Effect Of Alkali Research Articles

Effect of alkali and halide ion doping on the energy storage characteristics of ionic liquid based supercapacitors

The electrochemical properties of supercapacitors based on carbide-derived carbon electrodes doped with up to 5 wt% mixture of halide or alkali ion salts in 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide (EMImTFSI) have been studied to exploit their specific energy storage mechanism. To separately highlight the effect of redox active mixture doped electrodes, neat EMImTFSI is applied as the electrolyte for all studied supercapacitor systems. A noticeable increase of capacitance for carbon electrodes doped with halide ions has been observed, as measured by three different electrochemical analysis techniques. Compared with neat EMImTFSI based system, carbon electrodes doped with alkali ion salt mixtures do not show a noticeable improvement of energy storage characteristics. Interestingly, both 5 wt% alkali and halide ion salt mixture doped system exhibit a stable high capacitance up to 124 F/g at 3 V. It is shown that this enhancement of capacitance is due to reversible faradaic processes and the specific adsorption of halide ions within the micro- and mesoporous electrode material and does not limit the bulk electrolyte properties. It is seen that the alkali and halide ion doped systems display greater electrochemical stability compared with neat EMImTFSI based system within constant voltage floating tests.

Effect of alkali and alkaline earth metals on co-pyrolysis characteristics of municipal solid waste and biomass briquettes

To investigate the influence of alkali and alkaline earth metals (AAEMs: K, Na, Ca, and Mg) on the co-pyrolysis of municipal solid waste (MSW) and biomass briquettes (CSBs), the pyrolysis properties and products distribution for the blends of pretreated CSBs and MSW were studied by thermogravimetric analysis with Fourier-transform infrared spectroscopy under N2 and CO2 atmospheres. Results showed that the AAEM salts were effective at reducing the initial temperature during pyrolysis process. The presence of AAEM salts inhibited the volatile release rate of the first pyrolysis stage of the blend, while the alkali and alkaline earth salts separately enhanced the volatile release rates of the second and third pyrolysis stages under both atmospheres. Replacement of N2 with CO2 caused lower residual masses of the blend, which were further reduced by the catalytic effect of the AAEM salts. The CO2 yields were enhanced by adding AAEM salts under the N2 atmosphere. Ca had the most obvious catalytic effect on the CO production in the third pyrolysis stage. Different AAEM salts added to the samples displayed different effects on the emissions of alkyl and carbonyl groups.

Effects of inherent alkali and alkaline earth metals on nitrogen transformation during steam gasification of Shengli lignite

This work evaluated the effects of inherent alkali and alkaline earth metals on nitrogen transformation during steam gasification of Shengli lignite at the temperature of 873–1173 K in a fluidized-bed/fixed-bed quartz reactor. The results indicated that the alkali metal Na and alkaline earth metals Ca, Mg in coal have different effects on inherent nitrogen transformation to NH3, HCN and char-N during the lignite steam gasification. Specifically during the steam gasification of Shengli lignite, Na and Ca, Mg not only catalyze the inherent nitrogen conversions to NH3, but also promote the secondary reactions of the nascent char-N as well as the generation of NH3 from the generated HCN, meanwhile they also inhibited the inherent nitrogen conversion to HCN and char-N. The presence of Na, Ca and Mg hindered the formation of oxidized nitrogen (N-X) functional groups, but enhanced pyridinic nitrogen (N-6) and quaternary nitrogen’s (N-Q) formation in char.

Effects of alkali and alkaline earth metals on the co-pyrolysis of cellulose and high density polyethylene using TGA and Py-GC/MS

The effects of the type and content of alkali/alkaline earth metals (AAEMs) on the co-pyrolysis of cellulose/high density polyethylene (HDPE) were studied using TGA and Py-GC/MS. AAEMs showed different effects on the decomposition characteristics of cellulose/HDPE mixtures. During cellulose/HDPE co-pyrolysis, AAEMs present in char could act as a base catalyst, with different catalytic effect on products distribution depending on the types of AAEMs. Na showed stronger catalytic cracking effect to promote alkenes formation compared to the use of K, Ca, and Mg. The comparison of experimental and calculated products distributions of raw cellulose/HDPE confirmed the existence of synergistic effect, which facilitated the cleavage of glycosidic linkages to form anhydrosugars and promoted the scission of HDPE chains to produce hydrocarbons. The effect of potassium on this synergy was also investigated. With increased potassium content, the yields of anhydrosugars and hydrocarbons decreased while the yields of furans and ketones increased, suggesting that potassium inhibited the cleavage of glycosidic bonds and promoted ring-opening reactions. This indicated that addition of potassium inhibited the synergy between cellulose and HDPE.

