Addition Of Sodium Carbonate Research Articles

Promoting the grinding of wheat bran through treatment by sodium carbonate and its mechanism

This work investigated the effect of treatment by sodium carbonate on grinding of wheat bran and the related mechanism. Specifically, wheat bran was treated by sodium carbonate solutions at the ratio of 1:2 to make addition of sodium carbonate at 0.0%, 4.0%, 8.0%, 12.0%, 15.0%, and 30.0% based on the mass of bran, dried, and ground using the universal high-speed grinder. It was found that treatment by sodium carbonate significantly reduced the particle size of ground bran and this effect was positively correlated with the sodium carbonate content, which suggested that treatment by sodium carbonate promoted the grinding of wheat bran. Besides, treatment by sodium carbonate improved the hardness of bran. On the other hand, treatment by sodium carbonate damaged the crystal structure, the cell wall and lignin of bran. Moreover, treatment by sodium carbonate converted bound phenolics, including ferulic acid, into free phenolics and insoluble dietary fiber, including unextractable arabinoxylan, into soluble dietary fiber. These results suggested that treatment by sodium carbonate had already damaged the structure of bran and altered the texture of bran before the mechanical stress during grinding was applied. As a result, treatment by sodium carbonate promoted the grinding of wheat bran.

Effective Removal of Arsenic from Copper Matte by Sodium Carbonate

Residual arsenic in copper matte is a source of arsenic contamination in subsequent processes in the smelting section of copper pyrometallurgy. In order to solve the impact of arsenic in copper matte on the subsequent process of smelting, this study removes arsenic from copper matte by adding an arsenic removal agent to the molten copper matte. The results show that the most difficult arsenic phase in copper matte is the residual arsenic in copper-arsenic alloys, based on which sodium carbonate was selected as the arsenic removal agent. The arsenic content in the copper matte was reduced by 98% under the optimal experimental conditions of a reaction temperature of 1250 °C, 4% sodium carbonate addition, and a reaction time of 60 min. The experimental results of the reaction mechanism show that sodium carbonate plays two main roles in the process of removing the intractable residual arsenic in copper matte. One is that sodium carbonate has a low melting point, which enhances the fluidity of the reactants. The other is that it can provide oxygen to the reaction system and convert arsenic in the copper-arsenic alloy into gaseous arsenic and arsenate. This study can provide new ideas for controlling arsenic pollution in copper pyrometallurgy.

Bioactivity of Amphidinol-Containing Extracts of Amphidinium carterae Grown Under Varying Cultivation Conditions.

Microalgae are of great interest due to their ability to produce valuable compounds, such as pigments, omega-3 fatty acids, antioxidants, and antimicrobials. The dinoflagellate genus Amphidinium is particularly notable for its amphidinol-like compounds, which exhibit antibacterial and antifungal properties. This study utilized a two-stage cultivation method to grow Amphidinium carterae CCAP 1102/8 under varying conditions, such as blue LED light, increased salinity, and the addition of sodium carbonate or hydrogen peroxide. After cultivation, the biomass was extracted and fractionated using solid-phase extraction, yielding six fractions per treatment. These fractions were analyzed using Liquid Chromatography-High-Resolution Mass Spectrometry (LC-HRMS/MS) to identify their chemical components. Key amphidinol compounds (AM-B, AM-C, AM-22, and AM-A) were identified, with AM-B being the most abundant in Fraction 4, followed by AM-C. Fraction 5 also contained a significant amount of AM-C along with an unknown compound. Fraction 4 returned the highest antimicrobial activity against the pathogens Staphylococcus aureus, Enterococcus faecalis, and Candida albicans, with Minimal Biocidal Concentrations (MBCs) ranging from 1 to 512µg/mL. Results indicate that the modulation of both amphidinol profile and fraction bioactivity can be induced by adjusting the cultivation parameters used to grow two-stage batch cultures of A. carterae.

