Band 22, Heft 1

Conventionally, it has been established that the salt ions have the tendency to reduce the surface charge of nanoparticles (NPs) and render them unstable, regulating the stability of nanofluids in a saline environment has been an issue for a long time. To overcome this problem, our work presents the application of a novel green surfactant obtained from Fenugreek seeds of an anionic nature for use as a stabilizing agent for 0.1 wt% silica nanofluids prepared using in DI water. To prevent phase separation, it is imperative to stabilize silica nanofluid solution during their use for subsurface applications. Thus, salt tolerant nanofluids can be prepared and utilized for further applications in enhanced oil recovery and carbon storage etc. The surfactant was extracted from fenugreek seeds by using Soxhlet extraction technique. The liquid solution of extracted surfactant thus derived was dried in hot air oven in order to get the powdered surfactant. The results obtained from dynamic light scattering and zeta-potential, the use of the green surfactant, even in limited concentration (0.2 wt%) not only increases the stability of the nanofluid (from 2 to 12 h) but also lowers the influence of salt, if it is present in moderate concentration (up to 2 wt% NaCl). In addition, when 4 wt% NaCl is dissipated in the solution, the presence of surfactant allows the nanofluid to remain stable for up to 4 h. Furthermore, the surfactant-enriched silica NPs showed higher CO 2 absorption than conventional NPs due to higher surface area and better bubble breakage, paving the way for future field deployment of green-surfactant stabilized silica nanofluids for gas storage and enhanced oil recovery applications.

Population and industrialization growth is the major reason for the indoor air quality depletion. So, air quality control in sensitive area is needed to avoid air pollution-based hazards. Small economical air pollutant controlling equipment may be helpful in indoor air quality control. Present work covers the performance study of lab scale air purifier tower, 37 × 37 × 140 cm 3 (LSAPT) for the removal of PM2.5, PM10 and TVOC from the polluted air in a control volume (75 m 3 ). LSAPT follow 3 step pollutants removal procedure in which coarse particles are separated by prefilter and the fine particles are separated with the help of negative ioniser and activated carbon beds. More than 99 % of percentage of PM2.5, PM10 and TVOC removal are achieved within 100 s for initial pollutants loading of PM2.5: 1000 μg/m 3 & PM10: 1000 μg/m 3 and TVOC: 7.2 mg/m 3 respectively. The assessment study suggests the proposed lab scale air purifier tower can be used continuously up to 10–15 days without much variation in pollutants removal efficacy. Approximately 7700 ₹ (92.40 US$) is used as installation cost and 30 ₹/hr (0.36 US$/hr) is used as consumable energy cost.

The objective of this work is to extract lutein from marigold petals by the ultrasound assisted extraction employing surfactant based aqueous solution. In this study the effect of various parameters i.e. different biocompatible surfactants, temperature, extraction time, pulse mode (ON/OFF), ultrasonicator power, solid/liquid (S/L) ratio, surfactant concentration were investigated. Under the optimum conditions (temperature: 35 °C, extraction time: 20 min, pulse mode (ON/OFF): 20 s ON/OFF, surfactant concentration: 1 % (v/v), S/L: 7.5, ultrasonicator power: 370 W), the maximum lutein content of 12.18 ± 0.39 mg/g was obtained. Further, the comparative study was done for the conventional extraction (CE) and the ultrasound assisted extraction (UAE), both using surfactants aqueous solution as solvent for the extraction of lutein. The results revealed that the amount of lutein obtained using UAE method was notably higher than the CE method. Furthermore, CE and UAE methods were compared in terms of their environmental impact by life cycle assessment approach. Global warming potential (GWP) was found to be lower for UAE (0.91 kg CO 2 /kg of lutein extract) than CE (1.55 kg CO 2 /kg of lutein extract). An antioxidant activity of lutein extract was studied using 1,1-diphenyl-2-picrylhydrazyl (DPPH). The results revealed that lutein can be extracted by UAE without affecting the antioxidant activity of lutein extract. The aforesaid results suggest that UAE employing surfactant based aqueous solution method is suitable for the extraction of lutein from marigold petals.

Higher density heat flux is the major cause of damage to the electronic component; therefore, cooling such components are of the utmost importance to operate in a safe zone and to increase their life. For this purpose, Microchannel heat sinks (MHSs) are among the most practical methods for dissipating unwanted heat. In this regard, the novel lozenge-shaped pin-fins in the flow passage of the microchannel heat sink (MHS) have been designed and proposed to achieve higher cooling performance. Aspect ratios ( λ  = 0.30, 0.39, 0.52, 0.69, 1.00) of several lozenge-shaped pin-fins have been used into the design of MHS to investigate their impact on heat transmission and fluid flow characteristics. A three-dimensional model of MHS with a lozenge-shaped has been generated and simulated numerically in the following range of Reynolds numbers, starting from 100 to 900. Heat transmission and flow characteristics have been presented and discussed in detail. It has been found that introducing lozenge-shaped pin-fins in MHS has greatly improved cooling performance. The highest improvement in Nusselt number has been observed when aspect ratio ( λ ) of lozenge-shaped pin-fins was 1.00. The Nusselt number have been varied in the following ranges of 6.96–12.34, 6.97–12.72, 7.01–13.62, 7.09–14.43, and 7.12–15.26 at λ  = 0.30, λ  = 0.39, λ  = 0.52, λ  = 0.69, and λ  = 1.0, respectively. In addition, a study of the thermohydraulic performance of the proposed lozenge-shaped pin-fins in the MHS found that this design is an effective means of lowering operating temperature.

