Search Results (51)

Glass microspheres are essential components in horizontal road markings due to their retroreflective properties, enhancing visibility and safety under low-light conditions. Traditionally produced from soda-lime glass made with high-purity silica from sand, their manufacturing raises environmental concerns amid growing global sand scarcity. This study explores the viability of rice husk ash (RHA)—a high-silica byproduct of rice processing—as a sustainable raw material for microsphere fabrication. A glass composition containing 70 wt% SiO₂ was formulated using RHA and melted at 1500 °C. Microspheres were produced through flame spheroidization and characterized following the Brazilian standard NBR 16184:2021 for Type IB beads. The RHA-derived microspheres exhibited high sphericity, appropriate size distribution (63–300 μm), density of 2.42 g/cm³, and the required acid resistance. UV-Vis analysis confirmed their optical transparency, and the refractive index was measured as 1.55 ± 0.03. Retroreflectivity tests under standardized conditions revealed performance comparable to commercial counterparts. These results demonstrate the technical feasibility of replacing conventional silica with RHA in glass microsphere production, aligning with circular economy principles and promoting sustainable infrastructure. Given Brazil’s significant rice production and corresponding RHA availability, this approach offers both environmental and socio-economic benefits for road safety and material innovation. Full article

Volcanic ash from explosive eruptions can significantly alter lake water chemistry through ash–water interactions, potentially influencing primary productivity. Alkaline (soda) lakes, mostly found in volcanic regions, are particularly sensitive due to their unique geochemical properties. However, the effects of volcanic ash on the biogeochemistry and phytoplankton dynamics of soda lakes remain poorly understood. This study presents the first nutrient release experiments using natural alkaline water from Lake Van (Türkiye) and volcanic ash from four volcanoes (Hekla, Arenal, Sakurajima, Rabaul-Tavurvur) with different compositions. Sixteen abiotic leaching experiments were conducted over contact durations ranging from 1 to 24 h. Results show rapid increases in pH (~0.4–0.5 units), enhanced silica and phosphate concentrations, and elevated levels of Na, K, Ca, Sr, and S. Nitrate and Mg were generally depleted. The low N:P ratio (~0.06) in Lake Van water indicated nitrogen limitation, partially mitigated by ash-derived inputs. Cyanobacteria dominated the phytoplankton community (95%), consistent with nitrogen fixation under low-nitrate conditions. Elevated silica may promote diatom growth, while changes in Mg/Ca ratios suggest possible impacts on carbonate precipitation and microbialite development. These findings highlight the biogeochemical and ecological relevance of volcanic ash inputs to soda lakes. Full article

To address the practical limitations of conventional alkaline activators (e.g., handling hazards, cost) and promote the resource utilization of industrial solid wastes, this study developed a novel all-solid-waste activator system comprising soda residue (SR) and carbide slag (CS). The synergistic effects of SR-CS activators on the hydration behavior of blast furnace slag (GGBS)–fly ash (FA) cementitious composites were systematically investigated. Mechanical performance, phase evolution, and microstructural development were analyzed through compressive strength tests, XRD, FTIR, TG-DTG, and SEM-EDS. Results demonstrate that in the SR-CS activator system, which combines with desulfuriation gypsum as sulfate activator, increasing CS content elevates the normal consistency water demand due to the high-polarity, low-solubility Ca(OH)₂ in CS. The SR-CS activator accelerates the early hydration process of cementitious materials, shortening the paste setting time while achieving compressive strengths of 17 MPa at 7 days and 32.4 MPa at 28 days, respectively. Higher fly ash content reduced strength owing to increased unreacted particles and prolonged setting. Conversely, desulfurization gypsum exhibited a sulfate activation effect, with compressive strength peaking at 34.2 MPa with 4 wt% gypsum. Chloride immobilization by C-S-H gel was confirmed, effectively mitigating environmental risks associated with SR. This work establishes a sustainable pathway for developing low-carbon cementitious materials using multi-source solid wastes. Full article

