In-Situ Rheological Studies of Cationic Lignin Polymerization in an Acidic Aqueous System

The chemistry of lignin polymerization was studied in the past. Insights into the rheological behavior of the lignin polymerization system would provide crucial information required for tailoring lignin polymers with desired properties. The in-situ rheological attributes of lignin polymerization with a cationic monomer, [2-(methacryloyloxy)ethyl] trimethylammonium chloride (METAC), were studied in detail in this work. The influences of process conditions, e.g., temperature, component concentrations, and shear rates, on the viscosity variations of the reaction systems during the polymerization were studied in detail. Temperature, METAC/lignin molar ratio, and shear rate increases led to the enhanced viscosity of the reaction medium and lignin polymer with a higher degree of polymerization. The extended reaction time enhanced the viscosity attributing to the larger molecular weight of the lignin polymer. Additionally, the size of particles in the reaction system dropped as reaction time was extended. The lignin polymer with a larger molecular weight and Rg behaved mainly as a viscose (tan δ > 1 or G″ > G′) material, while the lignin polymer generated with smaller molecular weight and shorter Rg demonstrated strong elastic characteristics with a tan (δ) lower than unity over the frequency range of 0.1−10 rad/s.

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In Situ Transesterification of Spirulina Microalgae to Produce Biodiesel Using Microwave Irradiation

Journal of Energy ◽

10.1155/2020/8816296 ◽

2020 ◽

Vol 2020 ◽

pp. 1-10

Author(s):

Alex K. Koech ◽

Anil Kumar ◽

Zachary O. Siagi

Keyword(s):

Fatty Acid ◽

Reaction Time ◽

Microwave Irradiation ◽

Spirulina Platensis ◽

Reaction System ◽

Conventional Heating ◽

Process Conditions ◽

In Situ Transesterification ◽

Algae Biomass

The present technology of transesterification of vegetable oils to produce biodiesel, which is suited to replace petrodiesel, has economic challenges, and therefore, alternative sources are being explored. Microalgae, a renewable, third-generation biofuel resource, have the potential to become a viable feedstock due to their high oil content and environmentally friendly nature. The present study investigates the effect of microwave irradiation on the simultaneous extraction and transesterification of algae lipids to produce fatty acid methyl ester (FAME), in a batch reaction system using sulphuric acid catalyst. In situ transesterification combines the two steps of lipid extraction and transesterification into a single step. The microwave synthesis unit comprised of a 3-neck round bottom flask inside a 1300-Watt microwave oven, fitted with a quick-fit condenser and having an external stirrer. Response surface methodology (RSM) was used to analyse the influence of process variables, dry algae to methanol ratio 1 : 4 − 1 : 14 g / ml , algae biomass to catalyst ratio 1 : 0.0032 − 1 : 0.0368 wt % , and reaction time 1 − 11 min , at 500 rpm stirring rate for in situ reaction. FAME was analysed using gas chromatography (GC). The total lipid content of Arthrospira Spirulina platensis microalgae biomass was found to be 10.7 % by weight. The algae biomass also contained proteins at 51.83 % , moisture content at 7.8 % , and ash content 14.30 % by weight. RSM gave the optimum process conditions as dry algae biomass feed to methanol wt / vol ratio of 1 : 9, catalyst concentration of 2 wt % , and reaction time of 7 minutes for a maximum FAME yield of 83.43 wt % . The major fatty acid composition of FAME was palmitic 43.83 % , linoleic 38.83 % , and linolenic 19.41 % . FAME properties obtained according to European Standards (EN 14214) and American Society for Testing and Materials (ASTM D 6751) standards were as follows: flash point 16 4 o C calorific value 32,911 kJ / kg , acid value 0.475 KOH / g , viscosity 4.45 m m 2 / s , and specific gravity 0.868 . The study showed that Arthrospira Spirulina platensis microalgae lipid FAME met the biodiesel standards (EN 14214 and ASTM D 6751) and has the potential to replace petrodiesel. Microwave irradiation increased the reaction rate resulting in a reduced reaction time of 7 minutes (as compared to 8 hours for conventional heating) and therefore was found to be a superior heating mode as compared to conventional heating.

