Optimization of solar photocatalytic biodegradability of seawater using statistical modelling

The performance of zinc oxide (ZnO) as a photocatalyst was evaluated for the treatment of pollutants present in seawater. Batch experimental studies were carried out by varying the dosage of photocatalyst (1–4 ​g/L). The effect of reaction time, pH and the dosage of photocatalyst was evaluated with the percentage removal efficiencies of chemical oxygen demand (COD), biological oxygen demand (BOD), total organic carbon (TOC) and the biodegradability (BOD/COD) of the seawater. Response surface methodology-central composite design (RSM-CCD) and artificial neural network-Levenberg Marquardt (ANN-LM) statistical models were employed to optimize the photocatalytic biodegradability (BOD/COD). A quadratic polynomial statistical model was obtained to predict the percentage removal efficiencies of COD, TOC, BOD and biodegradability. For the experimental runs, the maximum percentage removal efficiencies for COD, TOC, BOD was found to be 62.3, 40.1, and 18.8%, respectively. Whereas, the maximum biodegradability was 0.036. As per RSM-CCD and ANN-LM statistical model method the maximum percentage removal efficiencies were found to be COD ​= ​58.14, 60.39%, TOC ​= ​33.74, 40.09%, BOD ​= ​18.47, 18.7% and Biodegradability ​= ​0.0315, 0.0360, respectively. The predicted values from statistical models were well correlated with experimental values. ANN modelling predicted better values for the responses with an average of R² ​= ​0.99697 than RSM modelling with average R² ​= ​0.8948.     

CZTS nanoparticles by one-pot sonochemical route – Effect of power density,pH and bath temperature

One-pot synthesis of nanosized CZTS particles using ultrasound employing citric acid as the complexing agent has been studied. The CZTS nanoparticles synthesis at different bath temperatures, pH and power densities was attempted. The power density used for the reaction did not alter the crystallinity and morphology of the synthesized particles. However, the chemical composition and the bandgap of the particles showed significant variation with the applied power density. Apart from affecting the composition, bandgap and electrical characteristics, the bath temperature considerably affected the crystallinity of the CZTS nanoparticles. Based on the conditions of synthesis, the particle size ranged between 25 ​nm and 40 ​nm. Depending on the process conditions, the bandgap of the particles varied between 1.4 ​eV and 2.9 ​eV. The samples synthesized under a power density of 46 ​W ​L⁻¹ and 40 ​°C bath temperature with reactant pH of 3.5 showed composition closer to the required stoichiometry.     

The effect of the binder morphology on the cycling stability of Li–alloy composite electrodes

It is demonstrated that the design of the composite electrode, or more precisely the morphology and distribution of the binder poly(vinylidine fluoride) (PVdF) within the composite electrode, has a significant impact on the cycling performance of Li storage alloy (Sn/SnSb) electrodes. Different binder morphologies and distributions have been obtained by using different solvents for the slurry preparation, such as 1-methyl-2-pyrrolidinone (NMP), in which PVdF is dissolved, yielding electrodes with a homogeneously and finely distributed binder, or decane, in which PVdF is only dispersed, yielding electrodes in which the original particle morphology of the binder powder is preserved. In constant current cycling tests carried out in an excess of electrolyte, the electrodes with the ‘dispersed’ binder show far better cycling capacities and stabilities than those with the ‘dissolved’ binder. This is explained by the different binding strengths, swelling behaviour in the electrolyte, electrode porosities, and possible ‘buffer’ effects of the compact and the finely distributed binders.     

Green synthesis and characterization of Fe doped ZnO nanoparticles and their interaction with bovine serum albumin

Herein we report an eco-friendly and cost efficient synthesis of Fe doped ZnO (TPFZO) nanoparticles using the extract of Thespesia polpulanea flowers as a stabilizing agent. The synthesized NPs have been characterized by XRD, FT-IR, UV-DRS, SEM, EDAX and TEM studies. The synthesized NPs were found to have the crystallite size in the range of 30–60 ​nm. The calculated band gap energies for ZO and TPFZO nanoparticles were 3.00 ​eV and 1.97 ​eV respectively. The size distribution of the ZO and TPFZO obtained from TEM were observed to be lying in the range 50–120 ​nm and 4–22 ​nm respectively. The interaction of TPFZO NPs with bovine serum albumin (BSA) has been studied using fluorescence and absorption titration methods. The results indicated that the nanoparticles quenched the BSA fluorescence at 340 ​nm via static quenching mode having a bimolecular quenching rate constant value of 6.21 ​× ​10¹³ Lmol⁻¹s⁻¹.     

