scholarly journals Chemical Denitrification with Mg0 Particles in Column Systems

2020 ◽  
Vol 12 (7) ◽  
pp. 2984 ◽  
Author(s):  
Alessio Siciliano ◽  
Giulia Maria Curcio ◽  
Carlo Limonti
Keyword(s):  
Kinetic Constant ◽  
Operating Parameter ◽  
Process Efficiency ◽  
Main Reaction ◽  
Main Reaction Product ◽  
Reaction Products ◽  
Metallic Elements ◽  
Reactive Material ◽  
Maximum Reaction Rate ◽  
Maximum Reaction

The removal of nitrate from aqueous environments through zero-valent metallic elements is an attractive technique that has gained increasing interest in recent years. In comparison to other metallic elements, zero-valent magnesium (ZVM) has numerous beneficial aspects. Nevertheless, the use of Mg0 particles for nitrate reduction in column systems has not been investigated yet. To overcome the lack of research, in the present study, a wide experimental activity was carried out to develop a chemical denitrification process through ZVM in batch column equipment. Several tests were executed to evaluate the effects of recirculation hydraulic velocity, pH, Mg0 amount, N-NO3− initial concentration and temperature on the process performance. The results show that the process efficiency is positively influenced by the recirculation velocity increase. In particular, the optimal condition was detected with a value of 1 m/min. The process pH was identified as the main operating parameter. At pH 3, abatements higher than 86.6% were reached for every initial nitrate concentration tested. In these conditions, nitrogen gas was detected as the main reaction product. The pH increase up to values of 5 and 7 caused a drastic denitrification decline with observed efficiencies below 26%. At pH 3, the ratio (RMN) between Mg0 and initial nitrate amount also plays a key role in the treatment performance. A characteristic value of about RMN = 0.333 gMg0/mgN-NO3− was found with which it is possible to reach the maximum reaction rate. Unexpectedly, the process was negatively affected by the increase in temperature from 20 to 40 °C. At 20 °C, the material showed satisfactory denitrification efficiencies in subsequent reuse cycles. With the optimal RMN ratio, removals up to 90% were detected by reusing the reactive material three times. By means of a kinetic analysis, a mathematical law able to describe the nitrate abatement curves was defined. Moreover, the relation between the observed kinetic constant and the operating parameters was recognized. Finally, the reaction pathways were proposed and the corrosion reaction products formed during the treatment were identified.

scholarly journals The Photocatalytic Oxidation of 4-Chlorophenol Using Bi2WO6 under Solar Light Irradiation

2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
Lorean Madriz ◽  
José Tatá ◽  
Ronald Vargas
Keyword(s):  
Photocatalytic Oxidation ◽  
Oxygen Demand ◽  
Solar Light ◽  
Main Reaction ◽  
Reaction Products ◽  
Maximum Reaction Rate ◽  
Langmuir Adsorption ◽  
Maximum Reaction ◽  
Mineralization Kinetics ◽  
Spectroscopy Studies

This report discusses the effects of the initial concentration of 4-chlorophenol (4-CP) on its solar light photoinduced oxidation/mineralization kinetics on Bi2WO6 catalyst. Photocatalytic degradation followed the Langmuir-Hinshelwood (L-H) mechanism. From the kinetic data the Langmuir adsorption equilibrium constant of 4-CP on the Bi2WO6 surface and the L-H maximum reaction rate for 4-CP oxidation have been evaluated. Chromatographic and spectroscopy studies show the presence of p-benzoquinone and maleic acid as the main reaction products; these compounds first increase and then decay until they disappear. Chemical oxygen demand (COD) and produced CO2 measurement show that photocatalytic mineralization of the phenolic compound was readily possible in a wide concentration range.

scholarly journals Experimental Analysis and Modeling of Nitrate Removal through Zero-Valent Magnesium Particles