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Au Modified F-TiO2 for Efficient Photocatalytic Synthesis of Hydrogen Peroxide

Molecules ◽

10.3390/molecules26133844 ◽

2021 ◽

Vol 26 (13) ◽

pp. 3844

Author(s):

Lijuan Li ◽

Bingdong Li ◽

Liwei Feng ◽

Xiaoqiu Zhang ◽

Yuqian Zhang ◽

...

Keyword(s):

Hydrogen Peroxide ◽

Reaction System ◽

Reaction Medium ◽

Pure Tio2 ◽

H2o2 Production ◽

Tio2 Photocatalyst ◽

H2o2 Decomposition ◽

Spin Resonance ◽

Photocatalytic Synthesis

In this work, Au-modified F-TiO2 is developed as a simple and efficient photocatalyst for H2O2 production under ultraviolet light. The Au/F-TiO2 photocatalyst avoids the necessity of adding fluoride into the reaction medium for enhancing H2O2 synthesis, as in a pure TiO2 reaction system. The F− modification inhibits the H2O2 decomposition through the formation of the ≡Ti–F complex. Au is an active cocatalyst for photocatalytic H2O2 production. We compared the activity of TiO2 with F− modification and without F− modification in the presence of Au, and found that the H2O2 production rate over Au/F-TiO2 reaches four times that of Au/TiO2. In situ electron spin resonance studies have shown that H2O2 is produced by stepwise single-electron oxygen reduction on the Au/F-TiO2 photocatalyst.

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The utilization of the mesoporous Ti-SBA-15 catalyst in the epoxidation of allyl alcohol to glycidol and diglycidyl ether in the water medium

Polish Journal of Chemical Technology ◽

10.1515/pjct-2015-0064 ◽

2015 ◽

Vol 17 (4) ◽

pp. 23-31 ◽

Cited By ~ 1

Author(s):

Agnieszka Wróblewska ◽

Edyta Makuch ◽

Małgorzata Dzięcioł ◽

Roman Jędrzejewski ◽

Paweł Kochmański ◽

...

Keyword(s):

Hydrogen Peroxide ◽

Reaction Time ◽

Allyl Alcohol ◽

Water Solution ◽

Reaction Medium ◽

Diglycidyl Ether ◽

Molar Ratio ◽

Water Medium ◽

Catalyst Content ◽

Allyl Alcohol Epoxidation

Abstract This work presents the studies on the optimization the process of allyl alcohol epoxidation over the Ti-SBA-15 catalyst. The optimization was carried out in an aqueous medium, wherein water was introduced into the reaction medium with an oxidizing agent (30 wt% aqueous solution of hydrogen peroxide) and it was formed in the reaction medium during the processes. The main investigated technological parameters were: the temperature, the molar ratio of allyl alcohol/hydrogen peroxide, the catalyst content and the reaction time. The main functions the process were: the selectivity of transformation to glycidol in relation to allyl alcohol consumed, the selectivity of transformation to diglycidyl ether in relation to allyl alcohol consumed, the conversion of allyl alcohol and the selectivity of transformation to organic compounds in relation to hydrogen peroxide consumed. The analysis of the layer drawings showed that in water solution it is best to conduct allyl alcohol epoxidation in direction of glycidol (selectivity of glycidol 54 mol%) at: the temperature of 10–17°C, the molar ratio of reactants 0.5–1.9, the catalyst content 2.9–4.0 wt%, the reaction time 2.7–3.0 h and in direction of diglycidyl ether (selectivity of diglycidyl ether 16 mol%) at: the temperature of 18–33°C, the molar ratio of reactants 0.9–1.65, the catalyst content 2.0–3.4 wt%, the reaction time 1.7–2.6 h. The presented method allows to obtain two very valuable intermediates for the organic industry.

