Search

The synthesis, reactivity, structure, antimicrobial potential, and antioxidant property of some Schiff bases were extensively studied experimentally and theoretically using the B

Water pollution by recalcitrant compounds is an increasingly important problem due to the continuous introduction of new chemicals into the environment. Choosing appropriate measures and developing successful strategies for eliminating hazardous wastewater contaminants from industrial processes is currently a primary goal. Electroplating industry wastewater involves highly toxic cyanide (CN), heavy metal ions, oils and greases, organic solvents, and the complicated composition of effluents and may also contain biological oxygen demand (BOD), chemical oxygen demand (COD), SS, DS, TS, and turbidity. The availability of these metal ions in electroplating industry wastewater makes the water so toxic and corrosive. Because these heavy metals are harmful to living things, they must be removed to prevent them from being absorbed by plants, animals, and humans. As a result, exposure to electroplating wastewater can induce necrosis and nephritis in humans and lung cancer, digestive system cancer, anemia, hepatitis, and maxillary sinus cancer with prolonged exposure. For the safe discharge of electroplating industry effluents, appropriate wastewater treatment has to be provided. This article examines and assesses new approaches such as coagulation and flocculation, chemical precipitation, ion exchange, membrane filtration, adsorption, electrochemical treatment, and advanced oxidation process (AOP) for treating the electroplating industry wastewater. On the other hand, these physicochemical approaches have significant drawbacks, including a high initial investment and operating cost due to costly chemical reagents, the production of metal complexes sludge that needs additional treatment, and a long recovery process. At the same time, advanced techniques such as electrochemical treatment can remove various kinds of organic and inorganic contaminants such as BOD, COD, and heavy metals. The electrochemical treatment process has several advantages over traditional technologies, including complete removal of persistent organic pollutants, environmental friendliness, ease of integration with other conventional technologies, less sludge production, high separation, and shorter residence time. The effectiveness of the electrochemical treatment process depends on various parameters, including pH, electrode material, operation time, electrode gap, and current density. This review mainly emphasizes the removal of heavy metals and another pollutant such as CN from electroplating discharge. This paper will be helpful in the selection of efficient techniques for treatment based on the quantity and characteristics of the effluent produced.

The waste streams from various agencies like textile, leather, electroplating, and process industries are generating pollutants in the form of effluents or by products. These waste streams consist of various carcinogenic pollutants such as dyes and heavy metals above the permissible limits. Numerous effluent treatment techniques have been implemented for the removal of these pollutants before their discharge into the water body. In this work, reverse micellar extraction was used for the removal of copper ions (heavy metal ions) from the waste stream. Mathematical models namely, the ion exchange reaction model and electrostatic model were developed in order to compare the experimental data with model predictions with regard to the effect of process parameters such as initial metal ion concentration, sodium bis-2-ethyl hexyl sulphosuccinate (AOT) concentration, and organic to aqueous phase volume ratio on final copper ion concentration in the aqueous phase. The ion exchange reaction model was based on chemical and electrostatic interactions between heavy metal ions and the surfactant head groups at the reverse micellar interface, whereas the electrostatic model was based on the adsorption of metal ions on the reverse micellar interface due to electrostatic force of attraction with no chemical bonding. The developed mathematical models were found in close agreement with the experimental data. Atomic absorption spectroscopy (AAS) was used to measure the metal ion concentration in the aqueous phase.

Present work based on thermogravimetric analysis (TGA) to decipher in detail the pyrolysis of mustard stalk (MS) for investigating its potential for bioenergy feedstock at three heating rates (5, 10, and 20 °C/min). The thermal degradation behaviors of MS were carried out at three heating rates (5, 10, and 20 °C/min). The kinetic and thermodynamic parameters were examined using model-free isoconversional Flynn- Wall-Ozawa (FWO), Kissinger-Akahira-Sunose (KAS) model. The obtained activation energy for pyrolysis of MS using FWO and KAS to be 132.47 and 130.62 kJ/mol. Kissinger method was used to compute pre-exponential factor found to be in the range of 105 to 1016 s−1 at different heating rates. The average Δ H was 127.70, and 125.8 kJ/mol and Δ G is 127.74 and 127.87 kJ/mol from FWO and KAS respectively, all Δ H positive indicated endothermic nature. The Coats-Redfern approach was used to estimate the thermal degradation reaction mechanism, which revealed that the diffusion model was best suited to reflect the degradation process involving both exothermic and endothermic reactions. The analysis can help augment the experimental studies, and physicochemical characterization revealed its fuel characteristic since MS is sustainable and promising biomass for alternative processes in terms of waste management strategies.

