Acid Attack Research Articles

Corrosion behaviour of superaustenitic stainless steel N08029 in harsh acidizing environment

It is vital to examine the resistance to corrosion of corrosion resistant alloys (CRAs) in severe oilfield corrosive environments such as acidizing to validate their performance. Super austenitic stainless steel (SASS) UNS N08029 was recently developed to offer competitive and improved corrosion resistance in extreme and aggressive environments. However, no systematic studies have evaluated the N08029 performance in acidizing conditions. In this study, N08029 was investigated in harsh acidizing conditions of different HCl concentrations (up to 25 % HCl), long immersion duration (up to 48 h), and at elevated temperatures (up to 80 °C) using both weight loss and electrochemical measurement techniques. Interestingly, all the test methods show that the corrosion resistance of the SASS increases with increasing the concentration of HCl acid. This may be due to the formation of ferric chloride protective layer on the steel surface after the dissolution of the formed chromium oxide layer by the increasing acid concentration. The decrease in the corrosion rate observed at higher HCl concentrations is because the higher concentration of HCl causes the more ferric chloride layer to form on the metal's surface. This layer protects the metal from further acid attack. Also, after 24 h immersion duration, a decrease in corrosion rate with further increase immersion duration was observed which may is also due to the formation of more ferric chloride protective layer. However, the corrosion resistant of the SASS was observed to decrease with increase in temperature of the test solution. The decreased resistance of the SASS to corrosion with increase in temperature is associated with the instability or damage of the passive/protective film on the surface of the SASS at elevated temperatures.

Chemical resistance in acidic environments of alkali-activated lightweight composites based on secondary raw materials

The durability problems in Portland cement are related to decalcification of C–S–H; alkali-activated composites are proposed as alternative, focusing on acid exposure and resistance. They were prepared from recycled materials, basic oxygen furnace carbonated and desulfurization slags. The standard material is 100% metakaolin geopolymer compared to slag-based alkali-activated materials (AAMs) with and without reinforcement of fibers (basalt, and cellulose), added in 4 wt%. The acidic environments are H2SO4, HCl, and HNO3 N = 2.14 (10, 7.5, and 12.5 wt%, respectively). The chemical resistance is improved by the addition of basalt fibers. The decrease in weight loss is 48% in HNO3 and 47% in HCl for AAM-Bas sample, while for AAM-Cell it is 9% in HCl and 34% in HNO3. The compressive strength of the AAM and AAM-Bas samples remains constant after HCl attack, while this acid attacks cellulose samples, which are stable in HNO3 and have a compressive strength of 10 MPa.

Enhancing Concrete Performance with Waste Foundry Sand Using Ternary Blended Mixes of Ordinary Portland Cement, Silica Fume, and Ground Granulated Blast Furnace Slag

AbstractMineral admixtures play an important part in improving the strength characteristics of concrete. This manuscript presents the incorporation of silica fume (SF) and ground granulated blast furnace slag into the concrete mix to decrease the cement content and enhance the strength and concrete's durability. In addition, river sand deposits have started to dry up. Also, eco‐friendly disposal of industrial wastes acts as a major threat to industries. Hence, the use of waste foundry sand (WFS) and M‐sand (MS) as fine aggregate is attempted in this study. In the first phase of this research work, concrete specimens have been prepared by partially replaced cement with 0%, 10%, 20%, 30%, and 40% by Ground Granulated Blast Furnace Slag (GGBFS) and 0%, 5%, 10%, and 15% by SF to find their optimum replacements in Ternary Blended Concrete (TBC). In the second phase, concrete specimens replaced with 0%, 10%, 20%, 30%, and 40% by WFS for fine aggregate (MS) were prepared and found optimum usage of foundry sand in waste foundry sand concrete (WFSC). In the third phase, a ternary blended green concrete (TBGC) was prepared by partially replaced cement with 30% GGBFS and 10% SF and replaced MS with 30% WFS and conducted strength (flexural strength, compressive and split tensile strength) and durability (acid and sulfate attack) studies. The above combination was found to be a promising way for the development of environmentally friendly concrete.

