Alkali Consumption Research Articles

Increased pulp yield by prolonged impregnation in softwood kraft pulping

The effect on kraft cooking proceeded by an impregnation stage performed at 130 degrees C for 30 min was compared to kraft cooking following prolonged impregnation at 105 degrees C for 60-120 min. The alkali consumed during impregnation varied depending on the temperature and time of the impregnation stage. In order to study the impact of the impregnation stage on the subsequent kraft cook, the initial concentration of effective alkali was adjusted to be initially the same in all cooks before cooking for 180-290 min. The alkali consumed in the impregnation stage affected the alkali profile of the cooking stage. The more alkali consumed in impregnation, the lower the demand in cooking. Higher alkali consumption in the impregnation stage also led to faster delignification in the cooking stage. Prolonged impregnation resulted in 1-1.5 percentage points higher yield compared to the reference case. The yield increment was due to a higher cellulose retention. Although the impregnation time was prolonged from 30 min up to 2 h, the higher delignification rate and higher yield only decreased the production rate with 11% compared to the reference.

Investigation of phase formation in the system Fe2+/Co2+/O2/H2O

The dispersed iron oxide compounds are widely used as magnet carriers, pigments, catalysts, sorbents. Therefore, the study of phase formation in the system Fe 2+ /Co 2+ /O 2 /H 2 O, as well as the study of the influence of the basic oxidative environment parameters on the phase composition of iron (III) oxides over a wide pH range, and obtaining precipitates with a given chemical composition appear to be urgent. As a result of the studies involved, it was found that in the system Fe 2+ /Co 2+ /O 2 /H 2 O with constant cobalt content, the alkali consumption rate and the rate of product formation increase with increasing effective air flow rate. At constant rate of oxidation the oxidation time is reduced with the increase of cobalt content in the system. The phase composition of the resulting compounds is determined by the mode of OHCP (dynamic or static). Formation of Со x Fe 3-x O 4 spinel structure occurs at pH 11–12 and air flow rate 4 min -1 . In the presence of cobalt ions 3+, the rate of iron 2+compounds oxidation by atmospheric oxygen increases, because of their catalytic action.

Effect of eucalyptus bark contamination during pulping of mixed southern hardwoods

The use of eucalyptus as a partial replacement for mixed southern hardwoods can result in significant amounts of eucalyptus bark being incorporated into the chips going to the digester. When eucalyptus is first harvested, the bark peels off in large sheets, which will pass through chippers designed for southern hardwood. After being cut for more than about 4–6 weeks, the bark tightens onto the bole of the tree and again passes through chippers not designed for eucalyptus. As a result, significant quantities of eucalyptus bark could go to the digester. This study describes the effect of pulping eucalyptus bark in the laboratory. A series of control studies were performed on eucalyptus and mixed southern hardwood bark. The results show that incorporating bark into the cook results in increased kappa number, decreased pulp yield, and increased alkali consumption. If the percentage of applied active alkali is increased to counteract the increased alkali consumption, increased hexenuronic acid is generated

Effect of Salinity on Enhancing Waste Activated Sludge Alkaline Fermentation at Different Temperatures

Carbon source shortage and waste sludge treatment are two problems facing sewage treatment plants. The purpose of this work was to investigate the feasibility of using salt (NaCl) to enhance the production of short‐chain fatty acids (SCFAs) from waste sludge, reduce sludge production, and lower the operating cost. Four sodium chloride (NaCl) concentrations (0, 2, 15, and 25 g/L) and temperatures (20, 30, 35, and 40°C) were examined individually in batch‐mode sludge fermentation systems. The results showed that NaCl promoted the release of soluble proteins and polysaccharides, enhanced hydrolysis acidification and SCFAs accumulation, suppressed the activity of coenzyme 420 and the growth of methanogens. The optimal condition of hydrolysis acidification was 15 g/L NaCl and 35°C, and the acidification was deteriorated at 25 g/L NaCl and 40°C. Compared with the blank test (0 g/L NaCl), the sludge reduction and SCFAs production increased by 22.12 and 21.21%, respectively. With regard to the alkali consumption per unit (1 mmol), the SCFAs production and sludge reduction was increased by 9.6 and 21.99%.

