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A silver nanoprism solution was prepared by reacting silver nitrate (AgNO3), trisodium citrate dihydrate (C6H5Na3O7·2H2O), sodium borohydride (NaBH4), and ascorbic acid (C6H8O6) in distilled water. The successful formation of the silver nanoprisms was confirmed by UV–visible spectroscopy considering the 350–400 nm and 600–650 nm wavelength ranges. The C60 fullerene nanowhisker-silver nanoprism composite was synthesized through a liquid-liquid interfacial precipitation (LLIP) method using C60-saturated toluene, the silver nanoprism solution, and isopropyl alcohol and characterized by X-ray diffraction, Raman spectroscopy, scanning electron microscopy, and transmission electron microscopy. Its catalytic activity was assessed for the reduction of 2-nitrophenol by monitoring the reaction through UV–vis spectroscopy. A kinetics study was conducted, which indicated that the C60 fullerene nanowhisker-silver nanoprism composite catalyzed reduction of 2-nitrophenol follows a pseudo-first-order reaction. [ABSTRACT FROM AUTHOR]

The mesoporous Pd–Fe magnetic nanoparticles immobilized on the reduced graphene oxide were employed in the present work for the decolorization of toxic brilliant green in aqueous phase. The decolorization process was modeled using backpropagation artificial neural network and optimized by genetic algorithm and particle swarm optimization. These magnetic nanocomposites were synthesized by the two-step reaction in aqueous phase method and then characterized with various methods. According to response surface methodology, the effect of operating parameters on the decolorization of brilliant green in aqueous solution was studied through batch experiments. On the basis of these experiments, the prediction ability of response surface methodology and backpropagation neural network method was assessed. The decolorization process follows Freundlich isotherm and pseudo-second-order kinetics. Furthermore, thermodynamics studies demonstrate that the adsorption of brilliant green onto the nanocomposites was endothermic and spontaneous. Overall, these mesoporous nanomaterials have the advantages of strong adsorption capacity and fast decolorization for brilliant green, and modeling of the removal process with artificial neural network was successful. [ABSTRACT FROM AUTHOR]

Eggshell-derived calcium oxide (CaO) materials were used as a heterogeneous base catalyst for biodiesel production from palm oil with methanol at room temperature (30±2 C). The physicochemical properties of the catalyst were characterized by TG-DTA, XRD, FT-IR, SEM-EDX, Hammett indicator method, BET surface area, and CO2-TPD. The comparison of catalytic performance transesterification reaction at the temperature of 65 C against room temperature was investigated. Kinetics of the reaction were studied following pseudo-first order with under the optimal condition with catalyst loading amount of 15 wt.%, methanol to oil molar ratio of 15:1 and 10% v/v of the co-solvent in methanol. Under the optimal reaction conditions, the result showed that the yield of fatty acid methyl ester (FAME) was achieved 96.6% in 9 h and the obtained k value was 3.28×10-1h-1which higher than that of without co-solvent system (3.07×10-1h-1). After purification with a cation-exchange resin to remove calcium ion (Ca2+), high-quality biodiesel product with the fuel properties of the biodiesel especially the major physicochemical properties meet both the ASTM and EN standard specifications. Utilization of waste eggshell-derived CaO as catalysts and performing the reaction at room temperature were not only environmentally-friendly technique but also decreasing biodiesel production cost.

< p>Hydrogen in spite of having a chain transfer agent role is one of the most important factors which directly affecting on kinetic of propylene polymerization. Hydrogen causes to dramatically increase the percentage of activated sites in proportion to being total potential sites on the catalyst surface. On the other hand, the chain transfer agent role of hydrogen gives rise to changing some vital indices of final product properties. This study has attempted to present a validated mathematical model that able to predicting profile polymerization rate and also calculating some of the vital indices of the final product, properties to be derived from kinetic equations. Furthermore, in this paper, we present a developed model that calculates fraction activated sites catalyst via hydrogen concentration based on dormant site theory and determining the best process condition. The modeling approach is based on the polymer moment balance method, i.e. population balance technique, and validated by experimental works. The main aim of this study is assigned to investigate the behavior change of polymerization rate to hydrogen. The experimental data and model outputs were compared and concluded that the global errors were in the acceptable range.

The kinetics study of NCA leaching in the HCl system was proposed. Various kinetic models such as shrinking core, logarithmic rate law, and Avrami equation were used to find out the most appropriate kinetic models for this process. The effect of HCl concentrations, leaching temperatures, solid to liquid (S/L) ratio, and leaching duration were observed. The optimum conditions of NCA leaching were at HCl concentration of 4 M, temperature of 80 °C, S/L ratio of 100 g/L, and leaching time of 1 h. The result shows that shrinking core model with diffusion control process of residue layer describes well the leaching mechanism in this research, which is indicated by the good fitting of coefficient values of correlation (R2) and confirmed by the activation energy values of Ni, Co, Al that were less than 40 kJ/mol.

Alumina is found to be a good adsorbent for the removal of fluoride. In the present study, rice husk ash-derived NaA zeolite has been modified with colloidal hydrated alumina in a cost-effective process for efficient removal of fluoride ions. The prepared NaA zeolite powder was added into colloidal hydrated alumina under stirring at 70°C/2 h followed by drying at 100°C/6 h to obtain modified zeolite. The product reveals enhanced adsorption efficiency (95–99%) for the removal of fluoride ions at wide ranges of adsorbate concentration (~5–200 mg/L), adsorbent concentration (0.5–10 g/L), pH (3–10), and temperature (30–70°C). Regeneration study shows that adsorption remained >90% up to third cycle followed by gradual decrease of adsorption for consecutive cycles. Kinetics study of fluoride adsorptions shows best fit for pseudo-second-order model demonstrating chemisorption process through a monolayer formation. The adsorption isotherm reveals that Langmuir isotherm is the best fit model indicating maximum adsorption capacities of 104.16, 68.12 and 36.13 mg/g for the adsorbent doses of 0.5, 1 and 2 g/L, respectively. Colloidal hydrated alumina modified NaA zeolite derived from rice husk ash could be utilized as low cost adsorbent for effective removal of fluoride ions from water.

The present study reveals the enhanced bio‐sorption of methylene blue (MB) from an aqueous solution using iron oxide immobilized citrus bergamia biochar (Fe3O4CBC). The adsorption efficiency was increased dramatically from 64 % to 98 % after the magnetic iron oxide modification to citrus bergamia biochar (CBC) due to electrostatic interaction. Physico‐chemical alterations of CBC surface prior and post‐modification and after dye adsorption were evaluated using the following surface techniques such as FTIR, XRD, SEM, BET, Raman, TGA‐DTA, Zeta potential analysis. The retention of C−OH, C=O, C−O, C−H, and Fe3O4 groups were confirmed from FTIR spectra. BET analysis revealed that Fe3O4CBC showed an elevated surface area of 136.72 m2 g−1 with a reduced pore diameter of 3.73 nm than CBC. The Pseudo second order and Langmuir isotherm model was best fitted with R2=0.99 and adsorption capacity of 31 mg/g. The thermodynamic data (ΔS=0.1455 kJ mol−1 K−1, ΔH=33.87 kJ mol−1) revealed the spontaneity, endothermic nature, and feasibility of adsorption process. Regeneration studies revealed that the material has excellent sorption‐based performance over five consecutive cycles. The current work demonstrates that Fe3O4CBC can serve as a highly efficient, cost‐effective, bio adsorbent for the removal of MB with easy magnetic separation from aqueous medium. [ABSTRACT FROM AUTHOR]

Surface of pristine silica aerogel nanoparticles was hydrophobically modified with hexamethyldisilazane (HMDS). Then, the resultant modified nanoparticles were used for in situ atom transfer radical copolymerization of styrene and methyl methacrylate. Surface area and structural characteristics of the HMDS-modified silica aerogel nanoparticles (H-SANs) were examined by nitrogen adsorption/desorption isotherm. Evaluation of size distribution and morphological studies were also performed by scanning electron microscopy and transmission electron microscopy. Conversion and molecular weight determinations were carried out using gas chromatography and size exclusion chromatography, respectively. Adding of H-SAN by 3 wt% results in decrement of conversion from 98% to 79%. In addition, molecular weight of copolymer chains decreases from 20,372 g·mol−1 to 16,487 g·mol−1. However, polydispersity index values increases from 1.38 to 1.76. Linear increase of ln(M 0/ M) with time for all the samples shows that polymerization proceeds in a living manner. Increasing thermal stability of the nanocomposites is demonstrated by thermal gravimetric analysis. Differential scanning calorimetry shows a decrease in glass transition temperature from 67.4°C to 59.8°C by the addition of 3 wt% of the H-SAN. [ABSTRACT FROM AUTHOR]

