An efficient plasmonic photovoltaic structure using silicon strip-loaded geometry

We show that a silicon thin-film photovoltaic structure with silicon strips on the top and grooves on the silver back contact layer can absorb incident solar energy over a broad spectral range. The silicon strips on the top scatter the incident light and significantly help couple to the photonic modes in the smaller wavelength range. The grooves on the silver back contact layer both scatter the incident light and help couple to the photonic modes and resonant surface plasmon polaritons. We find an increase of ∼46% in total integrated solar absorption in the proposed strip-loaded structure compared to that in a planar thin film structure of same dimensions. The proposed structure offers simpler fabrication compared to similar plasmonic-inspired designs

Sulfur and nitrogen removal of model fuel using activated carbon derived from oil palm shell

This research was done to understand the suitability and effectiveness of oil palm shells (OPS) as low cost adsorbents via physically activation with carbon dioxide (CO2) as an adsorbent for desulphurization and denitrogenation of a model fuel under different concentration. Batch mode experiments were conducted to study the effects concentration of Benzothiophine, Quinoline and Indole. Activated carbon (AC) was prepared at three different activation temperatures (500°C, 600°C, and 700°C), which was characterized with Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (mR), and a mercury intrusion porosimeter. After adsorption, the solution was analysed with a Gas Chromatography (GC). Equilibrium adsorption isotherms and kinetics were investigated. The experimental data were analysed by the Langmuir and Freundlich models of adsorption. The adsorption isotherm data were fitted well to Langmuir isotherm and the most adsorption capacity on the best suited AC for Benzothiophene, Quinoline, and Indole were 3.64 mg/g, 4.19 mg/g and 2.98 mg/g respectively. The rates of adsorption were 0.19409 h-1, 0.08411 h-1, and 0.02883 h-1 for the adsorption of Benzothiophene, Quinoline, and Indole respectively. The kinetic data obtained at different concentrations have been analysed using a pseudo-first-order, pseudo-second-order equation and intraparticle diffusion equation. The pseudo-first­order model best described the sorption process and was employed in predicting the rate constant, equilibrium sorption capacity as well

Recovery and characterization of used lubricating oil using acid with two different adsorbents

This study is a form of experimental analysis that utilizes used lubricating oil (ULO) in order to reclaim base oil by using a combination of acetic acid and two different adsorbents namely aluminum oxide (Al2O3) and river sand (RS). The two different adsorbents were used to compare for better quality of oil using the same method. The characterization of the recovered ULO samples was conducted by using Fourier-transform infrared spectroscopy (FTIR) and the viscosity was tested by using the viscometer. Based on the results obtained, the Al2O3 seems to be a better adsorbent than RS in several tests such as density, sludge removal and viscosity. For better viscosity and mass of sludge values, the Al2O3 adsorbent is more suitable compared to the RS. It was found that by using Al2O3, there is a 26% viscosity reduction for ULO samples. By using RS, 6.67% viscosity reduction was found for ULO samples. 24.9% and 25.7% of sludge removal was found in ULO samples by Al2O3 and RS, respectively. FTIR analysis showed that before treatment oxidative compounds such as alkens and helides were present in the ULO and UEO samples. However, after treatment by both of the adsorbents, the oxidative compounds were removed. The removal of the alkenes and alkyl halides has evidently indicated the treatment was able to remove the oxidative compounds in the oil

Removal of Nitrogen containing compounds from fuel using modified activated carbon

This study was carried out to understand the suitability of activated carbon (AC) which is modified with hydrochloric acid (HCl) and tested by its adsorption capacity of nitrogen containing compounds (NCC) from fuel with three variables such as different concentrations of model fuel, contact time, and amount of modified AC (MAC). Batch mode experiments were conducted to remove quinoline (QUI) and indole (IND) from the model fuel prepared from n-hexane. All the experimental data were analysed using ultraviolet-visible spectroscopy after adsorption experiment between adsorbent and model fuel. Modification of commercial AC involved impregnation with different ratios of HCl solution. The characterization of modified and unmodified AC was done by using fourier-transform infrared spectroscopy (FTIR) and scanning electron microscope (SEM). The adsorption potential of the MAC was measured based on the two isotherms, which are Langmuir and Freundlich isotherms to determine the isotherm constants and two kinetic models which are pseudo-first order and pseudo-second order. The adsorption capacity for QUI and IND was found to be 0.4708 mg/g and 0.8094 mg/g, respectively. On the other hand, the rate of adsorption for QUI and IND was 6.3766 and 0.4992, respectively. The adsorption kinetic experiment for both QUI and IND was found to follow the pseudo first-order