Physico-Mechanical Properties of High-Strength Concrete Containing Supplementary Cementitious Materials Subjected to Acid Attack

Physico-Mechanical Properties of High-Strength Concrete Containing Supplementary Cementitious Materials Subjected to Acid Attack

Enhancing acid corrosion resistance in alkaline-activated materials with water treatment residue and blast-furnace slag

This study investigates the acid corrosion resistance of an alkaline-activated material (AAM) composed of ground granulated blast-furnace slag (GGBFS) and water treatment residue (WTR) as precursors. WTR, a byproduct of the drinking water treatment process rich in aluminium and silicon, proves to be a suitable precursor for AAM after cost-effective pre-treatment involving calcination and grinding. As its low-Ca content and aluminosilicate nature of the treated WTR, the AAM incorporating WTR exhibits significant potential for improving acid resistance. This is attributed to the formation of less acid-reactive N-A-S-H gels than C-A-S-H gels in high-Ca AAMs, indicating its applicability in concrete sewage pipes where microbiologically generated acid corrosion is prevalent. In the paper, a comprehensive analysis, including mechanical performance, ion leaching behaviour, and microstructural characteristics, was conducted on mortar samples containing varying WTR/GGBFS ratios before and after exposure to sulfuric acid. Incorporating WTR up to 40 % effectively reduced acid-induced strength loss compared to neat-GGBFS AAM. The obtained results reveal that high-Ca AAMs facilitate gypsum formation during acid attack, leading to mechanical degradation. The inclusion of WTR induces a Si-rich transition layer between the corroded and intact matrix, mitigating sulfate diffusion. The release of aluminium from WTR promotes secondary precipitation of aluminosilicate, beneficially increasing the thickness of the transition layer. This thicker transition layer in the higher WTR samples is advantageous in reducing the likelihood of cracks and reducing the sulfate transportation into the intact matrix.

Evaluation of high-volume fly-ash cementitious binders incorporating nanosilica as eco-friendly sustainable concrete repair materials

Nowadays, the use of environmentally friendly, long-lasting building materials with minimal energy and carbon dioxide emissions are highly recommended. Some of these materials can be made from industrial and agricultural wastes. By replacing ordinary Portland cement (OPC) with large volume of fly ash waste (FA), environmental issues associated with landfill disposal and cement manufacture can be mitigated. Nonetheless, using a high amount of FA (up to 50 %) to replace cement resulted in poor strength performance, particularly during early age. This experimental study created an increased strength cement mortar containing a high volume of FA (60 %) and bottle glass waste nanoparticles (BGWNPs). In this experiment BGWNPs were prepared and 2, 4, 6, 8 and 10 vol% of them were used as a replacement of OPC-FA binder. According to the results, by adding 0–6 % of BGWNPs to a high-volume FA matrix considerably increased the bond strength (from 12.5 % to 39.1 %). On the other hand, the findings revealed that the addition of nanoparticles (up to 6 %) caused a modest reduction in strength values. Other engineering and microstructure properties showed a similar pattern. The matrix with 6 % BGWNPs displayed the best performance when compared to other levels. The results also showed that replacing OPC by high volume FA incorporating BGWNPs significantly improved the durability of proposed mortar, such as reduction in drying shrinkage and increased acid attack and abrasion resistance. Related to the environment benefits, the proposed mortars contributed in a reduction of carbon dioxide emission, energy consumption and cost of binder by 61.9 %, 54.3 % and 50.6 % compared to OPC, respectively. To conclude, the use of BGWNPs make it possible to produce high volumes of FA-based cement mortars with acceptable mechanical and durable properties for concrete repair applications in the construction industry. Additionally, sustainability can be attained by lowering pollution, recycling waste, and finding solutions to landfill problems.

Effects of silver diammine fluoride with/without potassium iodide on enamel and dentin carious lesions in primary teeth.