The present work is focussed on treating dye-laden polluted water by using a mustard straw-based activated carbon prepared using ZnCl2 and H3PO4 activation methods. The activation conditions based on the parameters reported in the literature are taken as follows: 700 °C activation temperature, impregnation ratio 2.0, and heating time 2 h. The textural and surface properties of mustard stalk activated carbon (MSAC) were studied by using SEM, nitrogen adsorption, and FT-IR, whereas its adsorption capacity was obtained using the methylene blue (MB) adsorption method. Activation of ZnCl2 and H3PO4 resulted in a BET surface area of 402 and 496 m2/g, respectively. The average pore diameter of the MSAC was found to be 2.13 and 2.59 nm for ZnCl2 and H3PO4 activation respectively. The Langmuir and Freundlich models were applied to evaluate the equilibrium parameters of MB adsorption. The monolayer adsorption capacity of MSAC by ZnCl2 and H3PO4 for MB removal from the Langmuir model were 122.25 and 213.21 mg/g respectively. Activation with H3PO4 was found to be more effective in modifying the structure of the mustard straw when compared with ZnCl2 and also it resulted in a higher adsorption capacity of MB. The present work highlights that the MSAC produced using H3PO4 activation is a low-cost bio-based adsorbent using abundant agricultural by-product namely mustard straw, and this adsorbent can be used in numerous industrially important applications.

In this work, electro-oxidation of amaranth dye wastewater has been performed using dimensionally stable anode (DSA) and stainless-steel cathode. Ti/TiO2-Ru2O-IrO2 ternary electrode was used as the anode. Effect of various parameters such as current density, pH, voltage and time on the degradation and decolouration of dye was studied. Optimum conditions for the treatment of dye wastewater in batch setup were found. The complete decolouration was achieved in the first 5 min of the process. Decolouration and degradation of amaranth dye wastewater followed pseudo-first-order kinetics. The present research work unlocks the new horizon towards the degradation of dye wastewater employing the once through continuous process.

The demand of membrane distillation (MD) has increased since last few decades for numerous applications. The membrane used in MD is hydrophobic; therefore, the focus has been emphasised on the development of a suitable membrane with desired microstructure. In this study, the flat sheet hydrophobic membrane of suitable properties has been casted with various additives such as water, ethane-di-ol, and propan-2-ol in dope solution using a non-solvent induced phase separation (NIPS) technique. The effect of water content in dope solution has been studied on casted membrane porosity and contact angle. The maximum contact angle and porosity were found to be 96° and 53.23% at 4 weight percent of water content in dope solution of PVDF polymer and di.methyl.acetamide as solvent. It was found that SEM micrograph when ethane-di-ol and propan-2-ol are used as an additive shows more finger-like pores and nodules, respectively, in the microstructure of the casted membrane. Furthermore, synergistic effects using water with other additives were also identified using SEM micrograph of casted membrane and it was observed that water with ethane-di-ol and propan-2-ol form contact angle of 98° and 105°, respectively, for 2 weight percent each additive in dope. In this study, the membrane was also cast by dissolving PVDF powder in di.methyl.acetamide solvent with lithium chloride and the effect of the temperature difference between coagulation bath and film temperature was investigated using an SEM micrograph. Overall, it was found that water content and temperature difference aid in developing hydrophobic porous membrane of desired properties for MD applications.

