Coagulation behavior and floc characteristics of a novel composite poly-ferric aluminum chloride–polydimethyl diallylammonium chloride coagulant with different OH/(Fe3+ + Al3+) molar ratios

In this paper, flocculating performance and mechanisms of a new composite coagulant, poly-ferric aluminum chloride–polydimethyl diallylammonium chloride (PFAC-PD) with different OH−/(Fe3+ + Al3+) molar ratios, were investigated for humic acid (HA)–kaolin synthetic wastewater treatment. The impact of OH−/(Fe3+ + Al3+) molar ratios on the removal efficiencies of turbidity and dissolved organic carbon, specific UV absorbance, coagulation mechanisms and dynamics was explored during the coagulation process using composite coagulants. The coagulation experimental results revealed that the composite coagulants with lower OH−/(Fe3+ + Al3+) molar ratio exhibited better coagulation efficiency. When OH−/(Fe3+ + Al3+) molar ratio of the composite coagulant was 1.5, adsorption-bridging played a dominant role in coagulating HA–kaolin synthetic wastewater. The floc growth rate and floc size, increased with increasing OH−/(Fe3+ + Al3+) molar ratio and the highest peak height of the size distribution was obtained by PFAC-PD with OH−/(Fe3+ + Al3+) = 1.5. Also, the composite coagulants with higher OH−/(Fe3+ + Al3+) molar ratio formed more compact flocs, as reflected by the higher fractal dimension value. The flocs coagulated by PFAC-PD with basicity value of 1.0 gave strong strength and good recoverability.

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Impact of instrumental settings in electrospray ionization ion trap mass spectrometry on the analysis of multi-CH3-/CD3-isotopologs in cellulose ether analysis: a quantitative evaluation

Analytical and Bioanalytical Chemistry ◽

10.1007/s00216-021-03767-w ◽

2021 ◽

Author(s):

Sarah Schleicher ◽

Inka-Rosalia Lottje ◽

Petra Mischnick

Keyword(s):

Electrospray Ionization ◽

Ion Trap ◽

Total Concentration ◽

Degree Of Polymerization ◽

Polymer Chains ◽

Molar Ratio ◽

Cellulose Ether ◽

Molar Ratios ◽

Sodium Adducts ◽

The Impact

AbstractExact quantification of the molar ratios of isotopologous mixed O-methyl-O-methyl-d3-cellooligosaccharides (COS) comprising all combinations from fully methylated to fully deuteromethylated constituents within an individual degree of polymerization (DP) is the key step in the analysis of the substituent distribution over the polymer chains in methyl celluloses (MC). Deuteromethylation of MC is performed to level chemical differences, but due to a m/z range of 3 DP·ΔMe/Me-d3, bias during MS measurement cannot certainly be excluded. Therefore, ionization, ion transportation, and ion storage were studied with an electrospray ionization ion trap mass spectrometer (ESI-IT-MS) using binary equimolar mixtures of per-O-Me- and per-O-Me-d3-COS, defining the border cases of a particular Me/Me-d3-profile. Reference data of their molar ratio were determined after reductive amination with m-amino benzoic acid by HPLC-UV. COS of DP2–6 were measured as their sodium adducts at c = 10−6 M by syringe pump infusion. The impact of the RF voltage of the ion trap (TD), the octopole RF and DC voltages, and the Cap Exit potential on absolute and relative ion intensities were studied. Adapting the Cap Exit voltage was essential for correct quantification of DP2, while all COS of higher DP behaved insensitive with respect to bias. To check whether any bias occurs in the electrospray ionization process of the isotopologs, concentration-dependent measurements were performed with optimized instrumental settings for each DP. Intensity ratios IR = I (Me-d3)/I (Me) did not show any concentration-dependent trend and no selective ion suppression. Its decrease with DP observed under usually applied standard conditions (smart mode) is a consequence of discrimination according to m/z and can be overcome by appropriate instrumental settings of Oct 2 DC and TD. IR between 0.971 ± 0.008 and 1.040 ± 0.009 with no trend for DP (2-6) were obtained by averaging all measurements in the range 2 · 10−7 to 2 · 10−5 M total concentration. The DP-related optimized settings were applied to two MCs and compared with the results obtained under so far applied standard conditions. Graphical abstract

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Effect of Aluminum Incorporation on the Reaction Process and Reaction Products of Hydrated Magnesium Silicate

Frontiers in Materials ◽

10.3389/fmats.2021.810535 ◽

2022 ◽

Vol 8 ◽

Author(s):

Yuan Jia ◽

Yuxin Zou ◽

Xinmei Zou ◽

Yaoting Jiang ◽

Fangyuan Li ◽

...