Selective Hydrogen Sulphide Removal from Acid Gas by Alkali Chemisorption in a Jet Reactor

Abstract Natural gas is a primary energy source that contains a number of light paraffins. It also contains several undesirable components, such as water, ammonia, hydrogen sulphide, etc. In our study, a selective hydrogen sulphide removal process was achieved by alkali chemisorption in a custom-designed jet reactor. Several model gas compositions (CO2-H2S-N2) were evaluated to find parameters that enable H2S absorption instead of CO2. The negative effect of the presence of CO2 in the raw gas on the efficiency of H2S removal was observed. The beneficial effect of the low residence time (less than 1 s) on the efficiency of H2S removal was recognized. Optimal operational parameters were defined to reach at least a 50% efficiency of H2S removal and minimal alkali consumption.

The comparison study of IFT and consumption behaviors between organic alkali and inorganic alkali

Alkali plays an important role in alkali/surfactant/polymer (ASP) technology. The mechanisms of alkali were reviewed in this paper and the advantages were significant. In this study, three main steps were conducted. Firstly, ethanolamine was selected from four organic alkalies (ethanolamine, diethanolamine, triethanolamine and triethylamine) by interfacial tension (IFT) tests. Then the selected organic alkali, ethanolamine, was compared with inorganic alkali (sodium carbonate) by IFT performance. The results showed that ethanolamine had low IFT like inorganic alkali and it has lower IFT than sodium carbonate when concentration was higher than 0.8%. Secondly, alkali consumption experiment was conducted to compare organic alkali and inorganic alkali. The results indicated that ethanolamine had lower consumption than inorganic alkali, which maintained the efficiency of ASP flooding. Finally, the concentrations of silicon and aluminum in solution were measured to evaluate the reservoir damage caused by alkali. The results found that ethanolamine system had the lower concentrations of silicon and aluminum than inorganic alkali, which means it caused less reservoir damage. Thus, ethanolamine may be a potential alkali which can replace inorganic alkali in ASP technology.

Improving yield and composition of protein concentrates from green tea residue in an agri-food supply chain: Effect of pre-treatment

Rather than improving crop-production yield, developing biorefinery technology for unused biomass from the agri-food supply chain may be the crucial factor to reach sustainable global food security. A successful example of food-driven biorefinery is the extraction of protein from green tea residues, however, alkali usage is high and the resulting low protein quality limits its application. The research objective was to investigate the influence of pre-treatments with ethanol, Viscozyme® L and/or H2O2 on the subsequent alkaline protein extraction, and on their possible products for food applications. Polyphenols and/or pigments can be obtained by ethanol pre-treatment. Galacturonic acid and glucose can be obtained using Viscozyme® L. Pre-treatments using ethanol or Viscozyme® L individually reduced alkali consumption by 25% and improved protein extraction yield and purity. Their combination has the best effect. Additionally, pre-treatment using 50% ethanol reduced browning by 59% while pre-treatment using Viscozyme® L increased contents of arginine, threonine, and serine in the final alkaline protein extract. H2O2 pre-treatment had a negative effect on the alkaline protein extraction. These pre-treatments and protein extraction can be added to the existing process.

Mechanistic Modeling of the Alkaline/Surfactant/Polymer Flooding Process under Sub-optimum Salinity Conditions for Enhanced Oil Recovery