Water ◽  
2019 ◽  
Vol 11 (6) ◽  
pp. 1276 ◽  
Author(s):  
Siciliano ◽  
Curcio ◽  
Limonti
Keyword(s):  
Nitrate Concentration ◽  
Nitrate Removal ◽  
Experimental Results ◽  
Process Efficiency ◽  
Main Reaction ◽  
Main Reaction Product ◽  
Nitrogen Forms ◽  
Sustainable Technologies ◽  
Batch Tests ◽  
Effects Of Ph

The pollution of water by nitrates represents an important environmental and health issue. The development of sustainable technologies that are able to efficiently remove this contaminant is a key challenge in the field of wastewater treatment. Chemical denitrification by means of zero-valent metallic elements is an interesting method to reduce the oxidized forms of nitrogen. Compared to other metallic reactants, zero-valent magnesium (ZVM) has many profitable aspects, but its use for nitrate removal has scarcely been investigated. In the present work, several batch tests were conducted to examine the concurrent effects of pH, initial nitrate concentration and Mg0 quantity on process performance. The experimental results proved that at pH 3, for a given initial nitrate concentration, the dose of ZVM largely influences process efficiency. In particular, with a ratio between Mg0 and initial N-NO3− amount (Mg/NNi) of 0.33 g/mg, it is possible to obtain complete denitrification within 30 min. Beyond this ratio, no further improvement of treatment was observed. The experiments allowed us to identify the nitrogen forms produced during the treatment. Nitrogen gas was generally the main reaction product, but the trends of the different compounds (NO3−, NO2−, NH4+ and N2) notably changed in response to the modification of operating parameters. Moreover, the results demonstrated that, in a highly acidic environment, when treating solutions with a low nitrate concentration, process performances are unsatisfactory even when using a high Mg/NNi ratio. By increasing the process pH to 5 and 7, a significant denitrification decline occurred. Furthermore, at these pH levels, the enhancement of nitrate concentration caused a progressive process deterioration. Through detailed analysis of experimental results, reactions kinetics and new mathematical equations, able to describe the trends of different nitrogen forms, have been defined. Moreover, reactions pathways have been proposed. Finally, the characterization of exhausted material allowed us to identify the corrosion products formed during the treatment.

scholarly journals Characterization of Tribofilm from Sulfurized Mohwa Oil

2011 ◽  
Vol 2011 ◽  
pp. 1-12
Author(s):  
Arun Kumar Singh
Keyword(s):  
Surface Characterization ◽  
Iron Sulfide ◽  
Analysis Data ◽  
Main Reaction ◽  
Main Reaction Product ◽  
Iron Sulfides ◽  
Reaction Products ◽  
X Ray Diffraction ◽  
Load Carrying

The reaction products of sulfurized Mohwa oil with iron powder in hydrocarbon medium at 150°C for 8 h were studied to investigate the type of lubricant films formed during their application as antiwear and extreme pressure additives. The main reaction product was isolated on the basis of its solubility in mixed solvent. Surface characterization was carried out using ultraviolet-visible spectroscopy (UV), fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR), X-ray diffraction spectroscopy (XRD), scanning electron microscope (SEM), and high frequency reciprocal rig (HFRR). An examination of their elemental analysis and instrumental analysis data reveals that there is reduction in the length of the alkyl chains and carbonyl ester groups with formation of inorganic iron sulfides. Polymerized product with a number of ketonic and aldehydic groups containing iron and sulfur in the polymeric films in the form of unsaturated cyclic rings was also formed. The films are organo-inorganic in nature, unlike the purely inorganic iron sulfide type. The load-carrying characteristic of this product is strongly influenced by the type of the film formed on the iron surfaces.

scholarly journals CO2 Reforming of CH4 on Co-Containing Supported Catalysts

2016 ◽  
Vol 2 (1) ◽  
pp. 41 ◽  
Author(s):  
Sh.S. Itkulova ◽  
K.Z. Zhunusova ◽  
I.S. Chanycheva ◽  
G.D. Zakumbaeva
Keyword(s):  
Carbon Dioxide ◽  
Bimetallic Catalysts ◽  
Supported Catalysts ◽  
Coke Formation ◽  
Carbon Oxide ◽  
Main Reaction ◽  
Main Reaction Product ◽  
Reaction Products ◽  
Co2 Reforming ◽  
Co2 Reforming Of Ch4

