Sulfuric Acid Research Articles

Investigation of the Thermokinetic and Thermodynamic Parameters of Biodiesel and Associated Oil from Palm Kernel Oil During Thermal Degradation

ABSTRACT This study investigates the kinetic and thermodynamic parameters of the thermal degradation of biodiesel produced from low-grade palm kernel oil. In this work, biodiesel was produced through a two-step transesterification from a palm kernel oil having a free fatty acid content of 5.7%. The first step uses 25% methanol (wt% of palm kernel oil) and 1% sulfuric acid (wt% of palm kernel oil) to reduce the free fatty acids content to 0.3% within 30 min reaction time. In the second step, a methanol-to-oil molar ratio of 6:1 and 0.6% (wt% of palm kernel oil) of KOH yielded a palm kernel oil conversion of 96.96% after 30 min reaction time. The palm kernel biodiesel was analyzed using Fourier Transform Infrared spectroscopy, gas Chromatography tandem mass spectrometry, nuclear magnetic resonance spectroscopy (1H and13C), and thermogravimetric analysis. The thermal stability of palm kernel biodiesel was assessed through the kinetic and thermodynamic parameters of biodiesel thermal decomposition using isoconversional techniques. The Flynn-Wall-Ozawa, Kissinger-Akariha-Sunose, and Starink models were used to evaluate the kinetic parameters, while the Coats and Redfern technique was used to forecast the most probable mechanism of the palm kernel biodiesel thermal degradation. The average activation energies of 108.60 kJ mol−1, 107.75 kJ mol−1 and 95.77 kJ mol−1 using the Flynn-Wall-Ozawa, Kissinger-Akahira-Sunose, and Starink methods, respectively. FWO method best described palm kernel oil and biodiesel decomposition, with the highest R2 values of 0.94 for the oil and 0.93 for biodiesel The results obtained from the thermodynamic study (ΔH = 218.48 kJ.mol−1, ΔG = 200.05 kJ.mol−1 and ΔS = 27.10 J.mol−1.K−1) revealed that the biodiesel thermal degradation was an endothermic, non-spontaneous process governed by a three-dimensional diffusion reaction mechanism.

Synthesis of Novel 2-Amino Thiazole Derivatives and Salicyaldehyde based Ligand to have Biological Activity

In inorganic chemistry, Schiff bases and complexes come in a variety of forms. Therefore, the discovery of new organic and inorganic compounds with remarkable anti-fungal, anti-bacterial, and anticancer characteristics represents a major advancement in biochemistry, pharmacy, and medicine. All of the chemicals that were employed in this study were A.R. grade. The following materials provided by SD's fine chemical Ltd. and Merck chemicals, Mumbai were utilised impurification: methanol, calcium hydroxide, sodium acetate, thiourea, ethylacetoacetate, benzoyl chloride, acetyl chloride, 1,4-dioxane, and sulfuric acid. Additionally, this Schiff base may combine with the ions of several transition metals, such as Ni(II), Cu(II), Co(II), and Cd(II), to create complexes. In addition to chemical analysis, conductivity, and magnetic tests, we further characterized the complexes using electronic and infrared spectroscopy in order to examine their structures. Every compound's antibacterial activity was evaluated. In the agar cup test method, all of the Schiff base metal complexes had a moderate level of antibacterial activity. Spectroscopic data suggests that these complexes are all of type ML2.(H2O)2 (M=Mn, Fe, Co, Ni, and Cu).