This study investigates the effect of electrolytic-plasma hardening (EPH) on the structure, phase composition, and tribological properties of the low-alloy steels 20Cr2Ni4A and 37Cr4 (1.7034) (EN). Hardening was carried out at a voltage of 320 V for 7 s in an aqueous solution containing 20% soda ash and 10% carbamide. Using scanning electron microscopy, the formation of a zonal structure with a hardened surface layer characterized by a needle-like martensitic morphology was revealed. X-ray diffraction analysis revealed the presence of Fe, Fe₃C, Fe₂C, and FeO phases. Microhardness measurements confirmed a significant increase in the hardness of the hardened layer. Tribological tests showed a reduction in the coefficient of friction to 0.574 for 20Cr2Ni4A steel and to 0.424 for 37Cr4 (1.7034) (EN) steel, indicating an improvement in wear resistance after EPH. Full article

Upper Cretaceous carbonate rocks in Jordan are the main resources for construction and paint-related industrial applications. This study evaluates the elemental composition, mineralogy, and petrography of two main geological formations from two localities in northern Jordan (Hallabat, Turonian age, and Ajlun, Santonian–Campanian age) to shed light on their composition, depositional environments, and potential industrial end uses. The elemental composition of the Hallabat Wadi Sir Limestone (WSL) Formation indicates notable variability between the middle and upper parts of the WSL carbonates in the area, with higher CaO content in the middle part (mean 55 wt.%) and higher silica content observed in the upper part (mean 2 wt.%) compared with the middle part (mean 0.9 wt.%). Meanwhile, analysis of the elemental composition of the Ajlun Amman Silicified Limestone (ASL) Formation indicates that the CaO content is relatively higher in the upper part (mean 56 wt.%). In addition, the lower part is more influenced by detrital input when compared with the upper part of the studied section, in contrast to the Hallabat WSL Formation. Petrographic analysis demonstrates that the WSL and ASL samples are predominantly micritic limestone. The XRD results for the Hallabat WSL and Ajlun ASL show that the mineralogical composition is dominated by calcite (CaCO₃). Statistical and PCA analyses also confirm these variabilities between the two sites, indicating that all samples from both sites were deposited under variable hydrodynamic and environmental conditions that affected their physical and chemical composition. The results show that all studied samples are in the range of pure limestone and can be used for specific industrial applications in addition to their current uses, including those in the pottery and porcelain ware, soda ash and caustic soda, steel industry, sugar, and textile production industries, thus contributing to the economic resources in Jordan. Full article

The reliance on greenhouse gas-emitting unrenewable energy sources such as coal, natural gas, and oil, increases climate change. Transitioning to renewable energy, such as biogas, is crucial to reducing environmental degradation and global warming. The existence of impurities such as hydrogen sulfide hampers the application of biogas. Utilizing natural resources for biogas purification is essential to improve access to clean energy for low-income communities. This study used soda ash derived from Lake Natron in Tanzania as a sorbent for H₂S removal. Effects of sorbent mass, flow rate, and particle size were investigated. Experimental data were analyzed using kinetic models, adsorption isotherms, and breakthrough curves. Soda ash of 280 μm particle size, a flow rate of 0.03 m³/h, and a mass of 75 g demonstrated the best performance, achieving an efficiency of 94% in removal and a sorption capacity of 0.02 g per 100 g in five repeated cycles. Freundlich and Jovanovich’s isotherms match the data with n = 0.4 and K_j = 0.003, respectively. Adsorption kinetics were best described by the intra-particle model (k_id = 0.14, c = 0.59 mg/g, and R² = 0.972). A breakthrough analysis indicated that the Yoon–Nelson model provided the best fit with an R² of 0.95. Soda ash from Lake Natron demonstrated great potential in biogas desulphurization, thus contributing to the production and access to clean energy. Full article