Hybrid and Nonhybrid Laminate Composites of Sugar Palm and Glass Fibre-Reinforced Polypropylene: Effect of Alkali and Sodium Bicarbonate Treatments

In recent years, the hybrid composites of cellulosic and synthetic fibres are tailored to yield materials with reduced cost and weight. Prior to the fabrication of the hybrid composite, in most case, the cellulosic fibre needs surface modification for proper bonding. Therefore, this study investigates the effect of sodium bicarbonate treatment on the physical and mechanical properties of the hybrid and nonhybrid laminate composites of sugar palm and glass fibre-reinforced polypropylene. The findings will be compared with the conventional alkali treatment. The laminate composites were fabricated using the film stacking technique and hot compression process. Prior to the fabrication process, the sugar palm fibre in it which is naturally woven mat was treated with 4 wt% and 10 wt% alkali and sodium bicarbonate, respectively. All the laminate composites were investigated by tensile, flexural, and impact test, water absorption, and morphological examination. The tensile strength increased with both alkaline and sodium bicarbonate treatments for the hybrid and nonhybrid composites. The increase was more pronounced with the alkaline-treated SPF composite (L03) which displayed the highest value of 61.75 MPa, while that of the sodium bicarbonate-treated SPF composite (L04) recorded 58.76 MPa against 53.01 MPa for the untreated SPF composite (L02). The same trend was observed for the flexural strength. In overall, the alkaline treatment yielded better performance in comparison with sodium bicarbonate treatment.

Effects of alkali and steaming on tensile strength of aren (arenga pinnata) fiber

The aim of this research is to investigate the alkali treatment and steaming influence on mechanical properties of Aren frond fiber. The presence of surface impurities and the large amount of hydroxyl groups makes natural fiber less compatible for composite materials reinforcement. Effort to remove the impurities can be done by few treatment that consist of physical, chemical and mechanical treatment. First, Aren frond single fiber were subjected to alkali treatments with 1%- 5% NaOH for a period of 4 - 7 hours to room temperature and followed by steaming 1 - 2 bar in pressure. Treatment of alkali and alkali-steaming combination can increase cellulose content. The tensile tests showed that the alkali and steaming treatment combination resulted the highest tensile strength of Aren frond fiber by 512 MPa. Then the impurities in surface fiber single effect interfacial stress and tend decrease bonding strength. These results show that the combination of alkali treatment and steaming can increase mechanical properties of Aren frond fiber.

Comparison of Different Hydrophobic Treatments for the Durability Improvement of Palmyra Natural Fiber Composites under Hydrothermal Ageing Environments

ABSTRACT Experimental and numerical investigations are performed to assess the durability of Palmyra natural fiber composites under hydrothermal ageing conditions. The effect of alkali and stearic acid pretreatments is analyzed on the moisture uptake. The natural fiber composite specimens were subjected to accelerated ageing under water and humidity conditions at controlled temperatures between 0°C-75°C. The 4% stearic acid treatment lead to a remarkable reduction in moisture diffusivity. The coefficient of moisture diffusion of different specimens of is calculated using edge correction factor for rectanguloid specimens. The methods presented here can be used to assess and improve the hydrothermal durability of Palmyra fiber composites.