Reducing friction between drill string and wellbore wall is one of the key functions of drilling fluid which may result from tight holes, key seats, differential sticking, or cutting build up along the drill string. However due to growing environmental concerns, biodegradable lubricants which are also cost-efficient are appreciated and mandated in many countries. This study discusses the performance analysis of biodegradable biodiesel produced from pomelo peels and Petroleum-based lube oil as drilling fluid lubricants. The test samples comprise 700 mL of water + 10 % bentonite + 3 % barite + 0.25 % CaCO 3 + 0.25 % KOH + 1 % CMC + lubricant. Two sets of lubricants were utilized to prepare 10 samples of drilling fluid, one set with petroleum-based lubricant and other with biodiesel. Essential oil was extracted from pomelo peel with the help of the Clevenger apparatus. The oil was then converted to biodiesel through the process of transesterification. Biodiesel properties were tested for the ASTM standards. Both sets of drilling fluid samples were tested for their rheological, filtration and lubricating properties and from the results obtained it can be concluded that both type of lubricating agents have almost negligible impact on rheological and filtration loss properties. However, the lubricity coefficient values drastically decreased as we increased the lubricant content, which is an indication that biodiesel extracted from pomelo peel acts as a better lubricant. The values of the lubricity coefficient for biodiesel based drilling fluid also fell well within the advised range (<0.30). We can therefore draw the conclusion that biodiesel made from pomelo peel can replace petroleum-based lubricants while also lowering the environmental concerns related to lubricants.

Herein, we have introduced the electrode material made up of a composite of an electrochemical active organic molecule (i.e. methyl orange (MO)) and reduced graphene oxide (rGO) composite. This composite is found to be a potential material for supercapacitor application due to the sustainability, redox reversibility of organic molecules, and good conductivity of rGO. For fabricating symmetric solid-state cell (MO/rGO//PVA/H 2 SO 4 //MO/rGO), polyvinyl alcohol–sulphuric acid (PVA/H 2 SO 4 ) aqueous gel polymer electrolyte (GPE) has been sandwiched between the two MO/rGO electrodes. It was found that a MO/rGO based symmetric cell interfaced with a PVA/H 2 SO 4 gel electrolyte has a specific capacitance of 166.79 F g −1 and an energy density of 11.58 Wh kg −1 at a power density of 6.25 kW kg −1 . Here, good specific capacitance is the result of a combination of both electric double-layer capacitor (EDLC) and pseudo-capacitive behaviour observed in a fabricated cell. The specific capacitance is stable after 2500 cycles of charge and discharge, with an initial fade of 32 %. This synthesized material and fabricated device found its potential to be used for the supercapacitor application.

Environmental sustainability and energy security are two major issues, which are globally attracting the attention of the scientists and researchers. The sustainable development goal (SDG-7) calls for sustainable and modern energy for all. Solar energy has great potential and it can be transformed in other usable forms through various energy harvesting technologies. The photovoltaic cell utilizes solar radiation to generate green electricity. Photovoltaic cells follow the mechanism of photon to electron conversion for electricity production. Recently, organic solar cell, which is a type of photovoltaic cells, has shown potential to overcome demerits faced by photovoltaic cell like low flexibility, weight and environmental biodegradability issues. Dye sensitized solar cell (DSSC) is a kind of the organic solar cell. A (DSSC) has been fabricated using Punica Granatum (pomegranate juice) as sensitizer. The maximum efficiency of the solar cell is observed to be 0.16 %. The effect of various climatic parameters the performance of fabricated dye sensitized solar cell has also been evaluated and reported.

The widespread use of composites in an ionizing environment raises durability concerns, particularly when performance is required over a longer period, in a radiation environment. The goal of this study was to measure the attenuation coefficient for the polymer composite developed for the radiation shielding application and validate it with the well-known Monte Carlo simulation. A radiation-hardened epoxy resin was developed in the laboratory by utilizing various compositions which is capable of being employed as a shielding material in a nuclear environment. To develop a radiation-hardened layer, to some extent, raised the density of the material, using suitable fillers. Polymer stabilizers were used single or in combination. The specimens were irradiated to determine the developed material’s shielding properties. The prepared composites’ radiation absorption is evaluated using an absorption coefficient. Experiments with gamma radiation using an Am Be Neutron source were conducted to determine the linear absorption coefficient. Monte Carlo simulation was utilized to predict the absorption coefficient for developed composites and the results were compared with experimental data.

The impact of ZrO 2 as a catalytic promoter for nickel-based alumina supported catalysts has been studied for the hydrogen synthesis via glycerol steam reforming. Hydrogen is a promising contender of clean fuel and has a key significance in the quest of an environment-preservation, low emission and more sustainable energy approach. Glycerol is a by-product produced during production of biodiesel by trans-esterification of vegetable oils. The higher hydrogen content in glycerol makes it the potential renewable feedstock for hydrogen production. Steam reforming process is the best method available which is highest in energy efficiency and most importantly most economical. The production of catalysts was based on the wet impregnation and co-precipitation methods. The majority of the bulk and surface properties of different synthesized catalysts were considered and determined by several characterization techniques like X-ray diffraction technique, BET surface area and scanning electron microscopy. The performance of catalyst is based on glycerol conversion and hydrogen yield obtained from the steam reforming process taking place in the fixed bed catalytic reactor. The effect of different operating conditions like contact time, temperature, metal loading, and steam to glycerol ratio were investigated to produce maximum hydrogen and glycerol conversion. The results show that the incorporation of promoter 2 % ZrO 2 improved the activity of Ni/Al 2 O 3 catalysts significantly resulting 96 % glycerol conversion, 84 % hydrogen production and greater stability at contact time = 15 kg cat s/mol, temperature = 800 °C, steam to glycerol ratio = 9:1 mol/mol, and pressure = 1 atm.