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Background: Disastrous effects and lifelong complications, ranging from respiratory and gastrointestinal burns to death can result from caustic soda ingestion. Accidental and non-accidental ingestions occur in different age groups. However, it is very troubling to find ingestion of caustic soda a very common occurrence among children below 5 years since they do not have the developmental level required to independently weigh up risks and are also under parental and societal protections. This study was therefore planned to investigate the ingestions of caustic soda by these children for purposes of proposing measures to curb the problem. Methods: Descriptive survey was employed for this study. A 14-item, semi-structure questionnaire was purposively issued to 57 parents/guardians whose wards had ingested caustic soda. Data was analysed with SPSS V.20. Results: Twenty-seven (47.4 %) children got access to the soda at storage, 1 (1.86 %) was administered accidentally by a sibling while 29 (50.9 %) ingested during soap preparation. In respect of the former, the majority got access because it was stored in soft drink and water bottles in their parents/guardians rooms or kitchen. For the later, the children got access to the left-over soda because the soap-makers failed to adhere to good storage and disposal practices. Conclusion: Storage of caustic soda in soft drink and water bottles in accessible places, and training of children to drink directly from bottles influence caustic soda ingestion in children under five. Non-compliance to good practices of storage and disposal of caustic soda during soap preparation increases exposure and access of children to caustic soda ingestion. [ABSTRACT FROM AUTHOR]

Perlite is a volcanic aluminosilicate abundant in several countries that are major producers of portland cement. The amorphous nature and silica-to-alumina ratio of ground perlite indicate that it can be activated with alkaline solutions. This study presents the strength development of mixtures containing only ground perlite as their powder binder, activated with sodium hydroxide and/or sodium silicate solutions, at room temperature or using oven curing. The structure of the formed geopolymers is investigated using X-ray diffraction, Fourier transform infrared spectroscopy, and nuclear magnetic resonance spectroscopy. The thermal stability and acid resistance of the mixtures are evaluated. Sodium silicate-activated mixtures slowly reach moderate strengths at room temperature but sodium hydroxide-activated ones do not develop strength regardless of activator concentration. Both activators produce geopolymers with high strengths with 100°C dry oven curing. Sodium silicate-activated specimens are more resistant to high temperatures but less resistant to a sulfuric acid solution than are sodium hydroxide solution-activated specimens. Being natural and having a more consistent chemical composition compared with most artificial pozzolans make perlite an attractive geopolymer raw material. [ABSTRACT FROM AUTHOR]

Reprocessing soiled cleaning-in-place (CIP) solutions has large economic and environmental costs, and it would be cheaper and greener to recycle them. In food industries, recycling of CIP solutions requires a suitable green process engineered to take into account the extreme physicochemical conditions of cleaning while not altering the process efficiency. To this end, an innovative treatment process combining adsorption-coagulation with flocculation was tested on multiple recycling of acid and basic cleaning solutions. In-depth analysis of time-course evolutions was carried out in the physicochemical properties (concentration, surface tension, viscosity, COD, total nitrogen) of these solutions over the course of successive regenerations. Cleaning and disinfection efficiencies were assessed based on both microbiological analyses and organic matter detachment and solubilization from fouled stainless steel surfaces. Microbiological analyses using a resistant bacterial strain ( Bacillus subtilis spores) highlighted that solutions regenerated up to 20 times maintained the same bactericidal efficiency as de novo NaOH solutions. The cleanability of stainless steel surfaces showed that regenerated solutions allow better surface wettability, which goes to explain the improved detachment and solubilization found on different types of organic and inorganic fouling. [ABSTRACT FROM AUTHOR]

A rational temperature-time regime for obtaining an alkaline concentrate based on quartz and caustic soda is determined. The physical and chemical properties of the concentrate and its effect on the glassmaking properties are studied. The possibility of using the alkaline concentrate with full substitution for glass sand and soda in the composition of the glass batch is substantiated. [ABSTRACT FROM AUTHOR]

Abstract: Life cycle assessment was conducted to estimate the environmental impact of caustic soda production. Electricity and raw salt production accounted for >90% of the overall environmental burden. These findings can be attributed to electrical consumption for bipolar electrolysis and brine extraction, diesel consumption for generating electricity during well production, and direct heavy metal emissions during drilling fluid loss and waste disposal. The key factors in reducing the overall environmental impact include optimizing raw salt production, electricity, and steam consumption efficiency, choosing drilling fluids with less toxic heavy metals (e.g., arsenic, barium, molybdenum, selenium, vanadium, beryllium, and nickel), minimizing brine leakage during brine transport, reducing the volume of drilling fluid lost, and decreasing the transport distance from brine buyers to suppliers. [Copyright &y& Elsevier]