Application of X-ray Spectroscopic Techniques to Determine the Inorganic Composition and Sulfur Chemical Speciation of the Amazonian Plant Bixa orellana

Bixa orellana is a plant that has a variety of uses, such as applications in the food and cosmetic industries, as well as culinary uses, and body painting for Indigenous people. Despite its versatility, few studies have explored its inorganic composition, and its sulfur chemical speciation has only been assessed from the point of view of sulfurous amino acids. Here, we report on the inorganic composition of Bixa orellana fruits, pericarps, and seeds obtained using Wavelength Dispersive X-ray Fluorescence (WD-XRF) and sulfur chemical speciation using X-ray Absorption Near-Edge Structure (XANES). Our results show that the seed is a source of potassium, calcium, magnesium, and phosphorous. But also, the pericarp, which is considered waste, contains a high amount of nutrients. From the XANES measurements, the distribution of the oxidation state of the sulfur atom was obtained, and it was shown that although several oxidation states of sulfur are present, oxidized sulfur (sulfate) is the dominant form of sulfur in all samples.

Hydrogen Embrittlement of Advanced High-strength Steel S960MC Used in Transport and Vehicle Industry and the Influence of Potassium Thiocyanate during Hydrogenation

Advanced high-strength steels (AHSS) are currently facing a serious challenge from hydrogen embrittlement, which significantly affects their mechanical properties. Problems arise when hydrogen diffuses into the material and accumulates at grain boundaries, inclusions, or microcracks, degrading the material's characteristics. The main objective of the study is to investigate the effects of adding potassium thiocyanate (KSCN) to the sulfuric acid base solution during electrolytic hydrogenation using microalloyed martensitic AHSS grade S960MC. An increase in hydrogen diffusion into the examined material across its full surface is produced by adding thiocyanate ions to the electrolyte. This is the rationale behind the decision to add KSCN to the sulfuric acid base solution. The addition of KSCN to the base environment induced a considerable reduction in fracture strain, and the degradation was attributed to hydrogen buildup at grain boundaries, impurities and microcracks. These steels have an extensive list of applications in the automotive industry and are frequently used in the form of sheets for welding. Therefore, it is important to understand how their mechanical characteristics and behaviour vary in various circumstances, including hydrogen-rich environments.

Removal of sulphur and nitrogen compounds from model fuel by adsorption of modified activated carbon

This study aimed to achieve the highest percentage removal of dibenzothiophene (DBT), quinoline (QUI), and indole (IND) adsorbed by double-impregnated modified activated carbon (MAC). Modification of commercial activated carbon (AC) by sulphuric acid (H2SO4) of 15%, 30%, 45%, 60%, and 75% w/v followed by subsequent 1 zinc chloride (ZnCl2): 1 AC impregnation ratio and activated at 500 oC in a muffle furnace under self-generated atmosphere for an hour. The determination of optimized MAC was identified through the highest removal rate of DBT, QUI, and IND from adsorption experiments which were analysed using an ultraviolet-visible (UV-Vis) spectrophotometer. It was found that DBT and IND showed a removal high percentage of up to 86.23% and 82.77% respectively by using 75% H2SO4 with ZnCl2 MAC. Meanwhile, QUI favoured 30% H2SO4 with ZnCl2 MAC with a removal percentage of 33.17% which was still higher than unmodified AC. Physical and chemical properties such as the morphological structure, elemental analysis, porosity, pore size, surface functional group, percentage yield, pH, bulk density, content, ash content, and iodine number were studied for the optimized MAC. Scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) spectroscopy and Fourier transform infrared spectroscopy (FTIR) were used to characterize the MAC. Both MACs showed high percentage yields of 72.08% and 71.13% for 30% and 75% H2SO4 and ZnCl2 MAC respectively. Meanwhile, the pH was between the ranges of 5.36-5.53 for both MACs. Bulk densities were also favourable while the moisture and ash content were within acceptable limits. Iodine numbers for 30% and 75% H2SO4 and ZnCl2 MAC were 857 and 861 mg/g respectively, hence indicating that the MAC achieved high porosity and good adsorption performance. Langmuir, Freundlich, and Temkin adsorption isotherm models as well as pseudo-first order (PFO) and pseudo-second order (PSO) kinetic models were considered for understanding the adsorption mechanisms. The study revealed that DBT, QUI, and IND removal processes, followed the Langmuir adsorption isotherm model with correlation coefficients, R2 of 0.9905, 0.9791, and 0.9964 respectively. Moreover, the adsorption kinetic data of DBT, QUI, and IND provided a better fitting to the PSO kinetic model with R2 of 0.9992, 0.9987, and 0.9998 respectively. According to the Langmuir isotherm model and PSO kinetic model, the adsorption mechanisms of DBT QUI and IND were chemisorbed under monolayer formations.