Preparation of polymeric aluminum chloride from secondary aluminum dross and its water purification effect

ABSTRACT Aluminum dross is solid waste generated by the aluminum industry. Currently, a large amount of aluminum dross is produced annually year. Aluminum dross, a hazardous waste, contains harmful substances such as aluminum metal, aluminum nitride, fluoride and chlorine salts, which pose a serious threat to human health and also cause damage to the ecological environment. Thus, it is important to recycle secondary aluminum dross and realise its high-value utilisation. Polymeric aluminum chloride (PAC) is a polymer flocculant, at present, China's annual use of PAC in the field of water treatment is about 5 × 105 t, and with the continuous improvement of water purification requirements, the annual use of PAC increased year by year. Here secondary aluminum dross was used as a raw material to prepare PAC by hydrochloric acid (HCl) leaching, followed by the addition of sodium carbonate. The optimal conditions for the acid leaching of secondary aluminum dross for the preparation of PAC were as follows: HCl concentration, 18%; liquid-to-solid ratio, 4.5:1; stirring rate, 200 r/min; reaction temperature, 90 °C; and 60 min. An aluminum leaching rate of 85.5% was obtained under these conditions. The results showed that the acid leachate after adding sodium carbonate, under the conditions of polymerisation temperature of 70 °C, polymerisation time of 6 h, and polymerisation pH value of 3.0, the PAC prepared had an alumina content of 10.19%, salinity of 32.37%, density of 1.32 g/cm3, 1% aqueous solution pH 4.3. The water purification effect of the prepared PAC surpassed that of the commercially available PAC. The utilisation of secondary aluminum dross can reduce the environmental pollution caused by aluminum slag.

In-syringe homogeneous liquid–liquid microextraction as an economical, convenient, and one-step analytical method for the extraction and preconcentration of five plasticizers and one antioxidant from different city tap water samples

In this study, an analytical method called in-syringe homogeneous liquid–liquid microextraction was developed and applied for the extraction and preconcentration of plasticizers including di ethyl phthalate, di isobutyl phthalate, di-n-butyl phthalate, di(2-ethylhexyl) adipate, and di(2-ethylhexyl) phthalate and one antioxidant, (butylated hydroxytoluene). Only a few microliters of dibutyl amine was used as the extraction solvent. This switchable solvent became miscible in the solution of interest by adding acetic acid at µL-level to extract the analytes. Also, the addition of sodium carbonate (in mg-level) into the solution led to the release of carbon dioxide, which facilitated the extraction of plasticizers into the extractant. Also, sodium carbonate caused to the regeneration of the extractant in the upper narrow bore of the syringe. The enriched analytes were determined by a gas chromatographic equipped with a flame ionization detector. Under the optimum conditions, extraction recoveries and enrichment factors were obtained in the ranges of 39–78 % and 196–394, respectively. Also, the limits of detection and quantification were in the ranges of 1.76–12.51 µg/L and 5.80–41.28 µg/L, respectively, and the r2 values were equal to or better than 0.991. Development of the method as a one-step analysis processed which was electrically independent in extraction and preconcentration stage (no centrifugation or vortexing) and inexpensive. The use of only µL-level of organic solvent, convenient operation, and short extraction time are the other highlights of the method. This method was successfully applied to the extraction, preconcentration, and determination of several plasticizers in eight different city water samples.

Addition of sodium carbonate to reinforce unglazed ceramic tile

Nowadays, the study of the improvement of mechanical properties is of great importance in the ceramic industry. The strenuous demand to which industrial processes are subjected leads to the search for new raw materials in the production lines that transfer superior characteristics to the finished product, standing out in the search for non-synthetic raw materials of mineral origin that contribute greater savings when added to the manufacturing process of the material. This study is focused on the use of sodium carbonate as an alternative raw material in the process of making ceramic tiles, sodium carbonate was obtained from two sources, one synthetic (soda ash) and the other mineral (trona). Within the research, additions of 0.15, 0.30, 0.45% of soda (Na2CO3) and 0.30, 0.60 and 0.90% of trona were made in the formulation of the ceramic body and properties such as density, compressive strength and modulus of rupture were evaluated. The results obtained indicate an improvement of up to 65% in the compressive strength when adding 0.9% of the trona and a 30% increase in the modulus of rupture thanks to the insertion of sodium carbonate.

