Solution Of CaO Research Articles

Extraction of natural dyes from tarum leaves (Indigofera Tinctoria L.) using the Ultrasound-Assisted Extraction (UAE) method

The rapid development of the textile industry has led to increased use of synthetic dyes. Although synthetic dyes are more practical and economical, their use can have adverse effects on health and the environment. Natural dyes are utilized as alternatives with indigo leaves (Indigofera tinctoria L.) being one source known for producing a blue color. However, the commonly used extraction methods require long extraction times and significant solvent consumption. Given the limitations of current methods, innovation is needed for an efficient extraction method that produces safe and environmentally friendly natural dyes, one of which is ultrasound-assisted extraction (UAE). Therefore, this study aims to determine the extraction process of indigo leaves using UAE method, then identify the parameters influencing the extraction process using the UAE, determine the extraction yield using UAE, assess the dyeing results of the extracted dye from indigo leaves on cotton fabric, and compare the extraction results of indigo dye through the UAE method with the addition of CaO and NaOH solutions. The results of this study indicate that the natural dye from Indigofera tinctoria obtained the best conditions at extraction time of 90 min, feed-to-solvent ratio of 0.05 g/ml, and CaO-to-solvent ratio of 0.005 g/ml. Furthermore, the addition of CaO solution obtained the highest yield at 4.25 %, while the addition of NaOH solution resulted in 4.8 %. Additionally, the analysis and test results of the application of natural dye from Indigofera tinctoria on cotton fabric revealed a darker color with the addition of NaOH solution compared to the addition of CaO solution.

Degradation-controlling mechanisms in natural organic acid solutions of CaO–Al2O3–SiO2–B2O3 glass-ceramics by partially substituting Ca2+ with Ba2+ and Sr2+

The degradation of environmentally friendly CaO–Al2O3–SiO2–B2O3 (CASB) glass-ceramics, which consist of anorthite and glass phase, was investigated in three natural organic acid solutions. The results indicated that citric acid had the most significant effect on the degradation of CASB glass-ceramics. While the chemical stability of anorthite is relatively poor, the glass phase also contributed significantly to the effective degradation of CASB glass-ceramics. Subsequently, Ba2+ or Sr2+ was used for full or partial substitution of Ca2+ in CASB glass-ceramics, and the degradation-controlling mechanism of the substituted CASB glass-ceramics was further researched. The full substitution of Ca2+ in CASB glass-ceramics by the two cations resulted in the occurrence of borate [BO4] units in the glass phases, and the interlinkage of [BO4] with broken silicate [SiO4] network structures caused a complementary network effect. Consequently, the degradation of CASB glass-ceramics by organic acids was reduced due to the improvements in the chemical stability of the modified glass-ceramics. Additionally, degradation control can also be achieved based on a mixed-alkali effect, originating from the partial substitution of Ca2+ in CASB glass-ceramics by Ba2+ or Sr2+. The degradable glass-ceramics have the potential to be applied in low-temperature co-fired ceramic technology because of their good physical properties, which include a dielectric constant of 3–5, a dielectric loss as low as 10−3, a coefficient of thermal expansion of 3–9 × 10−6/°C, and an average bending strength of about 47 MPa. Noticeably, the development of the degradable glass-ceramics is helpful to the low-cost and pollution-free recycling of valuable metal electrodes, which is significant for the sustainable development of electronic packaging technologies.