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Study on Synthesis of Ester of Citric Acid and Palmityl Alcohol

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.900.361 ◽

2014 ◽

Vol 900 ◽

pp. 361-364

Author(s):

Xiao Hui Wang ◽

Xi Hua Du ◽

Li Min Dong

Keyword(s):

Reaction Time ◽

Citric Acid ◽

Cation Exchange ◽

Sulfonic Acid ◽

Exchange Resin ◽

Cation Exchange Resin ◽

Molar Ratio ◽

Esterification Reaction ◽

Process Conditions ◽

Toluene Sulfonic Acid

Esters of Citric acid and palmityl alcohol were synthesized by esterification reaction under catalysis of cation exchange resin and P-toluene sulfonic acid respectively. The effects of amount of catalyst, ratio of raw materials, reaction time and temperature on the synthesis reaction were investigated . The experimental results showed that optimum of process conditions were 1:1~1:1.5 molar ratio of citric acid and palmityl alcohol, reaction temperature of 130~140°C, reaction time of 2 h. Conversion of palmityl alcohol were all more than 90% under 0.3% dosage using p-toluene sulfonic acid as the catalyst, or 0.5% dosage using 721 cation exchange resin with sulfonic acid type as catalyst. The synthesized product had good surface activity.

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Interesterification of Egg-Yolk Phosphatidylcholine with p-Methoxycinnamic Acid Catalyzed by Immobilized Lipase B from Candida Antarctica

Catalysts ◽

10.3390/catal10101181 ◽

2020 ◽

Vol 10 (10) ◽

pp. 1181

Author(s):

Magdalena Rychlicka ◽

Anna Gliszczyńska

Keyword(s):

Reaction Time ◽

Design Method ◽

Immobilized Lipase ◽

Reaction Medium ◽

Solvent System ◽

Novozym 435 ◽

Molar Ratio ◽

Binary Solvent ◽

Methoxycinnamic Acid ◽

Substrate Molar Ratio

The p-methoxycinnamic acid (p-MCA) is one of the most popular phenylpropanoids, the beneficial impact of which on the human health is well documented in the literature. This compound has shown many valuable activities including anticancer, antidiabetic, and neuro- and hepatoprotective. However, its practical application is limited by its low bioavailability resulting from rapid metabolism in the human body. The latest strategy, aimed at overcoming these limitations, is based on the production of more stability in systemic circulation bioconjugates with phospholipids. Therefore, the aim of this research was to develop the biotechnological method for the synthesis of phospholipid derivatives of p-methoxycinnamic acid, which can play a role of new nutraceuticals. We developed and optimized enzymatic interesterification of phosphatidylcholine (PC) with ethyl p-methoxycinnamate (Ep-MCA). Novozym 435 and a binary solvent system of toluene/chloroform 9:1 (v/v) were found to be the effective biocatalyst and reaction medium for the synthesis of structured p-MCA phospholipids, respectively. The effects of the other reaction parameters, such as substrate molar ratio, enzyme dosage, and reaction time, on the degree of incorporation of p-MCA into PC were evaluated by use of an experimental factorial design method. The results showed that substrate molar ratio and biocatalyst load have significant effects on the synthesis of p-methoxycinnamoylated phospholipids. The optimum conditions were: Reaction time of three days, 30% (w/w) of Novozym 435, and 1/10 substrate molar ratio PC/Ep-MCA. Under these parameters, p-methoxycinnamoylated lysophosphatidylcholine (p-MCA-LPC) and p-methoxycinnamoylated phosphatidylcholine (p-MCA-PC) were obtained in isolated yields of 32% and 3% (w/w), respectively.

