Materials, Energy and Environment Engineering

Citrus peel waste is an attractive feedstock of lignocellulosic biomass which can turn into bioethanol. In the present study, several characteristics of citrus peel are illustrated for investigating its suitability for energy generation. The proximate analysis, elemental analysis, FTIR analysis, TGA and DSC studies are conducted for the characterization of citrus peels. From ultimate analysis, it is observed that less amount of nitrogen and sulfur and good amount of carbon, hydrogen and oxygen which can lead to higher ethanol yields. Higher heating value of sweet lime peel and orange peel is obtained as 14,853 and 15,690 kJ/kg respectively which are comparable to other biomass feedstock for biofuel production. FTIR spectra give the information about the presence of cellulose, hemicellulose, lignin, and pectin. The extracted lignin, pectin, acid detergent fiber and neutral detergent fiber from biomass are subjected to thermal degradation studies. The results of thermogravimetric analysis show that the decomposition pattern is similar to that of other lignocellulosic biomass viz., bagasse, rice straw. At normal heating rate, the degradation of hemicellulose occurs at less than 350°C, cellulose degradation between 250 and 500°C, and lignin degradation is gradually distributing throughout the process even after 500°C. There is no definite weight reduction happens since lignin is more thermostable than cellulose and hemicellulose. DSC profile of the peel shows an endothermic reaction initially and exothermic in nature from 200°C. The results from the characterization studies show that the peels of citrus fruits have good potential for energy generation.

Aluminium matrix composites (AMCs) are widely being used for high performance applications such as automotive, military and aerospace because of their improved physical and mechanical properties. In this course an effort has been made to study the microstructure characterization and mechanical properties of aluminium alloy AA7175 reinforced with titanium boride (TiB₂) particles. Aluminium alloy AA7175 reinforced with various amounts (2.5, 5 and 7.5, by weight %) of TiB₂ particles was prepared by stir casting method, in which TiB₂ particles were precipitated in situ through an exothermic reaction between inorganic salts such as K₂TiF₆ (Potassium hexafluorotitanate) and KBF₄ (Potassium tetrafluoroborate). The study of dry sliding behaviour was conducted using a pin-on-disc wear testing machine on the prepared samples, as per ASTM standards and it was observed that with the increase in concentration of reinforcement the wear resistance also increased. The microstructures of the AMCs were examined by optical and scanning electron microscope. The formation of TiB₂ particles enhanced the micro-hardness and ultimate tensile strength (UTS) of the AMCs. The micro hardness of the in situ synthesized AA7175-TiB₂ composite was found to be 67.63 for 2.5 %, 73.254 for 5 % and 77.92 for 7.5 % TiB₂ reinforced composite.

Epoxidation of nahor oil was performed by peroxycarboxylic acid generated in-situ, in the presence of acid catalyst. The reaction was carried out at 50 °C under a stirring speed of 1600 rev/min. The performance of different carboxylic acids namely formic, acetic, and propanoic acid, and the effect of different catalysts namely H₂SO₄, Amberlite IR 120H, and Dowex 50 WX8 on epoxide yield was examined in the present study. It was possible to obtain around 70 % epoxide yield within 8 h at a moderate temperature of 50 °C. Among the catalysts studied, Amberlite IR 120H showed better epoxide yield compared to H₂SO₄ and Dowex 50 WX8. The performance of carboxylic acids was found to be in the order of formic acid > acetic acid > propanoic acid. The FTIR analysis confirmed the formation of glycol products. The findings of the present study will provide useful information for making bio-based plasticizers and lubricants.

The objective of the current study is to investigate the effect of E-glass fibers and fly ash reinforcements on the mechanical properties of Al-8011 hybrid composites. The Al-8011 alloy is reinforced with E-glass fibers and fly ash particulates by using stir casting technique. The metal matrix composites with different composition of E-glass fibers (weight percentage, %) and constant fly-ash particulates (weight %) were prepared. The tensile, compression and hardness behaviour of the composite were investigated experimentally. Maximum tensile and compression strength is observed for Al-8011+6 % fly ash+5 %+E-glass fiber composite. Improvement in hardness was observed with increasing percentage of E-glass fiber. Besides, tensile and compressive behaviour were analytically analysed using ANSYS Workbench 15.0. The experimental results were found to be in good accordance with the analytical results. An average error percentage of 4.5 and 6.5 % was found when experimental and analytical results were compared for both tensile and compression tests. The fracture surfaces of the tensile and compression specimens were examined using scanning electron microscope (SEM).