Removal of chlorinated phenol from aqueous solution utilizing activated carbon derived from papaya (carica papaya) seeds

Activated carbons (ACs) were prepared from papaya seeds with different dry weight impregnation ratios of zinc chloride (ZnCl2) to papaya seeds by using a two-stage self-generated atmosphere method. The papaya seeds were first semi-carbonized in a muffle furnace at 300 oC for 1 h and then impregnated with ZnCl2 before activation at 500 oC for 2 h. Several physical and chemical characteristics such as moisture, ash, pH, functional groups, morphological structure and porosity of prepared ACs were studied and presented here. AC2, with the impregnation ration of 1 : 2 (papaya seeds: ZnCl2), yielded a product that had the highest adsorption capacity, 91.75%, achieved after 180min contact time. The maximum Brunauer, Emmett and Teller (BET) surface area of AC2 was 546m2/g. Adsorption studies indicated that AC2 complied well with the Langmuir isotherm (qm=39.683mg g-1) and the pseudo-second-order (qe=29.36mg g-1). This indicated that chemisorption was the primary adsorption method for AC2. The intraparticle diffusion model proved that the mechanism of adsorption was separated into two stages: the instantaneous stage and the gradual adsorption stage. Overall, this work demonstrated the suitability of using papaya seeds as a precursor to manufacture activated carbon

Properties tuning of palm kernel shell biochar granular activated carbon using response surface methodology for removal of methylene blue

This study aimed to produce palm kernel shell granular activated carbon (PKSGAC) from slow vacuum pyrolysed PKS biochar (PKSB) via chemical activation using a horizontal tubular split zone furnace. The study also investigated the effects of varying parameters of the PKSGAC on its colour removal ability. The PKSB was activated through chemical activation using potassium hydroxide (KOH) at various parameters such as activation temperature (700oC to 850oC), KOH concentration (50 % w/v to 100 % w/v) and particle size of PKSB (0.4 mm to 2.5 mm). The novelty of this work lies in the study of chemical activation on various particle size ranges using response surface methodology (RSM) to model the relationships between various parameters. The PKSB was characterized to determine its thermal condition, and the PKSGAC was characterized to determine the iodine number, bulk density, ash content, moisture content, surface area and morphology structure. The parameters that were used for each sample were determined by using the RSM based on central composite design (CCD). In this study, design expert version 11.0 software was used and three parameters as independent variables were manipulated. Finally, three different PKSGAC samples of different particle sizes were used to test for the methylene blue (MB) dye removal with the concentration of 5 mg/l, 10 mg/l, 15 mg/l and 20 mg/l. Thermal analysis showed that the total weight loss of the PKSB sample was 58.30% and for PKSGAC the range of the product yield as shown from the RSM was from 33.23% to 96.33%. The RSM also showed that the values for moisture content were in a range from 0% - 39%, as for the ash content value from 2% - 12%, while for the bulk density ranged from 0.17 g/cm3 - 0.50 g/cm3. The highest iodine value achieved was 1320 mg/g at activation temperature of 850oC, KOH concentration of 50% w/v and particle size of 0.4 mm. From the RSM, an iodine number of 1100 mg/g could be obtained using an activation temperature of 850oC, the KOH concentration of 69.22% w/v and the particle size of 0.59 mm. From the BET analysis, the PKSGAC sample obtained 581 m2/g for SBET and 0.3173 cm3/g for the Vtot. The highest percentage dye removal of MB dye was 89.61% to 97.63% at 775oC activation temperature, 75% w/v KOH concentration and 0.4 mm particle size. This work produced RSM models to predict the relationships between the parameters and the response, as well as the performance on MB dye removal

Optimization and activation of renewable durian husk for biosorption of lead (II) from a aqueous medium

Background: Biosorption of lead Pb(II) by durian husk activated carbon (DHAC) was investigated. The main aim of this work is to explore the effect of operating variables such as pH, biosorbent dose, temperature, initial metal ion concentration and contact time on the removal of Pb(II) from synthesized aqueous medium using a response surface methodology (RSM) technique. The experimentation was performed in two sets, namely set 1 and set 2. Results: For experimental set 1, pH was set to 7.0. The optimum conditions for the remaining parameters were determined to be 0.39 g DHAC dose, 60 min contact time and 100 mg L−1 of initial metal ion concentration, which yielded maximum biosorption capacity of 14.6 mg g−1. For experimental set 2, 41.27 °C, 8.95 and 99.96 mg L−1 were the optimum conditions determined for temperature, pH and initial Pb(II) concentration, respectively; which revealed a maximum adsorption capacity of 9.67 mg g−1. Characterization of the adsorbent revealed active functional groups such as hydroxyl, carboxylic, alcohol and hemicellulose. The equilibrium adsorption data obeyed the Langmuir isotherm and pseudo‐second‐order kinetic models with maximum Langmuir uptake of 36.1 mg g−1. Conclusions: The biosorbent was capable of reuse, so that the abundant durian husk could be utilized effectively for the removal of Pb(II) from polluted water

