Abstract: Rice hull or rice husk (RH) is an agricultural waste obtained from milling rice grains. Since RH has no commercial value and is difficult to use in agriculture, its volume is often reduced through open field burning which is an environmental hazard. In this study, amorphous nanosilica from Philippine waste RH was prepared via acid precipitation method. The synthesized samples were fully characterized for its microstructural properties. X-ray diffraction pattern reveals that the structure of the prepared sample is amorphous in nature while Fourier transform infrared spectrum showed the different vibration bands of the synthesized sample. Scanning electron microscopy (SEM) and particle size analysis (PSA) confirmed the presence of agglomerated silica particles. On the other hand, transmission electron microscopy (TEM) revealed an amorphous sample with grain sizes of about 5 to 20 nanometer range and has about 95 % purity according to EDS analyses. The elemental mapping also suggests that leaching of rice hull ash effectively removed the metallic impurity such as potassium element in the material. Hence, amorphous nanosilica was successfully prepared via a low-cost acid precipitation method from Philippine waste rice hull.
Abstract: This paper discusses the catalytic activity of ZnO/CuO/nanographene platelets composites under visible light and ultrasound irradiation separately. The ZnO/CuO/nanographene platelets composites were synthesized using a sol-gel method. X-ray diffraction and nitrogen adsorption spectroscopy were employed to investigate the structural and surface area of the catalyst. The catalytic activity results showed that the presence of nanographene platelets in ZnO/CuO nanocomposites improved its efficiency in degrading methylene blue. A scavenger method was also used to understand the role of charged carriers and the active radical involved in the catalytic activity.
Abstract: The contamination of water by heavy metals is still a continuing threat to the surrounding environment and to the lives of those exposed to it. A group of techniques to remove ions from contaminated water may employ naturally occurring sorbent materials like hydroxyapatite (HA). HA was successfully extracted from waste fishbones of locally-sourced catfish and tilapia as shown by the diffractograms. The amount of ions removed from Pb2+ solutions at two pH levels using 30 and 60 mg HA powders were determined using Atomic Absorption Spectroscopy. Based on the data, increasing pH and HA dosage increased the adsorption efficiency for both types of HA. However, the saturation of HA has not been attained with calculated adsorption capacities decreasing further with sorbent dosage due to an increase in the number of adsorption sites for a limited amount of ions. Although the values obtained at this level are comparable for both catfish- and tilapia-extracted HA, further studies will be needed to measure their corresponding maximum adsorption capacities. With this investigation, wastewater treatment for lead (II) ion contamination may become more accessible using inexpensive raw materials.
Abstract: Magnetic heterogeneous Fe3O4/TiO2/CuO catalyst were synthesized using sol-gel method. The molar ratio of Fe3O4/TiO2/CuO were varied from 1:1:0.1 until 1:1:5. The all synthesized catalyst were characterized using X-ray Diffraction (XRD), Energy Dispersive X-ray (EDX), Field Emission Scanning Electron Microscope (FE-SEM), and Vibrating Sample Magnetometer (VSM). The result show that the magnetic heterogeneous Fe3O4/TiO2/CuO catalyst exhibit ferromagnetic behavior under room temperature. The catalytic performance were evaluated on the degradation of methylene blue under UV light and combination of ultrasound and UV-light Irradiation. The combination of ultrasound and UV-light irradiation exhibit batter catalytic performance than ultrasound irradiation only. The Magnetic heterogeneous Fe3O4/TiO2/CuO with molar ratio 1:1:0.1 shows highest catalytic performance. The reusability of catalyst were also observed.
Abstract: Adsorption of metal ions proves to be an effective method in treating wastewater due to its simplicity and flexibility in terms of processing. Particularly, iron-modified montmorillonite (Fe-MMT) has been used to treat arsenic ion contamination. However, the strength of association of the metal ion with the adsorbent has not yet been fully explored. This study aimed to determine the stability of the attachment of As2+ onto Fe-MMT by performing desorption experiments using HCl and EDTA as eluents.The Fe-MMT was synthesized via ion exchange while the adsorption and desorption experiments were performed using a batch set-up. Conditions for adsorption were set constant, while the eluent type and concentration (0.1 M and 0.01 M) were varied during desorption. Arsenic ion concentrations were determined using ICP-OES. SEM images and FTIR spectra of the Fe-MMT were also obtained before and after adsorption-desorption steps. Highest desorptions among the settings were observed in 0.1 M HCl and 0.01 M EDTA with 36.72% and 37.13% desorption capacities, respectively. Since the pH conditions also varied with the eluent type, desorption of As is feasible, though not highly efficient, in both acidic and basic conditions with ion exchange as the dominant mechanism. There is a preference in desorption at 0.1 M in HCl but at 0.01 M in EDTA. Furthermore, no significant change in the morphology was observed. The FTIR spectra showed that the absorbance of Fe-MMT after desorption remains in the same range as the absorbance after adsorption but had lost intensity of some of its peaks, indicating possible interactions with acid.