Extraction of acephate pesticide in environmental and agricultural samples by spectrophotometric method

In the present study, we have synthesis the azo dye for the reaction of p-amino antipyrine with HCl in NaNO₂ solution a 1:1 ​M ratio that was kept -5°C for 1–2 ​h, as result the absorption spectra observed at λ_max ​= ​460 ​nm. Beer’s law is obeyed over the awareness variety of 1 ​μg–100 ​μg ​mL^-1. The standard deviation and relative well-known deviation are 0.007 and 1.38%. The molar absorptivity and Sandell's sensitivity had been located to be 0.98 ​× ​10⁵ ​L ​mol^-1 ​cm^-1 and 0.99 ​× ​10^-3 ​μg ​cm^-2, respectively. Spectroscopy method used for the detection of Acephate pesticides on vegetable, fruit, soil, and water samples. FTIR method was used to consider and achieve structural information about the presented intermolecular interactions for vegetable samples. The eco-friendliness of the developed methods was assessed using the spectroscopy analytical tool on vegetables, fruit, soil, and water samples.     

Preparation and characterization of magnetic bioadsorbent for adsorption of Cd(II) ions

A facile magnetic chitosan composite used for heavy metal ions removal was prepared. The adsorbents with large specific area and rich carboxyl groups exhibited good removal of Cd(II) ions and could be easily separated with magnetic separation. The adsorption capacity of Cd(II) was 48 ​mg ​g⁻¹ and the removal efficiency reached 86.7% after five cycles. Thus, the prepared magnetic chitosan composite could act as a potential adsorbent for Cd(II) ions removal.     

Zeolite Y from kaolin clay of Kachchh,India: Synthesis,characterization and catalytic application

Kaolin clay obtained from Kachchh, Gujarat was used as alumina and silica source to synthesize zeolite Y by hydrothermal method. The synthesis route comprised of the following steps: sulfuric acid treatment at 110 ​°C (4 ​h) for impurity removal followed by calcination at 600 ​°C for 4 ​h, thermal activation of kaolin into metakaolin by NaOH fusion at 850 ​°C (8 ​h); aging of reaction mixtures at 50 ​°C (24 ​h); crystallization (24 ​h) followed by washing and drying. The synthesized zeolite Y was examined by multiple characterization techniques which revealed a pore volume of 0.22 ​cm³/g with pore size of 2.89 ​nm having essential surface area of 320 ​m²/g, indicating a porous material having majority of micropores and remaining mesopores. The zeolite exhibited good catalytic activity for succinic acid esterification using ethanol to produce monoethyl and diethyl succinate. The conversion of SA (72%) and yield (60%) of valuable diester indicated good conversion rate and selectivity at moderate reaction conditions. Detailed structural comparison with zeolite Y synthesized using standard chemical route is also carried out. This work demonstrated an effective way of preparing environmentally benign porous zeolite Y having high surface area and pore volume that can be useful for catalytic applications.     

Improved anode performance of thermally treated SiO/C composite with an organic solution mixture

A pristine composite anode material comprising of silicon monoxide and graphite was prepared through ball milling process and made in the form of a slurry using a simple solution mixture consisting of propylene carbonate (PC) and acetone (AC) and then heat treated. Cycle life study of the pristine composite and heat treated organic slurry composite showed the charge capacity values as 318 and 500 mAh g⁻¹, respectively at 100th cycle. Analysis of change of delithiation capacity with cycling and delithiation current between 0.3 and 0.6 V from cyclic voltammogram (CV) along with scanning electron microscope (SEM) and X-ray diffraction (XRD) of the electrodes/composites leads to conclude thermal processing of the organic slurry treated pristine composite converts dispersed active materials of the pristine composite into a compact structure trapped/wrapped with carbon particles (Cx, x varies from 1 to 3) providing apparently a resistor like behaviour and makes the anode deliver a stable reversible capacity with cycling.     

Ruthenium (III) catalysed and uncatalysed oxidation of torsemide by hexacyanoferrate (III) in aqueous alkaline medium: A kinetic comparative approach

The kinetics approach of oxidation of torsemide (TOR) by hexacyanoferrate (III) [HCF (III)] has been identified spectrophotometrically at 420 ​nm in the alkaline medium in the presence and absence of catalyst ruthenium (III) at 25 ​°C, by keeping ionic strength (1 ​× ​10⁻² ​mol ​dm⁻³) constant. The reaction exhibits at the stoichiometry ratio 1:2 of TOR and HCF (III), for uncatalysed and catalysed reactions. In the absence and presence of the catalyst, the order of the reactions obtained for TOR and HCF (III) was unity. However, the rate of the reactions enhanced by the increase in the concentration of catalyst, as well as the rate increases with an increase in alkaline concentration. The activation parameters for the reaction at the slow step were identified, and the effect of temperature on the rate of the reaction was analysed. A suitable mechanism has been demonstrated by considering the obtained results. The derived rate laws are reliable with analysed experimental kinetics.     

