Mechanisms of liquid extraction in a pilot plant sieve plate column

The literature pertinent to droplet hydrodynamics and mass transfer in perforated (sieve)plate liquid-liquid extractor columns has been reviewed. An experimental investigation was conducted in a 450 mm diameter perforated plate extractor with four plates using four different designs with holes of 1.588 mm, 3.175 mm, 4.763 mm and 6.350 mm, each with adjustable downcomers. Hydrodynamics were studied with the system Clairsol 350 (dispersed) and water.The parameters investigated included jet length, dispersed phase hold-up, coalesced dispersed phase and flocculation zone height beneath the plates, mean drop size and drop size distribution as a function of phase velocities. The results have been compared with the published correlations based on data from laboratory scale perforated plate columns or single ground glass nozzles; a wide divergence was found. The experimental data was therefore correlated independently to predict the jet length, dispersed phase hold-up, flocculation zone height and mean drop size. The correlation for mean drop size was modified to include terms involving column dimensions. The mean drop size was correlated within ±10%. Drop size distributions were obtained by analysis of photographic prints. Mugele-Evans upper-limit function gave a better fit compared to the log-nonnal. Mass transfer operation was with the system Clairsol (dispersed)­ acetone-water.Both directions of transfer were investigated In the calculation of the overall experimental mass transfer coefficient CKaD) expt the mean driving force was determined from the concentration profile along the column using Simpson's Rule. A novel method was developed to calculate the theoretical overall mass transfer coefficient using the drop size distribution diagram to determine the volume percentage of stagnant, circulating and oscillating drops in the sample population. Individual mass transfer coefficients were estimated for the corresponding droplet states using published single nozzle drop mass transfer models. A fairly wide divergence was found between the experimental and theoretical overall mass transfer coefficients based on the other workers' models. Recommendations for industrial column design include: (i) using drilled and punched plate to obtain effective use of all orifices and (ii) reduction in plate spacing to reduce back rnixing

Acid-modified montmorillonite for sorption of heavy metals from automobile effluent

An acid treated montmorillonite was utilized as a low-cost adsorbent for the removal of heavy metals from an automobile effluent. The adsorbent was characterized by the Fourier transform infrared spectrophotometer and scanning electron microscope. The effects of pH, adsorbent dose, particle size and contact time on the sorption process were determined by batch methodology. Acid modification increased the Brunauer Emmett and Teller (BET) surface area and total pore volume of the montmorillonite from 55.76 to 96.48 m2/g and from 0.0688 to 0.101 cm3/g, respectively. The removal of heavy metals from the effluent followed the order: Zn > Cu > Mn > Cd > Pb > Ni, which is directly related to the concentration of metal ions in the effluents. The Freundlich isotherm was found to fit the experimental data properly than the Langmuir, Temkin and Dubinin–Radushkevich isotherm models. Kinetic analysis was performed by the application of the pseudo-first order, pseudo-second order, intraparticle diffusion and liquid film diffusion model. The process was found to be physisorption, controlled by the film diffusion mechanism. The acid treatment enhanced the adsorption capacity of the montmorillonite and was suitable for the removal of heavy metals from the automobile effluent

Simultaneous adsorption of Ni(II) and Mn(II) ions from aqueous solution unto a Nigerian kaolinite clay

An unmodified Nigerian kaolinite clay (UAK) was utilized as a low-cost adsorbent for the removal of Ni(II) and Mn(II) ions from a binary solution of both metal ions. Batch adsorption methodology was used to evaluate the effect of solution pH, initial metal ion concentration, sorbent dose, particle size, contact time, temperature and ligand on adsorption. FTIR, XRD and SEM analysis were used to characterize the adsorbent. The equilibrium isotherm data were analyzed using the Langmuir, Freundlich, Temkin and Dubinin–Radushkevich (D–R) isotherm model. The Freundlich isotherm model provided the best fit to the experimental data for both metal ions as indicated by the values of the regression coefficient. The Langmuir monolayer maximum adsorption capacities for Ni(II) and Mn(II) ions are 166.67 mg/g and 111.11 mg/g, respectively. The kinetic data were analyzed using the pseudo-first order, pseudo-second order equations, the Elovich equation and intraparticle diffusion rate equation. The Elovich equation gave the best fit to the experimental data for both metal ions. The presence of intraparticle diffusion mechanism was indicated, although it was not the sole rate determining step. Thermodynamic studies indicated an endothermic, spontaneous and a physisorption process between both metal ions and UAK. The results showed that the kaolinite can be utilized as a low-cost adsorbent for the removal of Ni(II) and Mn(II) ions from solution

Treatment of an automobile effluent from heavy metals contamination by an eco-friendly montmorillonite