To assess the effects of SDF and SDF+KI treatment on enamel and dentin carious lesions in primary teeth using x-ray Microtomography (XMT) and back scattered scanning electron microscopy (BSE-SEM). Artificial enamel caries of 3 caries free primary teeth were created by immersion of the samples in 50 ml demineralization solution for 72 h. Three other teeth with natural dentin caries were selected. Both groups were divided into 3 subgroups: EC-Enamel Control; ES-Enamel with SDF application; ESK-Enamel with SDF followed by KI application; DC-Dentin Control; DS-Dentin with SDF application; DSK-Dentin with SDF followed by KI application. Each tooth was imaged using XMT at 3 time points: (1) Pretreatment; (2) after immersion in remineralization solution for 120 h, with or without SDF or SDF+KI; (3) after subsequent immersion in demineralization solution for 72 h. The change of radiopacities of the lesions in these time points were assessed from the XMT images. After the XMT scans, all teeth were investigated microscopically using BSE-SEM. In EC, no change in linear attenuation coefficient (LAC) was observed after remineralization, but LAC reduction was observed after subsequent demineralization. For ES, thin layer of high LAC material was deposited on the enamel surface after remineralization, and further reduction of LAC was observed after demineralization. In ESK, the surface layer was lost after SDF+KI, and small reduction of LAC was observed after demineralization. In DC, no LAC change was observed after remineralization, but reduction of LAC was detected after demineralization. In DS, high LAC material was formed on the carious dentin surface and randomly inside the lesion. No further LAC change was found after demineralization. In DSK, thick layer of high LAC material was deposited on the carious surface and inside the dentinal tubules. No further LAC reduction was found after subsequent demineralization. SDF and SDF+KI did not protect artificial enamel under acid attack even though Ag products were deposited in the porous enamel. However, SDF and SDF+KI shows protective properties against acid challenges and Ag products are deposited in carious dentin lesion without tubular structure randomly; and within dentinal tubules when these structures are retained.

For aqueous/soil cadmium immobilization under acid attack, does the hydroxyapatite converted from Pseudochrobactrum sp. DL-1 induced vaterite necessarily show higher stability?

Microbial induced carbonate precipitation (MICP) technology was widely applied to immobilize heavy metals, but its long-term stability is tough to maintain, particularly under acid attack. This study successfully converted Pseudochrobactrum sp. DL-1 induced vaterite (a rare crystalline phase of CaCO3) to hydroxyapatite (HAP) at 30 ℃. The predominant conversion mechanism was the dissolution of CdCO3-containing vaterite and the simultaneous recrystallization of Ca4.03Cd0.97(PO4)3(OH)-containing HAP. For aqueous Cd immobilization, stability test at pH 2.0–10.0 showed that the Cd2+ desorption rate of Cd-adsorbed vaterite (3.96–4.35 ‱) were 7.13–20.84 times greater than that of Cd-adsorbed HAP (0.19–0.61 ‱). For soil Cd immobilization under 60 days of acid-rain erosion, the highest immobilization rate (51.00 %) of exchangeable-Cd and the lowest dissolution rate (−0.18 %) of carbonate-Cd were achieved with 2 % vaterite, while the corresponding rates were 16.78 % and 1.31 % with 2 % HAP, respectively. Furthermore, vaterite outperformed HAP in terms of soil ecological thorough evaluation. In conclusion, for Cd immobilization by MICP under acid attack, DL-1 induced vaterite displayed direct application value due to its exceptional stability in soil and water, while the mineral conversion strategy we presented is useful for further enhancing the stability in water.

Vitriol attack on a young woman in Greece: The story of Ioanna's response.

An acid attack is a deliberate act of violence. Sulphuric acid is thrown at a person's face and body with the intention of harming and disfiguring the victim. Sulphuric acid is a dangerous weapon which can cause very serious injuries including severe skin damage, blindness, significant disfigurement and/or permanent disability. We report the case of Ioanna, a 34-year-old woman who was attacked with vitriol by a jealous woman in May 2020. Following her admission to hospital, where Ioanna was an inpatient for 85 days, she underwent nine operations. Since her discharge she has undergone ten more, with further interventions likely in the future. In addition, she has undergone various treatments and procedures to restore her skin. Ioanna's courage and strength has inspired thousands of young children and adults who cope with a variety of health problems.