Abstract: The performance of copper indium gallium disulfoselenide (CIGSSe) solar cells strongly depends on the band bap of absorbing layer of CIGSSe. The device performance can be improved by fabricating multi band gap layer of CIGSSe. However, the fabrication of multi band gap CIGSSe using non-vacuum techniques is challenging. In this study, we fabricated solar cell devices which consisted of multi band gap Cu (In,Ga)(S,Se)2 thin films. The CIGS thin films were prepared by the spray-pyrolysis of aqueous precursor solutions of gallium (gallium chloride; GaCl3), copper (indium chloride; CuCl2), indium (indium chloride; InCl3), and Sulphur (thiourea; (SC(NH2)2) sources on Mo-coated glass substrate. The as-sprayed thin films were then selenized at 500 °C for 10 minutes.After selenization, CIGS films were transformed to Cu (In,Ga)(S,Se)2 (CIGSSe). The CIGS films with different composition were deposited again on top of selenized CIGSSe films and selenization process was repeated, hence multi band gap CIGSSe films were fabricated. The Chemical bath deposition (CBD) process was used to deposit cadmium sulphide (CdS) buffer layer. The solar cell fabricated with the device configuration of glass/Mo/CIGSSe/CdS/i-ZnO/AZO showed a power conversion efficiency of 6.51%.
Abstract: Organo-metallic lead halide based solar cells have ushered in a new era of research in renewable energy technologies. Solution processing and earth abundant materials promise a reliable source for our energy needs. Challenges of controlled environment processing hinder the commercialization of this technology. We report a low cost synthesis protocol for these devices. Employing hole transport layer free architecture, we have tailored the synthesis to ambient air conditions of high humidity. Solution processed zinc oxide has been used as electron selective contact offering a stabilized efficiency of 3.03 %. This approach has the potential to lower the cost of this technology promising rapid commercialization.
Abstract: Natural dyes extracted from black rice are used as sensitizer for dye sensitized solar cell. The anthocyanin extracted with various pH in acidic and neutral coditions. Preparation of fotolectrode TiO2 film using doctor blade method and resulting average grain size 33,9 nm using X-Ray Diffractometer. Characterization of morphology and cross-section film TiO2 is confirmed by Scanning Electron microscopy (SEM). Optical absorption using UV-Visible Spectroscopy to obtain spectrum absorbance of anthocyanin in various pH. The current-voltage (J-V) characterization shows the performance DSSC have a match relation to the optical absorption. The best absorption of anthocyanin obtained at pH 6 as well as conversion efficiency reaches 2.26% at this pH condition.
Abstract: Solid polymer electrolyte with PVdF polymer and LiBOB salt has been prepared with doctor blade method. To improve the membrane ionic conductivity, TiO2 has been added. Surface morphology analysis was performed using SEM and EDX spectroscopy. Conductivity behaviour was studied with AC impedance spectroscopy (EIS). SEM and EDX analysis results have shown that TiO2 addition played a role in pore formation on solid polymer electrolyte membrane. The highest value of ionic conductivity in PVdF-LiBOB solid polymer electrolyte system in this research was found to be 5.79% x 10-6 Scm-1 in room temperature, i.e sample with 30% TiO2 addition. It was also studied that agglomeration of TiO2 particle occurred on the surface of the membrane resulted in decreasing of ionic conductivity.
Abstract: This work contributes to the melioration of the modeling and simulation of laboratory cultured fractals using poly (vinylidene fluoride-co-hexafluoropropylene)/poly (ethyl methacrylate)-ammonium trifluorome-thanesulfonate nanocomposite polymer electrolyte films as the media of growth. Main focus is given to fractals and fractal growth models particularly DLA (Diffusion Limited Aggregation). The DLA cluster formed through DLA is formed by particles moving in Brownian motion (diffusion) which meet and stick together randomly (aggregation) to form the cluster. The simulation of multiple cluster fractals is done using DLA methods incorporating different parameters such as its sticking coefficient, lattice geometry and number of particles. To compare the simulation with the real patterns obtained, one vital aspect would be the calculation of their fractal dimension values. The computer program developed is able to calculate the fractal dimension value of each of the simulated fractal patterns. Suitable fractal dimension calculation method is employed according to its usefulness and efficiency. Fractal growth modeling and simulation such as done here can contribute to the understanding of other related studies concerning fractal growth found in areas including medical (nervous systems, cancer growth and more).