Alkaline–surfactant–polymer (ASP) flooding is potentially the most efficient chemical EOR method. It yields extremely high incremental recovery factors in excess of 95% of the residual oil for water flooding on the laboratory scale. However, current opinion is that such extremely high recoveries can be achieved under optimum salinity conditions, i.e., for the Winsor Type III microemulsion phase characterized by ultralow interfacial tension (IFT). This represents a serious limitation since several factors, including alkali-rock interaction, the initial state of the reservoir water, and the salinity of injected water, may shift the ASP flooding design to either sub-optimum or over-optimum conditions. A recent experimental study of ASP floods, based on a single internal olefin sulfonate (IOS) in natural sandstone cores with varying salinity from sub-optimum to optimum conditions, indicated that high recovery factors can also be obtained under sub-optimum salinity conditions. In this paper, a mechanistic model was developed to explore the causes behind the observed phenomena. The numerical simulations were carried out using the UTCHEM research simulator (at The University of Texas at Austin), together with the geochemical module EQBATCH. UTCHEM combines multiphase multicomponent simulation with robust phase behavior modeling. An excellent match of the numerical simulations with the experiments was obtained for oil cut, cumulative oil recovery, pH profile, surfactant, and carbonate concentration in the effluents. The simulations gave additional insight into the propagation of alkali consumption, salinity, surfactant profiles within the core. The study showed that the initial condition of the core is important in designing an ASP flooding. Because of uncertainties in the various chemical reactions taking place in the formation, an accurate geochemical model is essential for operating an ASP flooding in a particular salinity region. The simulation results demonstrate also that, for crude oil with a very low total acid number (TAN), the ultralow IFT and low surfactant adsorption can be achieved over a wide range of salinities that are less than optimal. The results provide a basis to perform better modeling of the sub-optimum salinity series of experiments and optimizing the design of ASP flooding methods for the field scale with more-complicated geochemical conditions.

Extraction and separation of tungsten from acidic high-phosphorus solution

The utilization of high-phosphorus tungsten ores has attracted extensive attention with the mining and utilization of rich tungsten ores. To extract and separate tungsten from acidic high-phosphorus solution effectively, a novel process was developed. Firstly, tungsten was extracted directly in acid medium by solvent extraction. 99.8% tungsten in acidic high-phosphorus solution was extracted with Aliquat 336 in kerosene by one extraction stage under the conditions of O:A=1, pH=2, 25°C, t=10min, 5% v/v 2-Octanol and 10% v/v Aliquat 336. And then, tungsten and phosphorus were preliminary separated through stripping process. Over 95% tungsten were recovered after five stripping stages under the optimum stripping conditions of 2.5M ammonium bicarbonate, 8min stripping time, O:A=1:1, pH=9, and 60°C, but only about 1.2% phosphorus was recovered from feed liquor. Finally, a small amount of phosphorus left in strip liquor was deeply removed by magnesium salt precipitation method on the optimum conditions of pH=10.0, 25°C, reaction time 1h and Mg/P molar ratio of 1:2 and the ammonium tungstate solution meeting the requirements of producing high-quality ATP can be obtained successfully. Compared to traditional phosphorus removal route, the process in this paper can help extract tungsten directly in acidic medium and decrease the quantity of phosphorus through extraction-stripping process, significantly reducing the consumption of alkali and magnesium salt and improving the separation efficiency of tungsten from acidic high-phosphorus solution.

Integrated adsorptive technique for efficient recovery of m-cresol and m-toluidine from actual acidic and salty wastewater

An integrated adsorptive technique combining an m-cresol adsorption unit, an acid retardation unit and an m-toluidine adsorption unit in sequence was designed to recover m-cresol and m-toluidine from highly acidic and salty m-cresol manufacturing wastewater. In the first column packed with hypercrosslinked polymeric resin (NDA-99), most m-cresol was captured through π-π and hydrogen-bonding interactions as well as the salting-out effect, while m-toluidine was not absorbed due to protonation. To separate acid from salt, an acid retardation unit was introduced successively to adsorb sulfuric acid by strong base anion exchange resin (201×7). After the acid retardation unit and mild neutralization reaction, the last column filled with NDA-99 was applied to trap neutral m-toluidine from the salty effluent. Moreover, the eluent of the acid retardation unit was utilized as the regenerant to recover m-toluidine, and the recycled high-acidity and low-salinity solution of m-toluidine was directly used to produce m-cresol as the raw material. Therefore, the proposed method not only efficiently recycled m-cresol and m-toluidine, but also reduced the consumption of alkali dramatically (saving 0.1628t/t wastewater). These findings will inspire design of integrated adsorptive techniques for treating complex organic wastewater with high efficiency and low cost.

