Effect Of Active Agents Research Articles

Catalytic pyrolysis of wood dust for monophenol over macroalgal biochar-based catalyst: Effects of activation agents and atmospheres during catalyst synthesis on its performance

After introducing heteroatoms into the carbon material skeleton, the performance of carbocatalyst during catalytic pyrolysis of biomass for monophenol production is significantly improved. Algae, as a carbon source with intrinsic nitrogen content, is well-identified as a suitable raw material for preparing heteroatom-doped carbocatalyst. The present study aimed to investigate the effects of different alkaline activation agents (KOH/NaOH) and gas atmospheres (N2/CO2) during the carbonization-activation synthesis process of macroalgal biochar-based catalysts (MBBCs) on their properties and performances. Characterizations of carbocatalysts were carried out via BET and XPS analyses to investigate the porous structures and surface functional groups. Results showed that CO2, as a weakly oxidizing atmosphere, can promote the formation of porous structure of MBBCs. However, the promotion is not as strong as that of chemical activation agents (KOH/NaOH). Furthermore, KOH can promote the formation of porous structure more strongly than NaOH, but NaOH can substantially enhance the formation of surface oxygen‑nitrogen groups compared to KOH. All the MBBCs exhibited the increment of monophenols in the bio-oil obtained from catalytic pyrolysis of wood dust, especially phenol, o-cresol, and p-cresol. Amongst, the biochar-based catalyst activated with NaOH in CO2 atmosphere was the most effective one in promoting monophenols content (up to 59.46 %). Compared with the control group (without catalyst), the phenol content was increased from 5.03 % to 19.40 %. Moreover, it is found that the catalytic performance was positively correlated with the CO species percentage on the surface of MBBCs. The macroalgal biochar-based catalyst has an excellent catalytic performance, which is of great significance for achieving the complete utilization of algae and thereby improving the quality of catalytic pyrolysis products.

Hierarchical porous activated carbon derived from olives: Preparation, (N, S) co-doping, and its application in supercapacitors

For the structure and morphology of supercapacitor (SC) electrode materials, activation agent and processing technology are two important factors. Herein, we have developed an activated carbon material with high electrochemical performance obtained from olive husk, which is pre-treated by hydrothermal route followed activation treatment by dual activators. The effect of activation agents and heteroatom doping (N, S) on the structure and electrochemical performance of the obtained materials are deeply investigated. Optimized activation temperature at 700 °C was applied to create hierarchical porous carbon structure. The Olive husk-derived Activated Carbon with KOH/NaOH (OACKNa) has a specific surface area of 2900 m2·g−1, exhibits outstanding specific capacitance of 549 F·g−1 at 1 A·g−1 with high capacitance retention of 79.5% when the current density reaches up 30 A·g−1. Furthermore, OACKNa based symmetric SC device displays marvelous cyclic stability with rate capability of 93.2% after 10,000 cycles at 10 A·g−1. Interestingly, OACKNa device delivers high specific energy of 38.8 Wh·kg−1 even at ultrahigh specific power of 650 W·kg−1 at 1 A·g−1. Therefore, the obtained OACKNa with low-cost synthesis combined with the attractive electrochemical performances is a promising electrode material for supercapacitors.

Effect of Activation Agents on COD Reduction Using Activated Carbon from Agricultural Residue

This study investigated the effect of activating agent on activated carbon preparation and potential chemical oxygen demand (COD) reduction using activated carbons (AC) prepared. Zinc chloride, phosphoric acid and potassium hydroxide were utilized in impregnation of bamboo and rice husk. Result of SEM-EDX, FTIR as well as COD reduction were compared and discussed. The SEM displayed highest porosity in AC using KOH activation. FTIR analysis displayed obvious difference for each activation. AC using KOH activation obtained highest COD reduction.