In situ carbonation mediated immobilization of arsenic oxyanions

Arsenic oxyanions in water can pose severe environmental and health concerns due to associated toxic and carcinogen characteristics. In calcareous environment, calcium carbonate polymorphs (PCC) may have a dominant contribution in arsenic oxyanions immobilization and transmission in water. Arsenic oxyanions interaction with calcium of PCC is still controversial with claims of adsorption, incorporation, and precipitation. In present study, co-precipitation and sorption experiments of arsenic oxyanions (V and III) integrated with in situ carbonation of calcium oxide were investigated. Following a thermodynamic investigation to evaluate the probable chemical interactions between Ca2+, As(V/III), and CO32– ions, experiments were undertaken to further investigate various experimental factors impacting arsenic oxyanions solubility. Maximum As(V) and As(III) oxyanions immobilization efficiencies i.e., 97.3 % (0.4 mg) and 86.0 % (2.1 mg) respectively, were observed with CaO dosage (5 g), CO2 flowrate (100 mL Min−1), and solution temperature (60 °C). K-edge X-ray Near Edge Absorption Spectroscopy and Field Emission Scanning Electron Microscopy confirmed the occurrence of adsorbed and incorporated As(V) and As(III) on and within post As(V/III) oxyanions treated calcite crystals. When As(V) oxyanions were present in high concentrations, calcite crystals distorted by rounding the symmetric corners of the crystals, as well as the genesis of vaterite phase due to nucleation hindrance was observed, whereas no such distortions were observed with As(III) oxyanions treated precipitates. In addition, based on the corresponding stable energies, molecular dynamic simulations were used to evaluate the potential Ca2+ - As (V/III) interactions. The mechanism of arsenic oxyanions immobilization was discovered to be the synergistic effect of surface adsorption and incorporation of arsenic oxyanions within calcium carbonate polymorph. Theoretical and experimental results indicate that As(V) has considerably higher interaction propensity with calcite/vaterite formed during in situ carbonation than As(III), implying that calcite might be an important reservoir for arsenic in a variety of geological contexts.

Calcium‐activated geopolymer ceramics: Study of powder calcination and amorphous gel phases

AbstractBurnt coal cinder (BCC), the main solid waste in coal and electric power industries was used to prepare the geopolymer ceramics (GC) in this study. The optimum preparation technology of BCC‐based GC and the effects of calcination and calcification on the compressive strength of BCC‐based GC were studied. Through the calcification of BCC with CaO, NaAlO2 and sodium silicate solution (SS) were separately used as the co‐activator and silica additive to prepare BCC‐based GC. The optimal single‐factor conditions determined by the experiment were BCC:CaO:NaAlO2:SS = 18:3:2:4 (g:g:g:mL) and the liquid–solid ratio was 0.46. The compressive strength of BCC‐based GC was 32.78 MPa (28 days). It was obtained that the calcination of calcified BCC below the temperature of 1000°C can effectively remove the fixed carbon in BCC but will destroy amorphous active aluminosilicate. The microstructure study showed that BCC reacted in the ternary system of Ca–Al–Si to form a variety of amorphous products (C–(A)–S–H and (N, C) –A–S–H). Along with the three‐dimensional amorphous gel structure as the dominant phase, the coexistence and interlacing of various amorphous gels made the microstructure more compact and increased the compressive strength of the BCC‐based GC. GCs with various amorphous phases have been successfully prepared at low temperature, and it also provided a new idea for the utilization of low‐activity silicate solid wastes.

Inhibition of Total Nitrogen Loss in Urine through Integrated Alkali Stabilization and Carbonation

In this paper, total nitrogen (TN) has been recovered from waste diapers through alkaline stabilization as a liquid fertilizer. Nitrogen is one of the most dominant as well as difficult key nutrients to recover from human urine. However, nitrogen can easily be lost in the form of ammonia gas by enzymatic degradation of urea. In this work, a baby diaper has been used as a source of urine which is one of the environmental burdens. The experiment started with synthesizing CaO from the waste shell used to prevent the enzymatic degradation of urea. The waste diaper was soaked in the CaO solution with desired liquid to solid ratio and stirred at 200 rpm. In the present study, three experimental parameters were investigated: CaO dosage (0.05-0.5 M), liquid/solid ratio (L/S) (5-15), and temperature (20-80 ℃). The experimental design and optimization study was conducted by response surface methodology (RSM), Box−Behnken. The urine sample was analyzed for TN before and after the alkaline stabilization process. Initially, 1068.4 ㎎/L of TN was present in the fresh urine obtained from the baby’s diaper. Then, the TN in the stabilized urine increased with time and reached 1631.2 mg/L in 48 hrs whereas in the original urine (without CaO), it reached 606 mg/L within 48 hrs. Moreover, the optimization result highlights that 0.05 M, 40 ℃, and 5 of CaO dosage, temperature, and L/S ratio respectively were the optimized condition for obtaining maximized nitrogen recovery that is 2048.56 mg/L that is 91% recovery. Finally, carbonation of the stabilized urine was conducted to neutralize the pH of the liquid fertilizer solution. Enzymatic urea hydrolysis was not observed although the pH of the stabilized urine was lowered to neutral.