Insights on the effects of carbonates and phosphates on the hydration of magnesia (alumino-)silicate cements

Cements based on magnesium oxide (MgO) and reactive (alumino-)silicates (xSiO2-yAl2O3) have drawn increasing attention owing to their potential to be produced using raw materials with low CO2 emissions. This study examines how the phase assemblages and compressive strengths of magnesia (alumino-)silicate cements are influenced by the addition of sodium hexametaphosphate (NaHMP) and sodium carbonate (Na2CO3). Cement paste samples with a Mg/Si molar ratio of 1.5 and Al/Si molar ratios of 0 and 1.0 were prepared using microsilica (SF) and metakaolin (MK), respectively, and investigated using SEM, TGA, XRD, and 29Si, 27Al, 31P, and 13C MAS NMR. The results showed that the addition of NaHMP and sodium carbonate enhanced the reactivity of the raw materials in the Al-free MgO-SF systems, with magnesium silicate hydrate (M-S-H) being the primary hydrated phase. After 91 days, the degrees of reaction of microsilica were ∼86% and 96% for systems containing 0 and 2.5 wt % Na2CO3, respectively. In contrast, the reactivity of metakaolin in the Al-containing MgO-MK systems was limited to ∼53%, irrespective of Na2CO3 addition, likely due to the excess sodium hexametaphosphate covering the surface of MK. Here, the main reaction products were magnesium aluminosilicate hydrate (M-A-S-H) and hydrotalcite (Mg6Al2CO3(OH)16·4(H2O))-like phases. Despite the MgO-SF systems displaying higher degree of reaction than the MgO-MK systems, the latter exhibited higher compressive strength. Sodium carbonate increased the compressive strength of the MgO-SF systems but decreased that of the MgO-MK systems. Thermodynamic modelling was also carried out and the results generally agreed with the phase formation observed with XRD and solid-state NMR.

Catalytic pyrolysis and in situ carbonization of walnut shells: poly-generation and enhanced electrochemical performance of carbons.

In this study, walnut shell (WS) was used as feedstock, incorporating lithium carbonate (LC), sodium carbonate (SC), potassium carbonate (PC), and potassium hydroxide (PH) as pyrolysis catalysts and carbonization activators. A one-step method that allows catalytic pyrolysis and carbonization to be carried out consecutively under their respective optimal conditions is employed, enabling the concurrent production of high-quality pyrolysis oil, pyrolysis gas, and carbon materials from biomass conversion. The effects of LC, SC, PC, and PH on the yield and properties of products derived from WS pyrolysis as well as on the properties and performance of the resulting carbon materials were examined. The results indicated that the addition of LC, SC, PC, and PH enhanced the secondary cracking of tar, leading to increased solid and gas yields from WS. Additionally, it increased the production of phenolic compounds in bio-oil and H2 in syngas, concurrently yielding a walnut shell-based carbon material exhibiting excellent electrochemical performance. Specifically, when PC was used as an additive, the phenolic content in the pyrolysis oil increased by 27.64% compared to that without PC, reaching 74.9%, but the content of ketones, acids, aldehydes, and amines decreased. The hydrogen content increased from 2.5% (without the addition of PC) to 12.75%. The resulting carbon (WSC-PC) displayed a specific surface area of 598.6 m2 g-1 and achieved a specific capacitance of 245.18 F g-1 at a current density of 0.5 A g-1. Even after 5000 charge and discharge cycles at a current density of 2 A g-1, the capacitance retention rate remained at 98.16%. This method effectively enhances the quality of the biomass pyrolysis oil, gas, and char, contributing to the efficient and clean utilization of biomass in industrial applications.