Study on A-TIG welding of Q245R/321 dissimilar steel

This paper mainly studies the welding of stainless steel 321 and carbon steel Q245R dissimilar steel. Welding tests of stainless steel 321 and carbon steel Q245R are carried out by A-TIG welding method. The effect of active agent on weld penetration, weld formation and inner hole slag inclusion is studied. The mechanical properties of welded joints is measured by tensile and bending mechanics tests, and the macroscopic and microscopic structures are observed. Furthermore, these tests and research results are compared with conventional TIG welding. The results show that the welding of dissimilar steel with A-TIG welding method is well formed, and there are no pores, cracks and slag inclusion in the weld. The weld microstructure of the two welding methods is mainly austenite and ferrite. In the Q245R side heat affected zone (HAZ), the migration of carbon elements is obvious, but the A-TIG welding joint is superior to the conventional TIG welding in strength and toughness.

Effect of Activating Agents on the Adsorption of Ammoniacal Nitrogen Using Activated Carbon Papaya Peel

Ammoniacal nitrogen is one of the harmful pollutants in the waste water. High level of this pollutant can give a negative impact towards environment especially to aquatic life. Activated carbon has been known as an excellent adsorbent and widely used due to its large adsorption capacity. Papaya peel, a fruit waste, is a potential environmental friendly adsorbent. In this study, the efficiency of activated carbons from papaya peel to adsorb ammoniacal nitrogen by using different activating agents is investigated. The activated agents used are nitric acid (HNO3), phosphoric acid (H3PO4), acetic acid (C2H4O2), sodium hydroxide (NaOH), potassium hydroxide (KOH) and calcium chloride (CaCl2). The purpose of chemical activating agents is to enhance the adsorption capacity and its removal efficiency. Maximum adsorption capacity (qm) for ammoniacal nitrogen were determined by calculating the concentration of ammonium ion by using Nessler method (spectrophotometer, DR6000 Hach, US). The highest ammonium adsorbed was obtained from papaya peel activated with potassium hydroxide (KOH) with maximum adsorption capacity of 2.885 mg/g mass adsorbent used. The surface characterisation for the raw, after activation with potassium hydroxide and after adsorption was analysed by using Field Emission Scanning Electron Microscopy (FESEM) and the element analysis was conducted by using Energy-dispersive X-ray spectroscopy (EDX). FESEM morphology revealed that the activated carbons were found to be mainly micropores and mesopores. EDX revealed that nitrogen was the major component adsorbed by the activated carbon and it can be concluded that ammoniacal nitrogen has been adsorbed by the adsorbent. This result shows that papaya peel activated with KOH can effectively be used to remove ammoniacal nitrogen from the aqueous solution.

Utilization of walnut shell as a feedstock for preparing high surface area activated carbon by microwave induced activation: effect of activation agents

Abstract The present work attempts to convert walnut shell into a high surface area activated carbon by microwave heating and chemical activation. Different activation agents such as KOH, NaOH, K2CO3 and Na2CO3 were utilized to identify a suitable activation agent. The result indicated that KOH was the most suitable activation agent among those agents, with the highest porosity and surface area of activated carbon. The effect of KOH/C mass ratio on the pore structure characteristics of the activated carbon was investigated. An optimal KOH/C mass ratio of 4 was identified, beyond which the surface area as well as the pore volume were found to decrease. The surface area and the pore volume were estimated to be 3276 m2/g and 1.952 ml/g, respectively, meanwhile the microporous proportion was 77.51% under the optimized KOH/C mass ratio. The activated carbon was further characterized using Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The findings strongly support that the activation agent has a great effect on the preparation of activated carbon from walnut shell.

Chemical Activation of Durian Shell Activated Carbon: Effects of Activation Agents

Selection of suitable activation agent is important in order to produce high surface area of activated carbon. The present study was undertaken to develop high surface area of durian shell activated carbon (DSAC) using different chemical activation agents which were potassium hydroxide (KOH) and phosphoric acid (H3PO4). Surface porosity and surface area were directly measured from scanning electron microscopy (SEM) and surface area analyzer, respectively. For the optimum condition, it showed that H3PO4 treated DSAC had the highest surface area which was 257.50 m2/g compared to KOH treated DSAC which was 13.10 m2/g. H3PO4 treated DSAC also showed the highest micropore surface area, external surface area and total pore volume with 191.22 m2/g, 66.28 m2/g and 0.149 cm3/g, respectively. SEM result showed that H3PO4 treated DSAC had a well pronounce porosity than durian shell char. Surface area and surface porosity were important in an adsorption process.