Removal of algae from thermal mud pool: A case study in Koprukoy (Erzurum, Northeast (NE) Turkey) thermal spring area

ABSTRACT. Thermal spring areas, which are available globally, are used for recreational purposes or wellness applications because these areas have mineral-rich materials of thermal water and thermal muds. At the same time, thermal spring areas are one of the best habitats for algae among aquatic habitats. If algae formed on the surface of the thermal water in these areas, they create an ugly appearance and disrupt the aesthetics of the water because of their uncontrolled growth. The algae removal applications are the most effective methods for solution of these adversities in the thermal spring areas. In this work, experimental study was carried out to investigate the removal of algae from thermal water and thermal mud pools in the Delicermic-Koprukoy (Erzurum, NE Turkey) thermal spring area. For this purpose, some chemical materials were used for the removal of algae. The results of the experimental studies showed that the Al2SO3+CaO solution is a good material that provides 100% removal of algae from thermal water and thermal mud pools at pH 6.
 
 KEY WORDS: Algae, Algae removal, Thermal water, Thermal mud, Spring area 
 
 Bull. Chem. Soc. Ethiop. 2022, 36(3), 545-553. 
 DOI: https://dx.doi.org/10.4314/bcse.v36i3.5

A novel approach for lithium recovery from waste lithium-containing aluminum electrolyte by a roasting-leaching process

With the development of secondary resources, development of suitable methods for the recovery of high value metals from solid waste is crucial for sustainable development. Aluminum electrolysis of China, solid waste, such as waste aluminum electrolyte, has been largely idled and caused serious environmental pollution. In this paper, a novel approach is developed for achieving the separation/recovery of lithium from spent lithium-containing aluminum electrolyte by a sodium carbonate roasting–acid leaching process. The effect on the extraction behavior of lithium under different roasting and leaching conditions was systematically studied. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to elucidate the phase evolution. The results indicated that 73.1% of the lithium was obtained under the optimized conditions: a m(actual)/m(theory) ratio of 1.10 with roasting at 850 °C for 2.5 h; a HNO3 solution concentration of 2 mol/L, and a liquid to solid ratio of 10 at 60 °C for 180 min. Through the analysis of the roasting sample, it was found that the addition of Na2CO3 promoted the conversion of Na2LiAlF6 to LiF. The content of lithium in electrolyte significantly reduced from 2.20% to 0.71% after leaching, which made it possible for the residue to be reused as the raw material for the aluminum reduction cell. The leachate was neutralized and purified with CaO and Na2CO3 solution, respectively, and then lithium be recovered in the form of Li2CO3. Overall, this study highlights an effectively and environmentally feasible plan for the treatment of spent aluminum electrolyte and to recycle lithium.

Effect of calcined lime (CaO) on chlamydospores of the rice false smut pathogen, Villosiclava virens, and their root attachment and infection

AbstractRice false smut caused by Villosiclava virens is a devastating disease. The smut balls contain chlamydospores, which fall onto paddy soils to become the primary inoculum. After transplanting, the chlamydospores subsequently germinate and infect rice roots. The application of a CaO‐containing fertilizer to paddy soils can inhibit the development of rice false smut disease; however, the underlying mechanism is unknown. In this study, we evaluated the suppression of chlamydospore behaviour due to CaO. Specifically, we clarified the effects of the following on chlamydospore morphology and germination: (a) pH, (b) calcium (Ca) concentration, (c) Ca concentration (pH adjusted to 6.5), and (d) CaO‐added soil solution. Germination was suppressed at pH 4 and 10, in contrast with the normal germination at pH 6, 7, and 8. Treatments with more than 10 mg/L Ca melted the outer layer of chlamydospores and suppressed germination regardless of whether the pH was adjusted to 6.5. A saturated CaO solution induced bursting of chlamydospores. Suppressed germination and a melted outer chlamydospore layer were also observed, even though the soil buffering effect initially prevented the CaO‐mediated pH increase. Furthermore, the chlamydospores within 15 mm from the CaO small lump exhibited suppressed germination in soil. In addition, there was no effect of CaO treatment on chlamydospore attachment to rice roots and hyphal invasion of rice roots in in vitro inoculation tests. These results suggest that Ca concentration is an important factor for inhibiting the occurrence of rice false smut disease.