Evolution characteristics and mechanism of microstructure, hydraulic and mechanical behaviors of sandstone treated by acid-rock reaction: Application of in-situ leaching of uranium deposit

The main difficulty in understanding the effects of chemical-physical composite stimulation for low-permeability sandstone-type uranium deposits is clarifying the influence of acidification on pore response mechanism and permeability-mechanical properties evolution during loading-deformation-failure process. Therefore, the acid-rock reaction experiment was first performed, the multiple testing methods (X-ray Diffraction, thin-section identification, high-pressure mercury intrusion porosimetry, stress-seepage coupling experiment) were then conducted, the evolution laws and mechanisms of reservoir physical characteristics after acidification were finally clarified. Results show that after the acid-rock reaction, the contents of calcite, feldspar and kaolinite of samples are decreased and quartz content is increased, the permeabilities of samples are all promoted, the peak strength, elastic modulus, and shear modulus of samples are reduced and the Poisson’s ratio is raised. The acid-rock reaction changes the energy storage performance and promotes the plasticization of samples. It is suggested to adopt a lower sulfuric acid concentration (2 g/L) and longer reaction time (>45 d) for the ISL of uranium deposits. This work has important theoretical and practical significance for an in-depth understanding of the enhanced mining of low-permeability sandstone-type uranium deposits.The complex changes in reservoir physical characteristics during in-situ leaching of sandstone-type uranium deposits directly affect the effectiveness of uranium resource development. To thoroughly and comprehensively understand the influencing mechanism of sulfuric acid on the microstructure, and hydraulic and mechanical behaviors of sandstone under different reaction concentrations and reaction times, the acid-rock reaction experiment was first performed, the multiple analysis and testing methods (X-ray Diffraction, thin-section identification, high-pressure mercury intrusion porosimetry, stress-seepage coupling experiment) were then conducted, and the evolution laws and mechanisms of reservoir physical characteristics were finally clarified. Results show that after the acid-rock reaction, the contents of calcite, feldspar, and kaolinite of samples are decreased and quartz contents of samples are increased; the permeabilities of samples are promoted to varying degrees; the peak strength, elastic modulus, and shear modulus are reduced and the Poisson’s ratio is enhanced. All these physical characteristic changes depended on the reaction concentration and reaction time. Additionally, the acid-rock reaction causes the transition of samples from elastic energy to dissipative energy and from brittleness to plasticity during the loading-deformation-failure process. This research suggests a lower sulfuric acid concentration (2 g/L) and longer reaction time (>45 d) for the in-situ leaching of uranium. This work has important theoretical and practical significance for the in-depth understanding of the acid leaching process and the optimization of the leaching technology.