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Keggin-Type Heteropolyacid for Ring-Opening Polymerization of Cyclohexene Oxide: Molecular Weight Control

International Journal of Polymer Science ◽

10.1155/2015/826512 ◽

2015 ◽

Vol 2015 ◽

pp. 1-6 ◽

Cited By ~ 3

Author(s):

Ahmed Aouissi ◽

Zeid Abdullah Al-Othman ◽

Abdurrahman Salhabi

Keyword(s):

Molecular Weight ◽

Reaction Time ◽

Acetic Anhydride ◽

Ring Opening ◽

Weight Control ◽

Reaction Medium ◽

Resonance Spectroscopy ◽

Cyclohexene Oxide ◽

Scanning Calorimetry ◽

Catalyst Amount

Polymerization of 1,2-cyclohexene oxide (CHO) in dichloromethane was catalyzed by 12-tungstophosphoric acid (H3PW12O40·13H2O) as a super solid acid. The effect of polymerization parameters such as reaction time, temperature, and catalyst amount was investigated. The effect of acetic anhydride as a ring-opening agent was also investigated. The resulting poly(1,2-cyclohexene oxide) (PCHO) was characterized by Fourier transform infrared (FTIR), nuclear magnetic resonance spectroscopy (1HNMR), gel-permeation chromatography (GPC), and differential scanning calorimetry (DSC). It has been found that the PCHO prepared over H3PW12O40·13H2O has a stereoregularity higher than that prepared over clay and Aluminium alkoxide catalysts. TheTgvalue obtained is due to the microstructure but not to molecular weight. The yield and the molecular weight of the polymer depend strongly on the reaction conditions. Molecular weights can be readily controlled by changing reaction temperature, reaction time, and catalyst amount. Contrary to most polymerization reactions, the molecular weight increases with the temperature increase. Addition of acetic anhydride to the reaction medium increased the yield threefold.

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Catalytic Synthesis of Ethyl Acetate Using Ti2SnC

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.634-638.628 ◽

2013 ◽

Vol 634-638 ◽

pp. 628-631

Author(s):

Yun Hui Long ◽

Jun Ming Guo ◽

Du Shu Huang ◽

Gui Yang Liu

Keyword(s):

Acetic Acid ◽

Reaction Time ◽

Ethyl Acetate ◽

Reaction Temperature ◽

Conversion Rate ◽

Reaction System ◽

Catalytic Performance ◽

Catalytic Synthesis ◽

Molar Ratio ◽

The Ideal

The catalytic synthesis of ethyl acetate from ethanol and acetic acid using Ti2SnC in liquid phase under the atmospheric pressure was studied. The influences of some factors such as catalyst usage, initial reactant molar ratio, reaction temperature and reaction time on acetic acid conversion rate of this reaction system were investigated. The acetic acid conversion rate of 88.12% is achieved while the molar ratio of alcohol and acid is 1:3.6, the amount of catalyst is 0.2000 g, the reaction temperature is 80 °C and the reaction time is 30min. The catalyst Ti2SnC is the ideal catalyst for synthesis of ethyl acetate for good catalytic performance, non-corrosive to equipment, easily separated from product and used repeatedly.

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Biodiesel Production through Catalytic Microwave In-situ Transesterification of Micro-algae (Chlorella sp.)

International Journal of Renewable Energy Development ◽

10.14710/ijred.9.1.113-117 ◽

2020 ◽

Vol 9 (1) ◽

pp. 113-117

Author(s):

Mahfud Mahfud ◽

Ummu Kalsum ◽

Viqhi Ashwie

Keyword(s):