<p>Mono- and bimetallic cobalt-containing catalysts supported on alumina have been investigated in the reaction of interaction between carbon dioxide and methane at variation of experiment temperature and pressure. It was shown, that the bimetallic catalysts have a high activity in this reaction in compare with monometallic ones. The main reaction products are carbon oxide, hydrogen, water and oxygenates. The yield of latter reaches 30% at certain conditions (P &gt; 0.5 MPa, T &lt; 853K). The maximum conversion of both methane (100%) and carbon dioxide (94%) is reached at lower pressure (0.1MPa) and 1023 K. In these conditions the synthesis-gas is a main reaction product. One of the advantages of the bimetallic catalysts is their resistance to coke formation.</p>

Determination of deoxynivalenol sulphonates in cereal samples: method development, validation and application

2014 ◽  
Vol 7 (3) ◽  
pp. 233-245 ◽  
Author(s):  
H.E. Schwartz-Zimmermann ◽  
M. Paulick ◽  
S. Dänicke ◽  
D. Schatzmayr ◽  
F. Berthiller
Keyword(s):  
Thermal Treatment ◽  
Moisture Content ◽  
Method Development ◽  
Matrix Effects ◽  
Main Reaction ◽  
Prolonged Storage ◽  
Main Reaction Product ◽  
Reagent Concentration ◽  
Reaction Products

The first short and simple RP-UHPLC-MS/MS based method for co-determination of the Fusarium mycotoxin deoxynivalenol (DON) and its reaction products upon treatment with sulphur reagents, the DON sulphonates (DONS) 1, 2 and 3, in cereals was developed and validated. Recoveries of extraction from maize, wheat and barley were between 88 and 107%. Matrix effects ranging between 93 and 234% in concentrated extracts and between 99 and 134% in diluted extracts were compensated by quantitation against matrix matched standards. Measurement of concentrated and diluted extracts enabled determination of DONS-1, -2, -3 and DON in cereals in a concentration range from 0.015 to 120 mg/kg. The method was then applied to investigate the influence of reagent concentration, type of sulphur reagent, moisture content, presence of propionic acid, storage time and thermal treatment in the presence of sodium metabisulphite (SBS) and monomethylamine (MMA) on DON reduction and DONS formation. DON reduction greater than 80% was obtained in several experiments and required storage at moisture contents between 25 and 30% (at reagent concentration of 0.5%) for less than one week, storage with 0.5% SBS at 14% moisture for 6 weeks or thermal treatment in the presence of SBS and MMA. The efficiency of sodium sulphite for DON reduction was systematically compared with that of SBS and found to be lower at 14% moisture content, but similar at 30% moisture. Under most storage conditions, DONS-3 was the main reaction product, followed by DONS-2. Prolonged storage for more than 6-8 weeks shifted the pattern of formed DON sulphonates towards DONS-2. Likewise, thermal treatment in the presence of SBS and MMA caused exclusive formation of DONS-1 and -2. Due to partial degradation of DONS-3 to DON under physiological conditions, predominant conversion of DON into DONS-1 and DONS-2 is desirable.

scholarly journals Compressive Strength and Microstructural Characteristics of Natural Zeolite-based Geopolymer

2017 ◽  
Author(s):  
Sevgi Özen ◽  
Burhan Alam
Keyword(s):  
Compressive Strength ◽  
Natural Zeolite ◽  
Low Cost ◽  
Main Reaction ◽  
Main Reaction Product ◽  
Reaction Products ◽  
Zeolitic Tuff ◽  
Microstructural Characteristics ◽  
Alkaline Activator ◽  
Geopolymer Cement