Keyword(s):

Aluminum Content ◽

Magnesium Silicate ◽

Degree Of Polymerization ◽

Molar Ratio ◽

Reaction Products ◽

Obvious Effect ◽

Molar Ratios ◽

Aluminium Ion ◽

The Impact ◽

Silicon Oxygen

In this study, we investigated the impact of aluminium ion (Al3+) incorporation on the microstructure and the phase transformation of the magnesium silicate hydrate system. The magnesium silicate hydrate system with aluminium was prepared by mixing magnesium oxide and silica fume with different aluminium ion contents (the Al/Si molar ratios of 0.01, 0.02, 0.05, 0.1, 0.2) at room temperature. The high degree of polymerization of the magnesium silicate hydrate phases resulted in the limited incorporation of aluminium in the structure of magnesium silicate hydrate. The silicon-oxygen tetrahedra sites of magnesium silicate hydrate layers, however, were unable to substitute for silicon sites through inverted silicon-oxygen linkages. The increase in aluminium ion content raised the degree of polymerization of the magnesium silicate hydrate phases from 0.84 to 0.92. A solid solution was formed from residual aluminum-amorphous phases such as hydroxyl-aluminum and magnesium silicate hydrate phases. X-ray diffraction (XRD), field emission scanning electron microscope (F-SEM), and 29Si and 27Al MAS NMR data showed that the addition of Al3+ promotes the hydration process of MgO and has an obvious effect on the appearance of M-S-H gel. The gel with low aluminum content is fluffy, while the gel with high aluminum content has irregular flakes. The amount of Al3+ that enters the M-S-H gel increased with the increase of Al3+ content, but there was a threshold: the highest Al/Si molar ratio of M-S-H gel can be maintained at about 0.006.

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Transformations of xylenes in trimethylammonium hydrochloride—Aluminum chloride ionic liquid

Open Chemistry ◽

10.2478/bf02476231 ◽

2003 ◽

Vol 1 (3) ◽

pp. 305-313

Author(s):

V. Ksenofontov ◽

L. Kustov

Keyword(s):

Ionic Liquid ◽

Ionic Liquids ◽

Ammonium Salt ◽

Aluminum Chloride ◽

Molar Ratio ◽

Effective Catalyst ◽

Molar Ratios ◽

Mild Conditions

AbstractIsomerization of m-, o-and p-xylenes in the presence of trimethylammonium hydrochloride-AlCl3 ionic liquid with different composition was studied. Ionic liquids with the following ammonium salt: AlCl3 molar ratios were used: 1∶2, 1∶1.5 and 1∶1.25. It was shown that isomerization of xylenes proceeds under mild conditions at temperatures from 60°C to 110°C. It was found that the activity and selectivity of the ionic liquids depends on their composition. The most effective catalyst was the ionic liquid with the ammonium salt: AlCl3 molar ratio equal to 1∶2.

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The Impact of AN Contribution on the Thermal Characteristics and Molecular Dynamics of Novel Acrylonitrile–Styrene–Styrene Sodium Sulfonate Terpolymers

Polymers ◽

10.3390/polym13030420 ◽

2021 ◽

Vol 13 (3) ◽

pp. 420

Author(s):

Hamud A. Altaleb ◽

Abdullah M. Al-Enizi ◽

Hany El-Hamshary ◽

Sayed Z. Mohammady

Keyword(s):

Molecular Dynamics ◽

Glass Transition ◽

Molecular Model ◽

Thermal Characteristics ◽

Molar Ratio ◽

Thermal Stabilities ◽

Sodium Sulfonate ◽

Molar Ratios ◽

Donor Acceptor ◽

The Impact

We performed a free radical solution polymerization of new acrylonitrile (AN), styrene (St) and styrene sodium sulfonate (SSS) acceptor–donor acceptor monomer systems. The compositions and structures of the produced terpolymers were elucidated using CHNS elemental analysis, and Fourier transform infrared (FTIR) spectroscopies. Three terpolymers candidates were chosen for detailed thermal investigations, where the AN molar ratio varied almost threefold (from ~6.9% to ~17.4%) while the molar ratios of St and SSS varied slightly, at average values around 76.0% and 12.9%, respectively. The glass transition (Tg) values of the terpolymers were measured calorimetrically. In addition, thermal gravimetric analyses (TGA) of the samples were conducted in the temperature range from room temperature to 800 °C. All terpolymers exhibited a single Tg value, indicating random copolymerization of the monomeric species. TGA results revealed that variation of the AN molar ratio had a significant influence on the thermal stabilities of the terpolymers. The impact of AN contribution on the molecular dynamics of the glass transition in the terpolymers was explained quantitatively in a framework of a molecular model.