The objective of this study is to reduce energy consumption for cooling in buildings by passive solar design. This work presents the impact of single, double, triple and quadruple window glazing of four glass materials such as clear, bronze, green and bronze- reflective on heat gain in buildings. The solar thermal properties of the four glass materials were measured experimentally using Perkin Elmer lambda spectrophotometer. The climatic data of four climatic zones of India such as Hot and dry (Ahmedabad), temperate (Bangalore), warm and humid (Bombay) and composite (New Delhi) were considered for the study. The cement plastered burnt brick building walls with reinforced cement concrete roof and dense concrete floor were designed using Design builder and thermal simulations were carried out in Energy plus for heat gain in buildings. An unventilated air gap of 10 mm was maintained between the pane layers. Sixty four building models were simulated in four different window orientations such as East, West, North and south. The buildings located in composite climatic conditions with single, double, triple and quadruple bronze-reflective glass placed in the South orientation gain 41.54, 40.18, 39.55 and 39.19 kWh of heat, respectively. From the results it is observed that the heat gain in buildings decreases with the increase in the pane glazing layers. The bronze-reflective window glass materials with single, double, triple and quadruple glazing are found to be energy efficient among all window glass materials studied. The results of the study help in designing energy efficient building fenestration.

Ruthenium trichloride precursor and Poly (N-vinyl-2-pyrrolidone) (PVP as a stabilising agent) were dissolved in ethylene glycol which played as a solvent and as well as reducing agent. Microwave irradiation (MWI) was applied for the in situ activation of the reaction to reduce Ru3+ to Ru(0). Agglomerations of Ruthenium nanoparticles (metallic Ru) were restricted by using excess solvent and stabilizer (PVP). Nanoparticles were characterized by UV-Vis spectroscopy, Particle Size Analyzer and Transmission electron microscopy (TEM) etc. The influences of different parameters like PVP/RuCl₃ molar ratio (0.6–1) and microwave irradiation power (100–300 W) on the size and size distribution had been systematically investigated. Monodisperse, well-shaped ruthenium nanoparticles in the range of 4–20 nm with narrow size distribution (average diameter 14 nm) were synthesized using optimized reaction parameters.

Poly(styrene-co-methylmetharcylate)-HNT nanocomposites were synthesized successfully by mini-emulsion polymerization assisted by ultrasound. Sonication time and clay loading are the significant parameters which affect the stability of mini-emulsion and the resulting nanocomposite, hence effect of these parameters on nanocomposite morphology, structure and thermal stability was investigated. The intercalation of the HNT’s into the polymer was confirmed by Fourier transform Infrared (FT-IR) and X-ray diffraction (XRD) analyses. Nanocomposite morphology was revealed by Scanning electron microscopy (SEM). Differential Scanning Calorimetry (DSC) analysis shows enhancement in glass transition temperature (T_g) of nanocomposites over pure polymer which signifies an enhancement in thermal stability of nanocomposites.

A novel, facile, faster, safer, environmentally benign, single-step ultrasound assisted process for the simultaneous synthesis of micro-nano size palladium based transition metal oxides(s) have been successfully developed. The method involved sonolyzing a mixture of palladium salt or palladium metal, water and metal salts. Centrifugation of the slurry was done at 7000 rpm for 10 min to separate slurry into micro size particles and slurry of nano particles. Histograms from particle size analysis showed the presence of bimodal size distribution of both nano micro size particles. Both the micro and nano size samples were subjected to X-ray diffraction analysis to confirm the presence of palladium-copper oxide (Pd-CuO) in both the samples. Size distribution analysis was also done by Dynamic Light Scattering (DLS) technique. Diameters of the Pd-CuO particles were found to be 1.548 µm and 82 nm.

Ultrasound assisted processes are emerging as a promising route to replace the conventional methods for the unit operations and unit processes of chemical engineering. Typically the conventional methods for the synthesis of nano size metal oxides, metal carbides and metal nitrides are multiple step processes of longer duration requiring many chemicals and conducted at higher temperature. Hence there is need for a simple, single step and environmentally benign process for the synthesis of these materials. A novel single step ultrasound assisted process at room temperature using simple and non -toxic precursors have been develop for the facile synthesis of Silicon Carbide (SiC), Silicon nitride (Si₃N₄) and Titanium Carbide (TiC). Ultrasonic frequency 20 kHz was used for 60 min. Samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Zetasizer and Brunauer–Emmett–Teller (BET) surface area analyzer. All the synthesized samples were having particle sizes less than 200 nm. This process could be considered as general process for the ultrasound assisted synthesis of metallic compound of industrial importance.