Prediction of Methyl Orange (MO) Toxicity and Minimizing Its Pollution in Aquatic Environment by Activated Carbon Adsorption

Minimizing environmental pollution is an essential work of the official and scientific communities around the world, especially in water systems. In water, soluble dye works as a blockage in photosynthesis process because of its toxicity. One of these highly applicable dyes in industry is Methyl Orange (MO), documented with more than 10% released to water. Here, a new Iraqi try of converting environmental and health problems to solutions with high quantification was as done by using face tissue (Kleenex) as a carbon source. Primary in Silico testing of this anionic dye (Methyl Orange) was done based on online website confirmed MO dye is unsafe in several toxicological determinations such as foetus health (during pregnancy). Also, it is permeable material to skin, Blood- Brain system (BBB), and Human Colon Carcinoma cell line (CaCO2) compatible with Human Intestinal absorption (74.166%). In experimental section, low quality of face tissue (Kleenex) was subject to a high acidic medium (concentrated sulphuric acid), followed by addition of sodium carbonate to .increase activation of based carbon material with more structural pores yielding high removal efficiency and adsorption capacity ranged (88-98)% and (88-98) mg/g respectively. Qualitative and quantitative evaluations were based upon choosing two wavelengths in ultraviolet (272 nm) and visible (464 nm) regions. In this work, two removal steps were performed with the same adsorbent companied by multiple UV-Vis spectroscopic evaluation of several tested sections. Reviewing of published papers in MO removal presents the extraordinary performance of this prepared material towards using it as an excellent adsorbent of toxic material in aqueous solution.

Characterization of solids obtained from calcium and magnesium precipitation by sodium carbonate addition

The addition of sodium carbonate (Na2CO3) to the flotation water of complex sulfide ores is a strategy implemented to mitigate the adverse effect of calcium and magnesium present in the process water of complex sulfide flotation. These contaminating agents are due to the use of lime as pH regulator and to the presence in the ore of magnesium species. Na2CO3 is added with the aim of precipitating Ca2+ and Mg2+ as carbonates. In the case of calcium, it precipitates CaCO3, which has been identified by XRD as calcite and vaterite. In the case of magnesium, the precipitating solid is of amorphous nature. In order to identify the chemical nature of magnesium precipitates, thermogravimetric analysis was carried out. Additionally, the solids were analyzed by SEM–EDS to support the observations. The results suggest that the amorphous solid may consist of a hydrated basic magnesium carbonate, precursor of hydromagnesite (Mg5(CO3)4(OH)2·4H2O).Graphical abstract

A kinetic and thermodynamic study of the removal of calcium and magnesium from aqueous solutions similar to those of complex sulphide flotation by the addition of sodium carbonate

ABSTRACT The use of recycled water in flotation has a negative impact on flotation of sulphide mineral species because these waters contain chemical species that affect the recovery and selectivity of the process. This study aims to study the reaction mechanism between aqueous calcium and magnesium sulphate contained in the water released by complex sulphide flotation process, and the carbonate ions added to the water as sodium carbonate (Na2CO3). The addition of Na2CO3 has been shown to have a positive effect on the recovery and grade of the final Pb-Cu concentrate obtained, but the reasons of this are not yet fully understood. The present study was conducted by adding Na2CO3 to a saturated gypsum solution containing Mg(II). Analytical techniques such as XRD, TGA and zeta potential measurements were used to characterise the obtained solids. It was observed that the addition of Na2CO3 favoured the precipitation of the Ca(II) as calcite and vaterite. The reaction kinetics was found to be of second-order. In the case of magnesium alone, the precipitates are amorphous. This study provides new information on the reaction mechanism between metal ions and carbonates. The information collected can help design processes for the removal of ions from flotation water.