Reaction Time ◽

Microwave Power ◽

Biodiesel Production ◽

Molar Ratio ◽

In Situ Transesterification ◽

Chlorella Sp ◽

Low Concentrations ◽

Face Centered ◽

Hexane Solution

Aim of this research are to study and develop research related to the potential of Chlorella sp. into biodiesel with the help of microwaves in-situ transesterification by characterizing parameters such as microwave power (300; 450; 600 W) and reaction time (10; 30; 50 minutes) with catalyst concentration of KOH and molar ratio of microalga : methanol are 2% and 1:12 respectively and optimized by response surface methodology with Face Centered Central Composite Design (FCCCD). The study was carried out by dissolving the catalyst into methanol according to the variable which was then put into a reactor containing microalgae powder in the microwave and turned on according to the predetermined variable. After the reaction process is complete, the mixture is filtered and resuspended with methanol for 10 minutes to remove the remaining FAME and then the obtained filtrate is cooled. Water is added to the filtrate solution to facilitate the separation of hydrophilic components before being separated and pushed apart until 3 layers are formed. Amount of FAMEs in the first layer formed were extracted with n-hexane solution and washed with water and the FAME product obtained was then distilled to remove the remaining n hexane and then weighed. The results indicated that yield increased with increasing reaction time and microwave power with the best conditions of 50 minutes each and 440.53 watts with the highest yield reaching 35.72% (dry basis) through using of KOH catalysts with low concentrations, 2%.©2020. CBIORE-IJRED. All rights reserved

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Optimization analysis of separation conditions of washed water containing a lead complex and characterization of the precipitation products

Water Science & Technology ◽

10.2166/wst.2017.484 ◽

2017 ◽

Vol 76 (12) ◽

pp. 3220-3226 ◽

Cited By ~ 4

Author(s):

Wenmin Cai ◽

Jiajun Chen ◽

Qingwei Wang ◽

Meng Wei

Keyword(s):

Reaction Time ◽

Environmental Governance ◽

Sodium Sulfide ◽

Precipitation Method ◽

Molar Ratio ◽

Precipitation Process ◽

Process Conditions ◽

Precipitation Reaction ◽

Reaction Products ◽

X Ray Diffraction

Abstract Presently, the large amount of industrial leaded wastewater creates a great challenge to both environmental governance and wastewater recycling. Lead complexes in washed water must be removed mostly before the washed water can be recycled. This paper reports the mechanism and factors of removing Pb complexes in simulated washed water by the sulfide precipitation method. The reaction time, sodium sulfide dosage, pH, and polymeric aluminum chloride (PAC) dosage were analyzed and the optimal conditions were explored. The composition of the reaction products was also verified by scanning electron microscopy (SEM) and X-ray diffraction (XRD). Additionally, the kinetics of the precipitation reaction of sodium sulfide and Pb-EDTA were studied. These results showed that the Pb removal efficiency reached 91.7% under the optimal process conditions which were as follows: the dosages of Na2S and PAC were 188 mg/L (Na2S/Pb2+ molar ratio of 5:1) and 30 mg/L, respectively, the reaction time was 40 min, and the pH was 9. It was demonstrated using SEM and XRD that the reaction product in the separation process was PbS and the precipitation process was fitted to the following first-order reaction kinetics equation: Ct = 89.1e−0.1047t + 10.1 (R2 = 0.9929; Ct is Pb concentration at reaction time t).

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Silica supported Schiff-base cobaltIII complex-Lewis base system: a highly selective catalyst for alternating copolymerization of CO2 and propylene oxide

e-Polymers ◽

10.1515/epoly.2011.11.1.55 ◽

2011 ◽

Vol 11 (1) ◽

Author(s):

Yongsheng Niu ◽

Hongchun Li

Keyword(s):

Molecular Weight ◽

Schiff Base ◽

Reaction Time ◽

Propylene Oxide ◽

Cobalt Complex ◽

Catalyst System ◽

Cyclic Carbonate ◽

Lewis Base ◽

Molar Ratio ◽

Base System

AbstractAn binary catalyst system of a silica supported Schiff-base cobalt complex SalenCoIII (OAC)-MCM-41 (Salen = 3-[N,N-bis-2-(3,5-di-tert-butylsalicylidenamino) ethyl] amine) was developed to generate the copolymerization of CO2 and propylene oxide in presence of (4-dimethylamino)-pyridine (DMAP). The influence of the molar ratio of catalyst components, the operating temperature, reaction time, and CO2 pressure on the yield as well as the molecular weight of polycarbonate was systematically investigated. The high selectivity of polycarbonate over cyclic carbonate at 40 °C was maintained after a longer reaction time to attain quantitative formation of the alternating copolymer. High molecular weight of 67 000 were achieved at an appropriate combination of all variables.

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