Comparison of the Physico-Chemical Properties of Type-B Halal Gelatin from Bovine and Goat Skin Material

In this work aims to compare the physico-chemical properties of gelatin derived from bovine skin and goat skin. Bovine skin and goat skin were cured in 10% CaO solution for 30 days then neutralized using 0.1 N HCl. Extraction was carried out in three stages for 4 hours with different temperature ranges namely 60-80 oC for bovine skin and 60-66 oC for goat skin. Extraction results showed a higher yield of bovine skin gelatin compared to goat skin gelatin which results are in line with ash content. The water content and pH produced tend to be constant. The strength of bovine skin gelatin is lower than that of goat skin gelatin. Whereas the viscosity of bovine skin gelatin is higher. In the goat skin gelatin color parameters have a higher L * value which means it has a lighter color. .

Effect of hydrothermal nanosilica on the performances of cement concrete

A new technological method for producing a nano-modifier for cement concretes from renewable source of hydrothermal solution using the processes of polycondensation of orthosilicic acid and ultrafiltration membrane concentration is proposed. According to the data of dynamic light scattering, tunneling electron microscopy, and low-temperature nitrogen adsorption, it is shown that in sol samples the average diameters of amorphous SiO2 nanoparticles can be varied in the range 10–100 nm, the specific surface area of ​​SBET is 50–500 m2 / g, the density of chemically active surface silanol Si-OH groups up to σ = 4.9 nm−2. Increasing the compressive strength of concrete specimens modified with SiO2 sol (0.5–3.0 wt%) and polycarboxylate superplasticizer (0.2–3.98 wt%), liquid-binder ratio L/B = 0.5–0.7, with normal hardening and with accelerated hardening with heat-moisture treatment, it reached 128% at the age of 1 day, and up to 40% at the age of 28 days. According to the kinetic curves of water absorption, a significant decrease in the volume, average pore diameter and an increase in the uniformity of the distribution of pores along the diameter of the modified concrete were established, which led to an increase in its water impermeability. The kinetics of the pozzolanic reaction with the formation of crystalline calcium hydrosilicates has been studied by the methods of X-ray diffraction analysis, energy-dispersive spectroscopy, scanning electron microscopy, and thermogravimetry. The chemo-sorption capacity of hydrothermal SiO2 nanoparticles for binding Ca(OH)2 in CaO solution and cement matrice was determined, which, due to the high SBET and σ values ​​for the first 24 h of the reaction, is many times higher than that of silica fume. In modified Portland cement matrice at the age of 1 day, the δCaO value was 750 [mg CaO / g SiO2], which corresponded to a response of 60–70% of the introduced nano-SiO2 and an increase in the rate of alite hydration by 20–30%, and rised at the age 100 days to 1200 [mg CaO / g SiO2]. Hydrothermal sols and SiO2 nanopowders have prospects for the creation of cement composites.

Laboratory-scale experiment on a novel mineralization-based method of CO2 capture using alkaline solution

We propose a novel CO2 conversion technology that is based on use of an alkaline solution. In this investigation, alkaline solutions were used to fix CO2 in the presence of K+, Na+, and Ca2+ ions. NaOH and KOH were selected and used at a 30 wt% in H2O. All the experiments were conducted under normal temperature and pressure conditions to reduce the total energy in the system. We also used a 30 wt% mono-ethanolamine (MEA) solution to make a comparison with the selected alkaline solution. Metal ions were supplied as Ca2+ from a CaO solution. The product precipitate was then analyzed by X-ray diffraction. We found that the selected alkaline solution formed a metal carbonate by reacting with injected CO2. The NaOH and KOH solutions reacted directly with the CO2. The NaOH did not form CaCO3 in the first conversion experiment. However, its CO2 reduction capacity was dramatically increased after a CaO solution was added. In addition, we believe that the formed precipitates could be used in various industries. Therefore, this research contributes not only to the basic research into alternatives to the use of an MEA solution for CO2 fixation, but may also be applicable to CO2 reduction technologies.