The significance of textile coloration is inevitable as coloration is a critical process and it can be affected by several parameters i. e. time, temperature, pH, and liquor ratio (M:L). This research reveals the behavior of different dye bath pH (2 to 12) on the basis of spectrophotometric characteristics and colorfastness using the most useable brand of reactive dye in Bangladesh i. e. Remazol Yellow RR. Earlier researches were performed on the basis of other coloration controlling factors i. e. temperature, time and liquor ratio (M:L) where pH acts as the dependent variable. However in this study, pH was taken as an independent variable where lower pH (2, 4 and 6), medium pH (8 and 10) and higher pH (12) were taken into consideration for verifying the dyeing performance. Meanwhile, the mentioned pH was achieved by adding acetic acid, soda ash and caustic soda respectively. In this study, the impact of pH is analyzed on the basis of color strength, chromaticity, hue angle, CIELAB color space, spectrophotometric image, reflectance percentage and color fastness tests i. e color fastness to rubbing, color fastness to wash, color fastness to perspiration, color fastness to light. Gradually elevated pH boosts up the color strength and chromaticity, at the same time downgrades of hue angle results orangish tone in the dyed fabric. Even more, the lightness of dyed fabric decreases and redness rises with the increment of dyebath pH which results in orangish red darker tone of dyed fabric. Consequently, fabric dyed at acidic dye bath pH exhibits higher resistance in case of color change and color staining from the dyed fabric and multifiber fabric respectively and vice versa., Competing Interests: The authors declare no conflict of interest., (© 2022 The Authors.)

Aqueous fluosilicic acid solutions were once considered to be only adverse by-products of phosphoric acid production, which required treatment to prevent ecosystem destruction when discharged into the sea. However, a range of chemicals can be generated by the transformation of this industrial waste product. Through experiments undertaken in the laboratory, we have shown the possibility of caustic soda production. Volumetric analysis showed caustic soda to be present as a 6% – 7% solution with yields of about 70% – 80% by weight. Two processes were investigated for the caustification of sodium fluoride, using different precipitates: sodium chloride and ethanol and are described by modelling caustification curves. The activation energies of precipitation determined by semi-empirical correlations showed that precipitation by ethanol (EA = 933.536 J/mol) was more successful than precipitation by sodium chloride(EA = 7452.405 J/mol). Analyses performed on the precipitates highlighted compositions that are essential and useful constituents in the cement industry.

Aqueous fluosilicic acid solutions were once considered to be only adverse by-products of phosphoric acid production, which required treatment to prevent ecosystem destruction when discharged into the sea. However, a range of chemicals can be generated by the transformation of this industrial waste product. Through experiments undertaken in the laboratory, we have shown the possibility of caustic soda production. Volumetric analysis showed caustic soda to be present as a 6% – 7% solution with yields of about 70% – 80% by weight. Two processes were investigated for the caustification of sodium fluoride, using different precipitates: sodium chloride and ethanol and are described by modelling caustification curves. The activation energies of precipitation determined by semi-empirical correlations showed that precipitation by ethanol (EA = 933.536 J/mol) was more successful than precipitation by sodium chloride(EA = 7452.405 J/mol). Analyses performed on the precipitates highlighted compositions that are essential and useful constituents in the cement industry.

Experience in upgrading the equipment for raw-benzene rectification at Evraz Koks Siberia is considered. [ABSTRACT FROM AUTHOR]

Abstract: Adhesives play a fundamental role in many modern technologies, and adhesive failure can have catastrophic consequences. It is, therefore, valuable to understand the factors important for the production of a good durable adhesive bond. The additives are also used to enrich the properties. The objective of this paper is to increase the drying speed of the starch adhesive by adding suitable additives and thereby increasing the production speed of corrugated board manufacturing. The other functional additives that could be incorporated in minor amounts for better drying speed are studied and selected. Their properties such as drying speed, strength, viscosity and pH are tested. The results from the tests are compared and the best additive for fast drying is selected. [Copyright &y& Elsevier]