The design of industrial installations using digital design techniques (digital twin), aligned with the concept of Industry 4.0, provides a tool to optimize maintenance costs, process gas emissions, energy consumption and to reduce the risks associated with production testing. Modern manufacturing plants conduct chemical processes by combining production experience with model-based research. Analyzing processes using advanced digital techniques can replace traditional methods of technological process balancing. The methodology based on the digital twin already serves as a holistic system of process connections, supporting production, research and development, production planning, and quality control. This paper presents the digital design, optimization, and comparison of process data obtained through simulations for two different types of ammonia recovery units in soda ash production using the ammonia–soda process. Using specialized modeling software and relying on historical data, engineering assumptions, and new concepts, virtual models were created in which the material and thermal balances of the process were simulated. This research is divided into two stages. In the first stage, a model-based approach and model optimization techniques are presented, while in the second stage, the preparation of models of the distillation installation is presented, and the influence of various structural parameters of the equipment on the temperature profile and gas flow rate in the ammonia recovery section is discussed. The process of the research method, based on simulations in a virtual environment, allows for evaluating the implementation potential of the proposed concepts, optimizing process parameters, and redefining the approach to conducting chemical processes. A series of simulations conducted in studies on ammonia recovery indicated a potential increase in gaseous ammonia recovery by up to 14.09%, taking into account the type of distillation apparatus or the height of the packing section. Full article

This work presents an analysis of the relationship between strength parameters determined in the laboratory and the results of a cone penetration test with pore water pressure measurement (CPTU) of waste soils in the “White Seas” area in Cracow. Anthropogenic soil is an alkaline waste formed during the production of soda ash and deposited in the area of the former Solvay Sodium Plant factory in Cracow, Poland. Due to the large area of the land and numerous investment plans and completed buildings, there was a need to identify reliable functional relationships enabling the determination of the strength parameters of these soils based on the results of the CPTU. Statistical analysis showed that the best correlation with the test results was provided by two logarithmic functions in which the dependent variables were the effective friction angle and effective cohesion. The dependent variable for both cases was the corrected cone resistance q_t. The functional relationship combined data from labour-intensive, long-lasting and costly laboratory measurements with quick and less expensive measurements, i.e., in situ CPTUs. The obtained relationships enable the determination of the strength properties of the subsoil of these anthropogenic soils. Full article

This article presents the results of a thermodynamic analysis of the oxidation soda conversion reactions of minerals in ilmenite concentrates in the temperature range of 373–2273 K. The thermodynamic parameters of pseudorutile, pseudobrukite, and the new minerals, zhikinite and spessartine, were calculated for the first time. It has been established that the most important criterion relating to the stability of titanium minerals and related elements, as well as the reaction properties of the structural oxides of metals and silicon, is their degree of oxidation. Oxides of silicon (IV) and manganese have the best reactivity in solid-phase oxidizing alkaline environments (VI). Modeling this process scientifically substantiates the mechanism involved in the destruction of minerals in ilmenite concentrates in the low-temperature region in the presence of atmospheric oxygen and sodium oxide of soda ash, which are decomposed through the absorption of heat and the evaporation of moisture during the dehydration of hydrated minerals of iron and manganese and the dehydration of the soda–ilmenite batch. Tests conducted during pilot metallurgical production at the Institute of Metallurgy and Enrichment (PMP of JSC) confirmed the feasibility of processing high-chromium and siliceous rutile leucoxene ilmenite concentrates, which are unsuitable for traditional pyro- and hydro-metallurgical enrichment methods, through single-stage oxidation soda roasting, followed by the leaching of easily soluble sodium salts of iron and associated impurities with water and a dilute hydrochloric acid solution. The proposed energy-saving method ensures the production of high-purity (>98%) synthetic rutile while eliminating the formation of strong deposits on the lining of roasting units. Full article