The present study investigates the performance of the draft tube spouted bed reactors of two different sizes on biodenitrification under aerobic condition conducted using Pseudomonas syringae pv kjdr2 (an isolate) immobilized on granular activated carbon (GAC). The time taken to attain steady state increased nearly form 30 to 60 h for a influent nitrate concentration from 100 to 1200 mg/L for given flow rate The maximum nitrate removal of 99.1 % was observed for a nitrate loading of 16.66 mg/L-h where the minimum nitrate removal was 77.2 % for a nitrate loading rate of 600 mg/L-h. For the ratio of influent nitrate loading rate to attached biomass 0.5 g/h-g for reactor-I and 0.42 g/h-g for reactor-II, nitrate removal efficiency decreased to below 90 %. Thus study has generated important design parameter which has a barring of the performance of reactor.

Mixed culture enriched for anammox process over 400 days were used in this study to check the feasibility of anaerobic ammonia oxidation in the presence of HCO₃−. Batch studies proved the feasibility of bio-chemical anaerobic ammonia oxidation in the presence of HCO₃− and the ammonia removal obtained was around 36 % within 24 h. The role of bicarbonate as an electron acceptor yet to be proved thermodynamically. The batch kinetic studies showed that the rate of anoxic ammonia oxidation was higher within 2 h and the rate of ammonia oxidation increased as the concentration of ammonia increased. The total nitrogen removal from the system was very effective without having much accumulation of NO₂− and NO₃−. The specific substrate utilization rate of the biomass for ammonia oxidation was 31 mg/g MLVSS/h. From the results of this study, the new process may be employed for the economic removal of ammonia from wastewaters having low to moderate concentrations of ammonia.

During the operation of radio-chemical plants, low and intermediate level alkaline waste streams containing nitrates is generated. Some of these waste streams contain large concentrations of nitrates exceeding 100,000 ppm and is of highly alkaline nature. To remediate such wastes, a two stage denitration process was developed—with chemical denitration as the first stage, followed by biological denitrification. The chemical denitration process was developed using catalytic reduction technique for destructing the nitrates and converting them to harmless nitrogen gas using a suitable reductant, in the presence of bimetallic Pd-Cu catalysts. The reductant used was formalin (37–41 % formaldehyde) for the experimental work and different reaction parameters were determined to yield a higher reduction. For studies at laboratory scale, approx. 97 % nitrate reduction of synthetic waste prepared using sodium nitrate was achieved in 5 h and denitration of simulated waste resulted in nitrate reduction of approx. 96 % in 6 h and the final nitrate concentration was near 5000 ppm for both cases. According to Indian standards, the maximum permissible limit of nitrate in water is set at 100 ppm and since the reduced concentration doesn’t match the environmentally safe limits, the biological denitrification process was used for further reduction. Biological process was developed for treating effluent containing approx. 5000 ppm of nitrate, formic acid and unreacted formaldehyde, traces of catalyst and NaOH. The bacteria used were denitrifying bacteria. A continuous anaerobic packed bed reactor was used for denitration process.

Cadmium (Cd) is an occupational environmental contaminant gets transported through air, water and soil. The nephrotoxicity of Cd is well authenticated. Hence, to study the individual and interaction effects of different physicochemical parameters namely, temperature, pH, biomass dosage, initial Cd ion concentration and to determine the optimum values of process conditions to maximize the removal of Cd from the aqueous synthetics solutions, Box–Behnken design using response surface methodology was employed. Regression analysis indicated that quadratic model was highly significant. Maximum Cd removal of 89.143 %with sea urchin test as biosorbent was obtained using optimization by response surface methodology at optimum conditions of pH 5.97, temperature 31.98 °C, initial concentration of Cd, 20.56 mg/l and biosorbent loading of 0.5 g/l.

Batch biosorption experiments were conducted to find the effect of pH and biosorbent dosage on the metal species sorption using brewery sludge biosorbent. Optimum conditions of pH (X1) and biosorbent dosage (X2) for the biosorption of Nickel (II) [Ni (II)] and Cadmium (II) [Cd (II)] on brewery sludge were determined by response surface methodology using experiments designed as per central composite design (CCD). The optimum conditions for Ni (II) removal was obtained at initial pH of metal solution 5.3 and biosorbent dosage 12.6 g/L. Similarly, optimum conditions for Cd (II) removal was obtained at initial pH of metal solution 6.2 and biosorbent dosage 14.42 g/L. The experimental data were fitted to second order polynomial equation and the analysis of variance (ANOVA) of the polynomial model demonstrates the statistical significance of the model. This study has demonstrated the use of central composite design by determining the optimum conditions for nickel and cadmium biosorption leading to high metal removal efficiency.