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Abstract: Annually, a great amount of Cold Filter Cake (CFC) residue is produced in lead and zinc plants in Iran. CFC, the Ni–Cd purification step residue, with elemental analysis of 45–55% Zn, 11–16% Cd, 2.5–4% Ni and 0.2–1.5% Cu can be used as a secondary source of zinc, nickel and cadmium. Unfortunately, despite its hazardous content, the waste is treated in such a way that most of the hazardous constituents get easily exposed to the environment. In the present study, treatment of CFC for separation of zinc and recovery of cadmium has been conducted employing alkaline leaching and electowinning processes respectively. Affecting factors, such as alkaline concentration, leaching temperature, holding time, and liquid:solid ratio (volume/weight, L/S), and stirring rate were studied on zinc leaching from CFC with NaOH solution. Results showed that under two-stage alkaline leaching, when CFC was leached for 1h at 75°C in the presence of 8mol/l sodium hydroxide and liquid:solid ratio of 10:1, the leaching rate of Zn was 98% while Ni and Cd remained intact in residue. Thus, zinc was separated from Ni and Cd selectively. In the next step, sulfuric acid leaching of alkaline leach residue, with 1mol/l H2SO4 at 70°C and liquid/solid ratio of 10:1, provided a stock sulfate solution containing 49.92g/l Cd, 2.77g/l Zn, 12.76g/l Ni, and 1.18g/l Cu. The Cd electrowinning experiments and the effects of current density (A/m2) and electrolysis time (h) were studied on stock sulfate solution in the presence of Ni and Zn. The electrowinning was carried out at various current density (100, 180, 250 and 400A/m2) and electrolysis time (5, 8, and 18h). Concentrations of Cd2+, Ni2+ and Zn2+ were determined every hour. Cadmium recovery of 9.8% at 100A/m2 increased sharply to 87% at 400A/m2 in 5h. Maximum total recovery of cadmium from solution was 99.9% achieved at 25°C and 400A/m2 in 18h. Final product was cadmium sponge of high purity 98% and copper was considered the main impurity in cadmium sponge deposit (1.7%). A complete flow sheet of process for the selective separation of zinc and cadmium recovery is presented. [Copyright &y& Elsevier]

Abstract: Strength development of alkali activated slag (AAS) mortars, activated using alkali hydroxide and sodium silicate, was investigated at room and elevated temperatures. Heat evolution at room temperature was measured using isothermal calorimetry. Important differences were observed between critical activation parameters. Heat cured specimens gain strength rapidly, humid oven conditions being favorable, but given sufficient time room temperature curing yields comparable strengths. Both activators are needed for high strength at room temperature, NaOH solution is more critical and its concentration greatly influences strength. At 80°C however, sodium silicate is essential and even sufficient. KOH is more effective than NaOH at 80°C, but not at room temperature. Lower water-to-slag ratios give higher strength at early ages. AAS hydration evolves less heat than Portland cement hydration. Time to significant strength gain of mixtures can be predicted using their time and heat evolution at setting. Twenty eight-day strength of AAS mortars is roughly related to total evolved heat and increases nearly linearly with the amount of NaOH activator for fixed water glass content. [Copyright &y& Elsevier]

Abstract: A technology has been developed for extracting tungsten from scheelite concentrate with caustic soda by an autoclaving process. In this process, the effects of different variables on the digestion of scheelite, and on the evaporation of the crude sodium tungstate leach solution, has been investigated. The results showed that 98.8% W was leached in 2h at 160°C under the conditions of 2.2 stoichiometric ratio of NaOH and liquid /solid ratio 0.8:1 stirred at 400rpm. After evaporation, about 90% sodium tungstate was crystallized, leaving impurities of PO4 2-, AsO4 2− and SiO3 2− in the mother solution. The filtered mother solution contained about 93% of the unconsumed caustic soda which can be recycled for a new round of leaching. This technology has been successfully put into industrial practice and can treat almost any tungsten ore, including scheelite middling and wolframite–scheelite mixed concentrates. [Copyright &y& Elsevier]

Abstract: After two years of non-continuous service of three boilers, weld seams for the super heater and header tubes showed severe circumferential cracking and failure. Extensive cracking was noticed after emergency shutdown to investigate the cause of tubes leakage. On-site investigation revealed the fact that tubes were suffered from extensive circumferential cracking initiated at the weld heat affected zone (HAZ) area. Over the cracked area thick crystalline white deposit was visible. The analysis using X-ray diffraction revealed that the white deposits compose mainly of sodium carbonate (nitrite) which resulted from the oxidation of caustic soda. Little amount of burkeite and thermonarite were also detected. Detailed investigation such as the visual, microscopic and metallographic examination revealed the fact that circumferential cracks were initiated at the heat-affected zone and propagated through the grain boundaries (intergranular). However, at and adjacent to the weld seams the fracture was not intergranular (quasi-cleavage) owing to the non-granular martensitic structure. Scanning electron microscope (SEM) confirms the finding that the fracture morphology was mainly intergranular at the parent metal and quasi-cleavage around the weld seams. All the above mentioned findings confirm that the cracking of boiler tubes was mainly by caustic embrittlement owing to the high concentration of caustic soda. [Copyright &y& Elsevier]