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The impact of applying the Common Customs Tariff on the armenian export of Cut and Polished Gems to Russia

Economics and Management ◽

10.35854/1998-1627-2019-11-33-41 ◽

2019 ◽

pp. 33-41

Author(s):

V. L. Harutyunyan ◽

S. V. Dokholyan ◽

A. R. Makaryan

Keyword(s):

Manufacturing Sector ◽

Practical Implication ◽

Dominant Role ◽

New Technology ◽

Manufacturing Companies ◽

Medium Term ◽

Diamond Cutting ◽

Global Trends ◽

The Common ◽

The Impact

The presented study discusses the issues of applying the Common Customs Tariff (CCT) rates of the Eurasian Economic Union (EAEU) on rough diamonds and the impact thereof on the exports of stones cut and polished inArmeniaand then exported toRussia.Aim. The study aims to identify the possible strategies Armenian diamond cutting and polishing companies could adopt as a response to the application of the CCT rates on rough diamonds and how it would affect exports to various destinations, namely to Russia.Tasks. The authors analyze the current state of the gems and jewelry sector and substantiate the need to either integrate it into the jewelry manufacturing sector or to apply various strategies to facilitate exports to either Russia or other destinations in the medium term in response to the application of the CCT rates.Methods. This study uses general scientific methods of cognition, including analytical and methodological approaches and elements of forecasting. Possible strategies the Armenian diamond cutting and polishing companies could adopt in the medium term in response to the application of the EAEU CCT rates are determined using the analytical research method, forecasts in the context of the developments in the Armenian gem processing and jewelry market and global trends, statistical data on the imports and exports of cut and polished gems and jewelry for 2014–2018 published by the UN Comtrade Statistics.Results. Statistics on the exports of processed diamonds from 2014 to 2018 highlights the issue associated with the loss of competitiveness suffered by Armenian companies (mainly in comparison with Indian diamond cutters). The major global trends in the diamond cutting and polishing business indicate that it could be virtually impossible for Armenian cutters and polishers to compete with Indian companies in the medium term if they do not comes to investing in new technology to achieve operational efficiency. For these companies, it is important not to lose the Russian market due to an increase in the tariff rate and concentrate on the processing of gems that are larger than 1 carat. Another strategy to avoid an increase in the customs tariff rates would depend on the Armenian government’s ability to negotiate with Russia in respect of direct imports of diamond stones from Russian manufactures. Two other options for Armenian cutters involve focusing on cutting and polishing of rubies, sapphires, emeralds, etc. or integrating into the jewelry sector either by being the primary supplier or by considering this business as a channel to sell processed diamond stones by setting up their own jewelry manufacturing companies.Conclusions. With CCT going into effect in January 2021 and India’s dominant role in the diamond cutting and polishing business, Armenia needs to carefully consider all of the strategies the Armenian companies could adopt, as discussed above. As a member state of the EAEU, Armenia freely exports to Russia, however, further exports to Russia would depend on Armenia’s ability to ensure that cost-effective operations are in place, or to concentrate on the processing of precious gems rather than diamonds, or to switch to the manufacturing of jewelry items as a major export item.Practical Implication. The findings of this study could be of interest to the Ministry of Economy of the Republic of Armenia and Business Armenia that could be used in elaborating the strategy for the development of Armenian gems and jewelry sector of the economy.

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Photocatalytic Reduction of CO2 to Methanol Using a Copper-Zirconia Imidazolate Framework

Catalysts ◽

10.3390/catal11030346 ◽

2021 ◽

Vol 11 (3) ◽

pp. 346

Author(s):

Sonam Goyal ◽

Maizatul Shima Shaharun ◽

Ganaga Suriya Jayabal ◽

Chong Fai Kait ◽

Bawadi Abdullah ◽

...