Biosorption utilises plant materials and microorganisms for the treatment of wastewater. Studies were conducted for removal of Copper ions from aqueous solutions by Spirulina algal species by changing the parameters such as contact time, biosorbent dosage, pH and initial metal concentration. The batch study results depicted that Spirulina algal species as good adsorbent by showing maximum removal of 85% for Copper. Column studies conducted for synthetic copper solution showed the bed saturation at 33rd hour and maximum removal efficiency of 95.4% at 10th hour. Column studies conducted for electroplating industrial effluent showed the bed saturation at 29th hour and maximum removal efficiency of 98.4% at 11th hour. Development of adsorption isotherms revealed that the best fit for Spirulina Sp., as Langmuir isotherm for Copper.

Chromium (Cr) as Cr(+VI) is a well known environmental pollutant being highly toxic to most organisms including humans and are difficult to remove. Pharmaceuticals have also become a cause of environmental concern in recent years. Photocatalysis has emerged as a potential technology for treating variety of environmental pollutants and has gathered research interest in recent years for removing Cr(+VI). Among the reported photocatalysts titanium dioxide (TiO₂) and zinc oxide (ZnO) had been widely studied due to high bandgap energy. However, the potential of ZnO as photocatalyst in the removal of Cr(+VI) is less explored. Studies also reported that presence of iron (Fe) ions and sacrificial organic electron donor greatly influence the photocatalytic removal of Cr(+VI). Accordingly the present study evaluated the efficacy of ZnO and Fe-impregnated ZnO (Fe–ZnO) in photocatalytic removal of Cr(+VI) with a model pharmaceutical compound, methylene blue (MB), as sacrificial electron donor under solar radiation. Fe incorporated ZnO was fabricated and X-ray diffraction (XRD) confirmed thet Fe penetrated into the ZnO lattice. The incorporation of Fe in ZnO resulted in shift in bandgap energy and allowed better utilization of solar radiation. Fe incorporation and presence of organic electron donor (MB) enhanced the Cr (+VI) in comparison to ZnO. Also, increase in catalyst loading enhanced the photo-reduction of Cr (+VI). A maximum of 48 % reduction of Cr(+VI) was recorded with 98 % MB discoloration with Fe-ZnO in 4 h of exposure in solar radiation. The present work demonstrates an alternative approach wherein two different toxic and problematic waste was simultaneously remediate in a sustainable manner.

Green route of nanoparticle synthesis has been steering research in the field of Nanobiotechnology of late, as it is known to be safer, cleaner, effective and environmentally benign in comparison to chemical and physical methods of synthesis. Plants are known to possess huge paraphernalia of bioactive phytocompounds that mediate the biosynthesis of silver nanoparticles. In the quest of green biosynthesis of silver nanoparticles, plant parts having commercial and food value have been utilized as sources. The aqueous leaves of Terminalia catappa (Indian almond tree) and T. grandis Linn f (Teak tree) are used in the present study in the biosynthesis of silver nanoparticles, as these resources of bioactive phytocompounds are effectual in biosynthesis of nanoparticles, abundantly available as an agrowaste and inexpensive. Green biosynthesis of silver nanoparticles was successfully carried out using the aqueous leaf extracts of Terminalia catappa (Indian almond tree) and T. grandis Linn f (Teak tree). The effect of the precursor salt solution concentration upon the morphology and size of the silver nanoparticles being synthesized by the aqueous leaf extracts of Terminalia catappa and T. grandis Linn f was studied. Studying the effect of precursor salt concentration upon the size of nanoparticles shall enable the maneuvering of synthesis parameter to obtain nanoparticles of desired dimensions. This route of biosynthesis was found to be cost effective, offered easy downstream processing with low chemical footprint and is reliable and can be used for large scale synthesis of silver nanoparticles.

Titanium dioxide (TiO₂), one of the most fundamental nanomaterial had found numerous applications in our daily life due to it’s efficient photoactivity properties with relatively low cost and low toxicity. For instance, the photocatalytic environmental applications have been widespread from clean up and remediation, air, water and wastewater purification, hazardous waste control, to water disinfection. TiO₂ in nanoscale is preferred for all these applications to attain a remarkable improvement in its physical, chemical and electrical properties since the particle size, surface area, crystal structure, morphology, porosity and phase strongly influences the activity of the nanoparticles. In this paper, the impact of varying volume of hydrochloric acid on the phase formation while synthesis of nano TiO₂ by hydrolysis method has been studied in view of its applications for the photocatalytic reduction of carbon dioxide to methanol. Rutile-anatase composite of TiO₂ nanoparticles has been successfully synthesized by hydrolysis of titanium tetrachloride in hydrochloric acid. One mL of pure titanium tetrachloride was added dropwise to 1 mol dm−3 of the hydrochloric acid solution with varying volume that range from 50 to 200 mL was used. It occurs that yield of titanium dioxide decreases with the increase in the volume of the hydrochloric acid. X-Ray Diffraction (XRD) and Field Emission Scanning Electron Microscopic (FESEM) analysis were used for the structural and morphological characterization of the synthesized nano TiO₂ particles. XRD results indicate that the rutile phase diminished with the increase in the volume of sample. It was observed through FESEM analysis that particle size ranges from 20 nm to 90 nm, and it increased with increasing volume of sample. The knowledge of the impact of processing parameters on phase formation of TiO₂ nanoparticles during synthesis could be implied further for the conversion of carbon dioxide to methanol.