Chemical weathering processes in the Chinese Loess Plateau

Covered by erodible loess and affected by significant seasonal climate variations, chemical weathering in the Chinese Loess Plateau (abbreviated as CLP) has important effects on the hydrochemistry of the Yellow River and the global carbon cycle. However, chemical weathering processes in the CLP are still unclear. Based on 296 river water samples in the CLP in the different seasons, hydrochemistry, weathering processes, and their controlling factors were revealed. River waters in the CLP exhibited slightly alkalinity (pH = 8.4 ± 0.5) with much high total dissolved solids (TDS) values (691 ± 813 mg/L). The water types of river water in the CLP were primarily O42− − Cl− − Na+, HCO3− − Ca2+ − Mg2+, and SO42− − Cl− − Ca2+ − Mg2+. According to the forward model, evaporite dissolution has the largest contribution (55.0 % ± 0.2 %) to riverine solutes in the CLP, then followed by carbonate weathering (36.0 % ± 0.2 %) and silicate weathering (6.0 % ± 0.1 %). For spatio-temporal variations, the contribution of evaporite dissolution in the CLP decreased from northwest to southeast with higher proportion in the dry season, carbonate weathering increased from northwest to southeast with a higher proportion in the wet season, and silicate weathering showed minor spatio-temporal variations. Ca2+ and Mg2+ were affected by carbonate precipitation and/or incongruent calcite dissolution, and about 50 % samples exhibited cation exchange reactions. The physical erosion rate in the CLP, which was 372 ± 293 t·km−2·yr−1, varied greatly and was greater than that of the other worldwide rivers. Chemical weathering rates in the CLP showed an increasing trend southward. During the wet season, high runoff led to the release of evaporite and carbonate from loess, while the interfacial reaction kinetic limited the increase of the silicate weathering rates. The CO2 consumption budget by carbonate weathering (6.1 × 1010 mol/yr) and silicate weathering (1.6 × 1010 mol/yr) in the CLP accounted for 0.29 % and 0.08 % of the global carbon cycle, respectively. Meanwhile, the weathering proportion by sulfuric acids was relatively high with a CO2 release flux of 6.5 × 109 mol/yr. By compiling the data, we propose that the interfacial reaction kinetic and runoff controls CO2 consumption rate by silicate and carbonate weathering, respectively. These results contribute to the understanding of modern weathering processes of loess in the CLP, thus helping to deduce the environmental and climatic evolution of the basin.

515. LAPAROSCOPIC PHARYNGO-COLOPLASTY WITH RIGHT COLON FOR A CASE OF COROSSIVE INJURY

Abstract Introduction Corrosive stricture of esophagus and stomach is more common in Acid poisoning. Management these cases requires good surgical planning, technical expertise in doing these complex procedures Case report A34 year gentleman consumed small quantity of sulphuric acid. Feeding jejunostomy was done for improving the nutrition. After 9 months of initial insult Upper GI scopy and CT NECK, CHEST, ABDOMEN was done which confirmed complete esophageal stricture from cricopharyx, thickened entire stomach. We Did LAPAROSCOPIC PHARYNGO-COLOPLASTY WITH RIGHT COLON. Intraoperatively thickened stomach, total gastrectomy done, Right colon used for Coloplasty.Post procedure patient recovered well, Drins removed on 4th post op day, patient was discharged on 6 th day. https://drive.google.com/file/d/15OkPYKjsoQ-NVceBUzUArFAqMzcnA02S/view?usp=drive_web

Utilization of cotton stalk waste for sustainable isopropanol production via hydrolysis and coculture fermentation

The present investigation focused on isopropanol production from lignocellulosic cotton stalk biomass (CSB) using conventional pretreatment, enzymatic hydrolysis and fermentation methods. In comparison to alkaline (NaOH) pretreatment, dilute sulphuric acid (H2SO4) pretreatment showed higher cellulose exposure (448.5 mg/g). Further, ultrasono assisted acid and alkali pretreatment was performed for maximum exposure of cellulose and it was found 616.9 and 586.15 mg/g respectively. Chemical pretreated CSB was additionally exposed to independent enzymatic hydrolysis using commercial enzymes (Celluclast and Viscozymes) following Response Surface Methodology (RSM), which revealed a maximal production of glucose and xylose yield (544.6 mg/g and 41.8 mg/g). Pretreated and enzymatic hydrolyzed cotton stalk biomass at various conditions were analysed using SEM, FTIR, and XRD to determine the structural and functional changes. Further, a co-culture strategy was employed on pretreated and hydrolyzed CSB using two fermented yeast strains (Saccharomyces cerevisiae and Pichia pastoris) for isopropanol production. HR-MS analysis revealed that the maximum concentration of isopropanol (126.228 mM) was produced in 2:1 proportionate ratio of two fermented yeasts with 20 g/L of substrate loadings at 72 h of incubation time. These results indicate that the production of isopropanol (7.46 g/L) from CSB with different parametric conditions is an encouraging step and can be exploited further for various industrial applications.