The routine dredging of waterways produces huge volumes of sediments. Handling contaminated dredged sediments poses significant and diverse challenges around the world. In recent years, novel and sustainable ex situ remediation technologies for contaminated sediments have been developed and applied. This review article focuses on cement-based binders in stabilizing contaminants through the stabilization/solidification (S/S) technique and the utilization of contaminated sediments as a resource. Through S/S techniques, heavy metals can be solidified and stabilized in dense and durable solid matrices, reducing their permeability and restricting their release into the environment. Industrial by-products like red mud (RM), soda residue (SR), pulverized fly ash (PFA), and alkaline granulated blast furnace slag (GGBS) can immobilize heavy metal ions such as lead, zinc, cadmium, copper, and chromium by precipitation. However, in a strong alkali environment, certain heavy metal ions might dissolve again. To address this, immobilization in low pH media can be achieved using materials like GGBS, metakaolin (MK), and incinerated sewage sludge ash (ISSA). Additionally, heavy metals can be also immobilized through the formation of silicate gels and ettringites during pozzolanic reactions by mechanisms such as adsorption, ion exchanges, and encapsulation. It is foreseeable that, in the future, the scientific community will increasingly turn towards multidisciplinary studies on novel materials, also after an evaluation of the effects on long-term heavy metal stabilization. Full article

The efficacy of spray dry systems compared to wet flue gas desulphurisation (FGD) units depends on applying a highly reactive scrubbing reagent. This study assessed sodium-based compounds derived from natural sources and waste by-products as potential agents for treating sulphur dioxide (SO₂). Sodium carbonate (Na₂CO₃) and sodium bicarbonate (NaHCO₃) were acquired from mineral deposits, whereas the black ash waste (Na₂CO₃·NaHCO₃) was obtained from the pulp and paper sector. The sorbents introduced in slurry form were subject to SO₂ absorption conditions in a lab-scale spray dryer, including an inlet gas phase temperature of 120–180 °C, flue gas flow rate of 21–34 m³/h, and sodium to sulphur normalised stoichiometric ratio (Na:S) of 0.25–1. The comparative performance was evaluated using the metric of %SO₂ ($\%{\eta }_{DeS{O}_X}$) removal efficiency. The results showed that NaHCO₃ had the highest overall result, with a removal efficiency of 62% at saturation. Black ash was the second best-performing reagent, with a 56% removal efficiency, while Na₂CO₃ had the lowest efficiency (53%). The maximum degree of SO₂ reduction achieved using NaHCO₃ under specific operating parameters was at an NSR of 0.875 (69%), a reaction temperature of 120 °C (73%), and a gas inlet flow rate of 34 m³/h. In conclusion, the sodium reagents produced significant SO₂ neutralisation, exceeding 50% in their unprocessed state, which is within acceptable limits in small- to medium-sized coal-fired power plants considering retrofitting pollution control systems. Full article

Soda ash (Na₂CO₃) is produced using the traditional Solvay process. It entails the reaction of CO₂ with high-salinity water in the presence of ammonia (NH₃), which produces insoluble sodium bicarbonate (NaHCO₃) and soluble ammonium chloride (NH₄Cl). In the current work, a newly combined approach has been developed to effectively manage the removal of ammonia and sulfate from the effluent of the Solvay process. The devised technique centers on an electrochemical coagulation process, complemented with the utilization of calcium oxide (CaO) as a buffering reagent. This innovative approach excels at achieving high recovery rates for both ammonia and sulfate. The recovered ammonia holds the potential for recycling, thereby contributing to the sustainability of the Solvay process by reusing ammonia in its initial stages. Furthermore, sulfate ions are recuperated in the form of calcium sulfate, a value-added product boasting various industrial applications. The results gleaned from this study underscore the efficacy of the ammonia recovery process, particularly when operating at elevated current densities and with higher calcium oxide concentrations. On the other hand, sulfate recovery demonstrates superior performance when exposed to moderate current densities and limited calcium oxide concentrations. Consequently, the integration of both stages within a single, cohesive process necessitates the development of an optimization methodology to cater to varying operational conditions. To address this need, second-order polynomial equations were formulated and employed to anticipate ammonia and sulfate removal rates in the integrated approach. Four independent variables come into play: calcium oxide concentration, current density, temperature, and mixing rate. The findings reveal that most of these variables exert substantial influences on both ammonia and sulfate removal rates, underscoring the need for careful consideration and fine-tuning to optimize the overall process. The maximum ammonia and sulfate removal were found to reach 99.50% and 96.03%, respectively, at a calcium oxide concentration of 3.5 g/100 mL, a current density of 19.95 mA/cm², a temperature of 35 °C, and a mixing rate of 0.76 R/s. The results are promising, and the developed process is also suitable for recovering high concentrations of sulfate and ammonia from various wastewater sources. Full article