X線回折法による製鋼スラグ中遊離石灰の固溶度の決定および定量

X-ray diffraction analysis was performed on steel slag samples, and free-lime, which tend to cause hydration and result in swollen slags, were quantitatively analyzed. Simple CaO and solid solutions in the slag samples that correspond to free-lime could be distinguished from each other from the angles of 200 reflections. The contents of divalent-metal oxides that dissolved in CaO forming solid solution were determined from the lattice parameters calculated from the angles of reflection. The values of the contents were sufficiently large for the slags analyzed in this study to suppress the hydration reaction of the solid solution. Quantities of the free-lime were analyzed by the standard addition method. The reflection intensities of slag samples, to which different amounts of pure CaO were added, were measured, and the contents of the simple CaO and solid solution in the slags of each sample were determined separately.

In-situ defect repairing in hydroxyapatite/phytic acid hybrid coatings on AZ31 magnesium alloy by hydrothermal treatment

To improve the corrosion resistance of AZ31 magnesium alloy, a crack-free hydroxyapatite/phytic acid (HA/PA) hybrid coating was synthesized on AZ31 substrate via a chemical conversion deposition to form precursor coating, and followed by a hydrothermal treatment in the saturated CaO solution. During the hydrothermal treatment, the phosphate and calcium ions diffused to the interface of the precursor coating/solution to form amorphous CaP compound and subsequently crystallized into HA particles that repaired the defects in the precursor coating and exhibited a high bonding strength of 24.3 ± 1.7 MPa between the hybrid coating and the magnesium alloy substrate. Electrochemical measurements in simulated body fluid (SBF) revealed that the HA/PA hybrid coating could effectively provide protection for magnesium (Mg) alloy on account of the stable barrier properties.

Modification of Molten Steelmaking Slag for Cement Application

The use of metallurgical slags in cement production depends on the phases present in such slags, which are affected by changes in slag composition as well as the cooling rates adopted during solidification. In this work, slags with distinct chemical compositions were melted and subjected to different cooling conditions. Slag samples were characterized by X-ray diffraction to identify and quantify mineralogical phases and by X-ray fluorescence to determine chemical composition. The microstructure of the samples was characterized by scanning electron microscopy coupled to energy dispersive spectroscopy for phase identification. The solidification of the slags was simulated using FactSage™ for solidification path evaluation, enabling a comparison of the phases determined by thermodynamic equilibrium with those analysed in slag samples. Slags with low basicity (CaO/SiO2 <1.25) and Al2O3 content of 11 wt% exhibited a high glassy phase content depending on the cooling conditions. The phases formed in slags with higher basicity (1.4 and 3.8) were less affected by cooling rate and were different silicates, such as larnite, merwinite, monticellite, akermanite, gehlenite and melilite, whereas slags with basicity ≥1.37 exhibited RO phase (solid solution of FeO, MgO, CaO and MnO).

Methane enrichment of biogas by carbon dioxide fixation with calcium hydroxide and activated carbon

Although, Biogas generated from anaerobic digestion process is a clean, carbon neutral and environmental friendly energy alternative, raw biogas needs to be purified necessarily before using. The removal of CO2 from raw biogas ensures its better applications in engines, heating purposes and electricity generation. Reduction of CO2 content also enhances the calorific value. Biogas generated from vegetable, fruit and cafeteria wastes for duration of 30 days with the average concentration for CH4 and CO2 as 62 and 34%, respectively have been observed. The CO2 content was possible to reduce significantly by treating the raw biogas with purifying agents as: solid CaO, CaO solution and activated carbon. Purifying agent's mass and concentration and treatment time dependent biogas upgradation profile reveals that these novel purification processes are effective and affordable.

A Green, Simple Chemical Route for the Synthesis of Pure Nanocalcite Crystals

A new, simple chemical route was developed for the synthesis of pure nanocalcite crystals by controlling the reaction of an aqueous solution of CaO and CO2 gas. Results revealed formation of well-defined and pure nanocalcite crystals with controlled crystallite and particle size, without additives or organic solvents. The crystallite and particle size can be controlled, and smaller sizes are obtained by decreasing the CaO concentration and increasing the CO2 flow rate. The decrease of crystallite and particle size below a certain threshold provides the nanocalcite crystal signature characteristics that can be clearly observed in XRD patterns, TEM images, FTIR spectra, Raman spectra, XPS spectra, and thermal stability measurements.