Here we developed a continuous flow microreactor system to synthesis N-benzoylpiperazine, which is an important intermediate of novel nootropic Sunifiram. And the kinetics of the condensation amidation of piperazine and benzoic acid using HATU as coupling reagent was revealed in microreactor. A kinetic model was established, all the reactions kinetics parameters, including the reaction order of each reactant, rate constants, pre-exponential factors and activation energies were acquired. With this model the selectivity vs. reaction temperature/molar flow ratio were obtained to help understand this kind of reaction and further optimize operating conditions. Under the condition of using equivalent piperazine, 95.6% of selectivity and 91.2% of yield were obtained in microreactor with 50 s. To further expand the scope of carboxylic acid, cyclopropanecarboxylic acid was tried as acylating agent, and 92.8% of selectivity and 86.1% of yield were obtained in microreactor. [ABSTRACT FROM AUTHOR]

In this paper, the kinetics of acylation reaction of o‐phenylenediamine/p‐phenylenediamine and benzoic anhydride were determined in microreactors, respectively. A kinetic model was established, all kinetic parameters including reaction orders, reaction rate constants, pre‐exponential factors, and activation energies were acquired. Validation experiments showed experimental data fit well with calculated data at different reactant concentrations and residence times. The comparisons of the reaction rate constants and activation energies were summarized to show the difference of chemical reactivities of phenylenediamines. According to the calculation of the kinetic model, the optimized reaction conditions were listed to meet the monoacylation selectivity equal to 97.0%. [ABSTRACT FROM AUTHOR]

[Display omitted] • Facile preparation of Zn 2 SiO 4 /g-C 3 N 4 nanocomposites by ultrasonic-assisted co-precipitation methods. • The various amounts of Zn 2 SiO 4 influenced morphology and size of Zn 2 SiO 4 /g-C 3 N 4 nanocomposites. • Zn 2 SiO 4 / g-C 3 N 4 showed the maximum decolorization percentage over eriochrome black T. • The maximum photocatalytic performance was achieved at a higher rate constant reaction. • Superoxide radicals and positive holes are the most prominent active species. This paper presents an approach to prepare zinc silicate (Zn 2 SiO 4) and its nanocomposites with graphitic carbon nitride (g-C 3 N 4) for enhanced photocatalytic performance. Zn 2 SiO 4 was synthesized using a simple and cost-effective sonochemical method, followed by the fabrication of Zn 2 SiO 4 /g-C 3 N 4 through an ultrasonic-assisted co-precipitation method. The characterization of Zn 2 SiO 4 and its nanocomposites was carried out using various techniques such as XRD, FTIR, EDS, SEM, TEM, BET, and DRS. The main focus of this study was to investigate the photocatalytic efficiency of g-C 3 N 4 , Zn 2 SiO 4 , and different Zn 2 SiO 4 nanocomposites for the degradation of eriochrome black T (EBT) and erythrosine (ER). It is worth noting that this is the first time Zn 2 SiO 4 has been combined with carbon nitride, which resulted in excellent photocatalytic performance. The experimental results revealed that several factors influenced the efficiency of the photocatalytic process, including the content of Zn 2 SiO 4 in the nanocomposite, catalyst loading, and initial concentration of EBT. Among all the tested compositions, Zn 2 SiO 4 /g-C 3 N 4 with 10 % Zn 2 SiO 4 exhibited the best performance. Specifically, when 70 mg of 10 % Zn 2 SiO 4 /g-C 3 N 4 was used as a catalyst, it achieved a remarkable degradation efficiency of 75.5 % for 10 ppm EBT. This finding highlights the potential application of Zn 2 SiO 4 /g-C 3 N 4 nanocomposites as efficient photocatalysts for environmental remediation. The results of scavenger test indicated that superoxide radicals and positive holes played significant roles in driving the photodegradation reactions. Furthermore, a kinetics study was performed to determine the rate constant (k) associated with the photocatalytic process. It was observed that a higher rate constant (k = 0.011 min−1) corresponded to a higher efficiency of 75.5 %. This finding suggests that the Zn 2 SiO 4 /g-C 3 N 4 nanocomposites possess excellent photocatalytic activity and can effectively degrade organic pollutants. [ABSTRACT FROM AUTHOR]

The current investigation is a comparative study of anaerobic co-digestion (AcoD) of cattle dung (CD) and cooked kitchen waste (CKW) without and with biochar addition under ambient and mesophilic (35 ± 2 °C) temperatures. The novelty of the investigation is that it focuses on the effect of substrate mixing ratio (SMR), biochar addition, and temperature on AcoD. Initially, four sets of biochemical methane potential (BMP) tests were performed simultaneously, considering the same SMR of 100:0,0:100, 70:30, 60:40, 50:50, 40:60, and 30:70 on mass basis without and with biochar (15 g/L) addition. Considerably, a higher rate of methane (CH 4) yield was achieved for the biochar-added and mesophilic digesters. The maximum specific methane yield (SMY) was detected for the SMR 40:60 for all sets of BMP tests, wherein the SMY for the biochar-added digesters under ambient and mesophilic temperatures were 213.29 and 249.98 mLCH 4 /gVS, respectively. Consequently, considering the SMR 40:60, another set of BMP test was performed under ambient temperature by adding varying quantities of biochar: 5, 10, 15, 20 and 25 g/L, to identify the most feasible needed amount of biochar to be added for maximum CH 4 generation. The digester containing 15 g/L biochar exhibited 14.23 %, 9.89 %, 3.00 %, and 7.91 % higher cumulative CH 4 yield than the digesters containing 5, 10, 20 and 25 g/L biochar, respectively, confirming that 15 g/L biochar addition in the slurry of SMR 40:60, can be recognised as the most effective SMR for AcoD of CD and CKW. This study reveals that biochar addition improves the AcoD process. [Display omitted] • Substrates mixing ratio significantly affected the anaerobic co-digestion process • Biochar blended with mesophilic digesters resulted in an increased CH 4 yield rate • The highest CH 4 yield was found for cattle dung-kitchen waste mixing ratio of 40:60 • 15 g/L was detected as the best amount of biochar to be blended • A kinetic study using the Gompertz equation validated the experimental findings [ABSTRACT FROM AUTHOR]

Supercritical water (SCW) has gained substantial interest for shale exploitation due to its high conversion efficiency. To quantify the generated gases and the mutual conversion of gases on reaction of shale in SCW, experiments were carried out in batch reactor at 400–600°C and residence time up to 480 min. The products are classified as residual solids, liquid intermediates and gases. Experimental results show that the generated gases are mainly C 1 , C 2 , C 3 alkanes, H 2 and CO 2. The concentrations of C 1 and C 2 alkanes decrease with temperature and residence time but the other three are the opposite. A kinetic model of shale-intermediates-gases reaction is developed. This model can characterize the gas generation features of shale and SCW resulting from chemical reactions, and can quantitatively describe the mutual conversion between gases. The calculated results demonstrate well applicative for predicting gas concentration at various residence time within an acceptable deviation. The reaction process can be divided into three stages: pyrolysis of organic matter to generate intermediates, hydrolysis reaction and alkyl thermal cracking of intermediates to generate gases, mutual conversion between the generated gases. Reactions among gases involve methanation reaction, water-gas shift reaction and hydrocarbon gas decomposition. This study provides a potential kinetic model for the gas generation characteristics of reaction with shale and supercritical water. [Display omitted] • Kinetics characteristics of reaction about shale and supercritical water was studied. • The concentration of CH 4 and H 2 increase with temperature and residence time. • At higher temperature, the concentration of C 2 H 6 and C 3 H 8 first increase and then decrease with residence time. • The coefficient of determination between experimental and calculated values is 0.9793 in average. • The reaction can be divided into three stages: pyrolysis of organic matter, conversion of intermediates and mutual conversion of gases. [ABSTRACT FROM AUTHOR]