In-depth insights into transformation mechanism of synthetic saponite to amorphous silica under acid attack

Amorphous mesoporous materials derived from synthetic saponite (Sap) by acid treatment have been used in catalysis for several decades. Uncovering the transformation process of Sap from layered to amorphous structure under acid attack is beneficial to optimize the structure of Sap-derived mesoporous materials, yet such transformation process remains unclear. Herein, a magnesium-Sap was synthesized by hydrothermal method and then treated with sulfuric acid. By studying the changes in phase composition, morphology, chemical state of elements and surface area of the synthetic Sap after acid attack, a specified transformation mechanism of synthetic Sap to amorphous silica is clarified. The experimental results indicate that after leaching of Mg and Al cations from the Mg/AlO6 octahedral sheets of Sap during acid attack, the retained SiO4 tetrahedral sheets of Sap were transformed into amorphous short-range ordered silica phases and nanoscrolls with pseudohexagonal side pores. The transformation process of synthetic Sap under acid attack can be divided into leaching of metal ions from octahedral sheets of Sap to form layered silica particles, splitting and crimping of surface nano-silica layers from the formed silica particles, and completely amorphous transformation. The distortion of SiO bonds in SiO4 tetrahedral sheets during acid attack might be the driving force for such transformation. This work provides specific transformation process of synthetic Sap under acid attack which is conductive to the controllable preparation of acid-treated Sap derivates, and has certain significance for understanding of structural transformation of clay minerals with MgO6 octahedral structure.

Decoupling the air sensitivity of Na-layered oxides.

Air sensitivity remains a substantial barrier to the commercialization of sodium (Na)-layered oxides (NLOs). This problem has puzzled the community for decades because of the complexity of interactions between air components and their impact on both bulk and surfaces of NLOs. We show here that water vapor plays a pivotal role in initiating destructive acid and oxidative degradations of NLOs only when coupled with carbon dioxide or oxygen, respectively. Quantification analysis revealed that reducing the defined cation competition coefficient (η), which integrates the effects of ionic potential and sodium content, and increasing the particle size can enhance the resistance to acid attack, whereas using high-potential redox couples can eliminate oxidative degradation. These findings elucidate the underlying air deterioration mechanisms and rationalize the design of air-stable NLOs.

Activity of botulinum neurotoxin X and its structure when shielded by a non-toxic non-hemagglutinin protein

Botulinum neurotoxins (BoNTs) are the most potent toxins known and are used to treat an increasing number of medical disorders. All BoNTs are naturally co-expressed with a protective partner protein (NTNH) with which they form a 300 kDa complex, to resist acidic and proteolytic attack from the digestive tract. We have previously identified a new botulinum neurotoxin serotype, BoNT/X, that has unique and therapeutically attractive properties. We present the cryo-EM structure of the BoNT/X-NTNH/X complex and the crystal structure of the isolated NTNH protein. Unexpectedly, the BoNT/X complex is stable and protease-resistant at both neutral and acidic pH and disassembles only in alkaline conditions. Using the stabilizing effect of NTNH, we isolated BoNT/X and showed that it has very low potency both in vitro and in vivo. Given the high catalytic activity and translocation efficacy of BoNT/X, low activity of the full toxin is likely due to the receptor-binding domain, which presents very weak ganglioside binding and exposed hydrophobic surfaces.

New geopolymer preparation methods and its application by recycle of double-waste: ground granulated blast furnace slag and fly ash

ABSTRACT This article mainly studies new geopolymer preparation methods by recycle of double waste:ground granulated blast furnace slag (GGBFS) and fly ash as geopolymer precursor, through different mass ratio of GGBFS and fly ash, to prepare geopolymers by alkali activation, the samples is cured at ambient temperature and the mechanical test is carried out together with the analysis of XRD, SEM and EDS to research the mechanism of strengthening and geopolymerisation. After analysis we find that the sample prepared by 30% mass ratio of GGBFS have good initial strength and short setting time, as well as best mechanical performance, which is attributed to moderate Ca2+ introduction accelerates the speed of geopolymerisation and the reactants of N-A-S-H gel, C-A-S-H gel and hydrated C-S-H help to bridge the gaps between the different hydrated phases, unreacted particles and matrix, result in a homogeneous and compacted geopolymeric sample. When GGBFS mass ratio above 50%, the mechanical of samples is deteriorated due to too much hydrated calcium containing compounds are formed and covered on the unreacted GGBFS particles surface to block further geopolymerisation. The acid attack test and water resistance test are carried out to analysis the durability between 30% GGBFS introduced geopolymer and ordinary Portland cement (OPC). In additional, a field application in case of 30% GGBFS introduced geopolymer grouting repair material indicated desirable construction based on visual observation and ground-penetration radar scanning.