The leather industry is one of the most polluting sectors in terms of the volume and difficulty of waste disposal. In recent years special attention focused on the treatment of industrial wastewater using advanced treatment technologies, among all approaches, electrochemical technology appears to be one of the most promising methods for handling organic pollutant-containing wastewater. The benefits of electrochemical technology include durability, energy efficiency, automation, and environmental compatibility. The review found the feasibility of the electrochemical method for the treatment of effluent from the leather industry and also found that the rate of pollutant removal was significantly influenced by the type of anode material and electrochemical parameters.

Fate and health exposure linked with pollutants in water are one of the major environmental protests. Electroplating wastewater involves toxic pollutants, which are harmful to living organisms. During the last two decades, advanced oxidation processes (AOP’s) for effectively decontaminate water have drawn great attention. Among various AOP’s, electrochemical technologies appear to be the most promising methods for removing organic pollutants from industrial wastewater. The main objective of this review is to study the feasibility of electrochemical methods for the treatment of electroplating effluents and also found that the rate of toxic pollutants removal was significantly influenced by different anode materials.

Present work is focused on the preparation of mustard stalk activated carbon (MSAC) using chemical activation with H3PO4 and exploring its properties for its use in dye removal from wastewater. Adsorption variable (dosage, contact time, and solution pH), pore structure, morphology, surface functional groups, equilibrium kinetics and isotherm study for the removal of methylene blue (MB) using MSAC were investigated. The present study showed that an adsorption dosage of 0.2 g L-1 and pH 8 can be considered as optimum for the MB removal. SEM result showed that pore of MSAC was larger than the pore of the mustard stalk (MS). BET surface area and total pore volume of MSAC were found as 510 m2 g-1 and 0.33 cm3 g-1, respectively. Equilibrium adsorption data were examined by Langmuir and Freundlich isotherm models. Better correspondence to the Langmuir model with a maximum adsorption capacity of 212.76 mg g-1 (MB onto MSAC) was obtained. Dimensionless factor, RL revealed favourable nature of the sorption in the MSAC?MB system. Adsorption rates were found to follow the pseudo-second-order kinetics with good correlation. These results show that the MSAC could be used as a renewable and economical alternative to commercial activated carbon in the removal of MB dye from wastewater.

Present work is devoted to the study of independent operating parameters namely torrefaction temperature (TT), residence (torrefaction) time (RT), and heating rate (HR) on the slow pyrolysis or torrefaction of an important agro residue namely mustard stalk (MS). Response surface methodology along with three-factor and three-level Box-Behnken design is applied to find the effect of above mentioned three parameters on the higher heating value, energy yield, and fixed carbon of the torrefied MS. Experimentation and modeling analysis reveal that the effect of these three factors' responses follows the sequence: (TT) > (RT) > (HR). Also, the experimental data were analyzed using analysis of variance and fitted to a second-order polynomial model applying multiple regression analysis. Predictive models were obtained which were able to satisfactorily fit the experimental data, with the coefficient of determination (R2) values higher than 0.95. Derringer’s desirability function methodology was used for the optimization study which showed that the HHV, EY, and FC at optimum condition TT 300 °C, RT 20 min, HR 5 °C/min were obtained as 21.26 MJ/kg, 81.26 %, and 35.38 wt%, respectively for MS. Torrefied MS, as compared to raw MS, showed better solid fuel properties for co-combustion with coal and gasification. The experimental values closely agree with the corresponding predicted values. The functional behavior of raw and torrefied MS was studied by Fourier Transform Infra-Red Spectrometry.