We have investigated the effect of caustic soda as a nondurable finish on the flammability of 100% cotton fabric (plain 180 g m−2). On the contrary to the mercerization, during the impregnation process, no tension was applied. In order to attain the alkali cellulose onto the fabric, the subsequent neutralization was not followed. Each bunches of fabrics were dipped into individual aqueous solutions of sodium hydroxide, followed by means of squeeze rolls and drying at 110°C. After conditioning nightlong, by using our ‘vertical flame test’ the optimum add-on values to impart flame-retardancy into cotton fabric was determined as 1.3 g sodium hydroxide per 100 g fabric. Thermogravimetry and derivative thermogravimetry (TG/DTG) of pure cotton, treated cotton with sodium hydroxide at its optimum efficiency to impart flame-retardancy into the fabric was fulfilled and the obtained curves were compared and commented. The effectiveness of this hydroxide is attributed to the heat dissipation by the remaining material in the consumed ash. The results obtained are in favour of ‘dust or wall effect theory’ and also gas dilution theory. [ABSTRACT FROM AUTHOR]

Abstract: The recovery of caustic soda and concentration of disodium terephthalate (DST) from alkali waste of polyester fabrics were investigated using SelRo (MPT-34) nanofiltration membranes with membrane area of 0.024 m2 and 5.2 m2, respectively. Flux behaviors were observed with respect to filtration time, volumetric concentration factor (VCF), operating pressure, temperature, and cleaning. The mass balance of caustic soda, DST, and ethylene glycol (EG) were estimated according to different values of VCFs. As the VCF increased, more amounts of disodium terephthalate and ethylene glycol permeated while almost the same concentration of sodium hydroxide was permeable. The NF operation end with a concentrated disodium terephthalate solution that needed a reduced amount of acid for precipitation and a permeate of caustic soda solution containing EG and DST. Concentrations of EG and DST that govern reusability of permeate in the caustic treatment of polyester fabrics were measured to be dependent of VCF. The most suitable VCF in terms of maintaining relatively good membrane productivity and high rejection of DST was approximately 4.5. At a VCF of 4.5, the rejections of DST and EG were 86% and 42%, while NaOH recovery was 84% with fluxes between 12 to 36 LMH. [Copyright &y& Elsevier]

A 14-year-old girl was admitted to our hospital for treatment of abdominal pain after an attempt to commit suicide by swallowing a caustic soda solution. Severe esophageal stricture following corrosive esophagitis occurred 2 weeks after admission. First, we tried to dilate the stenotic esophagus by using an esophageal bougie, but it was not effective and was also painful, and the treatment was stopped. Next, we tried endoscopic balloon dilation. This procedure was less painful and more effective for dilating the stenotic esophagus than was the bougie. At first, we used a pneumatic balloon and injected a steroid locally under the mucosal layer after dilation. The same procedure was continued in the outpatient clinic, but each interval of the procedures, about 3 weeks, was not changed for about 1 year. After 1 year of consecutive trials of frequent dilatation using a pneumatic balloon, the type of balloon was changed to a hydrostatic type. Three months after changing the type of balloon, treatment with tranilast, which was expected to be effective for prevention of restenosis, was started instead of steroid injection to the stenotic portion. After starting tranilast treatment, the interval of dilation became longer and the stricture itself gradually became dilated. Twenty-one months later, the interval of dilation was 3–4 months and oral intake had improved greatly. We therefore concluded that frequent endoscopic balloon dilation is effective for dilating stenosis after corrosive esophagitis. In addition, this case suggests that treatment with tranilast could be effective for preventing esophageal restenosis after balloon dilation. [ABSTRACT FROM AUTHOR]

Acute death from caustic ingestion is uncommon. We report an autopsy case of acute fatality from suicidal ingestion of a liquid caustic soda solution with peritoneal leakage due to a stab wound to the stomach. The victim was a 58-year-old man, who died about 1 h after being transported to a hospital emergency care unit. There were corrosive erosions around the mouth and a stab wound in the lower chest. The tongue, pharynx, larynx, esophagus, stomach and the proximal portion of the duodenum were all eroded and edematous. The stab wound perforated the diaphragm and stomach, accompanied by liquefactive corrosion in the left-lower thoracic and left-upper peritoneal cavities. There was a marked elevation of the postmortem serum sodium concentration and alkalosis. The observations suggested peritoneal absorption of leaked caustic soda solution, which may have greatly contributed to the acute fatality despite an intensive clinical life support. [Copyright &y& Elsevier]