This study involves the synthesis of a mesoporous CaMoO 4 /TiO 2 solid catalyst through the impregnation method. The catalyst, known for its novelty, efficiency, and recyclability, was thoroughly characterized using various techniques, including Fourier Transform Infrared (FTIR) spectroscopy, X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Analysis (EDAX), Thermogravimetric Analysis (TGA), Brunauer-Emmett-Teller (BET), and Barrett-Joyner-Halenda (BJH) studies. Waste cooking oil is analysed using FTIR spectroscopy for its free fatty acid content. In addition, the specific catalytic activities are investigated under a variety of reaction conditions. A yield of 95.6 % is achieved under the standard trans esterification reaction operating parameters such as catalyst loading of 4 wt %, methanol to waste cooking oil molar ratio of 15:1 (v/v), reaction duration of 70 min, reaction temperature of 55 °C, stirring speed of 270 rpm, and temperature of calcination as 650 °C. The reaction kinetics (pseudo first order) is also studied. Solid catalysts can also be reused up to five successive times. Biodiesel is characterized by FTIR and 1H NMR studies to examine the presence of functional and methyl ester groups respectively, and the extracted biofuel met the specifications of ASTM D 6751 norms for standard diesel fuel. [Display omitted] [ABSTRACT FROM AUTHOR]

Ammonium salt vanadium precipitation process has excellent performance in industrial production, but its shortcomings such as high cost and environmental impact are not conducive to sustainable development. In this paper, ethylenediamine was selected as the precipitant, and vanadate was precipitated from acidic simulated vanadium-rich solutions by the ammonium salt precipitation process. The high purity V 2 O 5 product was obtained after calcination. Under optimal conditions, the precipitation rate of vanadium reached 94.8 %, and the purity of vanadium was as high as 99.1 %. The vanadium precipitation product was hexamethyl ammonium, and the vanadium product was V 2 O 5. It can be derived by the differential method that the reaction order was n = 2.4, the reaction rate equation was C V - 1.4 = k t + a , and the apparent activation energy was 27.8097 kJ/mol, which can be classified as the diffusion-controlled reaction. This innovative process enables a savings of 5050 yuan per ton of V 2 O 5. On this basis, a complete V 2 O 5 production process with zero waste discharge was designed. [ABSTRACT FROM AUTHOR]

Saponin is an important plant-derived compound that is commonly found in sapindaceae plants, such as Sapindus rarak DC. Saponin is extensively used in plenty of industries as a detergent or emulsifying agent in cleansers, shampoos, and cosmetics. The extraction of saponin was previously studied and shows that the extraction assisted by ultrasonic waves was found to be an effective method. However, the previous studies have rarely examined the extraction kinetic study of the ultrasound-assisted extraction (UAE). In the present study, the extraction of saponin from Sapindus rarak DC and its extraction kinetics is conducted. The results show that the highest saponin yield of 354.92 (mg of saponin per gram of dry feed) was obtained from the extraction using a solid-to-liquid (S/L) ratio of 1:50 (w/v) at 50 °C. The amount of extracted saponin increased with the increase of extraction temperature as well as the solute ratio in the solution. However, increasing the temperature to 60 °C decreased the saponin yield. The results of a simple kinetics study of saponin extraction also show that the second-order kinetics model can better describe the UAE process, with an R2 value of 0.929 and a rate coefficient of 0.00495 L.g-1.min-1. The experimental results agree well with the practical calculations obtained using the second-order kinetics model based on an average error of 6.79%.

In this work, we studied the effect of various amounts (0.2-1.2 % mole ratio) of Cu doping to TiO2 nanoparticles (Cu/TiO2) on the photocatalytic removal efficiency of the food colorant E 131 VF. Two series of doped TiO2 (P25) photocatalysts were prepared in two different media (50%ethanol-50%acetone and 5% surfactant (Tween 20)-95%H2O) by using the impregnation method. The prepared samples were characterized by XRD, FTIR, Raman, diffuse reflectance spectroscopy and SEM/EDX analyses. The XRD results showed that the crystal dimension of TiO2 increased from 23 to 35 nm and rutile/anatase ratio decreased from 16% to 9% after Cu doping in two different media. The photoactivity of TiO2 was reduced in the presence of Cu even at low molar ratio. The photocatalytic degradation rate constant of TiO2 (P25) was 0.24 (au) but it decreased to 0.015 (au) in the presence of the sample containing 0.6% Cu. Several reasons were suggested to explain the dramatic decrease in the activity of the prepared Cu/TiO2samples.

ABSTRACT: Lipase enzyme originated from wheat germ was immobilized on nylon -6- grafted with polyglycidyl methachrylate (PGMA). The immobilization of enzyme experiments were designed and studied using face centred central composite design (FCCCD) under response surface methodology (RSM). Prior to immobilization, the polymer was activated with diethyl amine/ethanol to introduce an amine functional group to facilitate covalent bonding with the enzyme. The immobilized and free enzymes were characterized for effect of temperature and pH on enzyme activity, stability, storage and reusability as well as kinetics studies. ANOVA revealed that optimum lipase activity of 0.287 U/ml was achieved at immobilization time of 5 h, pH of 6 and 1.0 mg/ml for enzyme concentration. The optimum temperatures and pH for immobilized and free enzymes were 45 °C and 35 °C, and 8 and 7, respectively. The immobilized enzyme showed higher stability compared to free enzyme. The immobilized enzyme retained 18% of its activity after being recycled 8 times. In a storage stability test, immobilized lipase was able to retain 70% of its activity after being stored for 30 days, while free enzyme activity dropped to 15 % after 20 days of storage. ABSTRAK:Enzim Lipase telah dihasilkan daripada mikroorganisma pegun gandum di atas nilon -6- dan digraf bersama poliglisidel methakrilet (PGMA). Enzim pegun ini direka dan dikaji secara eksperimen menggunakan reka bentuk campuran pusat pada permukaan (FCCCD) di bawah kaedah tindak balas permukaan (RSM). Sebelum menjadi pegun, polimer ini telah diaktifkan dengan dietil amine/ethanol bagi menghasilkan kumpulan fungsi amine bagi membantu ikatan kovalen atom pada enzim. Enzim pegun dan bebas ini telah dikategorikan mengikut kesan enzim ke atas suhu, aktiviti enzim ke atas kesan pH, kestabilan, keboleh-simpanan dan keboleh-gunaan balik, serta ujian tindak balas kinetik. ANOVA membuktikan bahawa aktiviti optimum enzim lipase ini adalah sebanyak 0.287 U/ml telah terhasil selama 5 jam pegun, pada pH 6 dan kepekatan enzim sebanyak 1.0 mg/ml. Suhu dan pH optimum, pada enzim pegun dan enzim bebas ini adalah pada 45 °C dan 35 °C, dan pH 8 dan 7, masing-masing. Enzim pegun ini menunjukkan lebih stabil daripada enzim bebas. Enzim pegun dilihat kekal 18% daripada aktivitinya selepas 8 kali ulangan. Melalui ujian kestabilan simpanan, enzim lipase pegun dapat mengekalkan 70% daripada aktivinya selepas disimpan selama 30 hari, manakala aktiviti enzim bebas telah menurun kepada 15% selepas 20 hari dalam simpanan.

Abstract Heavy metal has become a public health concern because of its tendency to accumulate in living organisms. The biosorptive removal of hexavalent chromium (Cr(VI)) from aqueous solution was investigated by using waste mosambi peel dust, and response surface methodology was applied as optimizing technique. The adsorbent was characterized by pHZPC, scanning electron microscope and Fourier transform infrared spectroscopy. The optimize condition for removal of Cr(VI) was recorded as follows: pH 2; dose: 0.5 g/50 mL; initial concentration: 5 mg/L; contact time: 30 min; agitation speed: 150 mg/L. The significance of independent variables and their interactions were tested by the analysis of variance and t test statistics. The adsorption data are nicely fitted with D–R isotherm and followed pseudo-second-order kinetic model. The monolayer adsorption capacity was recorded as 3.623 mg/g. Finally, thermodynamic results demonstrated that Cr(VI) adsorption is endothermic in nature and spontaneous. Therefore, the present results highlighted that mosambi peel dust is an efficient adsorbent and its versatility represents an eco-friendly alternative that can be implemented as agricultural waste management.