Biodegradation of organophosphorus insecticide chlorpyrifos into a major fuel additive 2,4-bis(1,1 dimethylethyl) phenol using white-rot fungal strain Trametes hirsuta MTCC-1171

Biodegradation of chlorpyrifos, a widely used organophosphorus insecticide, was accomplished by using a white-rot fungal strain (Trametes hirsuta MTCC-1171). The experimental results showed that the fungal strain can effectively and rapidly degrade chlorpyrifos while using it as a sole source of carbon and energy when provided with mineral salt medium (MSM). The optimum experimental conditions for degradation of chlorpyrifos in liquid media can be summed as follows: initial pH 6.0; mycelial inoculum 0.18 ​± ​0.01 ​g ​L⁻¹ (dry weight); chlorpyrifos concentration 150 ​mg ​L⁻¹; pH 6.0; temperature 30 ​°C; and shaking speed 150 ​rpm. Under these optimal experimental parameters, T. hirsuta MTCC-1171 achieved ≥95% degradation of chlorpyrifos in 16 ​h of incubation. The degradation rate was quantified by employing HPLC followed by identification of degradation metabolites using gas chromatography–mass spectrometry (GC-MS). 2,4-Bis (1,1 dimethylethyl) phenol, a fuel additive, was found to be a major metabolite product of chlorpyrifos degradation. However, no metabolite bioaccumulation was observed in the process. Additionally, soil studies were carried out to investigate the degradation ability of the strain against chlorpyrifos, in a natural environment. During the assessment 37 ​± ​2.3% degradation was observed after 15 days of incubation. These results illustrate that T. hirsuta MTCC-1171 has a potential of using chlorpyrifos as a sole source of carbon. Besides, fundamental understanding gained through this work lays a foundation to investigate efficient and rapid bioremediation processes in agricultural and forest environments.     

Experiment of subcritical water (Fenton) oxidation treatment of methyl vanillin wastewater

In this paper the oxidative degradation process of methyl vanillin wastewater was studied by the subcritical water oxidation (HCWO) technology. A subcritical Fenton oxidation (HCFO) system formed while Fe²⁺ was added as a catalyst. The oxidation degradation kinetics of methyl vanillin wastewater was also studied. The results showed that the suitable process conditions for degradation of methyl vanillin wastewater by HCWO were as follows: temperature of 340 ​°C, pressure of 24 ​MPa, oxidant multiple of 1.5, residence time of 217.3 ​s (flow rate of 2.0 ​mL ​min^-1). For methyl vanillin wastewater, the HCFO system has no obvious advantages compared to the HCWO system. The activation energy (Ea) of HCWO oxidized methyl vanillin wastewater reaction was 32.6 ​kJ ​mol^-1, and the pre-exponential factor A was 5.64 s^-1.     

Application of Artificial Neural Network and Particle Swarm Optimization for modelling and optimization of biosorption of Lead(II) and Nickel(II) from wastewater using dead cyanobacterial biomass

Removal of heavy metals through biosorption using biomass offers several advantages over other conventional techniques such as low cost, high efficiency, environmentally friendly, etc. In the present article, biosorption of Nickel(II) and Lead(II)was investigated using dried biomass of cyanobacterial consortium. OFAT (one-factor-at-a-time) analysis was used to assess the effect of input parameters on the removal of potentially toxic elements by varying initial metal ion concentration (2–10 mgL⁻¹), adsorbent dose (0.1–1.0 gL^-1), pH (for Pb(II): 2–6, for Ni(II): 2–8) and temperature (25°C–45°C) individually, at constant shaking speed of 150 ​rpm. Results showed that removal using biomass attained highest values in as short time as 15 ​min. The investigations also showed the removal is highly effective at lower initial concentrations of heavy metals. Maximum removal of Lead(II) (87.27 ​± ​1.75%) and Nickel(II) (92.57 ​± ​0.77%) was obtained at pH 6 and 45°C and at pH 7 and 25°C, respectively, within 15 ​min with 0.1 gL^-1 biomass. Both the Langmuir model and Freundlich model were seen to fit the equilibrium data. Further, Artificial Neural Network was used to model the biosorption process. Subsequently, Particle Swarm Optimization was applied to optimize the operating conditions for the removal of both the metals.     