Insights on the reactivity of chondroitin and hyaluronan toward 1,4-butanediol diglycidyl ether

Hyaluronic acid (HA) cross-linked with 1,4-butanediol diglycidyl ether (BDDE) are hydrogels with many biomedical applications. Degree of substitution, cross-linking and substitution position of the cross-linker might influence the properties of the hydrogels. We showed earlier that the most common substitution position of the cross-linker on the hyaluronan chain was the 4-hydroxyl of N-acetylglucosamine. This result has led us to investigate unsulfated chondroitin (CN) which only differ from HA in the primary structure by the configuration at C4 of the aminoglycan. In the present study, we have investigated (i) the substitution positions of the cross-linker in CN using NMR and LC-MS and compared the results to the data obtained for HA (ii) the effect of alkali on the 13C and 1H chemical shifts in CN and HA (iii) the temperature coefficients and chemical shifts of hydroxyl protons in CN and HA. In CN, the 2-hydroxyl of glucuronic acid and 6-hydroxyl of N-acetylgalactosamine were found to be the major sites of substitution by BDDE. Moreover, while chondroitinase was not able to cleave HA tetrasaccharide substituted at the 4-hydroxyl GlcNAc reducing end by BDDE, it is able to degrade CN-BDDE down to disaccharide units.

Performance of ASP compound systems and effects on flooding efficiency

Based on practical needs of oil fields, the viscosity, interfacial tension, static absorption, phase behaviors, molecular clew dimension (Dh), molecular configuration and flooding effect of the alkali/surfactant/polymer (ASP) systems were studied by instrumental analysis and physical modeling. The mechanisms of enhanced oil recovery were also discussed. As alkali concentration increased, the viscosity, interfacial tension and Dh of ASP decreased. As surfactant concentration increased, the viscosity and Dh increased, while the interfacial tension first decreased and then rose. The viscosity, interfacial tension and Dh of weak-alkali ASP all surpassed those of the strong-alkali ASP. The saturated absorption quantity of ASP ranked as surfactant > alkali > polymer. The saturated adsorption quantity and the ability to reduce the surfactant adsorption loss of the strong alkali were both higher, but the ability to reduce polymer adsorption loss was lower, compared with the weak alkali. As the concentrations of alkali and surfactant rose, the stability of emulsions was enhanced. The effect of alkali on the polymer molecular aggregation surpassed that of the surfactant. Physical modeling showed as the viscosity of the flooding agent rose, the recovery rate of weak-alkali ASP increased by 22.0% under the conditions of 1.2 wt% alkali, 0.3 wt% surfactant and 2500 mg/L polymer. The contribution rate to the recovery efficiency of A compound flooding ranked as the extended swept volume effect of the polymer (αp) > displacement effect (β) > the extended swept volume of emulsification (αe). The results were αp = 73.5%, β = 19.9%, αe = 6.6% (weak-alkali ASP); αp = 68.5%, β = 23.0%, αe = 8.4% (strong-alkali ASP).

Effect of organic alkali, n-alkanol, and nonionic surfactant ternary compound system on viscosity reduction of viscous crude oil

To reduce the viscosity of viscous crude oil and flow resistance, the effect of a ternary compound system including organic alkali, n-alkanol, and nonionic surfactants on viscous crude oil viscosity reduction was studied. The results showed that n-alkanol effectively reduced the droplet size of an emulsion and the viscosity of viscous crude oil and improved the fluidity of viscous crude oil. Of the low-carbon n-alkanols, n-pentanol has the best viscosity-reducing effect. The organic alkali avoids the phenomenon of fouling and corrosion caused by inorganic alkali and reacts with the acidic macromolecular components in viscous crude oil to generate alkanolamides, which produce synergistic effects with nonionic surfactants and reduce the interfacial tension between oil and water. In the ternary compound of organic alkali, n-alkanol, and nonionic surfactant, the viscosity reduction effect of viscous crude oil is significantly enhanced compared with that of a single reagent. The viscosity reduction rate of viscous crude oil of the diethanolamine ternary compound system reached 98.1% and was the best choice by experimental validation. It is shown that a reasonable formula of compound system and dosage can significantly reduce the viscosity of viscous crude oil.