Amine-Modified Silica (AMS) and Quaternary Amine-Modified Silica (QAMS) has been synthesized through the sol-gel process for adsorption Au(III) in aqueous solution. The aim of this work was to compare the effect of addition three methyl group of AMS to form QAMS on its character, thermodynamics and kinetics parameter of sorption of Au(III) in aqueous solution. Characterizations performed by FT-IR, XRD, SEM and BET analyzer. Sorption study was carried out in a batch system under the various experimental conditions including the effect of medium acidity, a variation of Au(III) concentration (thermodynamics study), and variation of contact time (kinetics study). Optimum pH of sorption Au(III) on AMS was 3 and shift into 5 on QAMS. Thermodynamics sorption study by Langmuir isotherm models indicates that there was an increase of sorption capacity from 37.94 mg/g (AMS) to 74.47 mg/g (QAMS). Kinetics sorption studies by Lagergren, Ho, and RBS models indicate that the sorption Au(III) in this research fitted well with the RBS models. The addition of 3 methyl group also increased the sorption rate of Au(III) on QAMS (ka = 77.29 min-1 (mole/L)-1) over AMS (ka = 69.22 min-1 (mole/L)-1) and reinforce the electrostatic interaction between active site of QAMS.

Dye is a common pollutant present in many chemical industrial waste water. Advanced oxidation processes are widely used for dye degradation. In this study, the degradation of trypan blue dye was examined by Fenton process. Neutralized red mud catalyst was used as a source of ferrous ion for Fenton's process. The dye degradation performance has been analyzed by using circulating fluidized-bed reactor. The influence of some key parameters such as pH, initial dye concentration, catalyst dosage and hydrogen peroxide concentration on the degradation of dye has been investigated. All the experiments were performed for 90 min. The initial dye concentration was taken as 1.56 × 10−5 and 2.60 × 10−5 mol L−1 and the amount of catalyst was varied from 0.5 to 0.7 gm/L. The hydrogen peroxide was taken in the ratio of 1:20 with the catalyst. The effect of pH was studied in the varying range from 3–5. It was found that the more the acidic pH, more will be the rate of degradation. The increase in pH results in the lower degradation rate. As the amount of catalyst was increased, the degradation rate got increased. The optimized results were obtained at pH 3, catalyst dosage of 0.7 gm/L and dye concentration of 1.56 × 10−5 mol L−1. Subsequently, the reaction kinetics of Fluidized-bed reactor was also studied. [ABSTRACT FROM AUTHOR]

In situ copolymerizations of styrene and methyl methacrylate (MMA) by atom transfer radical random copolymerization in the presence of mesoporous diatomite were performed to synthesize various poly (styrene- co -methyl methacrylate)/diatomite composites. Special characteristics of the mesoporous diatomite were evaluated by X-ray fluorescence, thermal gravimetric analysis (TGA), transmission electron microscope, and nitrogen adsorption/desorption isotherm. Conversion and molecular weight determinations were carried out using gas chromatography and size-exclusion chromatography, respectively. Due to the pendant hydroxyl groups on the surface of the diatomite platelets and polarity change of the reaction medium, addition of 3 wt% mesoporous kieselgur platelets leads to increase of conversion from 69% to 81%. In addition, polydispersity index values of the poly (styrene- co -methyl methacrylate) chains increases from 1.14 to 1.39 by addition of 3 wt% mesoporous diatomite platelets. Increasing the thermal stability of the nanocomposites is demonstrated by TGA. Differential scanning calorimetry shows an increase in glass transition temperature from 66.4°C to 72.5°C by adding 3 wt% of mesoporous diatomite platelets. [ABSTRACT FROM AUTHOR]

2-(2H-Benzotriazol-2-yl)-4,6-di-tert-pentylphenol (UV 328; CAS: 25973-55-1) is an ultraviolet light (UV) absorber which belongs to the class of hydroxy phenol benzotriazoles. Therefore, UV 328 is added to plastics and other polymers due to its photostability to prevent discoloration and prolong product stability which may result in an exposure of consumers. However, information about the toxic effects on humans and the human metabolism are still lacking. In the present study, human metabolism pathways of UV 328 and its elimination kinetics were explored. For that purpose, three healthy volunteers were orally exposed to a single dose of 0.3 mg UV 328/kg bodyweight. UV 328 and its metabolites were investigated in blood and urine samples collected until 48 and 72 h after exposure, respectively. Thereby, previously published analytical procedures were applied for the sample analysis using dispersive liquid–liquid microextraction and subsequent measurement via gas chromatography coupled to tandem mass spectrometry with advanced electron ionization. UV 328 was found to be oxidized at its alkyl side chains leading to the formation of hydroxy and/or oxo function with maximum blood concentrations at 8–10 h after exposure for UV 328-6/3-OH, UV 328-4/3-OH and UV 328-4/3-CO. In contrast, a plateau for UV 328-4/3-CO-6/3-OH levels was reached around 10 h post-dosage. The highest blood levels were found for native UV 328 at 8 h after ingestion. Furthermore, biphasic elimination kinetics in blood were revealed for almost all detected metabolites. UV 328 and its metabolites did not occur in blood as conjugates. The renal elimination kinetics were very similar with the kinetics in blood. However, the prominence of the metabolites in urine was somewhat different compared to blood. In contrast, mostly conjugated metabolites occurred for renal elimination. In urine, UV 328-4/3-CO-6/3-OH was found to be the most dominant urinary biomarker followed by UV 328-6/3-OH and UV 328-4/3-OH. In total, approximately 0.1% of the orally administered dose was recovered in urine within 72 h. Although high levels of UV 328 in blood proved good resorption and high systemic availability of the substance in the human body, the urine results revealed a rather low quantitative metabolism and urinary excretion rate. Consequently, biliary excretion as part of the enterohepatic cycle and elimination via feces are assumed to be the preferred pathways instead of renal elimination. [ABSTRACT FROM AUTHOR]

The three metal composite catalyst Cu/Mn/La/MCM-41 molecular sieve is synthesized by hydrothermal synthesis method and impregnation method. The morphology and structure of Cu/Mn/La/MCM-41 molecular sieve samples are studied by means of XRD, SEM, BET and FT-IR. Cu/Mn/La/MCM-41 molecular sieve is used as catalyst to degrade the reactive black 5 dye wastewater. The catalytic performance of the catalytic degradation of the reactive black 5 dye wastewater is studied and its apparent kinetic equation is obtained. Results show that compared with the material containing a single metal, Cu, Mn, La load can improve the activity of the catalyst. When the crystallization temperature is 120 ℃, Cu load is 20%, the molar ratio of Cu/Mn/La is 15∶5∶2, the surface area and morphology are larger and more regular. Decolorization rate of reactive black 5 after 120 min can reach 95.6%. Cu/Mn/La/MCM-41 molecular sieve catalytic degradation of reactive black 5 dye waste water dynamics is in line with the pseudo first-order kinetics curves. [ABSTRACT FROM AUTHOR]

Investigation into the solid-state transition among drug polymorphs has been more intense lately. Many factors induce the transformation of polymorphs during manufacturing processes. Efavirenz (EFV), an AIDS therapy drug, has more than 23 polymorphs, but very little information has been reported on them. This study aimed to perform a characterisation of EFV polymorph properties and to predict the kinetics and mechanism of the polymorphic transformation of EFV during manufacturing processes. The bimorphism study was conducted by Differential Scanning Calorimetry (DSC) thermal analysis. The phase transition kinetics of the polymorphs was monitored by X-ray powder diffraction and the quantification of concomitant polymorphs was examined using Rietveld refinement with MAUD ver. 2.7 as a software aid. To predict the solid-state transition, correlation coefficients of solid-state kinetic models were fitted to the experimental data. The results show that Form I and Form II of EFV were thermodynamically shown to be monotropy related. By fitting the experimental data, it was found that isothermal treatment had the best model fit with the phase boundary reaction in the two-dimensional model (G2). Accordingly, by employing mechanical treatment (grinding), it was predicted that the transition mechanism is a second-ordered reaction (R2). The activation energy of the transition during isothermal treatment calculated by the Arrhenius plot was found to be 23.051 kJ mol−1; the half-lif of Form II at ambient temperature was 428.05 min (~7.1 h).