A Mechanistic Integrated Geochemical and Chemical-Flooding Tool for Alkaline/Surfactant/Polymer Floods

SummaryMechanistic simulation of alkaline/surfactant/polymer (ASP) flooding considers chemical reactions between the alkali and the oil to form in-situ soap and reactions between the alkali and the minerals and brine. A comprehensive mechanistic modeling of such process remains a challenge, mainly caused by the complicated ASP phase behavior and the complexity of geochemical reactions that occur in the reservoir. Because of the lack of the microemulsion phase and/or lack of reactions that may lead to the consumption of alkali and resulting lag in the pH, a simplified ASP phase behavior is often used.A state-of-the-art geochemical package, IPhreeqc, of the United States Geological Survey was coupled with UTCHEM, an in-house research chemical-flooding reservoir simulator developed at The University of Texas at Austin (UT), for a robust, flexible, and accurate integrated tool to mechanistically model ASP floods. UTCHEM has a comprehensive three-phase (water, oil, microemulsion) flash package for the mixture of surfactant and soap as a function of salinity, temperature, and cosolvent concentration.Through this integrated tool, we are able to simulate homogeneous and heterogeneous (mineral dissolution/precipitation), irreversible, surface complexation, and ion exchange reactions under nonisothermal, nonisobaric, and both local-equilibrium and kinetic conditions. Italic words are defined in Appendix A. IPhreeqc has rich databases of chemical species and also the flexibility to include the alkaline reactions required for modeling ASP floods. Hence, to the best of our knowledge, for the first time, the important aspects of ASP flooding are considered.An algorithm is presented for modeling the geochemistry in an implicit-in-pressure-and-explicit-in-concentration solution algorithm. Finally, we show how to apply the integrated tool, UTCHEM-IPhreeqc, to match three different reaction-related chemical-flooding processes: ASP flooding in an acidic active crude oil, ASP flooding in a nonacidic crude oil, and alkaline/cosolvent/polymer flooding.

Evaluation of Lignin Syringyl/Guaiacyl Ratio inEucalyptus Camaldulensisacross Three Diverse Sites Based on near Infrared Spectroscopic Calibration Modelling with FiveEucalyptusSpecies and its Impact on Kraft Pulp Yield

Lignin composition [syringyl/guaiacyl (S/G) ratio] and cellulose content in wood have an important bearing on pulp yield. This paper deals with the development of a calibration model for S/G ratio using five Eucalyptus species from different sites by diffuse reflectance near infrared spectroscopy. The model was constructed with 120 samples covering an S/G ratio range from 1.8 to 3.6, determined by pyrolysis-gas chromatography-mass spectrometry. The calibration plot has an R2value of 0.825 which was validated in E. camaldulensis, E. urophylla and E. pellita. Variation in S/G ratio was studied in more than 3000 E. camaldulensis trees across three diverse sites in southern India. The S/G ratio was lower in a low rainfall site (Mahabubnagar) compared to a higher rainfall site (Ongole). A positive correlation ( R2= 0.72) was observed between S/G ratio and Kraft pulp yield in E. camaldulensis. Alkali consumption in Kraft pulping experiments was inversely proportional to the S/G ratio ( R2= 0.914).

Modified Rice Straw as Adsorbent Material to Remove Aflatoxin B1 from Aqueous Media and as a Fiber Source in Fino Bread.