Sustainable mainstream deammonification by ion exchange and bioregeneration via partial nitritation/anammox

The partial nitritation and anammox (PN/A) process has gained popularity for the treatment of nitrogen removal in wastewater due to significant energy savings and its potentially much lower CO2 footprint. However, the treatment of mainstream municipal wastewater by PN/A has been limited mainly due to its unsuitable composition. In this research, we apply ion exchange using a zeolite column to selectively remove and concentrate ammonium from mainstream municipal wastewater. After an absorption phase, the ion exchange column is regenerated using a brine solution. The ammonium rich brine is “bioregenerated” in a PN/A reactor where ammonium is converted to nitrogen gas allowing the brine to be reused in another cycle of ion exchange regeneration. To successfully remove ammonium from the spent brine, anammox and ammonia oxidizing bacteria (AOB) were first cultivated in separate reactors under hypersaline conditions (4.0 %) and later combined in a single PN/A reactor. After continuous operation with sea water, the PN/A reactor treated recirculating brine from the ion exchange column for 48 cycles of ammonium absorption and bioregeneration with minimal blowdown. The various cations of the regenerant solution were stable except for calcium that reached very high values upwards of 3000 mg/L as Ca2+ and finally caused PN/A reactor failure due to mineral precipitation. The buildup of high concentrations of calcium in the regenerant was addressed in two ways: 1) 20 % regenerant replacement per cycle, and 2) precipitation of CaCO3 via the addition of sodium carbonate. Both methods were applied to 30 absorption and bioregeneration cycles each and shown to be effective in keeping calcium concentrations from accumulating in the regenerant allowing for stable PN/A reactor operation.

Titanium Impurity Control in V-Bearing Pig Iron Prepared via the Sodium Smelting of Vanadium–Titanium Magnetite

The sodium smelting of vanadium–titanium magnetite (VTM) can realize a multi-component comprehensive utilization of VTM. To broaden the application of the vanadium-bearing pig iron produced through this process, it is imperative to maintain the titanium content in molten iron at a very low level. In this study, the effects of temperature, the added amounts of sodium carbonate and anthracite, and the smelting time on the titanium content of molten iron were investigated using thermodynamic calculations and experiments. The results indicate that the introduction of sodium carbonate makes the reduction reaction of VTM a relatively low-temperature smelting system. In the smelting process, the Ti content in molten iron increases with the increase in temperature and decreases with the addition of sodium carbonate, while the amount of anthracite added has little effect on it. The appropriate technological parameters were determined as temperature: 1150–1250 °C, smelting time: ≥2 h, anthracite consumption: 25–35%, and sodium carbonate consumption: ≥60%. In addition, it was determined that the Ti impurities in the V-bearing pig iron were mainly (Ti,V)(C,N), CaTiO3, and Na2TiO3. All results obtained from this work contribute to the comprehensive utilization of VTM, and also provide theoretical support for the sodium smelting of VTM.

Phase-Assisted Tailored Conductivity of Doped Ceria Electrolytes to Boost SOFC Performance.

Efforts to lower the operating temperature of solid oxide fuel cells include producing electrolytes that are sufficiently conductive and stable below 600 °C. Doped ceria is one such electrolyte being considered. During this study, codoped ceria powders (Ce0.8Sm0.2-xMxO2-δ, M = Bi3+, Zn2+ and x = 0, 0.05, 0.1, 0.15, 0.2) were prepared via coprecipitation by the addition of sodium carbonate and annealed at 800 and 1200 °C, respectively. Poor solubility of the codopants in the ceria was observed for samples annealed at 800 °C, resulting in a mixed-phase product including stable phases of the oxides of these codopants. A second-stage partial incorporation of these codopants into the ceria lattice was observed when the annealing temperature was increased to 1200 °C, with both codopants forming cubic-type phases of their respective oxides. Materials were characterized using X-ray diffraction (XRD), Raman spectroscopy, and Fourier transform infrared spectroscopy (FTIR), as well as scanning electron microscopy (SEM) for structural and morphological investigations. The oxide ion conductivity was evaluated using electrochemical impedance spectroscopy between 550 and 750 °C. Fuel cell performance tests of selected samples (annealed at 1200 °C) showed remarkable improvement in peak power densities when the test temperature was increased from 500 to 600 °C (∼720 mW/cm2 for Ce0.8Sm0.15Bi0.05O2-δ and ∼1230 mW/cm2 for Ce0.8Sm0.15Zn0.05O2-δ), indicating possible contribution from the distinct cubic-type oxide phases of the codopants in performance enhancement.