Development of fiber-reinforced polypropylene with NaOH pretreated rice and coffee husks as fillers: Mechanical and thermal properties

Incorporation of agricultural wastes as fillers in fiber-reinforced plastics is gaining momentum in plastics engineering research. In this study, fiber-reinforced polypropylene (PP) with rice and coffee husks as filler material were developed. The effect of alkali (sodium hydroxide) pretreatment of the husks on mechanical and thermal properties of developed PP biocomposites was observed. Filler material loading was varied from 0% to 20% for rice husks and 0% to 10% for coffee husks. A twin-screw extruder was used for compounding the PP matrix with rice and coffee husk filler materials. Tensile strengths and percentage elongation results varied from 27.4 to 37.4 MPa and 2.4% to 70.3% (unmodified coffee husks), 31.1 to 37.4 MPa and 5% to 70.3% (unmodified rice husks), 30.7 to 37.4 MPa and 5.3% to 70.3% (modified coffee husks), and 30.7 to 37.4 MPa and 4.8% to 70.3% (modified rice husks). Young’s modulus ranged between 1656 and 2247.8 MPa for biocomposite PP samples with unmodified filler material. Young’s modulus ranged between 1740 and 2160 MPa after alkali treatment of the filler material. Charpy impact strengths ranged from 1.2 to 4 kJ/m2and 3.1 to 19.6 kJ/m2for samples containing unmodified and modified filler material, respectively. Thermogravimetric analysis showed that an increase in filler content resulted into delayed weight loss at high degradation temperatures. The results suggest that these developed fiber-reinforced plastics can be used in applications requiring high thermal stability and good mechanical properties.

Water adsorption on olivine(010) surfaces: Effect of alkali and transition metal cation doping.

Dopants have the potential to locally modify water-olivine interactions, which can impact geological processes, such as weathering, CO2 sequestration, and abiotic hydrocarbon generation. As a first step in understanding the role of dopants on the water structure and chemistry at water-olivine interfaces, water monomer adsorption on alkaline earth (AE) and transition metal (TM) doped forsterite(010) [Mg2SiO4(010)] surfaces was studied using density functional theory (DFT). Dopants that occur in olivine minerals were considered and consisted of Ca, Sr, and Ba for the AE dopants and Cr, Mn, Fe, Co, and Ni for the TM dopants. The water molecule adsorbs on the olivine surface through a metal-water bond (Me-Ow) and a hydrogen bond with an adjacent surface lattice oxygen (Ox-Hw). A frontier orbital analysis reveals that the 1b2, 3a1, and 1b1 (HOMO) of the water molecule are involved in the bonding. All of the TM dopants show strong net Me-Ow covalent bonding between 3a1 and 1b1 water orbitals and TM d states, while the AE dopants except for Mg2SiO4(010) show negligible Me-Ow covalent bonding. Both the AE and TM dopants show similar hydrogen bonding features involving both the 1b2 and 3a1 orbitals. While the AE cations show an overall lower Me-Ow covalent interaction, the AE dopants have strong electrostatic interactions between the positive metal cation and the negatively charged water dipole. A bonding model incorporating a linear combination of the covalent Me-Ow bond, the Ox-Hw hydrogen bond, the electrostatic interaction between the dopant cation and the H2O molecule, and the surface distortion energy is needed to capture the variation in the DFT adsorption energies on the olivine surfaces. The bonding analysis is able to identify the dominant contributions to water-dopant interactions and can serve as a basis for future studies of more realistic water-olivine interfaces.

Influences of alkali on the quality and protein polymerization of buckwheat Chinese steamed bread

The effects of alkali (NaHCO3 or Na2CO3) on the quality and protein polymerization of buckwheat Chinese steamed bread (CSB) were investigated. The alkali addition increased the specific volume of CSB, for NaHCO3 from 1.84 ml/g (control) to 2.66 ml/g. Image analysis showed that alkali increased the pore area fractions. The addition of Na2CO3 exhibited a greater pore count and lower pore average size. The texture properties were improved with the increase of crumb hardness and resilience. The extractability of protein in sodium dodecyl sulfate containing medium (SDSEP) decreased. Furthermore, SDS–PAGE showed an obvious decrease in the intensity of protein bands with lower molecular weight, while intensity of higher molecular protein bands increased. This demonstrated that alkali addition promoted protein aggregation in buckwheat CSB. In addition, the content of degydroalanine and lanthionine increased and free SH decreased, which indicated alkali addition prompted protein to form dehydroalanine-derived and disulfide cross-linkings.