The aims of the current work are in large part the benefit of rice straw to be used as adsorbent material and natural source of fiber in Fino bread. The rice straw was subjected to high temperature for modification process and the chemical composition was carried out and the native rice straw contained about 41.15% cellulose, 20.46% hemicellulose, and 3.91% lignin while modified rice straw has 42.10, 8.65, and 5.81%, respectively. The alkali number was tested and showed an increase in the alkali consumption due to the modification process. The different concentrations of modified rice straw, aflatoxin B1, and pH were tested for removal of aflatoxin B1 from aqueous media and the maximum best removal was at 5% modified rice straw, 5 ng/mL aflatoxin B1, and pH 7. The modified rice straw was added to Fino bread at a level of 5, 10, and 15% and the chemical, rheological, baking quality, staling, and sensory properties were studied. Modified rice straw induced an increase of the shelf life and the produced Fino bread has a better consistency.

Effect of shortening kraft pulping integrated with extended oxygen delignification on biorefinery process performance of eucalyptus

The aim of this work was to study the impact of shortening kraft pulping (KP) process integrated with extended oxygen delignification (OD) on the biorefinery process performance of eucalyptus. Data showed that using kraft pulps with high kappa number could improve the delignification efficiency of OD, reduce hexenuronic acid formation in kraft pulps. Pulp viscosity for a target kappa number of ∼10 was comparable to that obtained from conventional KP and OD process. The energy and alkali consumption in the integrated biorefinery process could be optimized when using a KP pulp with kappa number of ∼27. The process could minimize the overall methanol formation, but greater amounts of carbonate and oxalate were formed. The information from this study will be helpful to the future implementation of short-time KP integrated with extended OD process in actual pulp mill applications for biorefinery, aiming at further improvement in the biorefinery effectiveness of hardwood.

Feasibility and mechanism of compound flooding of high-temperature reservoirs using organic alkali

Abstract The technical feasibility of using organic alkali instead of an inorganic one during alkaline/surfactant/polymer (ASP) flooding in a heterogeneous reservoir under a high temperature of 95 °C in China was investigated. Laboratory experiments were performed to evaluate the alkali consumption, adsorption, and retention in formation and its formation damage. Also viscosity of the ASP compound flooding system, oil/water interfacial tension, and chromatographic separation were investigated. A comparison of results obtained through organic alkali with those obtained from inorganic alkali was conducted to evaluate the flooding effect of this system, and the mechanism of increasing recovery ratio was analyzed. Experimental results indicated that the consumption and dynamic adsorption of ethanolamine and formation damage observed through the organic alkali were significantly lower than those observed through the inorganic alkali. When compounded with the surfactant, ethanolamine could further decrease the oil/water interfacial tension. Moreover, ethanolamine exerted a protective effect on the surfactant, thereby decreasing adsorption loss. A flooding experiment with a 5-spot pattern was performed on a heterogeneous reservoir. Findings revealed that the organic ASP (OASP) compound flooding system achieves good displacement effects and mobility control even under high temperature conditions and significantly improved recovery ratios. As such, the proposed method is feasible for compound flooding in high-temperature reservoirs. The mechanism of OASP compound flooding was discussed to provide a theoretical basis for optimizing compound flooding systems for high-temperature heterogeneous reservoirs.

Correlation of CsK2Sb photocathode lifetime with antimony thickness

CsK2Sb photocathodes with quantum efficiency on the order of 10% at 532 nm, and lifetime greater than 90 days at low voltage, were successfully manufactured via co-deposition of alkali species emanating from an effusion source. Photocathodes were characterized as a function of antimony layer thickness and alkali consumption, inside a vacuum chamber that was initially baked, but frequently vented without re-baking. Photocathode lifetime measured at low voltage is correlated with the antimony layer thickness. Photocathodes manufactured with comparatively thick antimony layers exhibited the best lifetime. We speculate that the antimony layer serves as a reservoir, or sponge, for the alkali.