Jarosite formation in Permian-Triassic strata at Xiakou (South China): Implications for jarosite precipitation from H2S upwelling on Mars

Abstract The source of sulfuric acid and associated aqueous alteration of ancient martian sedimentary rocks remain under debate in the context of divergent models of jarosite formation. Here, we report the formation of sulfates, including jarosite in K-bentonites within shallow-water facies of the Permian-Triassic (P-T) transition at Xiakou in South China. In these strata, jarosite is dispersed in the clay matrix or forms aggregates in pore spaces, has a euhedral morphology, and coexists with variably 34S-depleted paragenetic gypsum and bassanite (δ34S = –37.23‰ to +3.20‰ VCDT). Subaqueous alteration of volcanic tuffs concurrently with oxidation of upwelled, biogenically sourced H2S is the process of jarosite formation in the Xiakou K-bentonites. This mechanism of jarosite precipitation and stability over geological time challenges the long-held view of acidic, water-limited conditions leading to iron(III) sulfate precipitation and would be consistent with possible microbial or nanobial life on early Mars.

THE EFFECTS OF NaClO2 AND H2O2 AS BLEACHING AGENTS IN THE SYNTHESIS OF CELLULOSE ACETATE FROM OIL PALM EMPTY FRUIT BUNCH

Indonesia is one of the largest palm oil-producing countries in the world. The results of palm oil processing produce a lot of waste, such as oil palm empty fruit bunches (OPEFB). The utilization of OPEFB in Indonesia is minimal, so it needs further development. OPEFB has a very high α-cellulose content, so that it can be used as raw material for manufacturing cellulose acetate. Making cellulose acetate from OPEFB consists of three main steps: delignification, bleaching, and acetylation. This study aims to compare the effects of the concentration of NaClO2 or H2O2 in the bleaching process on the physical properties of cellulose acetate from OPEFB. In the delignification process, 100 mesh-sized OPEFB powder is reacted with 5% sodium hydroxide (NaOH) at 100oC for 2 hours. The residue from deliglinfication was washed using distilled water until pH 7, filtered using filter paper, and dried using an oven at 50oC. The next step is the bleaching process using NaClO2 or H2O2 with concentration variations (1%, 2%, 3%, 4% and 5%). The bleaching process was carried out at 90oC for 1.5 hours. After filtration, the bleached residue was washed using distilled water until pH 7, filtered using filter paper, and dried using an oven at 50oC. After the bleaching process, α-cellulose powder was produced. The next step is acetylation, containing three main steps. The first step is the reaction between α-cellulose powder with acetic acid (CH3COOH) and sulfuric acid (H2SO4) at 40oC for 1.5 hours to perform activation. The second step is the addition of anhydrous cellulose in a ratio of 1:10 and mixed at 40oC for 1.5 hours. The third step is the addition of distilled water, acetic acid, and sodium acetate (CH3COONa) at 40oC for 5 minutes. Then, followed by filtration, the residue was washed using distilled water and methanol until pH 7 and dried at 50oC. The best result is using NaClO2 as a bleaching agent with a concentration of 2%, resulting in cellulose acetate yielding 98.85%, density of 1.954 g/mL, and L value of 91.897 for colorimetric test results. The density and L-value were close to commercial cellulose acetate (Sigma Aldrich). From the results of FTIR analysis, it can be concluded that the acetylation of α-cellulose into cellulose acetate has been successful, as evidenced by the formation of carbonyl groups (C=O).