Effect of Recycling Cycles on the Mechanical and Damping Properties of Short Alfa Fibre Reinforced Polypropylene Composite

This paper aims at studying the effect of recycling on the static and dynamic properties of short alfa fibre reinforced polypropylene. For this purpose, alfa fibres reinforced composites were elaborated by an injection moulding process and were subjected to different mechanical recycling cycles. Then, non-recycled and recycled materials were subjected to static tests and Dynamic Mechanical Analysis (DMA) to evaluate the effect of recycling on their behaviour. Besides, the effects of alkali and salt water treatments on the static and dynamic properties of the alfa composite were also investigated. The obtained results show that tensile and flexural properties of alfa fibres reinforced composites decrease during recycling cycles. Moreover, the recycling induces a drop in the storage modulus and enhances the loss factor of these composites. The composites with alfa fibre especially the alkali treated composite show the same resistance to recycling as composites with hemp fibres. Further, SEM observations indicate a decrease in the fibres dimension with the recycling cycles, especially for alfa fibres, which can explain the decrease in the properties of the alfa composite during recycling operations.

Study on Tensile, Bending and Water Uptake Properties of Sugarcane Bagasse Fiber Reinforced Polypropylene Based Composite

In this study, sugarcane bagasse fiber reinforced polypropylene based composites were fabricated successfully and their tensile, bending and water uptake behavior were studied. The composites were prepared by compression molding process. The fiber composition in the composites was 30% by weight. Results revealed that due to reinforcement by fiber, composites achieved 51% increase in tensile strength, 151% in tensile modulus, 109% in bending strength and 68% in bending modulus over that of polypropylene. Elongation at break was reduced due to the lower elongation property of fiber. The composites were treated by alkali for checking out the effects of alkali on composites. The concentrations of alkali used for treating the composites were 3%, 5% and 7% solution of sodium hydroxide (NaOH) and it was found that 7% solution of sodium hydroxide demonstrated lowest tensile and bending properties. Sheared composite samples were immersed into deionized water and it was noticed that composite samples were absorbed 2.10% water within 40 minutes of water absorption test. Soil degradation test was carried out for 16 weeks and it was observed that, the tensile and bending properties of sugarcane bagasse fiber reinforced polypropylene based composites were degraded slowly. The composites lost 35% of their original mechanical properties and retained 54% of actual weight after 16 weeks of degradation in soil medium.

Effect of Pretreatment on the Biogas Production from Energy Plant Using Batch Reactor

The proposed study aims at biogas potential estimation of sugar beet using different total solid concentration and pretreatment methods. The effect of alkali (Sodium hydroxide), acid (Hydrochloric acid) and mechanical (particle size reduction) pretreatment of sugar beet over un-pretreated substrate have been investigated for the potential of biogas production using biphasic continuous bio digester–TEAM (TERI’s Enhanced Acidification and Methanation) process (50 kg/day capacity) developed by TERI+. The estimation of biogas potential of sugar beet has also been studied in single phase batch digester (2 L capacity) using three different Total Solids (TS) concentration viz. 5%, 7.5% and 10%. However the effect of particle size reduction was also studied in two phase digester. The biogas yield from single phase batch digester fed with 5% TS, 7.5% TS, 10% TS, were recorded as 44 m3/ton, 58 m3/ton, 57 m3/ton of substrate fed respectively whereas the yield from un-pretreated, HCl (6%; v/v) pretreated and NaOH (1%; w/v) pretreated sugar beet are, 72 m3/ton, 60 m3/ton and 61 m3/ton respectively. The biogas yield from mechanically pulverized is estimated to be 90 m3/ton which is 25% more than not pretreated substrate that too in Total Hydraulic Time (HRT) of less than six days.