In situ deposition of amorphous zirconia to enhance corrosion and tribocorrosion resistance of dentin surface

With global aging and the prevalence of acidic diets, dentin exposure is becoming commonplace; thus, it is necessary to develop a treatment technology that combines resistance to wear, corrosion, and tribocorrosion. Herein, we present a promising treatment strategy that induces in situ deposition of amorphous zirconia on exposed dentin surface. The deposited amorphous zirconia bonds to dentin surface through strong chemical connection, and acts as a protective layer against acid attack and contact wear due to its acid-inertness and good mechanical properties. Consequently, the treated dentin surface exhibits encouraging corrosion and tribocorrosion performance. The deposit also provides antibacterial protection.

Impact of the partial substitution of cement and sand by ash from several types of wood species in cementitious materials manufacture: valorization in the industrial field

The main objective of this article is to evaluate the potential use of wood ash as a substitute for cement and sand in mortars. Three types of wood were selected: Ayous, Sapelli and Fraké, all of which were sourced from carpentry in Cameroon. The sawdust was dried and combusted to obtain ash, then ground and sieved. Six types of mortar were produced, with cement substitution at 0%, 5%, 10%, 15%, 20% and 25%. The physico-mechanical properties of these substitutions were determined after 7, 28 and 56 days. The results of the cement paste consistency show that it increases with the addition of ash, due to the fact that sawdust ash requires a large quantity of water. The addition of ash caused an increase in setting time due to the fact that sawdust ash is less reactive than Ordinary Portland cement, resulting in a delay in the rate of cement hydration. Apparent density values decreased with the addition of sawdust ash, probably due to the hygroscopic behavior of type of ash in mortar specimens. The highest pozzolanic index is that of 5% replacement by ash and almost identical absorption for all mortars at this substitution percentage. Acid attack results revealed a higher durability of mortar specimens with the higher percentage of ash substitution. Optimum compressive strengths for the different substitution percentages were observed at 5%, 15% and 10% respectively for Ayous, Sapelli and Fraké. The best wood ash is Sapelli because of its chemical composition and resistance to compression in mortars. At 56 days, compressive strength values exceed those of the reference composition. This may be due to pozzolanic reactions in the mortars of ash.

An Investigation of the Mechanical and Durability Properties of Hollow Concrete Blocks Made with Copper Mine Tailings as a Partial Cement Replacement

The increase in copper productivity in Zambia has resulted in the expansion of disposal areas occupied by mineral wastes and tailings. This not only consumes land but also, due to insufficient management, poses negative environmental impacts and health risks to people. Therefore, efficient and sustainable approaches for the proper management of these waste materials must be developed. In this study, the potential utilization of copper mine tailings was assessed. After analyzing the physical and chemical properties of copper mine tailings from Kitwe Tailings Dam (TD25), hollow concrete block specimens were prepared. Copper mine tailings were used as a partial replacement for cement in the mix design, with replacement ratios as follows: 0% for CBCMT O% (control specimen), 10% for CBCMT1O%, 20% for CBCMT2O%, 30% for CBCMT3O%, 40% for CBCMT4O%, and 50% for CBCMT5O%, all aimed at achieving a target strength of 5 MPa. Specimen compressive strength was evaluated, and it was found that CBCMT1O% and CBCMT2O% achieved the target compressive strength at 28 days of age. Water absorption rates and resistance to acid attack were also assessed. Findings revealed that all specimens outperformed the control specimen in terms of these properties. Furthermore, the environmental feasibility of the hollow concrete blocks specimens was examined, and the results showed limited leaching of heavy metals from the specimens, with concentrations within permissible thresholds. Additionally, a statistical analysis was conducted to study the influence cell shape has on the specimens’ compressive strength. Aimed at identifying the optimal specimen type for achieving compressive strength at an early age, results indicated that cell shape had a significant impact on the 28-day age of hollow concrete blocks. The study proposes a novel copper mine tailings (waste) management approach, by utilizing the potential it has to replace cement in the production of hollow concrete blocks, evident from the observed enhancement of the mechanical and durability properties.