Approach towards the Purification Process of FePO4 Recovered from Waste Lithium-Ion Batteries

The rapid development of new energy vehicles and Lithium-Ion Batteries (LIBs) has significantly mitigated urban air pollution. However, the disposal of spent LIBs presents a considerable threat to the environment. Recycling these waste LIBs not only addresses the environmental issues but also compensates for resource shortages and generates substantial economic benefits. Current recycling processes primarily focus on the extraction of valuable metals, often overlooking the treatment of residual waste post-extraction. This project targets the iron phosphate (FePO4) derived from waste lithium iron phosphate (LFP) battery materials, proposing a direct acid leaching purification process to obtain high-purity iron phosphate. This purified iron phosphate can then be used for the preparation of new LFP battery materials, aiming to establish a complete regeneration cycle that recovers lithium carbonate and iron phosphate from waste LFP materials for the production of LFP. The study investigates process parameters such as acid types and concentrations, leaching time, and the number of leaching cycles. The results demonstrate that, after purification, the levels of impurity metals decrease while the iron content increases correspondingly. Under optimized experimental conditions, the dilute sulfuric acid leaching rates of Al, Cu, Ca, and Ni reached 36.0%, 51.4%, 89.5%, and 90.9%, respectively. Furthermore, hydrothermal treatment in dilute phosphoric acid achieved leaching rates of 87.9%, 85.8%, 98.4%, and 99.1% for Al, Ca, Cu, and Ni, respectively. The microstructure characterization revealed significant changes in phase and grain morphology during the leaching process in dilute phosphoric acid, which are likely associated with the liberation of impurity atoms from the lattice. These findings indicate that acid leaching is highly effective in removing impurities from the iron phosphate recycled from waste LIBs.

Impact of mechanical activation and mechanochemical activation on microstructural changes, leaching rate and leachability of natural chalcopyrite

The influence of mechanical activation (MA) and mechanochemical activation (MCA) with Fe and Fe2O3 on the microstructural changes, leachability and leaching rate of natural chalcopyrite was investigated and compared. MCA pretreatments were carried out by chalcopyrite co-milling with Fe and Fe2O3 for 20 and 50 min. The XRD analysis indicated that even after 50 min MA and MCA, constituent phases of chalcopyrite, Fe and Fe2O3 could be detectable beside the newly formed bornite. Regarding the peak broadening and peak intensity reduction, MCA generally intensified the microstructural changes of chalcopyrite in comparison with MA. The microstructural study performed by the Rietveld method also proved that all microstructural parameters changed in favor of reactivity, such that the amorphization degree and microstrain were increased to 96 % and 0.164 (%), respectively, while crystallite size was reduced to 14.6 nm after 50 min MCA of chalcopyrite with Fe2O3. It could be concluded from the leaching tests that MCA along with Fe and Fe2O3 addition could promote the leachability and leaching rate of chalcopyrite, as compared to MA and nonactivated chalcopyrite. Although both the MCA of chalcopyrite with Fe and Fe2O3 could enhance copper extractions in the 1 M sulfuric acid leaching tests at 80 °C, Fe addition was slightly more effective than Fe2O3. The results obtained from the kinetic study also revealed that the leaching mechanism of nonactivated chalcopyrite, mechanically activated chalcopyrite and mechanochemically activated chalcopyrite with Fe2O3 changed from diffusion control to chemical control due to MCA with Fe. Finally, the combination of kinetic and microstructural studies proved that all microstructural parameters, except for the microstrain parameters of chalcopyrite MCA with Fe2O3, could be effective in chalcopyrite reactivity promotion.

