Statistical modeling and performance optimization of a two-chamber microbial fuel cell by response surface methodology

Microbial fuel cell, as a promising technology for simultaneous power production and waste treatment, has received a great deal of attention in recent years; however, generation of a relatively low power density is the main limitation towards its commercial application. This study contributes toward the optimization, in terms of maximization, of the power density of a microbial fuel cell by employing response surface methodology, coupled with central composite design. For this optimization study, the interactive effect of three independent parameters, namely (i) acetate concentration in the influent of anodic chamber; (ii) fuel feed flow rate in anodic chamber; and (iii) oxygen concentration in the influent of cathodic chamber, have been analyzed for a two-chamber microbial fuel cell, and the optimum conditions have been identified. The optimum value of power density was observed at an acetate concentration, a fuel feed flow rate, and an oxygen concentration value of 2.60 mol m-3, 0.0 m3, and 1.00 mol m-3, respectively. The results show the achievement of a power density of 3.425 W m-2, which is significant considering the available literature. Additionally, a statistical model has also been developed that correlates the three independent factors to the power density. For this model, R2, adjusted R2, and predicted R2 were 0.839, 0.807, and 0.703, respectively. The fact that there is only a 3.8% error in the actual and adjusted R2 demonstrates that the proposed model is statistically significant

Synthesis and characterization of Mn-doped CdSe quantum dots via inverse micelle technique / Nor Aliya Hamizi

Various sizes of manganese-doped cadmium selenide quantum dots (Mn-doped CdSe QDs) synthesized using inverse Micelle technique with organic solvent and surfactant possesses zinc blende structure with physical size ranging from 3 to 14 nm and crystallite size 2.46 to 5.46 nm respectively for 0 to 90 mins samples with narrow size distribution. Mn-doped CdSe QDs observed to growth larger QDs compared to pure CdSe QDs at significantly same reaction times. The lattice parameter compressed with QDs sizes growth due to the introduction of lattice strain due to the incorporation of Mn atoms into CdSe QDs lattice. The Mn-doped CdSe QDs shows a slight blue-shift on absorption and emission spectra’s compared to pure CdSe even though is possessed larger QDs. The band gap structure modification prominently affected by the lattice strain were transition of Stoke`s, Rayleigh to anti-Stoke`s shifts observed as the Mn doped CdSe QDs size growth. The typical red-shift of absorption and emission wavelength observed with growth of QDs sizes. The role of oleic acid acid as a surfactant and capping agent shows in FTIR spectra. The lattice strain tailored the binding energy between the ion prominently on the surface of the QDs with growth of QDs sizes

Tailoring the structural, morphological, optical, thermal and dielectric characteristics of ZnO nanoparticles using starch as a capping agent

Using Starch as a capping agent, zinc oxide (ZnO) nanoparticles (NPs) have been synthesized by the low cost and simple chemical precipitation technique. The confirmation of the hexagonal crystal structure of ZnO NPs were demonstrated by X-ray powder diffraction (XRD) pattern. The Fourier-transform infrared spectroscopy (FTIR) spectroscopy confirms Zn-O stretching vibrations. The scanning electron microscopy (SEM) and Transmission electron microscopy (TEM) images reveal the surface morphological properties of ZnO NPs. Optical properties were investigated by UV–Visible spectroscopy. The optical characterization shows that the ZnO NPs exhibits a low absorbance in the visible range. Thermal behavior of ZnO NPs studied using thermogravimetric analysis (TGA) and differential thermal analysis (DTA). Dielectric properties of ZnO NPs are analysed in the different frequencies at different temperatures. The dielectric properties of ZnO NPs were attributed to the interfacial polarization at low frequencies and orientational polarization at higher frequencies. Therefore, the synthesis method has potential for application in manufacturing units due to ease processing and more economical reagents. © 2019 The Author

Enhanced Photocatalytic Activity of rGO-CuO Nanocomposites for the Degradation of Organic Pollutants

Copper oxide (CuO) nanoparticles (NPs) were decorated on reduced graphene oxide (rGO) through the effective synthetic route method. Powder X-ray diffraction, Fourier transform infrared, ultraviolet-visible absorption, and scanning electron microscopy techniques were used to analyze the chemical structure, functional groups, absorbance, and morphology. Under visible light illumination, the CuO/rGO nanocomposites have higher catalytic activity compared to the bare CuO NPs which were suitable for degradation of methylene blue (MB) and Congo red (CR) dyes. According to the findings, the CuO/rGO nanocomposites possess excellent photocatalytic efficiency. Thus, the synthesized CuO/rGO nanocomposite is a promising photocatalyst for the deterioration of organic pollutants in water and wastewater treatment

Raman spectroscopy and FTIR spectroscopy studies of Mn-doped CdSe QDs at different particles size

In this paper, we exclusively report on raman spectroscopy and fourier-transform infrared (FTIR) spectroscopy results and analysis of zinc blende manganese-doped cadmium selenide quantum dots (Mn-doped CdSe QDs) that synthesized using inverse Micelle technique with physical size ranging from 3 to 14 nm. Two significant peaks were observed correspond to the raman scattering by longitudinal optical (LO) of phonon and its first overtone (2LO) which located near ∼ 200 and 400 cm−1 under an exposure of 532 nm incident laser The role of oleic acid acid as a surfactant and capping agent shows in FTIR spectra

