Column performance of granular activated carbon packed bed for Pb(II) removal

The excessive release of lead from lead acid batteries, smelting plant into the environment is a major concern worldwide. Adsorption process is among the most effective techniques for lead removal from wastewater and activated carbon has been widely used as an adsorbent. In this paper an attempt has been made to investigate the adsorption behaviour of Pb(II) from aqueous systems onto granular activated carbon using the batch mode and continuous mode in a packed bed column with more successive service and regeneration. The experiments were performed at constant temperature and dimensions of column and packed bed of granular activated carbon with variation of flows through the bed and concentrations of lead solutions. Breakthrough points were found out for the adsorption of lead on the adsorbent using continuous-flow column operation by varying different operating parameters like hydraulic loading rate from 4 to 16 m(3)/h m(2) and feed concentrates from 20 to 60 mg/l. Granular activated carbon column regeneration using 0.5 M concentration of HNO(3) has been investigated. Results indicate encouraging performance towards removal of Pb(II).     

Application of ion exchange resin in floating drug delivery system

The purpose of this study was to explore the application of low-density ion exchange resin (IER) Tulsion(R) 344, for floating drug delivery system (FDDS), and study the effect of its particle size on rate of complexation, water uptake, drug release, and in situ complex formation. Batch method was used for the preparation of complexes, which were characterized by physical methods. Tablet containing resin with high degree of crosslinking showed buoyancy lag time (BLT) of 5-8 min. Decreasing the particle size of resin showed decrease in water uptake and drug release, with no significant effect on the rate of complexation and in situ complex formation for both preformed complexes (PCs) and physical mixtures (PMs). Thus, low-density and high degree of crosslinking of resin and water uptake may be the governing factor for controlling the initial release of tablet containing PMs but not in situ complex formation. However, further sustained release may be due to in situ complex formation.     

Optimization of electrophoretic deposition of alumina onto steel substrates from its suspension in iso-propanol using statistical design of experiments

Statistical design of experiments was used to investigate the effect the process parameters on electrophoretic deposition (EPD) of alumina onto steel substrates from its suspension in iso-propanol. The process parameters considered were (i) concentration of particles in the suspension (solid loading), (ii) electrode separation, (iii) applied potential, and (iv) deposition time on the quantity of ceramic particles electrophoretically deposited. A 2⁴ full factorial matrix, with four repetitions of the center point, was used to develop the predictive regression equation for deposition of alumina per unit area of the electrode in the design space. The results show that particle concentration has the most dominant effect with more than 50% contribution to the deposited amount. A good correlation was obtained between predicted and experimental values suggesting that the model can predict data accurately in the experimental matrix.     

Role of Mo<Superscript>6+</Superscript> during nickel electrodeposition from sulfate solutions

The effect of Mo⁶⁺ on the current efficiency, deposit quality, surface morphology, crystallographic orientations and polarisation behaviour of the cathode during electrodeposition of nickel from sulfate solutions was investigated. Mo⁶⁺ did not have a significant effect on current efficiency over the concentration range 2–100 mg dm⁻³. However; a decrease in current efficiency by a magnitude of more than 20% was seen at 500 mg dm⁻³. The quality of the nickel deposit with reference to the visual appearance and contamination level varied with varying concentration of Mo⁶⁺; this was also reflected in the morphology and crystallographic orientations of the deposits. Addition of Mo⁶⁺ to the electrolyte introduced two new crystal planes i.e., (220) and (311). Depolarisation of the cathode was noted at lower concentrations of Mo⁶⁺ (2–40 mg dm⁻³) whereas polarisation of the cathode was observed at Mo⁶⁺ concentration >40 mg dm⁻³ .The effect of Mo⁶⁺ on parameters such as Tafel slope (b), transfer coefficient (α) and exchange current density (i ₀) were also determined.     

Mixing characteristics of binary mixtures using promoters and secondary fluidizing medium

In the present investigation, a new technique for augmenting mixing of particles, expressed through the mixing index (I_M), has been found. Correlations for the mixing index have been developed with system parameters such as static bed heights, average particle densities, average particle sizes and gas mass velocities under four different experimental conditions, viz., only primary air, simultaneous primary and secondary air, disc promoter and rod promoter using the factorial design approach. The values of the mixing index obtained through the developed model are found to agree well with their experimental counterparts. Furthermore, it has been observed that the best mixing performance is achieved (I_M ≈ 1) under conditions of simultaneous primary and secondary air supply.     

Thermal fragmentation and deactivation of combustion-generated soot particles

The effect of thermal treatment on diesel soot and on a commercial soot in an inert environment under isothermal conditions at intermediate temperatures (400–900 °C) is studied. Two important phenomena are observed in both the soot samples: soot fragmentation leading to its mass loss, and loss of soot reactivity towards _O2${\mathrm{O}}_2$. Several experimental techniques such as high resolution transmission electron microscopy, electron energy loss spectroscopy, thermo-gravimetric analysis with mass spectrometry, elemental analysis, Fourier transform infrared spectroscopy and X-ray diffraction have been used to identify the changes in structures, functional groups such as oxygenates and aliphatics, σ$\sigma$ and π$\pi$ bonding, O/C and H/C ratios, and crystallite parameters of soot particles, introduced by heat. A decrease in the size of primary particles and an increase in the average polycyclic aromatic hydrocarbon (PAH) size was observed in soots after thermal treatment. The activation energies of soot oxidation for thermally treated soot samples were found to be higher than those for the untreated ones at most conversion levels. The cyclic or acyclic aliphatics with sp³${\mathrm{sp}}^3$ hybridization were present in significant amounts in all the soot samples, but their concentration decreased with thermal treatment. Interestingly, the H/C and the O/C ratios of soot particles increased after thermal treatment, and thus, they do not support the decrease in soot reactivity. The increase in the concentration of oxygenates on soot surface indicate that their desorption from soot surface in the form of CO, _CO2${\mathrm{CO}}_2$ and other oxygenated compounds may not be significant at the temperatures (400–900 °C) studied in this work.     