A detailed study of geopolymeric reaction products and mechanical properties of geopolymer pastes prepared with natural zeolite has been investigated by means of compressive strength, XRD and SEM/EDX analysis. Sodium silicate and sodium hydroxide solutions are used as an alkaline activator. The results of the investigation show that the activator ratio plays an important role on the mechanical development of geopolymer pastes. The geopolymeric gel and CSH phase with a low Ca/Si ratio are found as the main reaction product. The increased intensity of CSH phase has a significant effect on the improvement of the compressive strength. Decreased intensity of clinoptilolite and totally consumed clay mineral upon geopolymerization proves the involvement of the aluminosilicate phases in the geopolymeric reaction. The existence of sodium and increment of Si/Al ratio with respect to original zeolitic tuff were detected. The results also show that the investigated natural zeolite, which is emerged as an environmentally friendly, low-cost material, is suitable for the production of geopolymer cement.

scholarly journals Impact-Induced Reaction Characteristic and the Enhanced Sensitivity of PTFE/Al/Bi2O3 Composites

Polymers ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 2049 ◽  
Author(s):  
Ying Yuan ◽  
Baoqun Geng ◽  
Tao Sun ◽  
Qingbo Yu ◽  
Haifu Wang
Keyword(s):  
Particle Size ◽  
Impact Sensitivity ◽  
Main Reaction ◽  
Reaction Products ◽  
Reactive Material ◽  
Bismuth Trioxide ◽  
Enhanced Sensitivity ◽  
The Impact ◽  
Bi2o3 Content ◽  
Reaction Characteristic

In this paper, the reaction characteristic of a novel reactive material, which introduced bismuth trioxide (Bi2O3) into traditional polytetrafluoroethylene/aluminum (PTFE/Al), is studied. The effect of Bi2O3 with different content and particle size on the reaction behaviors of PTFE/Al/Bi2O3 are investigated by drop-weight test and X-ray diffractometer (XRD), including impact sensitivity, energy release performance under a certain impact, and reaction mechanism. The experimental results show that the content of Bi2O3 increased from 0% to 35.616%, the characteristic drop height of impact sensitivity (H50) of PTFE/Al/Bi2O3 reactive materials decreased first and then increased, and the minimum H50 of all types of materials in the experiment is 0.74 times that of PTFE/Al, and the particle size of Bi2O3 affects the rate of H50 change with Bi2O3 content. Besides, with the increase of Bi2O3 content, both the reaction intensity and duration first increase and then decrease, and there is optimum content of Bi2O3 maximizing the reaction degree of the PTFE/Al/Bi2O3. Furthermore, a prediction model for the impact sensitivity of PTFE-based reactive material is developed. The main reaction products include AlF3, xBi2O3·Al2O3, and Bi.

BioArena System for Knowing and Understanding the Biological World: A Review with New Experimental Results

2013 ◽  
Vol 96 (6) ◽  
pp. 1189-1199 ◽  
Author(s):  
Ernő Tyihák ◽  
Ágnes M Móricz ◽  
Péter G Ott ◽  
Zsuzsa Király-Véghely ◽  
György Kátay ◽  
...  
Keyword(s):  
Antimicrobial Effect ◽  
Main Reaction ◽  
Main Reaction Product ◽  
Reaction Products ◽  
Chemical Structures ◽  
Antibiotic Effect ◽  
New Findings ◽  
Biological World

Abstract A simple observation is the basis of the development of BioArena system: according to the first observations during the biological incubation after inoculation there is formaldehyde (HCHO) emission from the chromatographic spots; in this emission process, the level of HCHO molecules decreases time dependently. In fact, the antibiotic effect of an antibiotic-like compound decreases in parallel with the HCHO emission. The investigations demonstrated clearly a unique function and role of endogenous HCHO and its one main reaction product, ozone (O3), in the antiproliferative (e.g., antimicrobial) effect of different molecules with diverse chemical structures. The results in BioArena can be extended for in vivo conditions (e.g., greenhouse experiments), as well. For the pretreatment with different doses of inducers (immunostimulation-inducing molecules) there are always four bioequivalent immunostimulating response ranges (quadruple bioequivalent immune response system) in plants. The inducers (e.g., N-methylated basic amino acids, salicylic acid, cinnamic acid, and trace elements) do not participate directly in the induction of the immunostimulating effect. These new findings support a statement that HCHO and its reaction products (mainly O3), as bioreactive small molecules, are responsible for the immunostimulating activity (in vivo conditions), as well.