Keyword(s):

Photoelectron Spectroscopy ◽

Catalyst Support ◽

Oxidation Potential ◽

Molar Ratio ◽

X Ray Diffraction ◽

X Ray ◽

Molar Ratios ◽

Optimum Parameters ◽

Reduction Of Co2 ◽

Enhanced Yield

A set of novel photocatalysts, i.e., copper-zirconia imidazolate (CuZrIm) frameworks, were synthesized using different zirconia molar ratios (i.e., 0.5, 1, and 1.5 mmol). The photoreduction process of CO2 to methanol in a continuous-flow stirred photoreactor at pressure and temperature of 1 atm and 25 °C, respectively, was studied. The physicochemical properties of the synthesized catalysts were studied using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and photoluminescence (PL) spectroscopy. The highest methanol activity of 818.59 µmol/L.g was recorded when the CuZrIm1 catalyst with Cu/Zr/Im/NH4OH molar ratio of 2:1:4:2 (mmol/mmol/mmol/M) was employed. The enhanced yield is attributed to the presence of Cu2+ oxidation state and the uniformly dispersed active metals. The response surface methodology (RSM) was used to optimize the reaction parameters. The predicted results agreed well with the experimental ones with the correlation coefficient (R2) of 0.99. The optimization results showed that the highest methanol activity of 1054 µmol/L.g was recorded when the optimum parameters were employed, i.e., stirring rate (540 rpm), intensity of light (275 W/m2) and photocatalyst loading (1.3 g/L). The redox potential value for the CuZrIm1 shows that the reduction potential is −1.70 V and the oxidation potential is +1.28 V for the photoreduction of CO2 to methanol. The current work has established the potential utilization of the imidazolate framework as catalyst support for the photoreduction of CO2 to methanol.

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Biogas Dry Reforming for Hydrogen through Membrane Reactor Utilizing Negative Pressure

Fuels ◽

10.3390/fuels2020012 ◽

2021 ◽

Vol 2 (2) ◽

pp. 194-209

Author(s):

Akira Nishimura ◽

Tomohiro Takada ◽

Satoshi Ohata ◽

Mohan Lal Kolhe

Keyword(s):

Energy Source ◽

Reaction Temperature ◽

Negative Pressure ◽

Membrane Reactor ◽

Reaction Chamber ◽

Dry Reforming ◽

Molar Ratio ◽

Effect Of Pressure ◽

The Impact

Biogas, consisting of CH4 and CO2, is a promising energy source and can be converted into H2 by a dry reforming reaction. In this study, a membrane reactor is adopted to promote the performance of biogas dry reforming. The aim of this study is to investigate the effect of pressure of sweep gas on a biogas dry reforming to get H2. The effect of molar ratio of supplied CH4:CO2 and reaction temperature is also investigated. It is observed that the impact of psweep on concentrations of CH4 and CO2 is small irrespective of reaction temperature. The concentrations of H2 and CO increase with an increase in reaction temperature t. The concentration of H2, at the outlet of the reaction chamber, reduces with a decrease in psweep. It is due to an increase in H2 extraction from the reaction chamber to the sweep chamber. The highest concentration of H2 is obtained in the case of the molar ratio of CH4:CO2 = 1:1. The concentration of CO is the highest in the case of the molar ratio of CH4:CO2 = 1.5:1. The highest sweep effect is obtained at reaction temperature of 500 °C and psweep of 0.045 MPa.

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Lipozyme 435-Mediated Synthesis of Xylose Oleate in Methyl Ethyl Ketone

Molecules ◽

10.3390/molecules26113317 ◽

2021 ◽

Vol 26 (11) ◽

pp. 3317

Author(s):

Maria Carolina Pereira Gonçalves ◽

Jéssica Cristina Amaral ◽

Roberto Fernandez-Lafuente ◽

Ruy de Sousa Junior ◽

Paulo Waldir Tardioli

Keyword(s):

Oleic Acid ◽

Methyl Ethyl Ketone ◽

Molar Ratio ◽

Methyl Ethyl ◽

Sugar Ester ◽

Molar Ratios ◽

Emulsion Capacity ◽

Ping Pong ◽

Commercial Sugar ◽

Repeated Use

In this paper, we have performed the Lipozyme 435-catalyzed synthesis of xylose oleate in methyl ethyl ketone (MEK) from xylose and oleic acid. The effects of substrates’ molar ratios, reaction temperature, reaction time on esterification rates, and Lipozyme 435 reuse were studied. Results showed that an excess of oleic acid (xylose: oleic acid molar ratio of 1:5) significantly favored the reaction, yielding 98% of xylose conversion and 31% oleic acid conversion after 24 h-reaction (mainly to xylose mono- and dioleate, as confirmed by mass spectrometry). The highest Lipozyme 435 activities occurred between 55 and 70 °C. The predicted Ping Pong Bi Bi kinetic model fitted very well to the experimental data and there was no evidence of inhibitions in the range assessed. The reaction product was purified and presented an emulsion capacity close to that of a commercial sugar ester detergent. Finally, the repeated use of Lipozyme 435 showed a reduction in the reaction yields (by 48 and 19% in the xylose and oleic acid conversions, respectively), after ten 12 h-cycles.