Undoped and Mg doped CuO wire like nano structure were successfully synthesized in PVP by using Quick Precipitation method at a low reaction temperature (600 C) in the absence of a templates and additives. In this work, Copper acetate, PVP, NaOH, Magnesium chloride were used as copper precursor, stabilizer, accelerator and dopant (2, 5 wt %) respectively. XRD (X-ray diffraction), UV–vis spectroscopy, FE-SEM (Field Emission Scanning Electron Microscopy) and EDAX (Energy Dispersive Analysis of X-rays ) analysis are done for structural, optical, surface morphological, and compositional analysis. The XRD analysis revealed that there was a slight change in crystallite size which occurred with increasing concentration of Mg. The measurement of optical absorption spectra indicates that band gap shift with different percentage of Mg. The FE-SEM image reveals that the particles appear to be almost wire like in shape. The result of the EDAX confirmed the formation of CuO and CuO: Mg composition. Due to the excellent structural and optical properties of CuO nanoparticles have wide range of applications in gas sensors, solar cell etc.

An attempt was made to produce Nickel nanoparticle in continuous spiral microreactor, by reduction method. This microreactor junction is made of U-shaped, in order to avoid clogging and pressure drop. The I.D. of copper microreactor was 0.05 in. and length was 200 cm. In this process, the precursor nickel chloride hexahydrate with solvents water/ethylene glycol was first injected to capillary along with reducing agent hydrazine monohydrate followed by thermal reduction at temp 80 °C. It was attempted to prepare Nickel in this microreactor of much less nanoparticle size than that produced in conventional reactors. In this work, the effect of surfactant concentration, precursor concentration and type of solvent on nanoparticle formation was studied. Experimental results in the microreactor revealed that the size of nickel particle could be controlled by varying the reaction temperature. This microreactor is tool of process intensification which can be applied for continuous production of Ni nanoparticle.

The study explores the influence of oxidative pretreatment on the enzymatic saccharification of cassava pulp. Response surface methodology was used to optimize alkaline hydrogen peroxide pretreatment condition for maximum reducing sugar yield with respect to hydrogen peroxide concentration, pretreatment time and temperature. The maximum yield of reducing sugar, 87.5 % was attained at the optimized pretreatment condition of 4.9 % H₂O₂ concentration with pretreatment time of 20 min at 42 °C. ANOVA results revealed that the independent parameters (H₂O₂ concentration and temperature) and the model were found to be statistically significant at a 95 % confidence level. The results of FTIR analysis justified that this method could efficiently disrupt the crystalline structure of lignocellulose and remove lignin for a enhanced hydrolytic reaction. Furthermore, the hydrolysate from the pretreated cassava pulp after enzymatic hydrolysis under microwave energy was subjected to fermentation and produced ethanol with 83.5 % of theoretical yield.

Due to rapid depletion of fossil fuels, especially oil and natural gas, biodiesel provides a promising platform for clean energy production. The raw material and catalyst are the most important factors which affect the commercialization of biodiesel production. In this work, Neem oil is used as a feedstock, which contains high amount of free fatty acids accompanied by moisture content. Low quality feedstock require an additional esterification step for their processing. Bifunctional heterogeneous catalysts are gaining much attention as they possess both acidic and basic groups to carry out the transesterification as well as esterification reactions simultaneously. This study investigates the production of biodiesel from neem oil using pumice, a volcanic rock, as a bifunctional catalyst. The effect of process parameters—Process time, Oil—Ethanol ratio and Oil—Catalyst ratio respectively on biodiesel yield were studied and a maximum yield of 90.5 % was achieved.

Direct methanol fuel cells are known to suffer from methanol crossover, sluggish electrode kinetics and flooding in the channels which results in a decrease in the efficiency of the fuel cell. In this investigation experiments were conducted to establish the effect of vapour fraction on the performance of direct methanol fuel cell by varying the vapour fraction in the feed from 0 % (liquid) to 100 % (vapour) of the methanol solution. The methanol concentrations were varied between 1 and 3 M to find the optimal concentration. Experiments were also conducted to study the effects of neat methanol. The result of the experiments revealed that both the increase in the vapour fraction of feed, and the increase in the concentration of the feed increase the performance of fuel cell.