Novel aqueous foams for suppressing VOC emission

Reducing volatile organic compound (VOC) emissions from crude oil/gasoline distribution and storage facilities is important in controlling environmental pollution and enhancing workplace safety. Stable aqueous foam formulations are developed to provide a mass transfer barrier to the emission of VOCs during loading of gasoline. Experiments are carried out in a bench-scale foam cell using liquid hexane as oil. The foam columns of 32 cm in height were able to suppress the plateau concentration of hexane vapors in the effluent by 87% under experimental conditions tested. Vapor suppression increased with foam height but was almost insensitive to liquid viscosity. These experiments are then upscaled from bench-scale to a vessel having an exposed surface area of roughly 2 orders of magnitude higher. Gasoline is used as oil in the upscaled experiments, and the concentrations of volatile hydrocarbons in the effluent are measured during oil loading. A 40-cm-thick foam column is found to reduce the emissions by 96% for foams prepared with deionized water and by 93.8% for foams prepared with 3.5 wt % NaCl brine for 10 h of oil loading.     

Feasibility Evaluation of Pressurized Irrigation in Canal Commands

India has one of the largest and most ambitious irrigation programme in the world with net irrigated area exceeding 47 million hectares. However, the overall project efficiency from the headwork to the farmer’s field has been quite low which leads to not only poor utilization of irrigation potential created at huge cost, but also aggravates the degradation of soil and water resources and thereby endangers the sustainability of agricultural production system. As the cost of creating additional irrigation potential in terms of financial, human and environmental aspects has increased tremendously, need of the hour is to increase the irrigation efficiency of existing projects and use saved water for irrigating new areas or meeting the demand of non-agricultural sector. The contribution of application efficiency to poor irrigation efficiency is quite high and therefore increasing application efficiency by a shift in application method from surface to pressurized system has potential of vastly improving irrigation efficiency. To evaluate feasibility of this concept, a pilot study was initiated at Water Technology Centre for Eastern Region, Bhubaneswar, on one outlet of a minor irrigation command. The system has been designed in such a way that it provides pipe conveyance and surface irrigation for rice cultivation during monsoon season and pressurized irrigation during post monsoon period through a hybrid system of sprinkler and drip with four outlets for sprinkler irrigating 2.8 ha area and two outlets for drip irrigating 1.9 ha area. The system is also capable of providing irrigation through drip to part of a command during summer for third crop using water stored in service reservoir after the canal is closed in first week of April. To take care of sediment in the canal water, there are three stages of filtration: first by hydrocyclone filter which filters heavy suspended materials viz. sand, silt, etc., then by the sand filter and finally by the screen filter. The filtration at three stages reduces the turbidity to the desired level. It has been found that three-stage filtration reduced the turbidity to two NTU which is within permissible limit. Considering the cost of water saved, a benefit-cost ratio of the system was found out to be 1.126. This B: C ratio can be further increased by increasing the productivity of the fish and papaya in service reservoir area and better crop management during summer season.     

Production potential of plateau agriculture and food sufficiency in the Kandhamal district of Orissa

The requirement for food grains in the rainfed hill plateaus of the Kandhamal district of the State of Orissa, India was calculated according to accepted nutritional standards over 14 years from 1993 to 2006 and compared with actual production during this time. Owing to the increase in population, the requirement increased from 120 × 10³ MT in 1993 to 142 × 10³ MT in 2006. Production, however, ranged from 68.5 × 10³ MT in 2002 to 134.9 × 10³ MT in 1994 and was only sufficient in 2 of the 14 years. The requirement for food grains for a projected population of 753,542 in 2011 was estimated to be 152 × 10³ MT. At present the area sown is 115 × 10³ ha and would require cultivation 1.83 times per year (cropping intensity 1.83) to produce enough foodgrains for nutritional sufficiency. This could be reduced to 1.64 if the current fallow area of 13 × 10³ ha were cultivated. Increased productivity could be achieved by greater use of irrigation and groundwater.     

A Solvent Free Graft Copolymerization of Maleic Anhydride onto Cellulose Acetate Butyrate Bioplastic by Reactive Extrusion

Summary: Interfacial adhesion between fibers and matrix is a crucial factor for effective stress transfer from matrix to fiber; especially in short fiber reinforced composite systems. The use of a chemical compatibilizer is an efficient means to achieve such adhesion. Maleic anhydride‐grafted‐cellulose acetate butyrate (CAB‐g‐MA) is one such compatibilizer which can be used in biocomposite fabrication, and this has been synthesized in our laboratory by utilizing a twin‐screw reactive extrusion process in the presence of a free radical initiator (2,5‐dimethyl‐2,5‐di(tert‐butylperoxy)hexane). The unique feature of this process is its solvent‐free approach for grafting of maleic anhydride onto CAB, without hydroxyl group protection. CAB‐g‐MA was characterized using FTIR as well as by a non‐aqueous titration method. The effects of initiator and monomer concentrations and various processing conditions on the graft content were also investigated. The preliminary results show that by adding approximately 10 wt.‐% of CAB‐g‐MA into a plasticized cellulose acetate butyrate (TEB)‐industrial hemp fiber biocomposites system, an improvement in tensile strength (20%) and in tensile modulus (45%) were obtained. These results are promising in that they pave the way for future studies involving the use of CAB‐g‐MA as a suitable compatibilizer for cellulose ester‐natural fiber biocomposites.