Sodium-based bentonite is used for drilling operations because of its high swelling capacity. This type of bentonite clay is not sourced locally in many oil- and gas-producing nations. However, low-swelling clays (calcium- and potassium-based) are in abundant quantities in most of these countries. Hence, there is a need to convert low-swelling bentonite clays to sodium-based bentonite. The method used to convert low-swelling clays is more applicable to calcium-based bentonite. This research investigated a thermochemical treatment method that converted potassium-based bentonite to sodium-based bentonite. The raw clay materials were sourced from Pindinga (P) and Ubakala (U) clay deposits in Nigeria. An X-ray diffractometer (XRD), an energy dispersive X-ray (EDX), and a scanning electron microscope (SEM) were used to characterize the raw clay samples. Mud slurry was prepared by mixing 22 g of the local raw clays, 3 wt.% soda ash, and MgO at concentrations between 1 and 3 wt.% and heating at 90 °C. The result showed that the viscosities of samples P and U increased from 6 to 26 and 8 to 35.5 cP before and after thermochemical treatment, respectively. Also, due to the thermochemical treatment, the samples’ yield point, consistency factor, consistency index, and thixotropy behavior were all significantly improved. Full article

This study investigates the feasibility of using biodegradable secondary alcohol ethoxylate (SAE) non-ionic surfactant as a building block for the formation of reverse micelles, functioning as reactive dye carriers for the dyeing of cotton fabric in non-aqueous octane medium. Ten dyeing parameters were optimised, by a one-factor-at-a-time approach, namely: (i) effect of colour fixation agent; (ii) surfactant-to-water mole ratio; (iii) surfactant-to-co-surfactant mole ratio; (iv) volume of soda ash; (v) volume of dye; (vi) solvent-to-cotton ratio; (vii) dyeing temperature; (viii) dyeing time; (ix) fixation time; (x) soda-ash-to-cotton ratio. The colour properties, fastness properties and physical properties of SAE-dyed samples were experimentally compared with the conventional water-dyed samples. The optimised condition was found when SAE samples were dyed as follows: (a) 1:20 surfactant-to-water ratio; (b) 1:8 surfactant-to-co-surfactant ratio; (c) 10:1 solvent ratio; (d) 40 min dyeing time; (e) 60 min fixation time; and (f) 70 °C dyeing and fixation temperature. The results showed that SAE-dyed samples have better colour strength, lower reflectance percentage and comparable levelness, fastness and physical properties than that of water-dyed samples. SEM images revealed that the dyed cotton fibres had no severe surface damage caused by an SAE-based reverse micellar dyeing system. The TEM image depicts that the reverse micelle was of nanoscale, spherical-shaped and had a core–shell structure, validating the presence of reverse micelle as a reactive dye carrier and the potential of an SAE-based reverse micellar system for dyeing of cotton fabrics. Full article

Industries are rapidly moving toward mitigating errors and manual interventions by automating their process. The same motivation is carried out in this research which targets to study a conveyor system installed in soda ash manufacturing plants. Our aim is to automate the determination of optimal parameters, which are chosen by identifying the flow rate of the materials available on the conveyor belt for maintaining the ratio between raw materials being carried. The ratio is essential to produce 40% pure carbon dioxide gas needed for soda ash production. A visual sensor mounted on the conveyor belt is used to estimate the flow rate of the raw materials. After selecting the region of interest, a segmentation algorithm is defined based on a voting-based technique to segment the most confident region. Moments and contour features are extracted and passed to machine learning algorithms to estimate the flow rate of different experiments. An in-depth analysis is completed on various techniques and convincing results are achieved on the final data split with the best parameters using the Bagging regressor. Each step of the process is made resilient enough to work in a challenging environment even if the belt is placed in an outdoor environment. The proposed solution caters to the current challenges and serves as a practical solution for estimating material flow without manual intervention. Full article