Hybrid polymer/nanoparticle solar cells: preparation, principles and challenges

Hybrid polymer/nanoparticle solar cells have a light harvesting layer composed of semiconducting inorganic nanoparticles and a semiconducting conjugated polymer. They have potential to give high power conversion efficiencies (PCE). However, the PCE values reported for these solar cells are not currently as high as anticipated. This article reviews the main methods currently used for preparing hybrid polymer/nanoparticle solar cells from the colloid perspective. PCE data for the period of 2005-2011 are presented for hybrid polymer/nanoparticle solar cells and compared to those from polymer/fullerene cells. The key reasons for the relatively low PCE values for hybrid polymer/nanoparticle solar cells are uncontrolled aggregation and residual insulating ligands at the nanoparticle surface. Two hybrid polymer/nanoparticle systems studied at Manchester are considered in which the onset of aggregation and its affect on composite film morphology were studied from the colloidal perspective. It is concluded that step-change approaches are required to increase the PCEs of hybrid polymer/nanoparticle solar cells and move them toward the 10% value required for widespread commercialisation. A range of nanoparticles that have potential for application in possible longer term terawatt solar energy production are discussed.     

Research article green synthesis of zirconium oxide nanoparticles (ZrO2NPs) using Helianthus annuus seed and their antimicrobial effects

Monoclinic Zirconia (ZrO₂NPs) nanoparticles were successfully prepared by non-toxic and low-cost production using green synthesis analysis from the methanolic extract of Helianthus annuus (sunflower) seeds as the reducing agent. Mechanism of the chemical reaction has shown the reduction and which confirmed the formation of nanoparticles via chemical bonding in the IR spectrum at 502-498 ​cm^-1 ZrO₂ nanoparticles were characterized as sharp peak at 275 ​nm in the UV-Vis spectrum with 3.7eV in photon energy bandgap, it confirms the monoclinic crystal structure, as well as x-ray diffractometry, reveals zirconia crystallite is 40.59 ​nm. The internal morphology of crystal structure is exhibited by Scanning Electron Microscopy (SEM), and Transmission Electron Microscope (TEM). The stability of nanoparticles is represented in terms of zeta potential (-9.32 ​mV) and particle size distribution (~331 ​nm). Biosynthesized ZrO₂NPs were indicated as superior antimicrobial activity for biomedical applications.     

Electrodeposition of zinc + cobalt alloys.: Relation between the electrochemical response and the composition and morphology of the deposits

The electrodeposition of cobalt and zinc + cobalt alloy in aqueous chloride solution has been studied on vitreous carbon electrodes under different concentration conditions (total concentration of metallic ion 0.1 mol dm ⁻³, chloride ion 1 mol dm ⁻³, pH = 3), particularly during the initial stages of the deposition process. For the alloy a relation has been found between the shape of the current-time transients, the morphology of the deposits, the stripping analysis and the results of X-ray microanalysis. The different alloy phases present in the deposits were identified using X-ray microanalysis data, stripping voltammetry results and literature data.The results indicate that the electrocrystallization of cobalt is inhibited even at very low concentrations of zinc in solution: voltammetric and galvanostatic results indicate that the deposition potentials always correspond to more negative values than those for cobalt deposition. This inhibition depends strongly on both the metallic ion ratio in solution and the applied overpotential (or current density). For Zn(II)/Co(II) ratios greater than 1/9, low overpotentials (or low current densities) favoured homogeneous and compact deposits that were rich in zinc and were mainly composed of γ-phases of zinc + cobalt alloy. However, when high overpotentials or current densities were used and/or when the Zn(II)/Co(II) ratio was very low (< 1/9), dendritic and non-homogeneous cobalt-rich deposits were obtained.     

Gamma-ray induced thermoluminescence emission of green synthesized zinc oxide nanophosphors

The thermoluminescence (Thermally stimulated luminescence) technique has been applied in the field of radiation dosimetry and was found to be highly successful in dating ancient pottery samples. It is also used in the study of biological and biochemical systems. The present study reports the gamma-ray exposed thermoluminescence (TL) emission of ZnO nanophosphors. ZnO nanoparticles were prepared via phyto-mediated green routes according to our previous works. Different analytical techniques such as XRD, FESEM, HRTEM, XPS, EDS, FTIR, and UV-DRS were employed to characterize the samples. The ZnO nanoparticles possess hexagonal wurtzite crystal structure of with 29–71 ​nm particle dimension. TL emission of the samples was recorded with different gamma dosages10-50 Gy at a constant heating rate of 2^oCs^-1. A broad single glow curve above 300 ​°C was exhibited by the samples and good linearity was reserved in integrated TL profiles. The TL emission follows first-order kinetics and the activation energies of the traps located in the samples were determined.     