Torrefaction process is related to pyrolysis treatment in an inert atmosphere which is employed to improve the chemical and physical properties of biomass/solid fuels for energy generation. In present study, mustard crop residue (MCR) which is an abundantly available lignocellulosic waste was torrefied at three different temperatures (200 °C, 250 °C, and 300 °C) for three different residence time (30, 45, and 60 min). Mass yield, energy yield, high heating value, elemental composition, ash content, and volatile matter content of raw and torrefied MCR are computed. The functional behavior and combustion characteristics of raw and torrefied MCR was studied by Fourier Transform Infra-Red Spectrometry (FTIR). The mass and energy yield of torrefied MCR were found to decrease with an increase in torrefaction temperature and residence time. Elemental analysis of torrefied MCR showed an increase in weight percentage of carbon with increase in temperature and residence time of torrefaction due to release of oxygen congaing volatiles. The high heating value was found to upgrade from 16.92 MJ kg−1 for raw MCR to 21.93 MJ kg−1 of torrefied MCR at higher torrefaction temperature and time. FTIR analysis confirmed that hydroxyl group content decreased due to release of H2O, CO, and CO2. Therefore, torrefaction is found to be an effective treatment process for improving physicochemical properties of MCR.

Department of Chemical Engineering, Malaviya National Institute of Technology, Jaipur-302 017, Rajasthan, India E-mail: mvashishtha.chem@mnit.ac.in Manuscript received online 28 December 2019, revised and accepted 10 January 2020 In the present study mustard stalk is used for production of activated carbon with potential application in removal of methylene blue dye in its aqueous phase prepared by chemical activation route using ZnCl2 . Mustard stalk activated carbon (MSAC) was prepared at an activation temperature of 650ºC and using an impregnation ratio of 2.0 for 1.5 h of activation time. Different parameter such as initial methylene blue concentration, agitation time, pH and dosage of activated carbon were used for conducting adsorption studies in batch mode. MSAC was characterized using FESEM (field emission scanning electronic microscope) with EDX (energy dispersive X-ray spectrometer), and Brunauer-Emmelt-Teller (BET). The best fitted adsorption data was obtained by Langmuir isotherm model with an equilibrium adsorption capacity of 190.90 mg/g. BET surface area and total pore volume of MSAC were found to be 406 m2 /g and 0.328 cm3 /g, respectively.

Desert areas are the favorable geographical locations for desired solar resource and temperature variations for improving the performance of hybrid photovoltaic-thermoelectric generator (HPV-TEG) systems. Therefore, economic feasibility analysis of HPV-TEG system is carried out under real environment and market conditions for the Atacama Desert, Chile. The thermal, electrical and economic models of HPV-TEG system are developed and analyzed in MATLAB. Five different possible scenarios are considered for economic feasibility based on energy losses, system costs, nominal efficiencies of TEG and photovoltaic module and their contribution in the economic feasibility of HPV-TEG system is identified and payback period for all scenarios is determined at minimum and maximum PV temperatures for Atacama Desert including residential and industrial electricity prices. The results showed that with existing market costs and TEG efficiency, HPV-TEG system could not be economically competitive with photovoltaic system for environmental conditions of the Atacama Desert. However, the calculated levelized cost of energy (LCOE) of the HPV-TEG system is 0.071 USD/kWh which is relatively close to current LCOEs for PV systems in Chilean energy market. Further, LCOE analysis economically quantifies the advantages of HPV-TEG system over PV system and opens the possibility for HPV-TEG systems to be competitive in desert locations.

An accurate estimate of nutrient release pattern from controlled release fertilizer (CRF) is required both for manufactures as well for farmers because it helps them in understanding fertilizer potency and nutrient planning for the crops. Understanding the release pattern of different types of CRF under laboratory conditions as well as in the crop-field is essential in order to determine the fertilizer utilization efficiency on plant growth. The present work explains a simple experimental approach to understand the nutrient release from Neem coated urea (NCU). The coating of Urea with Neem oil (derived from seeds and leaves) inhibit the process of nitrification and reduce formation of nitrates which in-turn will reduce N2O emissions. It prevents the loss of urea in the soil. It also controls a large number of pests such as caterpillars, beetles, leafhoppers, borer, mites etc. Also Neem coating is biodegradable and so it is environment friendly as compared to many non biodegradable polymers used as coating materials in CRF.UV-Vis spectrometer is employed to determine the amount of nitrogen released. The approach reduced analytical error by preventing sample dilution before measuring. According to laboratory results obtained UV-Vis spectrometer proved to be a handy and efficient equipment for studying the nutrient release behavior from CRF. The release profile presents a sigmoidal shape which is in good agreement from the other works in the area reported in the literature. The experimental results obtained are also in tune with the criteria specified by European Committee for Standardization for CRF.