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Nitrate-dominated PM<sub>2.5</sub> and elevation of particle pH observed in urban Beijing during the winter of 2017

Atmospheric Chemistry and Physics ◽

10.5194/acp-20-5019-2020 ◽

2020 ◽

Vol 20 (8) ◽

pp. 5019-5033 ◽

Cited By ~ 8

Author(s):

Yuning Xie ◽

Gehui Wang ◽

Xinpei Wang ◽

Jianmin Chen ◽

Yubao Chen ◽

...

Keyword(s):

Atmospheric Aerosols ◽

Ammonia Concentration ◽

Historical Record ◽

Molar Ratio ◽

Effective Control ◽

Nitrate Content ◽

Chinese Government ◽

Low Level ◽

The Impact ◽

Pollution Episodes

Abstract. The Chinese government has exerted strict emission controls to mitigate air pollution since 2013, which has resulted in significant decreases in the concentrations of air pollutants such as SO2. Strict pollution control actions also reduced the average PM2.5 concentration to the low level of 39.7 µg m−3 in urban Beijing during the winter of 2017. To investigate the impact of such changes on the physiochemical properties of atmospheric aerosols in China, we conducted a comprehensive observation focusing on PM2.5 in Beijing during the winter of 2017. Compared with the historical record (2014–2017), SO2 decreased to the low level of 3.2 ppbv in the winter of 2017, but the NO2 level was still high (21.4 ppbv in the winter of 2017). Accordingly, the contribution of nitrate (23.0 µg m−3) to PM2.5 far exceeded that of sulfate (13.1 µg m−3) during the pollution episodes, resulting in a significant increase in the nitrate-to-sulfate molar ratio. The thermodynamic model (ISORROPIA II) calculation results showed that during the PM2.5 pollution episodes particle pH increased from 4.4 (moderate acidic) to 5.4 (more neutralized) when the molar ratio of nitrate to sulfate increased from 1 to 5, indicating that aerosols were more neutralized as the nitrate content elevated. Controlled variable tests showed that the pH elevation should be attributed to nitrate fraction increase other than crustal ion and ammonia concentration increases. Based on the results of sensitivity tests, future prediction for the particle acidity change was discussed. We found that nitrate-rich particles in Beijing at low and moderate humid conditions (RH: 20 %–50 %) can absorb twice the amount of water that sulfate-rich particles can, and the nitrate and ammonia with higher levels have synergetic effects, rapidly elevating particle pH to merely neutral (above 5.6). As moderate haze events might occur more frequently under abundant ammonia and nitrate-dominated PM2.5 conditions, the major chemical processes during haze events and the control target should be re-evaluated to obtain the most effective control strategy.

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Nitrification preservation in activated sludge during curative bulking chlorination

Water Science & Technology ◽

10.2166/wst.2003.0590 ◽

2003 ◽

Vol 47 (11) ◽

pp. 85-92 ◽

Cited By ~ 2

Author(s):

E. Cotteux ◽

P. Duchene

Keyword(s):

Activated Sludge ◽

Pilot Plant ◽

Wastewater Treatment Plants ◽

Oxygen Uptake Rate ◽

Ammonia Concentration ◽

Synthetic Wastewater ◽

Biological Wastewater Treatment ◽

Simple Method ◽

Method Of Measurement ◽

The Impact

The bulking that occurs in biological wastewater treatment plants using activated sludge is very often controlled by the injection of sodium hypochlorite into the return activated sludge (RAS) stream. In the present study undertaken at two pilot plants fed with synthetic wastewater, the impact of the pass frequency of the sludge at the chlorine dosing point on the nitrifying flora is analysed. The pass frequency is one for the pilot plant 1 and two for the pilot plant 2. A dose of chlorine of 4.85 ± 0.05 g/kg/MLVSS per day was applied at both pilots. The preservative effect on nitrifying activity of the lowest concentration of chlorine at the dosing point and therefore of the highest pass frequency was evidenced. Among other tools, a simple method of measurement of the oxygen uptake rate enabled us to monitor the effect of chlorination on nitrification before recording an increase in the ammonia concentration in the bulking.

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