Unmodified montmorillonite clay was utilized as a low cost adsorbent for the removal of heavy metals from a contaminated automobile effluent. Fourier transform infrared spectroscopy, X-ray diffraction and scanning electron microscopy were used to characterize the adsorbent. Batch sorption experiments were performed at an optimum effluent pH of 6.5, adsorbent dose of 0.1 g, particle size of 100 μm and equilibrium contact time of 180 min. Thermodynamic analysis was also conducted. Equilibrium data were analyzed by the Langmuir, Freundlich, Temkin and Dubinin–Radushkevich models. A heterogeneous surface of the adsorbent was indicated by the Freundlich model. The Langmuir maximum adsorption capacity of the montmorillonite for metals was found in the following order: Zn (5.7 mg/g) > Cu (1.58 mg/g) > Mn (0.59 mg/g) > Cd (0.33 mg/g) > Pb (0.10 mg/g) ≡ Ni (0.10 mg/g). This was directly related to the concentration of the metal ions in solution. The pseudo-first order, pseudo-second order, intraparticle diffusion and liquid film diffusion models were applied for kinetic analysis. The mechanism of sorption was found to be dominated by the film diffusion mechanism. The results of this study revealed the potential of the montmorillonite for treatment of heavy metal contaminated effluents

Potential of a low-cost bentonite for heavy metal abstraction from binary component system

A low-cost and easily obtainable Nigerian bentonite (UAB) was utilized for the removal of heavy metals (Nickel and Manganese) from a binary system. The bentonite was used without chemical modification in order to keep the process cost low. A Fourier transform infrared spectrum was utilized to determine the surface functional groups responsible for adsorption. Scanning electron microscopy revealed a porous surface of UAB. Batch adsorption methodology was applied to study the effect of pH, initial metal ion concentration, adsorbent dose, adsorbent particle size, ligands (citric acid and EDTA), contact time and temperature on the adsorption process. The isotherm data were analyzed using the Langmuir, Freundlich, Temkin and Scatchard isotherm. Scatchard plot analysis revealed the heterogeneous nature of UAB. Kinetic parameters were tested using the pseudo-first order, pseudo-second order, intraparticle and film diffusion models. The presence of film diffusion mechanism was found to play a major role in the adsorption process. Thermodynamic studies revealed an endothermic, spontaneous and physical adsorption process. Importantly, over 90% of both metal ions were desorbed from the bentonite in desorption studies. The results indicated the potential of UAB as a low-cost and eco-friendly adsorbent for the removal of Ni(II) and Mn(II) ions from aqua media

Mechanism on the sorption of heavy metals from binary-solution by a low cost montmorillonite and its desorption potential

The potential of a low-cost Nigerian montmorillonite for the adsorption of Ni(II) and Mn(II) ions from aqueous solution was investigated by batch mode. XRD, SEM and BET analysis were used to characterize the adsorbent. The experiments were performed as a function of pH, particle size, adsorbent dose, initial metal ion concentration, contact time, ligands and temperature. The process was found to be dependent on all the parameters investigated, with a pH of 6.0 obtained for optimum removal of both metal ions. The Langmuir monolayer adsorption capacity of 166.67 and 142.86 mg/g was obtained for Ni(II) and Mn(II) ions respectively. The Freundlich isotherm gave the best fit to the experimental data than the Langmuir, Temkin and Dubinin–Radushkevich isotherms. The scatchard plot analysis indicated the existence of more than one type of active site on the montmorillonite which corroborates the good fit of the Freundlich model. The pseudo-first order, pseudo-second order and intraparticle diffusion models were applied to the kinetic data. The best fit was achieved with the pseudo-first order model and the existence of intraparticle diffusion mechanism was indicated. Thermodynamic studies showed an endothermic, dissociative, spontaneous and a physical adsorption process between the metal ions and the montmorillonite. Desorption studies revealed over 90% desorption of both metal ions from the metal loaded adsorbent

Renew. Energy

Methanol was replaced by dimethyl carbonate for biodiesel production. In the process, fatty acid methyl ester (FAME) was produced through transesterification of soybean oil with dimethyl carbonate (DMC) using potassium methoxide as a catalyst. This method produced a more attractive by-product, glycerol carbonate (GC). Factors affecting the reaction such as vegetable oil to DMC molar ratio, catalyst concentration, reaction time and reaction temperature were optimized. Triglyceride conversion of 95.8% was obtained at the optimized condition. This process provided an insight into the reactivity of DMC at different temperature. Co-production of FAME and glycerol carbonate (GC) proceeded through carboxymethylation reaction because methoxyl group and carbonyl group are generated which subsequently attacked the carbonyl moiety in glyceride molecules to form the required products. (C) 2014 Elsevier Ltd. All rights reserved.Methanol was replaced by dimethyl carbonate for biodiesel production. In the process, fatty acid methyl ester (FAME) was produced through transesterification of soybean oil with dimethyl carbonate (DMC) using potassium methoxide as a catalyst. This method produced a more attractive by-product, glycerol carbonate (GC). Factors affecting the reaction such as vegetable oil to DMC molar ratio, catalyst concentration, reaction time and reaction temperature were optimized. Triglyceride conversion of 95.8% was obtained at the optimized condition. This process provided an insight into the reactivity of DMC at different temperature. Co-production of FAME and glycerol carbonate (GC) proceeded through carboxymethylation reaction because methoxyl group and carbonyl group are generated which subsequently attacked the carbonyl moiety in glyceride molecules to form the required products. (C) 2014 Elsevier Ltd. All rights reserved