Tungsten oxide supported over mesoporous carbon rich in nitrogen was analysed for electrochemical oxidation of borohydride as a potential candidate for anodic catalyst in direct borohydride fuel cell. The fabrication of composite catalyst included a hard template method employing SBA-15 with optimal tungsten content. This non-noble catalyst with a minimal tungsten oxide loading of 5 % over the mesoporous support was found to exhibit appreciable current density with an onset potential comparable to noble metals. Besides reliable activity the composite also exhibited significant stability under highly alkaline conditions necessary to keep a check over the competent and notorious borohydride hydrolysis reaction occurring simultaneously. The effect of temperature was also studied by performing borohydride oxidation at various temperatures and the catalyst was found to support the activity even at elevated temperatures.

Renewable energy sources contribution to the entire energy mix is increasing rapidly across globe in general, and in developing nations like India in particular. With 19,706 un-electrified villages in India (Web-1, 2014), government is currently looking vigorously into sustainable off-grid solutions to electrify these villages, as most of them are far from the reach of grid connection. Off-grid electricity generation is comparatively cost effective as the locally available surplus resources which come at a reasonable or no cost can be utilized. This study investigates on the various possible off-grid power generation configurations with mix of various energy sources (solar, wind and diesel) for Indian villages. Four different villages representing four different regions of India which vary in resource distribution as well as the electricity load profiles are considered for study. Also, analysis is extended to study the impact of different projected future population scenarios on the results. HOMER (Hybrid Optimization of Multiple Energy Resources), a soft tool from NREL (National Renewable Energy Laboratory) is used for the work. Based on the present study, an optimal off-grid hybrid energy generation solution with respect to the Levelized Cost of Electricity (LCoE) is identified for a steady and sustained power supply for the villages under consideration. The results show that the LCoE of electricity for an off-grid wind system is highly sensitive to the load profile and the load factor for the villages under study.

For many decades now, there has been an indicative change in nutrient cycling along with organic matter processing, caused prominently due to the release of leather industry effluents. In the present study, a new approach to treat the effluents of leather industry, especially Cr(VI) has been made, with the help of Microbial Fuel Cell (MFC). In the experiment, synthetic Cr(VI) containing wastewater has been used as catholyte and distillery wastewater as a substrate in the anodic chamber, which contains inherent microorganism acting as biocatalysts. The experimental results showed a peak power density of 135 mW/m2 corresponding current density of 520 mA/m2. Chromium reduction of 13.8 % was achieved at pH 4 on the 3rd day of MFC operation. The effect of pH and concentration of chromium was investigated on the basis of power production and performance of the MFC. This work paves way for the possibility of simultaneous removal of waste and generation of electricity.

Proton Exchange Membrane (PEM) fuel cells are an appealing alternative to fossil fuels as they operate on hydrogen fuel without any toxic byproducts. In this work, a single-cell PEM fuel cell with an active area of 25 cm2 using Nafion® 212 membrane was used. Electrodes were fabricated using 10 % platinum supported on high surface area carbon (Pt/C) with a loading of 0.5 mg/cm2. High purity H₂ and O₂ were used as fuel and oxidant gases. A significant number of experimental tests were conducted to investigate the effect of various operating parameters such as cell temperature, pressure, anode and cathode gas humidification temperatures and anode and cathode gas flow rates on fuel cell performance. The results are presented in the form of polarization curves which show the impact of operating parameters on cell performance. At a cell temperature of 318 K, cathode and anode humidification temperatures of 318 K and atmospheric pressure, with a Pt-loading of 0.5 mg/cm2 on both cathode and anode, it has been observed that a current density of 352 mA/cm2 was obtained at a cell voltage of 0.6 V.

The incremental discharge of organic waste has been of great environmental concern due to stringent environmental regulation and increased cost of waste treatment. Microbial degradation of waste is a conventional treatment route but harvesting energy from organic waste employing microbial route in microbial fuel cell (MFC) has generated considerable interest in recent years. Thus MFC presents a potential route for treatment and simultaneous energy recovery from organic waste. The present study is focused in that direction and is aimed at treatment of the latex processing effluent (LPE) with concurrent energy recovery. LPE is marked as pollutant due to high organic load, acidity and nitrogen content. LPE is of great environmental concern for north-eastern states of India and Tripura in particular, since Tripura is the second largest latex producer in India and around 25 L of effluent is produced per kilogram of latex processed. The present study fabricated a two-chambered MFC from low cost materials without membrane separator and monitored the degradation of LPE. 80 % degradation of substrate (LPE) was recorded in 18 days with 40 % total nitrogen removal. The MFC generated around 700 mV potential in open circuit condition. The maximum current generated was 0.083 A/m2 and the net power output was 64 mW/m2 of electrode area. Thus, the present study demonstrated the treatment of LPE in a low cost membrane-less MFC with concurrent energy recovery and thereby presents a sustainable utilization route of a problematic effluent, like LPE, using MFC.