scholarly journals Modelling and Multi-Objective Optimization of the Sulphur Dioxide Oxidation Process

Processes ◽  
2021 ◽  
Vol 9 (6) ◽  
pp. 1072
Author(s):  
Mohammad Reza Zaker ◽  
Clémence Fauteux-Lefebvre ◽  
Jules Thibault
Keyword(s):  
Sulphuric Acid ◽  
Sulphur Dioxide ◽  
Variable Number ◽  
Inlet Temperature ◽  
Multi Objective Optimization ◽  
Absorption Column ◽  
Maximum Reaction Rate ◽  
Multi Objective ◽  
Maximum Reaction

Sulphuric acid (H2SO4) is one of the most produced chemicals in the world. The critical step of the sulphuric acid production is the oxidation of sulphur dioxide (SO2) to sulphur trioxide (SO3) which takes place in a multi catalytic bed reactor. In this study, a representative kinetic rate equation was rigorously selected to develop a mathematical model to perform the multi-objective optimization (MOO) of the reactor. The objectives of the MOO were the SO2 conversion, SO3 productivity, and catalyst weight, whereas the decisions variables were the inlet temperature and the length of each catalytic bed. MOO studies were performed for various design scenarios involving a variable number of catalytic beds and different reactor configurations. The MOO process was mainly comprised of two steps: (1) the determination of Pareto domain via the determination a large number of non-dominated solutions, and (2) the ranking of the Pareto-optimal solutions based on preferences of a decision maker. Results show that a reactor comprised of four catalytic beds with an intermediate absorption column provides higher SO2 conversion, marginally superior to four catalytic beds without an intermediate SO3 absorption column. Both scenarios are close to the ideal optimum, where the reactor temperature would be adjusted to always be at the maximum reaction rate. Results clearly highlight the compromise existing between conversion, productivity and catalyst weight.

scholarly journals A Novel Sucrose Isomerase Producing Isomaltulose from Raoultella terrigena

2021 ◽  
Vol 11 (12) ◽  
pp. 5521
Author(s):  
Li Liu ◽  
Shuhuai Yu ◽  
Wei Zhao
Keyword(s):  
Ph Value ◽  
Wild Type ◽  
Michaelis Constant ◽  
Wild Type Enzyme ◽  
Maximum Reaction Rate ◽  
E Coli ◽  
Maximum Reaction ◽  
Conversion Rates ◽  
Raoultella Terrigena ◽  
Sucrose Isomerase

Isomaltulose is widely used in the food industry as a substitute for sucrose owing to its good processing characteristics and physicochemical properties, which is usually synthesized by sucrose isomerase (SIase) with sucrose as substrate. In this study, a gene pal-2 from Raoultella terrigena was predicted to produce SIase, which was subcloned into pET-28a (+) and transformed to the E. coli system. The purified recombinant SIase Pal-2 was characterized in detail. The enzyme is a monomeric protein with a molecular weight of approximately 70 kDa, showing an optimal temperature of 40 °C and optimal pH value of 5.5. The Michaelis constant (Km) and maximum reaction rate (Vmax) are 62.9 mmol/L and 286.4 U/mg, respectively. The conversion rate of isomaltulose reached the maximum of 81.7% after 6 h with 400 g/L sucrose as the substrate and 25 U/mg sucrose of SIase. Moreover, eight site-directed variants were designed and generated. Compared with the wild-type enzyme, the enzyme activities of two mutants N498P and Q275R were increased by 89.2% and 42.2%, respectively, and the isomaltulose conversion rates of three mutants (Y246L, H287R, and H481P) were improved to 89.1%, 90.7%, and 92.4%, respectively. The work identified a novel SIase from the Raoultella genus and its mutants showed a potential to be used for the production of isomaltulose in the industry.

Sign in / Sign up

Export Citation Format

Share Document