Utilization of carbide slag in autoclaved aerated concrete (CS-AAC) and optimization: Foaming, hydration process, and physic-mechanical properties

Autoclaved aerated concrete (AAC), a lightweight porous material, has been widely used in the building field because of its energy savings. A solid waste called carbide slag with a high Ca(OH)2 content is a potential substitution for CaO to prepare AAC. In this study, carbide slag was used to replace quicklime to prepare carbide slag-based autoclaved aerated concrete (CS-AAC). The temperature, foaming rate, and rheological properties of the slurry during the foaming stage, the strength of the rough body, and the physical and mechanical properties of the autoclaved products were investigated. Hydration products, microstructure, and pore structure were further analyzed to investigate the mechanisms of carbide slag on the properties of AAC, and the use of sodium carbonate (SC) to improve the performance of CS-AAC was explored. The results show that the addition of carbide slag causes a degradation of the properties, including foaming rate and physic-mechanical properties. The “water locking” effect due to the irregular surface of the carbide slag results in an increase in slurry consistency. The increase in slurry consistency, as well as the decrease in slurry temperature is the main reason for the decrease in slurry foaming rate and roundness of bubbles, which are unfavorable for the strength development of AAC. Due to the alkali excitation characteristics of sodium carbonate. The addition of SC can react with Ca(OH)2 in the slurry to produce OH-, to promote cement hydration, which can accelerate the development of rough body strength, and save pre-curing time. The carbide slag-based AAC with 0.25% SC has a significant improvement in foaming properties and facilitates the generation of more C-S-H gels to form tobermorite under hydrothermal conditions, which improves the AAC properties. However, too much SC can consume a large amount of Ca(OH)2 and affects the production of tobermorite, which is not beneficial to the mechanical properties.

Thermal analysis and isothermal reduction kinetics of alkaline hematite in an advanced suspension roaster

The reduction kinetics of hematite in alkaline environment has not been studied. In this paper, the possible chemical reactions in the process of iron extraction from red mud by suspension magnetization roasting were systematically calculated and analyzed, and the isothermal kinetic analysis of reduction reaction of the Na2O-Fe2O3-CO system was investigated. The results showed that Fe3O4 would be over-reduced to FeO or Fe easily if the CO concentration was high. The best kinetics model for Na2O-Fe2O3-CO system was the D6 model, the corresponding mechanism function was F(α) = [1− (1 − α)1/3]2 = kt, the pre-exponential factor (A) was 639051.29 min−1, the apparent activation energy (Eα) was 122.05 kJ/mol. The diffusion of CO in hematite was the restrictive step, and the addition of sodium carbonate hindered the reduction process of hematite. This research provides an important insight into the efficient and clean reduction of hematite in red mud.