Enhanced bonding of biomimetic apatite coatings on surface-modified titanium substrates by hydrothermal pretreatment

The biomimetic coating method was employed by soaking the titanium substrates in a 1.5X simulated body fluid (1.5XSBF). Calcium was implanted on the cleaned titanium surfaces under four different hydrothermal conditions before exposure to SBF. For this purpose, the substrates were immersed in aqueous solutions of CaO at 0.02 or 0.2mol/L concentrations for 1 or 8h in the temperature-controlled hydrothermal chamber kept at 230°C. The effects of hydrothermal solution concentration and immersion time on the substrate surfaces were assessed in terms of coating integrity. All the modified substrates were able to develop B-type hydroxy-carbonate apatite coatings. It was found that the titanium substrates pretreated for 8h developed on their surfaces well-adhering and scattered Ca(OH)2 crystals that contributed to roughness. The apatite coatings on such substrates exhibited higher bond strength compared to the coatings on the relatively “smoother” substrates (i.e., pretreated for 1h). The mean values for tensile and shear strengths increased up to 22.4±3.2 and 9.7±2.7MPa, respectively, for the mechanical test specimens prepared by soaking the substrates, which were pretreated for 8h in the 0.2mol/L CaO solution, in the SBF for 2weeks.

Thermodynamic model and structure of CaO–P2O5 glasses

The distribution of Q-units of CaO–P2O5 glasses was described by the thermodynamic model of Shakhmatkin and Vedishcheva. The glass was considered as the ideal solution of CaO, P2O5, CaP2O6, Ca2P2O7, and Ca3P2O8. In the first step, molar Gibbs energies of considered species were taken from the FACT thermodynamic database. The obtained result was compared with 31P solid-state NMR study of Roiland. It was shown that the calculated values were in fairly good agreement with the experimental values. After that, the nonlinear regression treatment was used for optimization of molar Gibbs energies by minimizing the sum of squares of deviations between experimental and calculated Q-distribution. In such a manner, the non-ideality of the system was reflected. In the studied case, no significant improvement of obtained results was achieved by this procedure—thus, the ideal solution assumption included in the thermodynamic model of Shakhmatkin and Vedishcheva holds very well for the studied binary glasses.

Study of the reuse of treated wastewater on waste container washing vehicles

The wheelie bins for the collection of municipal solid waste (MSW) shall be periodically washed. This operation is usually carried out by specific vehicles which consume about 5000L of water per day. Wastewater derived from bins washing is usually stored on the same vehicle and then discharged and treated in a municipal WWTP. This paper presents a study performed to evaluate the reuse of the wastewater collected from bins washing after it has been treated in a small plant mounted on the vehicle; the advantage of such a system would be the reduction of both vehicle dimension and water consumption. The main results obtained by coagulation–flocculation tests performed on two wastewater samples are presented. The addition of 2mL/L of an aqueous solution of aluminum polychloride (18% w/w), about 35mL/L of an aqueous solution of CaO (4% w/w) and 25mL/L of an aqueous solution of an anionic polyelectrolyte (1‰ w/w) can significantly reduce turbidity and COD in treated water (to about 99% and 42%, respectively); the concomitant increase of UV transmittance at 254nm (up to 15%) enables UV disinfection application by a series of two ordinary UV lamps. Much higher UV transmittance values (even higher than 80%) can be obtained by dosing powdered activated carbon, which also results in a greater removal of COD.

Role of organic admixtures on thaumasite precipitation

Thaumasite formation is normally a slow process; however some studies have shown that the presence of sucrose promotes its formation substantially. Many of today's concretes contain organic admixtures and no research has been conducted to date to determine whether the presence of these admixtures may induce or favour thaumasite formation. The present study aimed to ascertain whether, like sucrose, admixtures may further that process, and to propose a working methodology to do so.The methodology used was: mixing sodium carbonate, sulfate and silicate solutions with a CaO solution with eleven commercial admixtures. The precipitates obtained after different curing times (up to 1year) and temperatures (5 and 25°C) were characterised with FTIR and XRD.It was possible to distinguish between admixtures that did and those that did not favour thaumasite formation, i.e., products containing lignosulfonates or a mix of sodium carboxylate and polysulfonate as well as aluminium-based accelerating admixtures favoured thaumasite formation.