Impact of Pernicious Chemicals on Geopolymer and Alkali-Activated Composites Incorporated with Different Fiber Types: A Review

Over the past decade, developing geopolymer mixes to replace ordinary Portland Cement (OPC) composites has yielded positive results, leading to extensive research. The incorporation of fibers in geopolymers, besides impacting the mechanical properties, has also significantly impacted durability, mainly when dealing with the most pernicious forms of deterioration resulting from chloride attack, water penetration, sulfate attack, acid attack, as well as freeze-thaw, which occurred through chemical transgression. This study presents a systematic approach to thoroughly review the durability properties of fibrous geopolymer composites exposed to harmful chemicals and extreme environmental conditions. The multi-parameters and factors critically influencing fibrous geopolymers' physical and chemical stability are examined. The study is further aimed at providing an update on the research work undertaken to assess the impact of fiber incorporation on the durability of geopolymer and alkali-activated composites thus far. Furthermore, this review hopes to promote and facilitate research on durability for the long-term, large-scale adoption, and commercialization of advanced fibrous, non-OPC-based materials.

Acid Attack Survivors in Popular Culture and the Quest for Human Rights

Abstract Acid attack is a gender-based violence, the historical roots of which can be traced back to Victorian-era Britain and Europe. Over the years, acid emerged as a preferred choice of weapon in several other countries. The victims of acid violence are forced to live a life of suffering due to the resultant emotional and physical scars. By adopting an interdisciplinary approach and drawing on examples from literature, movies, and other media, the article will examine the popular culture portrayal of acid attack victims through the lens of Hall’s encoding/decoding model. It examines the ways in which narratives of acid attack victims are depicted and consumed by the public. Moreover, the article highlights the role of the popular media in challenging and perpetuating these narratives and the immense potential it holds to shape public discourse and policy surrounding human rights issues. The article discusses the human rights of the acid attack victims through the lens of Amartya Sen’s capabilities approach. Additionally, the article underscores the need for amplifying the voices and experiences of the acid attack victims in popular culture—thereby advocating for greater awareness, empathy, and activism.

Utilization of marble waste as fine aggregate in the composition of high performance concrete containing mineral additions

This study investigates the effect of adding marble waste as fine aggregate on the properties of high-performance concrete. To achieve this objective, 10%, 20%, 30%, and 40% of marble waste fine aggregate were substituted for ordinary fine aggregate in the composition of high-performance concrete mixtures containing silica fume and ground blast furnace slag. The fresh properties were studied using slump, fresh density and air content tests, while the hardened properties were assessed using compressive and flexural strengths, ultrasonic pulse velocity, water absorption, and chemical acid attack tests. The results obtained revealed that the addition of marble waste fine aggregate significantly improved the properties of high-performance concrete and increased its resistance to chemical acid attacks. The composition-based ground blast furnace slag containing 40% marble waste fine aggregate outperformed all other compositions, increasing compressive strength by 30.98%.

Politics and Violence in Representation of Acid Attack Victims in the Media: A Feminist Discursive Perspective

Abstract In recent times, narratives of acid attack survivors have become common in the media (newspapers and magazines), showcasing them simultaneously as fashion models and victims of a heinous crime. In a similar vein, the Hindi film Chhapaak underscores the barbarity of an acid attack and the subsequent struggles for justice by the protagonist. Drawing on feminist critical discourse analysis and insights from Nancy Fraser on cannibal capitalism, this article analyzes the discursive construction of acid assault victims through select extracts from media articles and the film to highlight the politics of representation of the survivors and their ordeals against patriarchal and androcentric arrangements in society. Linguistic analysis (through speech acts, vocabulary, and presupposition) reveals contradictory discourses of celebration and discrimination in the media in relation to fashion, where the acid survivors are used not only to increase awareness about the offense but also to promote sales of garments. The discourses of rampant unemployment, gender-based oppression, and racial violence, despite laws regulating the sale of acid, underscore the cannibalizing tendencies of a capitalist society that seeks to devour and shun women after incapacitating them. Furthermore, the complicity of public agencies (legal, medical, and governmental) hints at apathy, callousness, and the systemic violence symptomatic of a profit-driven capitalist society.