Simultaneous reverse and normal initiation technique for atom transfer radical copolymerization (SR&NI ATRP) of styrene and methyl methacrylate in the presence of hexamethyldisilazane (HMDS)-modified silica aerogel nanoparticles (H-SAN) and investigating the effect of addition of H-SAN on the copolymerization and thermal properties of the products are discussed. Some unique features of the H-SAN are evaluated using nitrogen adsorption/desorption isotherm, SEM and TEM. Conversion and molecular weight determinations were carried out using GC and SEC respectively. Adding of H-SAN by 3 wt% results in decrement of conversion from 94 to 73%. In addition, molecular weight of copolymer chains decreases from 19500 to 16000 g.mol-1. However, polydispersity index values increases from 1.29 to 1.65. Linear increase of ln(M0/M) with time for all the samples shows that copolymerization proceeds in a living manner. Increasing thermal stability of the nanocomposites is demonstrated by TGA. DSC results show a decrease in glass transition temperature from 70.3 to 63.5 °C by addition of 3 wt% H-SAN.

The Wagner‐Jauregg reaction, despite its potential utility, has remained largely unexplored since its discovery in 1930. Utilizing density functional theory (DFT) calculations and experimental 1H nuclear magnetic resonance (NMR) kinetics data to generate a Hammett plot, the reaction is shown to proceed via a highly asynchronous, concerted mechanism, analogous to the Diels–Alder reaction. Our development of milder, more reliable reaction conditions for the Wagner‐Jauregg reaction will facilitate the synthesis of novel, structurally complex, polycyclic molecules. [ABSTRACT FROM AUTHOR]

Aniline is a toxic chemical, and in many industries it is degraded by Fenton processes. In this study, an Fe(II)-nano-Fe3O4@PAC heterogeneous Fenton catalyst (MFC) was prepared with a coprecipitation and impregnation method, which is simple, efficient and cost effective. The results of the magnetic performance tests showed that the MFC has typical ferromagnetism properties. Nano-Fe3O4 was found both on the surface and inside the pores of the powdered activated carbon (PAC). MFC was found to be an efficient catalyst in the Fenton-like process for aniline degradation. The optimal conditions were obtained by the orthogonal experimental method. The results showed that under the optimal conditions (pH = 3.00, temperature = 20°C, concentration of MFC = 1.0 g/L, concentration of H2O2 = 0.27 g/L), the 5 mg/L aniline solution degradation ratio reached 91.2% and the mineralization ratio reached 75.77% in 30 min. In addition, kinetics studies indicated that the aniline degradation process follows a pseudo-first-order kinetics model. No refractory intermediate such as azobenzene, was found during the reaction. The pH value is an important factor in aniline solution degradation. This result indicates that in addition to the surface catalytic reaction, the Fenton reaction also occurs in solution. Fe2+/Fe3+ on the MFC surface and Fe2+/Fe3+ in solution both affect aniline degradation. This catalyst has the advantage of being easily magnetically separated from the aqueous phase. It has useful application prospects in solving organic industrial wastewater pollutions in developing countries because of its cost-effectiveness. [ABSTRACT FROM AUTHOR]

The application of the aroma compounds in cosmetics, food, medicine, textile, tobacco and so forth brings the charming senses of the smell and taste. However, their main ingredients tend to deterioration due to the fast release and oxidation during the storage and usage. The silica porous materials provide the effective protection for these volatile aroma compounds. In this paper, vinyl silica hollow spheres were successfully prepared via one‐step method with tunable size. Vinyl silica hollow spheres with two sizes of 390 and 650 nm were loaded with aroma compounds. Both of the silica hollow spheres showed the selective loading capacities for aroma compounds. Interestingly, silica hollow spheres with bigger size exhibited the higher encapsulation efficiency of 94.20% and the slower sustained release of 118.3 mg/g after 16 hours of phenylethanol. This is ascribed to bigger interior cavity volume per mass unit analysed by mathematic model. The kinetics of phenylethanol release was also studied. Our work is expected to trigger a new consideration of capsule design for sustained release with high loading efficiency. [ABSTRACT FROM AUTHOR]

Composites comprising platinum nanoparticles loaded on [C60]fullerene nanowhiskers were prepared by a liquid-liquid interfacial precipitation method. The synthesized platinum nanoparticle-[C60]fullerene nanowhisker composites were characterized by X-ray diffraction, Raman spectroscopy, scanning electron microscopy, and transmission electron microscopy. The catalytic activity of the platinum nanoparticle-[C60]fullerene nanowhisker composites was confirmed for the reduction of 4-nitrophenol by UV–vis spectroscopy. The reduction of 4-nitrophenol catalyzed by the platinum nanoparticle-[C60]fullerene nanowhisker composites followed the pseudo-first-order reaction rate law. [ABSTRACT FROM AUTHOR]

Eggshell-derived calcium oxide (CaO) materials were used as a heterogeneous base catalyst for biodiesel production from palm oil with methanol at room temperature (30±2 C). The physicochemical properties of the catalyst were characterized by TGDTA, XRD, FTIR, SEMEDX, Hammett indicator method, BET surface area, and CO2TPD. The comparison of catalytic performance transesterification reaction at the temperature of 65 C against room temperature was investigated. Kinetics of the reaction were studied following pseudofirst order with under the optimal condition with catalyst loading amount of 15 wt.%, methanol to oil molar ratio of 15:1 and 10% v/v of the co?olvent in methanol. Under the optimal reaction conditions, the result showed that the yield of fatty acid methyl ester (FAME) was achieved 96.6% in 9 h and the obtained k value was 3.28×10?1 h1 which higher than that of without cosolvent system (3.07×101 h1). After purification with a cation exchange resin to remove calcium ion (Ca2+), high quality biodiesel product with the fuel properties of the biodiesel especially the major physicochemical properties meet both the ASTM and EN standard specifications. Utilization of waste eggshell derived CaO as catalysts and performing the reaction at room temperature were not only environmentally friendly technique but also decreasing biodiesel production cost. [ABSTRACT FROM AUTHOR]

Nickel(II) oxide nanoparticles were prepared using the sol-gel method. Subsequently, a nickel(II) oxide nanoparticle-[C60]fullerene nanowhisker composite was synthesized using the nickel oxide(II) nanoparticle dispersion, C60-saturated toluene, and isopropyl alcohol via the liquid-liquid interfacial precipitation (LLIP) method. The resulting composite was characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman spectroscopy, and transmission electron microscopy (TEM). The catalytic activity of the nickel(II) oxide nanoparticle-[C60] fullerene nanowhisker composite for 4-nitroaniline reduction was evaluated with ultraviolet-visible (UV-vis) spectroscopy. The kinetic study confirmed that the reduction of 4-nitroaniline using the hybrid nanocomposite followed a pseudo-first order reaction. [ABSTRACT FROM AUTHOR]