The demand for non-renewable energy resources is created due to the increase in number of vehicles and its pollution problems. This has been led to search for alternative and renewable energy resources. Different methods have been adopted to reduce emissions and to increase the efficiency of engines include, modification in engine, fuel alteration, and exhaust gas treatment. Recently it was reported that blending of nanoparticles with biodiesel to has brought about alteration in chemical and electrical properties which resulted in increased engine efficiency and decreased emission level. In the current study, carbon nanoparticles were synthesized by a simple traditional method. The structural characterization was done using SEM has revealed the average size of the particles in the range of 80.3–88.6 nm. The blend of carbon nanoparticle-biodiesel was utilized to evaluate the engine characteristics. Due to nano-additive biodiesel blend, a significant enhancement in the brake thermal efficiency with substantial reduction in the harmful pollutants from the engine was observed. Maximum brake thermal efficiency of 25 % was obtained for biodiesel blended with 50 mg of carbon nanoparticles with considerable reduction in hydrocarbons, smoke capacity, NOx emissions compared to 25 mg blend, biodiesel and diesel.

Chitosan, the linear co-polymer of N-acetylglucosamine (GlcNAc) and glucosamine (GlcN) residues, is linked via ß-1,4-glycosidic bonds. Naturally, chitosan occurs in the cell walls of some fungi, but today’s commercial production is by partial chemical de-acetylation of chitin which is extracted from shrimp shell or squid pen wastes. As the only polycationic biopolymer, chitosan has a number of intriguing physico-chemical properties in aqueous solution such as spontaneous formation of nanoparticles and an ability to form physical hydrogels. The positive charge is also thought to be at least partly responsible for the broad range of biological functionalities reported, such as antimicrobial activities, disease resistance inducing activities in plants, and wound healing and as a fat scavenger activity in humans. A vast array of techniques is available for the preparation of chitosan nanoparticles. In the present study, the ionotropic-gelation method based on an organic acid is used for nanoparticles preparation. Three different organic acids, namely, acetic acid, lactic acid and citric acid, each at a concentration of 3 % were used for nanoparticles preparation. The nanoparticles obtained were in the range of 10–100 nm with a zeta potential value greater than 30 mV. A pilot study was conducted using three formulations of the chitosan nanoparticles for their capacity to sequester ω-3 fatty acid present in the olive oil. The fat absorption was estimated by the derivatizing the free fatty acid in the solution to their corresponding methyl esters and concentration determined using the gas chromatography. The study revealed absorption of 2873 mg ω-3 fatty acid per mg chitosan upon incubation of 24 h with the chitosan nanoparticles. The exact mechanism of this absorption will be studied in future experiments.

Although nanoparticles can be produced using various physicochemical methods, their synthesis using nontoxic environmental friendly biological method is gaining more attention especially from the point of view of in situ application in medicine. Biological synthesis of nanoparticles is not only useful because of its very low environmental burden compared with some of the physicochemical methods, but also it can be easily scaled up without much complication. Biosynthesis of silver nanoparticle under ambient condition using turmeric extract is reported here. The formation of turmeric nanoparticles (TUAgnps) were analyzed visually and spectrophotometrically. Appearance of brownish yellow colour indicated the formation of TUAgnps which was confirmed by the appearance of surface plasmon band at 435 nm by UV-Vis spectrophotometry. The synthesized TUAgnps were characterized by FT-IR, particle size analyzer, SEM and EDAX. FT-IR studies revealed the capping of nanoparticles by phytoconstituents present in the turmeric extract, and negative zeta potential indicated the stability of TUAgnps. The synthesized nanoparticles were used for methylene blue dye reduction and as a bactericidal agent. The TUAgnps impregnated cotton bandage gauze exhibited strong antimicrobial activity against Bacillus subtilis and Pseudomonas aeruginosa which was confirmed by anticontact study. SEM image of the nanoparticle impregnated cotton bandage gauze showed TUAgnps ranged from 120 to 160 nm hence TUAgnps could be effectively used in antimicrobial wound dressing. The biosynthesized TUAgnps were observed to have a positive catalytic activity of reduction of methylene blue dye, which can be confirmed by time dependent reduction in absorbance maxima which can be ascribed to the electron relay response.