Influence of alkali-surfactant-polymer flooding on the coalescence and sedimentation of oil/water emulsion in gravity separation

The emulsification and stabilization of the residual chemical within the recovered oil pose difficulties in the primary separation process. This study emphasis on the effectiveness of ASP injection on coalescence and sedimentation of oil and aqueous phases. In addition, the present work is focused at modifying an existing oil/water separation prediction model applicable in the presence of ASP fluids, as the existing model is applicable only to oil/water emulsion. Experimental and empirical techniques have been adopted as a methodology for investigating this work. The modification of the existing model for the prediction of the separation as well as the interaction effect of the parameters were explored. The influence of ASP on separation time in oil-water emulsion were explored in terms of sedimentation and coalescence profiles. Empirical expressions were generated from the batch experiments to find the coalescence and sedimentation constants for various alkali/surfactant/polymer concentrations. The outcomes of the study show that the presence of various ASP concentrations in the oil-water emulsions resulted in a variation in the required separation time. The results also show that alkali in the 500–1500 ppm range has the most significant negative impact on sedimentation. The effect of alkali in reducing sedimentation increases very significantly with surfactant interaction (200–600 ppm). While the polymer in the range of 400–800 ppm and alkali significantly reduced coalescence, as well as the interaction of alkali-surfactant and surfactant-polymer, also contributed significantly to reducing coalescence.

Correction to: Effect of alkali on konjac glucomannan film and its application on wound healing

The paper “Effect of alkali on konjac glucomannan film and its application on wound healing” was published in Cellulose, 22(1), 737–747 (2015). As we found out that Ca(OH)2 is a better alkali than KOH for treating the KGM film, the main purpose of this paper is to look into the effects of various concentrations of Ca(OH)2 on the properties of KGM film as a potential wound dressing. Unfortunately, Figure 6C, Figure 7A and Figure 8 of the original version were misused. We present correct version of the figures (Figs. 6, 7, 8) in this correction article.

Effects of alkali and alkaline-earth metals and retention time on the generation of tar during coal pyrolysis in a horizontal fixed-bed reactor

To reduce the tar yield, a horizontal fixed bed is proposed to replace a conventional fluidized bed in the pyrolysis stage of two-stage gasification. Effects of alkali and alkaline-earth metals on the generation of tar are studied. Roles of the interparticle and inner-furnace retention time are also investigated. Ultraviolet–visible spectrophotometry was used to determine the aromatic compounds in tars. The results showed that absorbance intensity of the tar solution increased linearly with its concentration within the examined concentration range. The removal of alkali and alkaline-earth metals increased the tar yield of coal. Increase in the absorbance intensity of tar is attributed to the increase in aromatic ring systems. Ion-exchangeable Na plays a dominant role in the retention of tar precursors, mainly polycondensed aromatic rings, by connecting them with the char matrix. Increasing the retention time in interparticle diffusion decreased the yield of tar, especially for polycondensed aromatic rings. Increasing the retention time in inner-furnace diffusion slightly decreased the tar yield. Introduction of a fixed bed could effectively solve the problems of high tar yield from coal and low catalyst contents in char.

Effects of alkali and alkaline earth metal species on the combustion characteristics of single particles from pine sawdust and bituminous coal

Alkali and alkaline earth metal (AAEM) species are the main components of the ash of biomass, and which would influence the combustion of biomass and coal during the co-firing process. The aim of this paper is to investigate the effects of potassium (K), sodium (Na), calcium (Ca), and magnesium (Mg) on the combustion characteristics of pine sawdust (PS) and bituminous coal (BC) by a single particle combustion method. The raw, ash-free and impregnated samples were prepared, and their combustion processes were recorded by a high speed camera. Based on the recorded flame images, the effects of K, Na, Ca and Mg on the combustion characteristics (ignition, volatiles combustion, char combustion) of PS and BC were analyzed. The results reveal that the demineralization treatment brings negative effects on the combustion of PS, which reflects in longer ignition delay time, volatiles and char burnout time, and lower combustion temperature, while the effects on the combustion of BC are opposite. The impregnated samples exhibit shorter ignition delay time, volatiles and char burnout time, and higher combustion temperature than the ash-free samples. In the entire combustion process of PS and BC, K exhibits the strongest promotion effect. When the concentration of K increases from 0 to 2 wt%, the ignition delay time of PS and BC decreases about 5.5 ms and 16.4 ms respectively, the volatiles combustion temperature increases about 41 °C and 77 °C respectively, and the char combustion temperature increases about 226 °C and 141 °C respectively.