Remediation of toxic dyes from an aqua matrix using novel nanocomposites as adsorbent is an attractive yet challenging task, especially when the adsorption process needs to be operated at near‐neutral solution pH. Recently, conducting polymer‐based novel nanocomposites have been studied widely for environmental remediation because of their high distinctive surface area, mesoporous nature, easy synthesis process, availability of the low‐cost monomer, and comprehensive range of functionality. This research deals with the fabrication and application of manganese ferrite and polyaniline nanocomposite (MnF‐PANI‐NC) for the ultrasound‐assisted adsorption of methyl red (MR) and congo red (CR) dye from binary dye solution at neutral pH. The X‐ray diffraction pattern of MnF‐PANI‐NC confirmed the successful impregnation of manganese ferrite onto polyaniline, and the field emission gun scanning electron microscopy and transmission electron microscopy images revealed the nanoscale formation of this composite. The saturation magnetization of ~20 emu/g endorses the easy magnetic separation of MnF‐PANI‐NC from dye solution. MnF‐PANI‐NC has revealed higher adsorptive affinity towards MR and CR dye concerning pure PANI and pure MnF nanoparticles at near‐neutral solution pH. Assimilation of ultrasound wavse in this adsorption procedure improved the mass transfer rate significantly, and within 6 min of reaction more than 95% of MR and CR dye removal was achieved. Ultrasound waves also enhanced the equilibrium dye uptake efficiency (more than 95%) of MnF‐PANI‐NC compared to the adsorption reaction by overhead stirring (40–50%) and shaking (40–60%) for both MR and CR dyes. Kinetic modeling of the experimental data revealed accurate fitting of the pseudo‐second‐order model in association with intraparticle diffusion. Binary dye adsorption onto MnF‐PANI‐NC obeyed the Langmuir isotherm model accurately, and maximum adsorption capacities of 294.12 and 317.46 mg/g were observed for MR and CR dyes, respectively. [ABSTRACT FROM AUTHOR]

Activators generated by electron transfer (AGET) for atom transfer radical copolymerization (ATRP) was employed to synthesize tailor‐made random poly (styrene‐co‐methyl methacrylate)/mesoporous kieselgur nanocomposites. Some inherent features of the mesoporous kieselgur platelets were studied by nitrogen adsorption/desorption isotherm and transmission electron microscopy images. Conversion and molecular weight determinations were carried out using gas chromatography and size exclusion chromatography respectively. Addition of 3 wt.% mesoporous kieselgur platelets results in increments of conversion from 72 % to 87 % and molecular weight of copolymer chains from 15986 g mol−1 to 18564 g mol−1 respectively; however, polydispersity index values increases from 1.19 to 1.48. Increasing thermal stability of the nanocomposites is demonstrated by thermogravimetric analysis. Differential scanning calorimetry shows an increase in glass transition temperature from 70.6 °C to 75.7 °C by adding 3 wt.% of mesoporous kieselgur platelets. [ABSTRACT FROM AUTHOR]

Alumina is found to be a good adsorbent for the removal of fluoride. In the present study, rice husk ash-derived NaA zeolite has been modified with colloidal hydrated alumina in a cost-effective process for efficient removal of fluoride ions. The prepared NaA zeolite powder was added into colloidal hydrated alumina under stirring at 70°C/2 h followed by drying at 100°C/6 h to obtain modified zeolite. The product reveals enhanced adsorption efficiency (95–99%) for the removal of fluoride ions at wide ranges of adsorbate concentration (~5–200 mg/L), adsorbent concentration (0.5–10 g/L), pH (3–10), and temperature (30–70°C). Regeneration study shows that adsorption remained >90% up to third cycle followed by gradual decrease of adsorption for consecutive cycles. Kinetics study of fluoride adsorptions shows best fit for pseudo-second-order model demonstrating chemisorption process through a monolayer formation. The adsorption isotherm reveals that Langmuir isotherm is the best fit model indicating maximum adsorption capacities of 104.16, 68.12 and 36.13 mg/g for the adsorbent doses of 0.5, 1 and 2 g/L, respectively. Colloidal hydrated alumina modified NaA zeolite derived from rice husk ash could be utilized as low cost adsorbent for effective removal of fluoride ions from water. [ABSTRACT FROM AUTHOR]

Hydrophobically modified silica aerogel nanoparticles (H-SiANp) were used for in situ polymerization of methyl methacrylate by reverse atom transfer radical polymerization to synthesize well-defined PMMA nanocomposites. Inherent characteristics of the prepared H-SiANp were evaluated by nitrogen adsorption/desorption isotherms, SEM, and TEM. Conversion and molecular weight determinations were carried out using GC and SEC, respectively. Addition of 3 mass% of the H-SiANp leads to decrement of conversion from 92 to 74%. Molecular weight of poly (methyl methacrylate) chains also decreases from 19,737 to 15,662 g mol−1 by addition of only 3 mass% H-SiANp; however, PDI values increase from 1.36 to 1.82. Linear increase of ln(M0/M) with time for all the samples shows that polymerization proceeds in a living manner. In addition, suitable agreement between theoretical and experimental molecular weight in combination with low PDI values can appropriately demonstrate the living nature of the polymerization. TG results indicate that by increasing H-SiANp content, improvements in thermal stability of the nanocomposites were obtained. DSC results show a decrease in glass transition temperature from 87.4 to 80.9 °C by addition of 3 mass% H-SiANp. [ABSTRACT FROM AUTHOR]

• Various reductants were examined in the leaching of pyrolusite, focusing on the detailed investigation of DL-malic acid as a green reductant. • Investigation and optimization of parameters such as particle size, DL-malic acid and sulfuric acid concentration, leaching time and temperature. • Kinetic modeling was performed for reductive leaching of manganese in the presence of DL-malic acid. • Mn 3 O 4 nanoparticles were produced. Securing critical metals is crucial for the transition from fossil fuels to renewable energies. In this regard, extracting metals from various sources and low-grade ores can lead to the sustainable production of metals. Manganese, as a strategic metal, can play a significant role in achieving this goal. In this study, various reductants such as oxalic acid, citric acid, ascorbic acid, acetic acid, tannic acid, hydrogen peroxide, iron (II) sulfate, sodium thiosulfate, and DL-malic acid were used to evaluate the feasibility and comparison on the manganiferous iron ore leaching. DL-malic acid was chosen as the main reductant to investigate other factors because it is novel (as a reductant), eco-friendly, cost-effective, accessible, and easily storable. Therefore, more detailed studies on the dissolution of manganiferous iron ore in the presence of DL-malic acid as the reductant were carried out considering different levels of temperature, particle size, acid concentrations, and leaching time. Increasing the temperature from 298 K to 348 K notably boosted the leaching recovery from 27.00 % to 70.11 %. It was observed that decreasing the ore particle size from -212 μm to -38 μm resulted in an enhancement of leaching recovery from 57.74 % to 70.11 %. Also, adding only 250 % stoichiometry of DL-malic acid notably increased the leaching recovery to 70.11 %, compared to just 5.32 % in a reductant-free medium. It should be noted that the concentration of sulfuric acid had a direct impact on leaching recovery, increasing by 28.28 % with a concentration of 0.5 M and by 93.08 % with a concentration of 4 M. In this research work, the kinetic of the leaching process was modeled using the modified shrinking core model (MSCM). The calculated activation energy was about 33 kJ/mole, which confirmed that the mixed mechanism controlled the reaction. Mn 3 O 4 nanoparticles were synthesized using a pregnant leach solution (PLS) and through a multi-stage co-precipitation method. In this method, hydrogen peroxide was used to modify the manganese hydroxide phase as a more eco-friendly method than other heat treatment methods. The SEM and EDX analyses revealed an average particle size of 80 nm with spherical shapes and no impurities. The XRD pattern of the synthesized nanoparticles confirmed the Mn 3 O 4 phase composition. [Display omitted] [ABSTRACT FROM AUTHOR]

Recycled paper mill effluent (RPME) consists of various organic and inorganic compounds. In this study, modified anaerobic hybrid baffled (MAHB) bioreactor has been successfully used to anaerobically digest RPME. The anaerobic digestion was investigated in relation to methane production rate, lignin removal, and chemical oxygen demand (COD) removal, with respect to organic loading rate (OLR) and hydraulic retention time (HRT). The analysis using kinetic study was carried out under mesophilic conditions (37 ± 2 °C) and influent COD concentrations (1000–4000 mg L−1), to prove its practicability towards RPME treatment. First-order kinetic model was used to clarify the behavior of RPME anaerobic digestion under different OLRs (0.14–4.00 g COD L−1 d−1) and HRT (1–7 d). The result shows that the highest COD removal efficiency and methane production rate were recorded to be 98.07% and 2.2223 L CH4 d−1, respectively. This result was further validated by evaluating the biokinetic coefficients (reaction rate constant (k) and maximum biogas production (ym)), which gave values of k = 0.57 d−1 and ym = 0.331 L d−1. This kinetic data concludes that MAHB presented satisfactory performance towards COD removal with relatively high methane production, which can be further utilized as on-site energy supply. [ABSTRACT FROM AUTHOR]