Present nano structured materials are showing very interesting properties compared with bulk materials. Due the high surface to volume ratio and quantum confinement effect these nanostructured materials were used in various applications such as electrical, optical, mechanical, metallurgy, computational, photo catalytic activity, batteries, solar cells, different sensors, seed germination, bio medical and drug delivery systems. This present paper was focused on the metal oxide nano materials synthesis and compares the applications of humidity sensor. The ZnO, CuO and TiO₂ metal oxide nano materials were synthesized by microwave-assisted method using room temperature ionic liquid. Zinc acetate, Copper acetate, Titanium tetra isopropoxide and 1-butyl-3-methyl imidazolium tetrafluoro borate ([bmim]BF₄) room temperature ionic liquid used as initial precursors. From X-ray diffractometer the structures obtained as hexagonal, monoclinic and anatase (hexagonal) for ZnO, CuO and TiO₂ respectively. The average particle sizes were observed in particle size analyser about 22, 35 and 29 nm for ZnO, CuO and TiO₂ respectively. The humidity sensor applications of the ZnO, CuO and TiO₂ nano materials were investigated using controlled humidity chamber, zig setup and digital multimeter.

Industrial revolution of 1700s resulted in rise in living standard through availability of modern amenities at affordable price. The boon of industrial revolution has turned into a bane by irresponsible consumption which is causing irreversible damage to the ecosystem. The current atmospheric CO₂ level (403.26 ppm) has increased by 44 % since 1700s and the plight of other air quality parameters is no different. This situation is particularly grave in ecologically sensitive Uttarakhand, India, where a number of hard-core manufacturing and processing industries have come up and are growing rapidly to meet the demands of growing population. Assessment of the air quality parameters of these industries is extremely important because of the environmental, health and safety concerns of the employees and also for the society at large. This study focuses on air quality assessment of 13 different industries in Uttarakhand. Four major air pollutants, i.e. respirable suspended particulate matter (RSPM), Sulphur dioxide (SO₂), suspended particulate matter (SPM) and Nitrogen dioxide (NO₂) were considered for the assessment. Assessment of the collected data shows that air quality parameters meet the set standards by CPCB suggesting good industrial practices. Suggestions to industries, to ensure sustainable development, are also given in the paper.

Rapid urbanization, industrialization and increase in number of vehicles have resulted in decrease in quality of ambient air. The considerable decrease in quality of ambient air is observed especially after the year 1990 in Hubli-Dharwad, a typical tropical climate region in Karnataka. The present study develops a model using Remote Sensing and Geographical Information System to identify the impact zones based on the meteorological and pollutant data surveyed in the year 2013 and other past records. From this model the impact zone for the year 2013 is assessed and found that RSPM level is above the permissible limits as per National Ambient Air Quality Standards (NAAQS) up to 20–30 % of the study region and a prediction model was also developed for the year 2030 to study the impact zones in the same region. The predictions show that 80 % of the study region is highly polluted especially with Respirable Suspended Particulate Matter (RSPM) along with SOx and NOx may reach to higher levels. Almost the entire Hubli-Dharwad region will be under the exceeded levels of air pollutants by the year 2030. Hence, the proper strategic planning have to be made to control the air pollution. This include, creation of buffer zones between the industrial and residential areas by the detailed study of source apportionment and impact assessment studies to be carried out before to start a new developmental projects in the region.

In textile/dye industry, the effluent contains higher chemical oxygen demand (COD) and disposal of this untreated wastewater causes pollution which indeed more toxic for human and aquatic life. Electro-chemical treatment is a simple, reliable and cost-effective method for treatment of such higher COD without any need of additional chemicals and it does not create any secondary pollutants. In this paper, electro-chemical treatment has been used for reduction of COD (mg/l) and various process parameters interaction through optimization technique i.e., Response Surface Methodology (RSM) such as pH, current density and time of electrolysis. The graphical results clearly show the optimum pH required is 5.0729 and a current density of 22.55 mA/cm2 enhanced the COD removal efficiency. The optimum time of electrolysis was found to be 17.717 min. The percent removal of COD was more than 70 % at above optimum values.

Secondary treatment of wastewater by trickling bed filters is commonly used since it has potential not only to reduce COD, but also nitrogen content in the wastewater. In the current study, 3 bed trickle filter containing gravels and pebbles were utilized to provide secondary treatment to wastewater. Flow path in 3 bed packing with wire mesh in between the packing showed that liquid maldistribution was minimum in comparison with beds without partitioning meshes. Pretreated dairy wastewater was subjected to secondary treatment and the results showed that COD, TKN (Total Kjeldahl Nitrogen) and organic nitrogen undergoes reduction, with a steady rise in percentage reduction of COD and TKN with the number of trials. However, percentage reduction in organic nitrogen showed a negative trend probably due to variation in microbial flora. Also, significant drop in the performance of the trickle bed filter in 5th trial was observed, probably due to sloughing or due to loss of activity of the biofilm on the media of trickle bed filter.