles appeared in 26 different journals, with 28% of all top-cited articles in Environmental Science & Technology, followed by Water Resources Research. The top-cited articles published since 1971 to 2002 were from 17 countries. The USA published the most of the articles and was ranked on top among the five indicators. The U.S. Geological Survey was the most productive institution while, the Brunel University, UK published the most inter-institutionally collaborative and corresponding author articles under environmental science category.

Application of Carbon Nanotubes in Heavy Metals Remediation

Carbon nanotubes (CNTs) are the engineered nanomaterial that has a very simple chemical composition and structure. Extremely high aspect ratios, molecularly smooth hydrophobic graphitic walls, and nanoscale inner diameters of CNTs give rise to the peculiar adsorption properties. This review provides an overview on CNTs functionalization and their application as an adsorbent for scavenging heavy metals and radionuclide from wastewater systems. A summary of recent information obtained using batch studies and deals with mechanisms involved during the adsorption have been reported. Adsorption capacity of CNTs has been observed by numerous investigators to increase substantially after functionalization/treatment with oxidizing agents such as NaOCl, HNO3, H2SO4, KMnO4, and other oxidizing agents. However, the selectivity of CNTs toward metal ions depends on both the route used for their synthesis and reagent employed for purification. The recovery of metal ions and the regeneration of CNTs have minimal impact on their performance. Desorption of metal ions from saturated adsorbent can be achieved using acid/base elution.

Adsorption Studies for the Removal of Nitrate Using Modified Lignite Granular Activated Carbon

The removal of nitrate on ZnCl2 modified lignite granular activated carbon (LGAC) was investigated. The LGAC was modified with varying chemical impregnation ratios (ZnCl2: LGAC) and activation temperatures. Modified LGAC (LGAC5), with a 2:1 chemical impregnation ratio and a 500°C activation temperature had the optimum adsorption capacity for , at a 200 mg/L initial concentration. The initial pH of the testing solutions significantly influenced the adsorption capacity of LGAC5. The contact time studies showed the effectiveness of LGAC5, up to 50 mg/L initial concentration with 30 min of equilibration time. Isotherm studies revealed the highest values of the Langmuir constant (b), confirming strong affinity of LGAC5 for ions. Thermodynamics studies verified the endothermic nature of the adsorption process with randomness at the solid/solution interface. Competitive ion testing demonstrated that interfering anions, such as Cl−, , significantly reduced adsorption on LGAC5.

The role of clay minerals in the reduction of nitrate in groundwater by zero-valent iron

Bench-scale batch experiments were performed to investigate the feasibility of using different types of clay minerals (bentonite, fullers earth, and biotite) with zero-valent iron for their potential utility in enhancing nitrate reduction and ammonium control. Kinetics experiments performed with deionized water (DW) and groundwater (GW) revealed nitrate reduction by Fe(0) proceeded at significantly faster rate in GW than in DW, and such a difference was attributed to the formation of green rust in GW. The amendment of the minerals at the dose of 25 g L(-1) in Fe(0) reaction in GW resulted in approximately 41%, 43%, and 33% more removal of nitrate in 64 h reaction for bentonite, fullers earth, and biotite, respectively, compared to Fe(0) alone reaction. The presumed role of the minerals in the rate enhancement was to provide sites for the formation of surface bound green rust. Bentonite and fullers earth also effectively removed ammonium produced from nitrate reduction by adsorption, with the removal efficiencies significantly increased with the increase in mineral dose above 5:1 Fe(0) to mineral mass ratio. Such a removal of ammonium was not observed for biotite, presumably due to its lack of swelling property. Equilibrium adsorption experiments indicated bentonite and fullers earth had maximum ammonium adsorption capacity of 5.6 and 2.1 mg g(-1), respectively.