• Hybrid catalysis were used for adsorbed toluene removal by non-thermal plasma. • The toluene mineralization fit with the pseudo-second-order kinetic model. • The model determined by P and n 0 is expressed as: 0.0009 n 0 − 2.402 ⋅ P ⋅ t = 1 / n − 1 / n 0. • The reliability of the kinetic model was verified. This study was designed to evaluate the effectiveness of adsorbed toluene removal using a coaxial cylindrical dielectric barrier discharge (DBD) reactor packed with a hybrid material catalyst [M/13X-γ-Al 2 O 3 (M: Ag, Ce, Mn, and Co)]. All experiments were conducted at atmosphere pressure and room temperature. Results showed that Ag/13X-γ-Al 2 O 3 (Ag/13X-Al) exhibited the highest breakthrough capacity (˜2.14 mmol) and the highest mineralization rate (MR) for toluene decomposition (˜68%) at 20 kV. The kinetic model on adsorbed toluene mineralization showed a good fit with the pseudo-second-order kinetic model for all catalysts. The model determined by discharge power (P) and initial amount of adsorbed toluene (n 0) is expressed as: 0.0009 n 0 -2.402 ⋅ P ⋅ t = 1/ n -1/ n 0 , where t and n denote the reaction time and the amount of adsorbed toluene, respectively. Finally, the model reliability was verified by comparing the experimental values of MR with the calculated values. [ABSTRACT FROM AUTHOR]

Cadmium is one of the toxic heavy metal that is discharged into the surroundings by various routes such as sedimentary rocks, weathering and erosion of rock, earth's crust, marine phosphate and phosphorites, forest fires etc. However battery manufacturing industry, plated containers, mining, auto exhaust, smelting of nonferrous metals, cigarettes ore dressing, and galvanized pipes are the main anthropogenic sources of cadmium heavy metal in environment. Ingestion of cadmium in human body increases the risk of many diseases. Many techniques have been applied for the removal of cadmium heavy metal ions from water. The aim of the current work is to propose economical material for effective cadmium ion removal from aqueous phase. A Pavo cristatus feather which is locally available and low-cost is used as an adsorbent for the removal of cadmium ions from water. The adsorption ability of Pavo cristatus feather has been investigated as a function of concentration of cadmium, pH of solution, adsorbate concentration, contact time and temperature. Maximum adsorption of cadmium on Pavo cristatus feather was observed at 5 pH of the solution. Adsorption of cadmium on Pavo cristatus feather was initially found to increase with increase in concentration of cadmium, time of contact and adsorbate concentration. The Langmuir, Freundlich and Temkin adsorption isotherm models were applied to analyse the experimental data. The experimental data was well fitted to Langmuir isotherm model. However, the maximum Langmuir adsorption capacity for cadmium on Pavo cristatus feather at pH 5 was 64.52 mg/g. The kinetics study was examined using the pseudo first order and pseudo second order kinetic models and was best described by the pseudo second order model. Thermodynamic parameters such as the change of Gibbs free energy, entropy and enthalpy of adsorption were also calculated. The study showed that Pavo cristatus feather can be used as a low cost and efficient adsorbent for removal of heavy metal ions from industrial wastewater/water. This material may also be utilized for removal of other toxic heavy mental ions from water. [ABSTRACT FROM AUTHOR]

Pristine mesoporous diatomite was employed to prepare polystyrene/diatomite composites. Diatomite platelets were used for in situ polymerization of styrene by atom transfer radical polymerization to synthesize tailor-made polystyrene nanocomposites. X-Ray fluorescence spectrometer analysis and thermogravimetric analysis (TGA) were employed for evaluating some inherent properties of pristine diatomite platelets. Nitrogen adsorption/desorption isotherm is applied to examine surface area and structural characteristics of the diatomite platelets. Evaluation of pore size distribution and morphological studies were also performed by scanning and transmission electron microscopy. Conversion and molecular weight determinations were carried out using gas and size exclusion chromatography, respectively. Linear increase of ln (M0/M) with time for all the samples shows that polymerization proceeds in a living manner. Addition of 3 wt% pristine mesoporous diatomite leads to an increase of conversion from 72% to 89%. Molecular weight of polystyrene chains increases from 11,326 g mol−1 to 14134 g mol−1 with the addition of 3 wt% pristine mesoporous diatomite; however, polydispersity index values increases from 1.13 to 1.38. Increasing thermal stability of the nanocomposites is demonstrated by TGA. Differential scanning calorimetry shows an increase in glass transition temperature from 81.9°C to 87.1°C by adding 3 wt% of mesoporous diatomite platelets. [ABSTRACT FROM AUTHOR]

Taguchi method was applied to optimize process parameters for the removal of Congo red (CR) dye from aqueous solutions by batch adsorption experiments. The L18 (35) orthogonal array was chosen for carrying out experimental trials. The selected parameters include initial solution pH, adsorbent dose, initial dye concentration, contact time, and adsorbent type. Signal-to-noise ratio and variance analysis were used to determine optimum removal conditions and significant operating parameters, respectively. The results showed that initial dye concentration, adsorbent dose, adsorbent type, and contact time were the significant parameters for CR removing with contribution percentages of 61.72%, 32.99%, 2.25%, and 1.18%, respectively. Under optimal conditions, the adsorption kinetic data fitted well to pseudo-second-order model. [ABSTRACT FROM AUTHOR]

The present study focuses on recovery of heavy metals from e-waste fungus isolated from heavy metal rich industrial sewage soil. Molecular identification revealed the organism to be Aspergillus nomius and was designated as A. nomius JAMK1. The isolate was subjected for heavy metals uptake following two mechanisms: bioaccumulation and biosorption. Atomic absorption spectroscopy (AAS) was primarily used to analyse the heavy metal ions uptake and further confirmed by scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDAX). Kinetics study was performed using pseudo-first-order, pseudo-second-order, Elovich, Weber and Morris and Boyd's kinetic model. Central composite design, a subunit of response surface methodology, was utilized to obtain design of experiments for the experimental values in bioaccumulation. Adsorption isotherm assessment, conducted for the biosorption activity of strain JAMK1, showed that the process followed Freundlich mode of isotherm. The adsorbed heavy metals were comprehensively desorbed from the metal-loaded sorbent using HCl and Ca(OH)2. The activity of A. nomius JAMK1 in bioleaching of metals from spent batteries was studied and analysed using AAS, X-ray diffraction, SEM and EDAX. The investigation proved A. nomius JAMK1 to be a potential strain for heavy metals uptake from aqueous solution as well as electronic waste. [ABSTRACT FROM AUTHOR]

To improve electro-catalytic degradation of phenol in wastewater and enhance the mass transfer, selfmade high-gravity electro-catalytic reactor with Ti/RuO2-IrO2-SnO2 anodes was developed for the degradation of phenol in the high-gravity field. Under the optimal operating conditions, the phenol removal efficiency reached 100% after 100 min electro-catalytic degradation, and reached 96.32% in the high-gravity field which increased by 10.93% compared with that in the normal gravity field after 60 min electro-catalytic degradation. For about the same phenol removal efficiency, the electro-catalytic time was 33.33% shorter in the high-gravity field than that in the normal gravity field. Results showed that the reason for increasing phenol removal efficiency and reducing electro-catalytic time is the fast generation rate of hydroxyl radicals, and the enhanced electro-catalytic degradation and kinetics of phenol by the high-gravity field. The study provides an efficient and environment friendly way for elimination of phenol from wastewater. [ABSTRACT FROM AUTHOR]