Se‐catalyzed process of sodium bisulfite disproportionation

AbstractBACKGROUNDSO2 is an important gaseous pollutant that seriously affects the environment and human health. The most common method for SO2 removal is absorption by NaOH solution and then forming HSO3−. Since generation of high‐value products and reduction of alkali consumption are important for the economy and practical application, selenium‐catalyzed HSO3− disproportionation was developed in this study.RESULTSSelenium decreased the reaction temperature of HSO3− disproportionation from >433 K to 343 K. The effects of HSO3− concentration, temperature, selenium dosage, and stirring intensity were investigated. Selenium could be used at least five times with stable catalytic performance, indicating satisfactory reusability. More importantly, a catalytic mechanism was proposed using dynamic light scattering, differential scanning calorimetry and UV‐visible transmittance spectrophotometry. Results showed that selenium‐catalyzed HSO3− disproportionation experienced a solid–liquid–solid phase transformation process. During this process, SeSO32− and HSe− were identified as the intermediates. Furthermore, products, i.e. sulfur and sodium bisulfate, were characterized to demonstrate their structure and composition.CONCLUSIONSelenium was an efficient catalyst for HSO3− disproportionation. This catalytic process offered the advantages of less consumption of alkali and production of high‐valuable products, and thus was a potential alternative to other technology for SO2 removal in practical applications. © 2015 Society of Chemical Industry

Microwave induced reactive base wash for the removal of oxidation debris from carboxylated carbon nanotubes

Removal of oxidation debris for generating high purity functionalized carbon nanotubes (CNTs) has been a challenge, where base washing has been found to be an effective purification treatment. In this paper we report microwave induced reactive base wash (MRW) as a fast, green alternate to conventional filtrate washing. Carboxylated CNTs of three different dimensions were subjected to MRW and the results were compared to conventional base-wash. The results showed that MRW was an effective method for the removal of oxidation debris which reduced the reaction time from 4h to 20min and alkali consumption by 75%. The CNTs from MRW were similar to those from conventional base wash in terms of dimensions, elemental composition, BET surface area and colloidal stability in aqueous media.

СОСТАВ ЭКСТРАКТОВ ЛУБА КОРЫ БЕРЕЗЫ

Planned experiment was done with variation of three parameters: the concentration of alcohol KOH and liquid flow module. Extraction was carried out in a microwave field.The effect of alkali consumption and the concentration of ethanol in the extract yield bast birch bark in the alcohol-alkaline treatment. It is noted that reducing the concentration of ethyl alcohol and alkali consumption increases yield of extractives (EW) increases. It is shown that the larger the alkali is used in the processing of the feedstock, the increasing its content in the solid residue formed excessive alkali content in the phloem after extraction. It has been found that the amount of free alkali in the solid phase is significantly less than in the extract. No clear relationship alkali content in the extracts from the amount of the alkali used for the experiments. Get adequate regression equations of the alkali content in the extract and a solid residue.Study the chemical composition of an alcohol-alkali bast birch bark extracts obtained after microwave extraction. A selective analysis of the obtained extracts. Standard chromatograms obtained mixture phenolic compounds and one of the extracts of the samples. Presented calibration dependence of the integral intensity of the chromatographic signal (S) the concentration c (mg / dm3) of analytes. Results of investigation of the compounds detected in the content of the extracts.

Kinetic leaching of high sulphur mine rejects amended with biochar: Buffering implication

In the present investigation, the effect of biochar incorporation into high sulphur mine rejects on buffering of the acid production was assessed. For this, kinetic experiments on pure mine rejects (LMR) and biochar amended mine rejects (LMRBC) were performed for 720h. Leachate samples were collected at 0, 20, 40, 60, 168, 336, 504 and 720h and characterized. Results revealed that incorporation of biochar inhibited the acid production rate (from 10.4kg/Mt/h to 3.81kg/Mt/h) and enhanced the alkali consumption (from 9.7kg/Mt/h to 13.9kg/Mt/h). Biochar was capable to neutralize all the acid produced. As a neutralizing agent, Mg2+ dominated over Ca2+. The efficiency of biochar to reduce the rate of acid production may be due to either the reduction in Fe3+ concentration or production of reduced sulphur compounds in reducing conditions of biochar. This is also supported by molar sulphur to iron ratio of leachate water. Principal component analysis applied on the data revealed that biochar altered the salt and carbon dissolution processes of mine rejects. It inhibits the acid production and accelerates the alkali releasing.