J. Chem. Technol. Biotechnol.

BACKGROUNDThe process of producing biodiesel from various oil feedstocks is well known but developments of commercial plants are being hampered by the high cost of production. The paper reports an integrated method in which the oil obtained by solvent extraction of Calophyllum inophyllum seed is converted to biodiesel over a biomass derived catalyst. The catalyst derived from the residual cake of C. inophyllum obtained after oil extraction can be incompletely carbonized to obtain an amorphous carbon followed by sulfonation in concentrated sulphuric acid. RESULTSThe activity of the catalyst was tested through esterification of free fatty acid present in C. inophyllum oil and comparison was made with a similar catalyst derived from glucose. Superior activity over glucose-derived catalyst was related to the SO3H acid density and higher surface area. The catalyst also achieved high conversion of the non-edible oil to biodiesel (96.6 wt%) in a single step at the optimized reaction conditions. CONCLUSIONA solid acid catalyst capable of simultaneous esterification and transesterification of free fatty acids and triglycerides present in C. inophyllum oil has been synthesized. An integrated process in which the waste generated during the oil extraction process of biodiesel production is effectively utilized could lead to cost reduction and possibly successful commercialization. (c) 2013 Society of Chemical IndustryBACKGROUNDThe process of producing biodiesel from various oil feedstocks is well known but developments of commercial plants are being hampered by the high cost of production. The paper reports an integrated method in which the oil obtained by solvent extraction of Calophyllum inophyllum seed is converted to biodiesel over a biomass derived catalyst. The catalyst derived from the residual cake of C. inophyllum obtained after oil extraction can be incompletely carbonized to obtain an amorphous carbon followed by sulfonation in concentrated sulphuric acid

Appl. Energy

Interest in biodiesel research has increased over the years due to diminishing petroleum reserves but biodiesel has to be derived from non-edible oils in order to avoid the competition with food supply. Here, we report a one step catalytic conversion of non-edible seed oil, Calophyllum inophyllum with free fatty acid of 15% into biodiesel over biomass-derived catalysts. The effective catalysts were prepared by incomplete carbonization of carbon materials under inert atmosphere and then SO3H groups were introduced to obtain catalysts whose activities are comparable to conventional acid catalysts. At the optimized conditions, high conversion (99%) was achieved. The stability of the catalysts was also investigated. (C) 2013 Elsevier Ltd. All rights reserved.Interest in biodiesel research has increased over the years due to diminishing petroleum reserves but biodiesel has to be derived from non-edible oils in order to avoid the competition with food supply. Here, we report a one step catalytic conversion of non-edible seed oil, Calophyllum inophyllum with free fatty acid of 15% into biodiesel over biomass-derived catalysts. The effective catalysts were prepared by incomplete carbonization of carbon materials under inert atmosphere and then SO3H groups were introduced to obtain catalysts whose activities are comparable to conventional acid catalysts. At the optimized conditions, high conversion (99%) was achieved. The stability of the catalysts was also investigated. (C) 2013 Elsevier Ltd. All rights reserved

Catalytic synthesis of renewable hydrocarbons via hydrodeoxygenation of angelica lactone di/trimers

Angelica lactone and its di/trimers is becoming an important renewable platform molecule but the development of simple hydrodeoxygenation (HDO) catalysts will play a major role in its utilization as feedstock for fuel production. In this study, Ni supported on ZSM-5 having Si/Al ratio of 40 and 300 or Ni supported on heteropoly acid/activated carbon (Ni/Ac-HPA) were synthesized and their HDO activities on angelica lactone di/trimers resulted in the production of gasoline ranged (C-6-C-15) hydrocarbon fuels. The HDO activities of the catalysts were dependent on the successful incorporation of Ni metals into the pores of the supports and the Ni metals were highly dispersed with average particle sizes of 20 nm. Considering recent advances in catalytic conversion of biomass to liquid fuels, the method provided in this study is simple and could be replicated in an industrial scale.</p