Inhibition of Localized Corrosion of Ni–Ti Superelastic Alloy in Sodium Hypochlorite Solution by Sodium Carbonate Addition

Inhibition of Localized Corrosion of Ni–Ti Superelastic Alloy in Sodium Hypochlorite Solution by Sodium Carbonate Addition

Influence of Reinforcing Efficiency of Clay on the Mechanical Properties of Poly(butylene terephthalate) Nanocomposite

In contrast to traditional fillers, clay, in particular, natural smectite clay, represents an environmentally significant alternative to improve the properties of polymers. Compared to conventional nanofillers, smectite clay can effectively enhance the physical and mechanical properties of polymer nanocomposites with a relatively small amount of addition (<5 wt%). The present study focuses on investigating the reinforcing efficiency of different amounts (up to 5 wt%) of a natural Brazilian smectite clay modified (MBClay) on the mechanical properties of poly(butylene terephthalate) (PBT) nanocomposites and also evaluates the correlation between MBClay addition and the mechanical and thermal behaviors of the PBT/MBClay nanocomposites. Natural Brazilian clay modified by the addition of quaternary salt and sodium carbonate (MBClay) was infused into the PBT polymer by melt extrusion using a twin-screw extruder. It was found that the best properties for PBT were obtained at 3.7 wt% of modified BClay. Tensile strength at break exhibited increased by about 60%, flexural strength increased by 24%, and flexural modulus increased by 17%. In addition, an increase in the crystallinity percentage of PBT/BClay nanocomposite was confirmed by DSC and XRD analysis, and a gain of about 45% in HDT was successfully achieved due to the incorporation of 3.7 wt% of MBClay.

Pyrolysis of Denim Jeans Waste: Pyrolytic Product Modification by the Addition of Sodium Carbonate.

Quickly changing fashion trends generate tremendous amounts of textile waste globally. The inhomogeneity and complicated nature of textile waste make its recycling challenging. Hence, it is urgent to develop a feasible method to extract value from textile waste. Pyrolysis is an effective waste-to-energy option to processing waste feedstocks having an inhomogeneous and complicated nature. Herein, pyrolysis of denim jeans waste (DJW; a textile waste surrogate) was performed in a continuous flow pyrolyser. The effects of adding sodium carbonate (Na2CO3; feedstock/Na2CO3 = 10, weight basis) to the DJW pyrolysis on the yield and composition of pyrolysates were explored. For the DJW pyrolysis, using Na2CO3 as an additive increased the yields of gas and solid phase pyrolysates and decreased the yield of liquid phase pyrolysate. The highest yield of the gas phase pyrolysate was 34.1 wt% at 800 °C in the presence of Na2CO3. The addition of Na2CO3 could increase the contents of combustible gases such as H2 and CO in the gas phase pyrolysate in comparison with the DJW pyrolysis without Na2CO3. The maximum yield of the liquid phase pyrolysate obtained with Na2CO3 was 62.5 wt% at 400 °C. The composition of the liquid phase pyrolysate indicated that the Na2CO3 additive decreased the contents of organic acids, which potentially improve its fuel property by reducing acid value. The results indicated that Na2CO3 can be a potential additive to pyrolysis to enhance energy recovery from DJW.

Selective H2S Absorption Using the Mixture of NaOH-NaHCO3-Na2CO3 Buffer Solvent Solution

Acid gas enrichment unit (AGEU) involves selective separation of H2S from acid gas mixture, for example using absorption with an NaOH solvent solution. Sodium carbonate (Na2CO3) and sodium bicarbonate (NaHCO3) buffer addition to NaOH solution suppresses CO2 absorption, thereby increasing the selectivity of H2S absorption. This study evaluated the effect of buffer addition to increase H2S absorption selectivity using an NaOH solution. It was shown that both buffer addition and L/G ratio decrease could increase H2S selectivity by limiting CO2 absorption. Based on the simulation results, in the 0.006 to 0.030 L/G ratio range and NaOH solvent concentration greater than 2%-mass, the addition of NaHCO3 with mass ratio greater than 1.5:1 to NaOH and the addition of Na2CO3 at 1.26 times NaHCO3’s mass increased H2S absorption selectivity up to 17.3%. The combination of an L/G ratio of 0.006 and solvent with a composition of 5%-mass NaOH, 15%-mass NaHCO3, and 18.9%-mass Na2CO3 produced the highest H2S selectivity of 23.1 (379.7% H2S selectivity increase).