Utilization of carbon derived from mustard oil cake (CMOC) for the removal of bivalent metal ions: Effect of anionic surfactant on the removal and recovery

Effect of sodium dodecyl sulfate (SDS) on the adsorption of Zn(II) and Ni(II) on CMOC was investigated. Addition of SDS favored the adsorption process. Adsorption process was found to be dependent on concentration, pH, dose, contact time and temperature. Thermodynamic studies showed that the process is endothermic and spontaneous. The spontaneity increases with increase in temperature. D-R isotherm suggests that the adsorption is chemical in nature. Kinetics studies showed better applicability of pseudo second order model. Reichenberg equation showed that pore diffusion was not only the rate determining step but some other process like film diffusion was also involved in the adsorption. These metals could be desorbed (75-80%) with 0.1M HCl as eluent.

Adsorption studies of Dichloromethane on some commercially available GACs: Effect of kinetics, thermodynamics and competitive ions

The objective of this work was to compare the effectiveness of four commercially available granular activated carbons (GACs); coconut (CGAC), wood (WGAC), lignite (LGAC) and bituminous (BGAC) for the removal of dichloromethane (DCM) from aqueous solution by batch process. Various parameters such as thermodynamics, kinetics, pH, concentration of adsorbate, dosages of adsorbent and competitive ions effect on DCM adsorption were investigated. Maximum adsorption capacity (45.5mg/g for CGAC) was observed at pH 6.0-8.0. The kinetics data indicate better applicability of pseudo-second-order kinetics model at 25 and 35 degrees C. Freundlich model was better obeyed on CGAC, WGAC, and BGAC, while LGAC followed Langmuir model. The adsorption process for 100mg/L initial DCM concentration on CGAC was exothermic in nature. The adsorption of DCM on various adsorbents involves physical adsorption process. The adsorption of DCM over a large range of initial concentration on CGAC and LGAC is effective even in presence of ionic salts.

Synthesis of CTAB intercalated graphene and its application for the adsorption of AR265 and AO7 dyes from water

Environmental applications of graphene (GN) are limited by the occurrence of aggregation. Herein, graphene oxide (GO) was synthesized, reduced to GN by ascorbic acid, and intercalated with cetyltrimethylammonium bromide (CTAB). GN-CTAB was characterized by Boehms titration, N2 adsorption/desorption, Fourier transform infrared spectroscopy, Raman spectroscopy, Fluorescence spectrophotometry, X-ray diffraction and Scanning electron microscopy. Then, GN-CTAB was used for the adsorptive removal of acid red 265 (AR265) and acid orange 7 (AO7) dyes from water both under batch and column operation. Under batch operation, the effect of pH, adsorbent dosage, initial dye concentration, contact time and temperature on dyes adsorption were assessed. Adsorption isotherms, kinetics, and thermodynamics were analyzed systematically. Regarding the fixed bed operation, the effect of both the bed height and flow rate were studied and experimental results fitted to the Thomas and BDST models. Then, the bed loss capacity along five adsorption-regeneration cycles was determined in order to further approach the practical application of GN-CTAB for wastewater treatment, namely for the removal of dyes.

Recent Developments in Ion-Exchange Membranes and Their Applications in Electrochemical Processes for in situ Ion Substitutions, Separation and Water Splitting

Abstract Membrane-based separation processes are achieving a remarkable attention both in academics and industrial research due to the versatility and economic considerations. Ongoing challenges in water and wastewater treatment, food and biotechnology industries accelerating applications of electro-membrane processes. Intensified research on ion-exchange membranes (IEMs) based electro-membrane processes has been accomplished during recent years to produce potable water and downstream processes for biomolecules separation and recovery. The choice of proper membrane, design and operational optimization of the process are highly essential for successful commercialization of any process. Thus, the development of cost effective membranes by eco-friendly route is highly required for researchers working in the field of membrane development by electro-membrane-based processes. This review provides a brief summary of different preparative procedures for IEMs, transport phenomenon and their applications in electro-membrane separation processes. The most relevant studies have been discussed.