Effects of activation agents and intrinsic minerals on pore development in activated carbons derived from a Canadian peat

Activated carbons (ACs) with very high specific surface areas up to approximately 900 m 2/g and total pore volume up to 0.5 cm 3/g were produced from a Canadian peat through chemical activation using either H 3PO 4 or ZnCl 2 as the activation agent, followed by activation/carbonization in air at 450 °C for 45 min. ZnCl 2 was found to be more effective for developing microporous structures in the ACs, while H 3PO 4 is more efficient in developing the mesopores. Demineralization of the AC precursor to remove intrinsic minerals greatly affected the development of pore structures during the activation process. The AC derived from the demineralized peat activated by ZnCl 2 attained the highest BET surface area with significantly increased micro-/mesopores.

Effect of activation agents on the surface chemical properties and desulphurization performance of activated carbon

Flue gas pollution is a serious environmental problem that needs to be solved for the sustainable development of China. The surface chemical properties of carbon have great influence on its desulphurization performance. A series of activated carbons (ACs) were prepared using HNO3, H2O2, NH3·H2O and steam as activation agents with the aim to introduce functional groups to carbon surface in the ACs preparation process. The ACs were physically and chemically characterized by iodine and SO2 adsorption, ultimate analysis, Boehm titration, and temperature-programmed reduction (TPR). Results showed that the iodine number and desulphurization capacity of NH3·H2O activated carbon (AC-NH3) increase with both activation time, and its desulphurization capacity also increases with the concentration of activation agent. However, HNO3 activated carbon (AC-HNO3) and H2O2 activated carbon (AC-H2O2) exhibit more complex behavior. Only their iodine numbers increase monotonously with activation time. Compared with steam activated AC (AC-H2O), the nitrogen content increases 0.232% in AC-NH3 and 0.077% in AC-HNO3. The amount of total basic site on AC-HNO3 is 0.19 mmol·g−1 higher than that on AC-H2O. H2O2 activation introduces an additional 0.08 mmol·g−1 carboxyl groups to AC surface than that introduced by steam activation. The desulphurization capacity of ACs in simulate flue gas desulphurization decreases as follows: AC-NH3 > AC-HNO3 > AC-H2O2 > AC-H2O. This sequence is in accord with the SO2 catalytic oxidation/oxidation ratio in the absence of oxygen and the oxidation property reflected by TPR. In the presence of oxygen, all adsorbed SO2 on ACs can be oxidized into SO3. The desulphurization capacity increases differently according to the activation agents; the desulphurization capacity of AC-NH3 and AC-HNO3 improves by 4.8 times, yet AC-H2O increases only by 2.62 as compared with the desulphurization of corresponding ACs in absence of oxygen.

Study of the effects of drugs on the structures of sucrose esters and the effects of solid-state interactions on drug release

Sucrose esters (SEs) have a wide range of hydrophilic–lipophilic balance (HLB) values (1–16), and hence can be applied as surfactants, or as solubility or penetration enhancers. In general, SEs are used in hot-melt technology, because of their low melting points, but literature data are not available on the effects of active agents on the structures of SEs and the possible solid-state interactions. In this study, drug–SE products were prepared by melt technology and investigated by differential scanning calorimetry (DSC), X-ray powder diffraction (XRPD), rheological measurements and dissolution tests. The model drugs meloxicam and diclofenac sodium and three SEs with different polarities (P1670, S970 and B370) were chosen for the preparation of the products. The DSC and XRPD results revealed that the structures of the SEs were rearranged, with a decrease in the degree of crystallinity. The dissolved drug molecules broke down the structures of the SEs, but were not built into the crystalline phase of the carrier. The dissolution of the drugs was influenced by the different HLB values and gel-forming behaviour of the SEs, and also by the polarity of the drug and the interactions between the drug and the SEs.