Jack bean urease inhibition by different root fractions of Cleome gynandra L – Kinetic mechanism and computational molecular modelling

Natural products with urease inhibiting potentialities would be valuable for enhancing nitrogen fertilizer formulations and developing new therapeutics against infectious diseases. Main focus of this research was to assess the inhibitory impact of various parts of Cleome gynandra (Cleomaceae) on jack bean urease activity, identify the responsible compounds, and ascertain their mode of enzyme inhibition and interactions with urease enzyme. Urease inhibitory potentiality of different plant parts of C. gynandra was determined using the phenol-hypochlorite method and mode of enzyme inhibition by Lineweaver-Burk kinetic analysis. LC-HRMS was carried out to identify the compounds of the active fractions. Molecular docking and simulations were executed to find out the binding affinity and interaction pattern of the isolated compounds at the active site of urease enzyme and to verify stability of protein-inhibitor complexes. The root of C. gynandra exhibited highest urease inhibitory potentiality with IC50 value of 1.529 mg/ml compared with leaf and stem. Among the different root fractions, water fraction revealed maximum anti-urease activity with IC50 values of 1.477 mg/ml followed by methanol (1.655 mg/ml) and acetone fractions (1.955 mg/ml). Inhibition kinetics indicated that these fractions were strong inhibitors of urease and exhibited a non-competitive mode of inhibition with Ki values of 184.911 µg/ml, 147.34 µg/ml, and 233.75 µg/ml respectively at 1000 mg/L concentration. LC-HRMS analysis confirmed the occurrence of glucocapparin, fluticasone propionate and lauryl hydrogen sulfate etc. in water fraction. Molecular modelling and simulation study suggested strong and stable interactions between the specified compounds of water fraction and active site of urease. Hence, the water fraction of C. gynandra roots represent a valuable source of natural urease inhibitors, for possible therapeutic applications and sustainable agricultural practices.

Improved conditions for the synthesis of tertiary fluorides using a KF/H2SO4 combination

In this paper, we report the deoxyfluorination of tertiary alcohol using a simple combination of potassium fluoride and sulfuric acid. These cheap and widely available reagents allow for the synthesis of tertiary fluorides in good to excellent yields. Extension of the reaction to other functional groups such as alkenes, acetates and ethers have also been studied.

Sustainable Biodiesel Production from Waste Cooking Oil and Crude Palm Oil Using a Custom Mini Pilot Plant

The widespread practice of reusing Waste Cooking Oil (WCO) in hawker food stalls, often for multiple frying cycles, presents a significant public health concern due to the degradation of the oil, which can lead to the formation of toxic compounds. These practices not only pose health risks, such as increasing the potential for cardiovascular diseases and cancer, but also contribute to environmental pollution when the oil is improperly disposed of. This study seeks to address these issues by converting WCO, along with crude palm oil (CPO), into biodiesel using a custom-designed mini pilot plant. The biodiesel production process involved a two-step reaction. The first step, esterification, was conducted using a 55:100 alcohol-to-oil volume ratio with 1% by volume sulfuric acid (H₂SO₄) as the acid catalyst, at 60°C, with a reaction time of 30 minutes and a stirring speed of 800 rpm. The second step, transesterification, utilized a 6:1 alcohol-to-oil molar ratio, with 1 wt.% sodium hydroxide (NaOH) as the alkaline catalyst, carried out at 70°C over the course of one hour. These conditions were carefully selected to optimize the conversion efficiency and to minimize the free fatty acid content, which is crucial for achieving a high yield of biodiesel. The results demonstrated that the mini pilot plant is highly effective in producing biodiesel from both WCO and CPO. The study also led to the development of a standard operating procedure (SOP) for the biodiesel production process, ensuring reproducibility and efficiency.