The transformer life and performance strongly depend on winding hot-spot temperature (HST). Various alternative techniques for HST prediction are gaining popularity over the conventional direct-measurement methods. In this context, the application of Computational Fluid Dynamics (CFD) based thermal models is particularly interesting because of their accurate assessment, higher precision and low cost. Besides, it can remarkably evaluate and improve the design efficiency of transformer without overshooting the capital cost. In the present work, a comprehensive understanding of CFD-based fluid-thermal assessment is attempted to encourage the readers to review transformer thermal models. It is also expected that these attempts will progressively assist in correlating various economical and operational parameters of transformer manufacturing and asset management.

Moisture measurement in transformer pressboard is an integral part of monitoring mechanical and dielectric strength of insulation. The existing correlations for pressboard moisture mostly considers non-impregnated and steady state (equilibrium) conditions at oil and pressboard interface. In this paper, we discuss the transient moisture migration in oil impregnated pressboard insulation between two consecutive equilibrium conditions with due emphasis on insulation properties. This study is helpful in determining the insulation drying time and moisture retention in impregnated pressboards without conducting extensive experimentation.

The present study aims to unveil the characteristics of fully developed laminar, incompressible, pressure driven non-Newtonian liquid flow in rough circular microchannels. In the present analysis Gaussian isotropic roughness distribution in circular microchannel is considered. The effect of varying surface wall roughness and flow behavior index has been studied numerically for both the pseudo plastic and dilatant fluids. It is found out that while increasing the relative roughness for a particular flow behavior index, the frictional resistance to flow in the microchannel increases and the effect is more pronounced in the case of pseudo plastic fluids. In the case of a pseudo plastic liquid flow for a constant relative surface wall roughness, on decreasing the value of flow behavior index below 1, the frictional resistance to the flow in the channel increases. While in the case of dilatant fluids with increasing the value of flow behavior index from 1 and above for a constant relative surface wall roughness the frictional resistance to the flow in the channel decreases.

Wastewater treatment and re-use of industrial process water are critical issue for the development of human activities and environment conservation. Catalytic wet air oxidation (CWAO) is an attractive and useful technique for treatment of effluents where the concentrations of organic pollutants are too low, for the incineration and other pollution control techniques to be economically feasible and when biological treatments are ineffective, e.g. in the case of toxic effluents. In CWAO, combustion takes place on a Pt/Al2O3 catalysts usually at temperatures several degrees below those required for thermal incineration. In CWAO process, the organic contaminants dissolved in water are either partially degraded by means of an oxidizing agent into biodegradable intermediates or mineralized into innocuous inorganic compounds such as CO2, H2O and inorganic salts, which remain in the aqueous phase. In contrast to other thermal processes CWAO produces no NOx, SO2, HCl, dioxins, furans, fly ash, etc. This review paper presents the application of platinum catalysts in bubble column reactor for CWAO of oxalic acid.

Granulation is a key process in several industries like pharmaceutical, food, fertilizer, agrochemicals, etc. Population balance modeling has been used extensively for modeling agglomeration in many systems such as crystallization, aerosols, pelletisation, etc. The key parameter is the coalescence kernel, β ( i , j ) which dictates the overall rate of coalescence as well as the effect of granule size on coalescence rate. Adetayo, Litster, Pratsinis, and Ennis (1995) studied fertilizer granulation with a broad size distribution and modeled it with a two-stage kernel. A constant kernel can be applied to those granules which coalesce successfully. The coalescence model gives conditions for two types of coalescence, Type I and II. A two-stage kernel, which is necessary to model granule size distribution over a wide size distribution, is applied in the present fluidized bed spray granulation process. The first stage is size-independent and non-inertial regime, and is followed by a size-dependent stage in which collisions between particles are non-random, i.e. inertial regime. The present work is focused on the second stage kernel where the feed particles of volume i and j collide and form final granule ij instead of i + j ( Adetayo et al., 1995 ) which gives a wider particle size distribution of granules than proposed earlier.