The preparation and properties of glass powder reinforced epoxy resin

A sealing composites were prepared by mixing superfine glass powder and epoxy resin. The effect of active agent (stearate) on glass powder size and size distribution and the effect of surface treatment of the glass powder on the microstructure and the mechanical properties of glass powder/epoxy composites were investigated. Glass powder size was measured using a laser particle size analyzer. The composite structure and property were investigated by means of SEM, material testing machine and thermo-gravimetric analysis (TGA). The results show that the adding of appropriate active agent during the grind process can reduce the glass powder size and size distribution. The results also show that the composite mechanical properties and thermostability are greatly improved by surface treatment of glass powder.

Preliminary definition of improvement in juvenile arthritis.

To identify a core set of outcome variables for the assessment of children with juvenile arthritis (JA), to use the core set to develop a definition of improvement to determine whether individual patients demonstrate clinically important improvement, and to promote this definition as a single efficacy measure in JA clinical trials. A core set of outcome variables was established using a combination of statistical and consensus formation techniques. Variables in the core set consisted of 1) physician global assessment of disease activity; 2) parent/patient assessment of overall well-being; 3) functional ability; 4) number of joints with active arthritis; 5) number of joints with limited range of motion; and 6) erythrocyte sedimentation rate. To establish a definition of improvement using this core set, 21 pediatric rheumatologists from 14 countries met, and, using consensus formation techniques, scored each of 72 patient profiles as improved or not improved. Using the physicians' consensus as the gold standard, the chi-square, sensitivity, and specificity were calculated for each of 240 possible definitions of improvement. Definitions with sensitivity or specificity of <80% were eliminated. The ability of the remaining definitions to discriminate between the effects of active agent and those of placebo, using actual trial data, was then observed. Each definition was also ranked for face validity, and the sum of the ranks was then multiplied by the kappa statistic. The definition of improvement with the highest final score was as follows: at least 30% improvement from baseline in 3 of any 6 variables in the core set, with no more than 1 of the remaining variables worsening by >30%. The second highest scoring definition was closely related to the first; the third highest was similar to the Paulus criteria used in adult rheumatoid arthritis trials, except with different variables. This indicates convergent validity of the process used. We propose a definition of improvement for JA. Use of a uniform definition will help standardize the conduct and reporting of clinical trials, and should help practitioners decide if a child with JA has responded adequately to therapy. We are in the process of prospectively validating this definition and several others that scored highly.

Effects of activation agents on uridine diphosphate glucuronosyltransferase activity towards acceptor substrates of different octanol/buffer partition coefficients [proceedings

Effects of activation agents on uridine diphosphate glucuronosyltransferase activity towards acceptor substrates of different octanol/buffer partition coefficients [proceedings

Clot Lysis in a Perfusion System

SummaryMost information on clot lysis is derived from in vitro methods whereby various components of the clotting and fibrinolytic systems are mixed before an actual clot is formed. This situation bears little relationship to thrombolysis in vivo. Therefore several techniques have been recently proposed, in which pre-formed clots are exposed to the effects of active agents by contact and diffusion rather than by intimate mixing prior to clotting. We describe an apparatus whereby a perfusion is delivered at controlled rates to clots of standard size and volume formed in calibrated tubes. The composition of the clots can be varied as well as the rate of perfusion and the content of perfusate. The surface of contact between the fluid and the fibrin gel is kept constant throughout and the clot-perfusate relationship is as close as possible to the in vivo situation during thrombolytic therapy. Under these conditions clot lysis by Streptokinase appears as a linear function of time, and the rate of lysis is directly related to kinase concentration. Since the clot intrinsic plasminogen-proactivator content is sufficient to ensure lysis, the lysis time finally depends upon the rate of diffusion of the kinase into the gel. Inhibition obtained with various amounts of E-aminocaproic acid incorporated to the clots or added to the perfusion fluid also suggests that diffusion problems are of major importance in physiological and therapeutic thrombolysis.