Effect of Citric Acid Hard Anodizing on the Mechanical Properties and Corrosion Resistance of Different Aluminum Alloys

Hard anodizing is used to improve the anodic films’ mechanical qualities and aluminum alloys’ corrosion resistance. Applications for anodic oxide coatings on aluminum alloys include the space environment. In this work, the aluminum alloys 2024-T3 (Al-Cu), 6061-T6 (Al-Mg-Si), and 7075-T6 (Al-Zn) were prepared by hard anodizing electrochemical treatment using citric and sulfur acid baths at different concentrations. The aim of the work is to observe the effect of citric acid on the microstructure of the substrate, the mechanical properties, the corrosion resistance, and the morphology of the hard anodic layers. Hard anodizing was performed on three different aluminum alloys using three citric–sulfuric acid mixtures for 60 min and using current densities of 3.0 and 4.5 A/dm2. Vickers microhardness (HV) measurements and scanning electron microscopy (SEM) were utilized to determine the mechanical characteristics and microstructure of the hard anodizing material, and electrochemical techniques to understand the corrosion kinetics. The result indicates that the aluminum alloy 6061-T6 (Al-Mg-Si) has the maximum hard-coat thickness and hardness. The oxidation of Zn and Mg during the anodizing process found in the 7075-T6 (Al-Zn) alloy promotes oxide formation. Because of the high copper concentration, the oxide layer that forms on the 2024-T6 (Al-Cu) Al alloy has the lowest thickness, hardness, and corrosion resistance. Citric and sulfuric acid solutions can be used to provide hard anodizing in a variety of aluminum alloys that have corrosion resistance and mechanical qualities on par with or better than traditional sulfuric acid anodizing.

Mechanical and fracture properties of concrete with recycled concrete aggregates treated with acids and addition of aluminium sulphate

The use of recycled aggregates, particularly concrete waste aggregate, has gained increasing popularity and has become current practice in day-to-day applications in many countries. Enhancing the physical and morphological characteristics of this type of aggregate is crucial to promote its widespread adoption. This study investigates the mechanical and fracture properties of concrete incorporating 100 % recycled concrete coarse aggregate (RCA), both untreated and treated with acid solutions of hydrochloric acid (HCl) and sulphuric acid (H2SO4), and addition to the addition of aluminium sulphate (AS). X-ray diffraction (XRD) and X-ray fluorescence (XRF) techniques were employed to characterize the cement and aluminium sulphate (AS). The performance of all mixes was evaluated in terms of mechanical properties, including compressive strength, tensile strength, and secant modulus of elasticity. Experimental fracture tests were conducted using the wedge splitting method on notched specimens aged for 28 days. The results demonstrate an improvement in the mechanical behaviour and fracture resistance of mixes incorporating RCA treated with acid solutions at concentrations of 0.3 M, 1 M, and 3 M for HCl, as well as at a concentration of 0.3 M for H2SO4. However, a decrease in properties was observed at higher concentrations of H2SO4 (1 M and 3 M). Furthermore, the addition of AS also resulted in improvements compared to mixes containing RCA.

The Influence of Carbon Nanotube Functionalization on Water Contaminated by Diesel and Benzoic Acid: A Comparison of Two Case Studies

This article simply aims to compare two case studies concerning the purification, using carbon nanotubes, of water contaminated by the following two different common pollutants: benzoic acid and diesel. In particular, the aim is to highlight how the different natures of both of the polluting molecules and the carbon nanotubes play a fundamental role in water treatment. These two pollutants were taken into consideration because of their different chemical natures: benzoic acid is a polar pollutant, while the molecules present in diesel are substantially nonpolar. The carbon nanotubes used were both functionalized and nonfunctionalized. Functionalization is a process that allows for the introduction of functional groups onto the surface of carbon nanotubes. In this research, carboxylic functionalization was performed, which allowed for the insertion of carboxylic groups through attacks with sulfuric and nitric acids. Thanks to the results obtained, it was possible to quantify the optimization of the purification process depending on the types of carbon nanotubes and polluting molecules considered. The functionalized nanotubes exhibited greater performances in the treatment of water contaminated by benzoic acid compared to the nonfunctionalized ones. Instead, in the treatment of water contaminated by diesel, a greater purification capacity was shown by the nonfunctionalized carbon nanotubes compared to the functionalized ones.

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.