In granulation, fine particles combine to form a coarse granule in the form of a particle matrix partially or fully saturated with a binder liquid. The final product of granulation possesses a wide variety of granule size distributions with surface mean diameters which differ with operating conditions. The final granule size depends on the operating conditions, e.g. operating gas velocity, inlet air temperature, initial feed particle size, and viscosity of the binder. The objective of this paper is to find out the uniformity in the relation between the granule mass fraction in the final granule size distribution and the number of feed particles present in the granules. The total number of granules obtained depends on the experimental conditions but the granule mass fraction and the number of feed particles forming a single granule are independent of operating variables, feed material and method of granulation. The paper purports further to compare the uniform nature of mass fraction of the granules in final granule size distribution and the primary particles required to form that particular granule size irrespective of experimental conditions of granulation.

Fluidized bed granulation is a process by which granules or coated particles are produced in a single piece of equipment by spraying a binder as solution, suspension, or melt on the fluidized powder bed. Heat and mass transfer correlation useful for designing a granulator has been derived based on the equivalence of evaporation rate of the liquid to the heat transferred from hot gas to particles: ( m / A ) D p 2 λ L mf ( 1 − e mf ) ( T g − T l ) K g = h D p K g . This equation is applied to data on granulation experiments by different workers to calculate Reynolds number and Nusselt number to obtain a relation between heat and mass transfer from gas to particles during granulation on a logarithmic scale from which the following empirical relation is obtained: N u = 0.0205 Re 1.3876 which is comparable to Kothari's correlation N u = 0.03 Re 1.3 . By using the heat and mass transfer correlation obtained, the entry length, that is the length of granulator up to which effective heat transfer from gas to bed particles takes place, is estimated, which is also validated with experimental study. The correct estimation of entry length is useful in optimal design of a granulator.

We study the early-stage kinetics of thermodynamically unstable systems with quenched disorder. We show analytically that the growth of initial fluctuations is amplified by the presence of disorder. This is confirmed by numerical simulations of morphological phase separation (MPS) in thin liquid films and spinodal decomposition (SD) in binary mixtures. We also discuss the experimental implications of our results., 15 pages, 4 figures

We study spinodal phase separation in unstable thin liquid films on chemically disordered substrates via simulations of the thin-film equation. The disorder is characterized by immobile patches of varying size and Hamaker constant. The effect of disorder is pronounced in the early stages (amplification of fluctuations), remains during the intermediate stages and vanishes in the late stages (domain growth). These findings are in contrast to the well-known effects of quenched disorder in usual phase-separation processes, viz., the early stages remain undisturbed and domain growth is slowed down in the asymptotic regime. We also address the inverse problem of estimating disorder by thin-film experiments., Comment: 12 pages, 7 figures

We study universality in the kinetics of spinodal phase separation in unstable thin liquid films, via simulations of the thin film equation. It is shown that in addition to morphology and free energy,the number density of local maxima in the film profile can also be used to identify the early, intermediate and late stages of spinodal phase separation. A universal curve between the number density of local maxima and rescaled time describes the kinetics of early stage in d = 2, 3. The Lifshitz-Slyozov exponent of -1/3 describes the kinetics of the late stage in d = 2 even in the absence of coexisting equilibrium phases., 5 figures

We present results from a comprehensive numerical study of {\it morphological phase separation} (MPS) in unstable thin liquid films on a 2-dimensional substrate. We study the quantitative properties of the evolution morphology via several experimentally relevant markers, e.g., correlation function, structure factor, domain-size and defect-size probability distributions, and growth laws. Our results suggest that the late-stage morphologies exhibit dynamical scaling, and their evolution is self-similar in time. We emphasize the analogies and differences between MPS in films and segregation kinetics in unstable binary mixtures., 17 pages, 6 figures; Accepted for publication in Physical Chemistry Chemical Physics