Optical structure modification induced by lattice strain in Mn-doped CdSe QDs

Narrow size distribution manganese-doped cadmium selenide quantum dots (Mn-doped CdSe QDs) successfully synthesized using inverse Micelle technique with organic solvent and surfactant possesses zinc blende structure with physical size ranging from 3 to 14 nm and crystallite size 2.46–5.46 nm. Mn-doped CdSe QDs observed to growth larger QDs compared to pure CdSe QDs at significantly same reaction times. The lattice parameter compressed with QDs sizes growth due to the introduction of lattice strain provoked by the incorporation of Mn atoms into CdSe QDs lattice. The Mn-doped CdSe QDs shows a slight blue-shift on absorption and emission spectra's compared to pure CdSe even though is possessed larger QDs. The band gap structure modification prominently affected by the lattice strain were transition of Stoke's, Rayleigh to anti-Stoke’s shifts observed as the Mn-doped CdSe QDs size growth. The typical red-shift of absorption and emission wavelength observed with growth of QDs sizes. The role of oleic acid as a surfactant and capping agent shows in FTIR spectra. The lattice strain tailored the binding energy between the ion prominently on the surface of the QDs with growth of QDs sizes

Uniformity improvement by integrated electrochemical-plating process for CMOS logic technologies

Reliability of metal interconnects and the integration of inspection and metrology with process tools are advancing rapidly to overcome obstacles in down stream production. A significant drawback associated with metal interconnects which has resulted from the recent trend is the difficulty in obtaining uniform electroplated layer thicknesses across the maximum lateral dimension of the CMOS logic wafer. The prime objective of this paper is, to-root-cause uniformity troubleshooting by the adoption of integrated diffuser in electrochemical-plating (ECP) system optimizations. These are to quantify the best degree of uniformity and high resistivity to enhance an even current distribution on the wafer. The results show that uniformity of the deposited film has been improved significantly with 1.9%. i.e., maximum deviation of the deposited film thickness is at about 1.9% of the average film thickness, while standard electroplating processes typically achieves uniformity at best within 5.5%. Furthermore, the origin of “hot spots’’ that caused poor uniformity was identified and greatly overcome with the improved ECP system comprising an integrated diffuser design and process modifications in real troubleshooting of back –end operation line (BEOL) of semiconductor foundry. © 2019 The Society of Manufacturing Engineer

Investigation on Surface Properties of Mn-Doped CdSe Quantum Dots Studied by X-ray Photoelectron Spectroscopy

In this work, we report on the effects of incorporating manganese (Mn) dopant into different sizes of cadmium selenide (CdSe) quantum dots (QDs), which improves the electronic and optical properties of the QDs for multiple applications such as light-emitting diodes, lasers, and biological labels. Furthermore, the greener inverse Micelle method was implemented using organic ligand, which is oleic acid. This binding of the surface enhanced the QDs’ surface trap passivation of Mn-doped CdSe, which then increased the quantity of the output. In addition, the inverse Micelle technique was used successfully to dope Mn into CdSe QDs without the risk of Mn dopants being self-purified as experienced by wurtzite CdSe QDs. Also, we report the X-ray photoelectron spectroscopy (XPS) results and analysis of zinc blended manganese-doped cadmium selenide quantum dots (Mn-doped CdSe QDs), which were synthesized with physical sizes that varied from 3 to 14 nm using the inverse Micelle method. The XPS scans traced the existence of the Se 3d and Cd 3d band of CdSe crystals with a 54.1 and 404.5 eV binding energy. The traced 640.7 eV XPS peak is proof that Mn was integrated into the lattice of CdSe QDs. The binding energy of the QDs was related to the increase in the size of the QDs

Influence of Reaction pH towards the Physicochemical Characteristics of Phosphorylated Polyvinyl Alcohol-Aluminum Phosphate Nanocomposite

The present study deals with the formation of a phosphorylated polyvinyl alcohol (PPVA)-Aluminum Phosphate (AlPO4) nanocomposite, changing the pH solution under the two-step process involving the phosphorylation of polyvinyl alcohol (PVA) followed by the conjugation with AlPO4. The composite was formed by varying the pH of the solution in the range of 7–12 and the reflected changes in the product’s morphology, crystallinity, surface nature, thermal stability, etc. were recorded using FESEM, XRD, FTIR, UV-Vis spectroscopy, TGA, etc. From the analysis, it was found that the particles formed with two different sizes of the probed pH, and at pH 10 they were homogeneously distributed. In addition, the morphology of the PPVA-AlPO4 composite also seems to be altered with respect to the pH and this is due to the differences in the amount of H+ and OH− anions. Thus, from the overall analysis, it can be indicated that pH 10 needs to be maintained for the formation of a spherical shape and uniformly distributed PPVA-AlPO4 nanocomposite