Constructing a Strongly Absorbing Low‐Bandgap Polymer Acceptor for High‐Performance All‐Polymer Solar Cells

All‐polymer solar cells (all‐PSCs) offer unique morphology stability for the application as flexible devices, but the lack of high‐performance polymer acceptors limits their power conversion efficiency (PCE) to a value lower than those of the PSCs based on fullerene derivative or organic small molecule acceptors. We herein demonstrate a strategy to synthesize a high‐performance polymer acceptor PZ1 by embedding an acceptor–donor–acceptor building block into the polymer main chain. PZ1 possesses broad absorption with a low band gap of 1.55 eV and high absorption coefficient (1.3×10⁵ cm⁻¹). The all‐PSCs with the wide‐band‐gap polymer PBDB‐T as donor and PZ1 as acceptor showed a record‐high PCE of 9.19 % for the all‐PSCs. The success of our polymerization strategy can provide a new way to develop efficient polymer acceptors for all‐PSCs.     

基于银纳米线复合透明电极的可弯折柔性聚合物太阳能电池

本文设计了一种可以通过刮涂方法制备的基于银纳米线(AgNWs)的柔性复合透明电极,并以此为基础实现了高性能柔性聚合物太阳能电池的制备。 基于银纳米线的柔性复合薄膜(APA)由银纳米线(AgNWs),聚乙烯醇缩丁醛(PVB)和铝掺杂氧化锌(AZO)纳米粒子在低温下通过多层刮涂的方法制备。 APA透明复合薄膜在550 nm处透光率达到90.90%,面电阻低至13.01 Ω/sq,在柔性基底上具有很高的粘附性。 在透明的APA/聚对苯二甲酸乙二醇酯(PET)基底上制备的柔性聚合物太阳能电池(PSCs),能量转换效率达到5.47%。 而且以5 mm为曲率半径,经过1000次循环弯曲实验,电池的能量转换效率仅下降了14%。     

基于新型交联聚合物电解质的准固态染料敏化太阳能电池

采用柠檬酸(CA)交联聚乙二醇(oligo-PEG, 平均分子量M_w=200, 400, 1000, 2000), 合成具有可生物降解性能的聚柠檬酸-乙二醇(PCE)交联聚酯, 并以此为基体材料制备得到准固态的三维交联型PCE/LiI/I₂聚合物电解质. 采用红外吸收光谱(IR)、核磁共振氢谱(¹H-NMR)、扫描电镜(SEM)和Raman光谱分别对PCE基体的分子结构、聚合物电解质的微观形貌以及导电离子对的存在形式进行表征; 通过线性扫描伏安法(LSV)研究了聚合物电解质的离子扩散系数、电导率以及电池的输出电流-电压(I-V)性能. 结果表明, PEG的分子量影响PCE基体膜的微观形貌及其吸液性能, 从而影响聚合物电解质的离子导电性能及电池的光电性能: 随着PEG分子量M_w从200, 400, 1000增大到2000, PCE基体膜的结构变得疏松, 吸液率增加, 吸液溶胀后的基体中I-3的跃迁活化能降低, 导致电解质的电导率和电池的短路光电流密度随之增加; 在60 mW·cm^-2的入射光强下, 四种电解质对应电池的光电转化效率依次为3.26%、3.34%、4.26%和4.89%.     

Polydivinylbenzene/Ethylvinylbenzene Composite Membranes for the Optimization of a Whole Blood Glucose Sensor

A novel ultra thin polydivinylbenzene/ethylvinylbenzene composite membrane has been developed for use as the outer covering barrier in a model amperometric glucose oxidase enzyme electrode. The composite membrane was formed via the cathodic electropolymerization of divinylbenzene/ethylvinylbenzene at the surface of gold sputter coated host alumina membranes, (serving solely as a mechanical support for the thin polymer film). Permeability coefficients were determined for the enzyme substrates, O₂ and glucose, across composite membranes formed with a range of polymer thicknesses. Due to the highly substrate diffusion limiting nature of the composite membrane, it was found that anionic interferents present in blood (such as ascorbate), were effectively screened from the working electrode via a charge exclusion mechanism, in a manner similar to previous findings within our laboratory. The enzyme electrode showed an initial 32% signal drift when first exposed to whole human blood over a period of 2 hours, after which time enzyme electrode responses remained essentially stable. Whole blood patient glucose determinations yielded a correlation coefficient of r²=0.97 in comparison to standard hospital analyses.