Synthesis and characterization of metal oxide promoted alumina catalyst for biofuel production

Alumina has been widely used as a support in catalysis process which owing to its extremely thermal and mechanical stability, high surface area, large pore size and pore volume. The aim of this study was to synthesize calcium oxide-supported basic alumina catalysts (CaO/Al2O3) by impregnation method and to characterize the properties of the catalyst based on its surface area and porosity, functional group, surface morphology and particle size. Impregnation method was chosen for the synthesization of catalyst which involved contacting the support with the impregnating solution for a particular period of time, drying the support to remove the imbibed liquid and calcination process. In the preparation of catalyst, catalytic performance of CaO/Al2O3 catalyst was measured at different calcined temperatures (650°C, 750°C and 800°C). Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), Mercury intrusion porosimetry (MIP), and particle size analyzer (Zetasizer) was used to characterize the catalyst. The highest total specific area and the total porosity of the catalyst was obtained at 750oC. FTIR analysis basically studied on the functional groups present in each catalyst synthesized, while SEM analysis was observed to have pores on its surface. Moreover, CaO/Al2O3 catalysts at 650°C produced the smallest particle size (396.1 mn), while at 750°C produced the largest particle size (712.4 mn). Thus it can be concluded that CaO/Al2O3 catalysts has great potential coimnercialization since CaO has attracted many attentions compared to other alkali earth metal oxides especially on the transesterification reaction

Used lubricating oil recovery process and treatment methods: A review

Used lubricating oil (ULO) is considered hazardous as it is able to cause pollution and affect the environment. The presence of degraded additives, contaminants, and by-products of degradation render ULO more toxic and harmful to health and environment than virgin base oils. Recovery of ULO generally comprises cleaning, drying, and adsorption in order to eliminate water, sludge, and impurities. As the ULO is one of the hazardous wastes generated in various industries, such as industrial and automotive, it should not be used or disposed of in ways that are harmful for the environment. Recovery of ULO carries out many advantages which includes lower environmental impact, higher energy saving and lower risks. The main objective of this paper was to thoroughly review various recovery process principles and treatment methods for ULO. Importance of ULO recycling and various techniques along with their limitations were also discussed. The significance of this study lies in reviewing the roles of adsorbent and adsorption reclamation processes of ULO and few promising adsorbents were earmarked for further study

Influence of Carrier Agents Concentrations and Inlet Temperature on the Physical Quality of Tomato Powder Produced by Spray Drying

The study aims to obtain spray-dried tomato powders with a high and effective product yield and enhanced powder quality. The experiment for this investigation entailed the use of several carrier agents, which were maltodextrin (MD) of 4-7 dextrose equivalents (DE), MD of 10-12 DE, and gum Arabic (GA), each in varied concentrations of 5% and 10% with spray drying inlet temperatures of 140°C, 150°C, and 160°C. Powder yield, bulk density, hygroscopicity, moisture content, water solubility, water absorption, color properties, particle size, and powder morphology were all evaluated in spray-dried tomato powders. The results revealed that the stability of the tomato powder is considerably better at high temperatures and concentrations (at 10%, 160o C), with MD 4-7 DE being the best carrier agent among the three tested carrier agents. According to the powder analysis, the product has a moisture content of 3.17 ± 0.29%, the highest yield percentage of 32.1%, a low bulk density of 0.2943 ± 0.01 g/cm3 , the lowest hygroscopicity at 5.67 ± 0.58 %, a high water solubility index (WSI) at 89.98 ± 1.25%, a low water absorption index (WAI) at 6.22 ± 0.22%, an intermediate particle size of 24.73 µm, and color L*, a*,b* values at 31.59 ± 0.03, 11.62 ± 0.08 and 13.32 ± 0.12. The result showed that at higher temperatures and higher concentrations, the powder characteristics are more likely to have a higher yield, WSI, and larger particle size, as well as lower bulk density, hygroscopicity, moisture content, WAI, and color index