Quaternized lignin-based flocculant (QL) was prepared by a single-step reaction of an extracted lignin (EL) derived from oil palm empty fruit bunches (OPEFB) with 3-chloro-2-hydroxypropyl trimethylammonium chloride (CHPTAC) under alkaline condition. The performance of QLs was studied for various β values (molar ratios of CHPTAC to phenylpropanoid unit of lignin), flocculant dosages, pH values, kaolin concentrations, slow mixing rates and sedimentation times. The QL10 achieved the highest turbidity removal efficiency (εt) with increasing flocculant dosage, pH and kaolin concentration to the optimal conditions of 5 mg L−1, pH 7 and 1000 mg L−1, and required 20 min of sedimentation time at all the mixing rates tested. The flocculation kinetics agreed well with the particle collision model. The QL10 has good sludge dewatering properties compared to the alum. It also showed encouraging results in water quality analysis for sewage wastewater flocculation in comparison to that of the alum. This indicates the potential application of QL in treating water and wastewater. [ABSTRACT FROM AUTHOR]

The potential of using Moringa oleifera coagulant (MOC) as a coagulant in colour concentration reduction from Crystal Ponceau 6R dye using spectrophotometric method has been studied. The kinetics and mathematical modelling were employed to study the particle transfer rate during coagulation- flocculation process. The proximate composition, structure, and surface morphology of the coagulant were analysed using standard official methods, Fourier-Transform Infrared (FTIR) spectroscopy, and scanning electron microscopy (SEM), respectively. The removal process was evaluated through time-dependent decrease in particle concentrations and consequently, flocs growth formations. Effects of the process parameters including pH, coagulant dosage, dye concentration, settling time, and temperature were tested and the best ranges were determined experimentally. The best operating conditions established were pH 2, 800 mg MOC/L coagulant dosage, 20 mg/L dye concentration, 420 min, and 303 K. The best colour removal was achieved at 93.8%. The values of rate constant, K and order of reaction, a obtained were 8.09E-04 L/mg min and 2, respectively. The coagulation time, of 87.72 min showed a rapid coagulation process. Coagulation-adsorption kinetics showed a high agreement of the process to pseudo-second order model implying that chemisorption is the rate controlling step. Adsorption of particles on the polymer surfaces occurred mostly as a mono-molecular layer according to chemisorption mechanism. Model equation was verified using experimental data and coagulation kinetics parameters in MATLAB environment. Cross validation test showed good prediction of the experimental data. The precursor extracts have potential for application as a coagulant while showing significant part of adsorptive phenomenon. Applying kinetics and modelling in wastewater treatment study is a requirement in separation processes that involves particle transfer. [ABSTRACT FROM AUTHOR]

The present work describes in vitro antibacterial activities and pharmacological effect of six mixed-ligand tris-chelates of copper(II) containing N-p-tolylpyridine-2-aldimine; 1,10-phenanthroline and 2,2'- bipyridine as neutral N,N-donors, towards some gram-positive and gram-negative bacterial strains in aqueous medium. All the six complexes have encouraging potentiality to inhibit the growth of some gram positive and gram negative bacteria and hence bacteriostatic agents. These copper(II) complexes were synthesized easily at room temperature by the novel silver(I) assisted trans-metallation reaction and kinetic study of the reactions suggest pseudo zero order. [ABSTRACT FROM AUTHOR]

• The iron-rich copper ore are evidenced to be a very suitable OC for CLC of methane. • The copper ore OC represented high methane conversion, CO 2 selectivity and stability during the long-term CLC testing. • The overall reduction of the ore OC is controlled by the nucleation-growth and diffusion-controlled mechanisms. Chemical looping combustion (CLC) has been considered as a revolutionary combustion technology for low-energy capture of CO 2. In this paper, an iron-rich copper ore, mainly containing CuO, CuFe 2 O 4 , SiO 2 and Al 2 O 3 , was used as an inexpensive oxygen carrier (OC) for chemical looping combustion of methane. The activity for methane oxidation, the stability during long-term CLC testing and the structural evolution after redox cycling were systematically investigated. In addition, kinetic study via a thermogravimetric analyzer (TGA) method was also performed on the recycled oxygen carrier to understand the reduction mechanism. The results show that the iron-rich copper ore OC can oxidize methane with very high selectivity (CO 2 selectivity > 95%), conversion (CH 4 conversion = 80%) and stability in the successive CLC process. No obvious sintering is observed after 30 redox cycling. This can be attributed to the enhanced diffusion of different components (Cu, Fe, Si and Al) in the redox process, which could improve the interaction between the active components (CuFe 2 O 4 and CuO) and the support components (SiO 2 and Al 2 O 3). The kinetic study shows that a nucleation-growth model and a diffusion-controlled model can be successfully adapted to depict the reduction of CuO and Fe 2 O 3 in the copper ore OC, respectively. The activation energies for CuO and Fe 2 O 3 reductions are 56.49 and 109.56 kJ/mol, respectively, which are similar with that for the synthetic CuO-based or CuFe 2 O 4 -based OCs. This work fully demonstrates the feasibility of using iron-rich copper concentrate as a lower cost OC for the CLC system. [ABSTRACT FROM AUTHOR]

Abstract Hydrophobically modified silica aerocgel was used for in situ random copolymerization of styrene and butyl acrylate by activators regenerated by electron transfer for atom transfer radical polymerization (ARGET ATRP) to synthesize tailor-made poly (styrene-co-butyl acrylate) nanocomposites. Nitrogen adsorption/desorption isotherm, SEM and TEM were employed to examine inherent characteristics of the hydrophobically modified silica aerogel. Conversion and molecular weight determinations were carried out using GC and SEC respectively. Addition of 3 wt% hydrophobically modified silica aerogel leads to decrement of conversion from 67 to 48%. Molecular weight of poly (styrene-co-butyl acrylate) chains also decreases from 15993 to 12401 g mol−1 by addition of only 3 wt% hydrophobically modified silica aerogel; however, polydispersity index values increases from 1.07 to 1.34. Linear increase of ln(M 0 /M) with time for all the samples shows that copolymerization proceeds in a living manner. TGA results indicate that by increasing hydrophobically modified silica aerogel content, slight improvements in thermal stability of the nanocomposites were obtained. DSC results show a decrease in Tg from 44.2 to 35.4 °C by addition of 3 wt% hydrophobically modified silica aerogel. Graphical abstract Image 1 Highlights . • Silica aerogel surface was modified with HMDS and the resultant silica aerogel were used in ARGET ATRP of styrene and butyl acrylate. • Tailor-made poly (styrene-co-butyl acrylate) chains were synthesized by ARGET ATRP. • Linear increase of ln(M 0 /M) with time for all the samples shows that copolymerization proceeds in a living manner. • Influences of adding hydrophobically modified silica aerogel on the kinetics parameters are discussed. • Improvement in thermal stability of the nanocomposites and decreasing Tg values was also observed by incorporation of hydrophobically modified silica aerogel. [ABSTRACT FROM AUTHOR]

Abstract In this study, a novel modeling approach (artificial neural networks (ANN) and ant colony optimization (ACO)) was used to optimize the process variables for alkaline-catalyzed transesterification of CI40CP60 oil mixture (40 wt% of Calophyllum inophyllum oil mixed with 60 wt% of Ceiba pentandra oil) in order to maximize the biodiesel yield. The optimum values of the methanol-to-oil molar ratio, potassium hydroxide catalyst concentration, and reaction time predicted by the ANN-ACO model are 37%, 0.78 wt%, and 153 min, respectively, at a constant reaction temperature and stirring speed of 60 °C and 1000 rpm, respectively. The ANN-ACO model was validated by performing independent experiments to produce the CI40CP60 methyl ester (CICPME) using the optimum transesterification process variables predicted by the ANN-ACO model. There is very good agreement between the average CICPME yield determined from experiments (95.18%) and the maximum CICPME yield predicted by the ANN-ACO model (95.87%) for the same optimum values of process variables, which corresponds to a difference of 0.69%. Even though the ANN-ACO model is only implemented to optimize the transesterification of process variables in this study. It is believed that the model can be used to optimize other biodiesel production processes such as seed oil extraction and acid-catalyzed esterification for various types of biodiesels and biodiesel blends. Graphical abstract Image 1 Highlights • CICPO is a potential feedstock for biodiesel production. • ANN-ACO is a reliable tool to optimize the transesterification process variables. • Methanol-to-oil molar ratio has the most significant effect on the CICPME yield. • The optimum CICPME yield predicted by the ANN-ACO model is 95.87%. • The optimum CICPME yield obtained from independent experiments is 95.18%. [ABSTRACT FROM AUTHOR]