Sulfuric Acid Research Articles

Removal of metaldehyde and acetamiprid by extracted cellulose from biomass incorporated with copper after acetylation

The presence of pesticides in water have reached to an alarming level in some parts of the world and have caused deteriorating effects on human health. Reclamation of portable water from such contaminants have become mandatory. Scientists around the world are trying to devise new methods of water purification. The target can be achieved either by limiting the use of pesticides for agriculture purposes or by devising unique methods for their recoveries from contaminated water. In this context, herein cellulose has been extracted from Populus nigra, subjected to acetylation using acetic acid in the acidic medium (sulfuric acid). The modified acetylated cellulose was treated with Cu-based salt to enable the metallic combination. The prepared sorbent was characterized by UV, SEM, EDX, XRD, and FTIR techniques. Two insecticides; metaldehyde and acetamiprid in synthetic waste-water solution were subjected for adsorption on the modified sorbent in a series of experiments to evaluate the impact of contact time, sorbent dosage, pH, and temperature. Optimum conditions established in a series of experiments such as 80 and 60 min of contact time for acetamiprid and metaldehyde respectively, pH of 8 and 9 (slightly basic) correspondingly for the mentioned pesticides, and a 0.08 g adsorbent dosage were used in the estimation of kinetics and isothermal parameters. The kinetic data successfully followed the pseudo-second-order kinetic model whereas, the isothermal data was found to be best fitted by Langmuir isotherm model in the case of acetamiprid and by Freundlich in the case of metaldehyde. The regeneration study was performed for both the pesticides showing more than 70 % removal capabilities of fabricated adsorbent after three consecutive cycles. The prepared adsorbent could be a better alternative of commercial activated carbon however, further experiments are encouraged to investigate the full environmental application spectrum of the fabricated sorbent.

Pre-sowing treatments for a better germination of Myrianthus holstii seeds

ABSTRACT The cultivation of the indigenous fruit and food security tree, Myrianthus holstii, is seriously constrained by its seed dormancy, change in land use and overexploitation, decreasing its wild population and limiting its on-farm planting in Rwanda. Therefore, we determined the effects of different pre-sowing treatments on the germination and seedling growth of M. holstii to promote its domestication in Rwanda, using mechanical nicking of seeds, boiling seeds in water for 5 min and sulphuric acid (98%) scarification for 15 and 30 min. The shortest acid-scarification produced the highest germination (93%) within 6 weeks after sowing and seedlings with longer heights and more leaves within 3 months, comparable to mechanical nicking, indicating that the two techniques are effective in improving the germination and seedling growth of M. holstii. However, mechanical scarification was recommended to small-scale farmers, since it is eco-friendly, economical and user-friendly to contribute to M. holstii domestication in Rwanda.

Effect of Curing Time and Ferric Chloride on a Copper Concentrate with a High Arsenic Content

As a result of changes in copper mineralogy, various treatment options for copper sulfides have been explored, including pretreatment processes aimed at enhancing material permeability and improving the dissolution of valuable minerals. Despite its significance, this topic has only recently gained attention. In this research, a copper concentrate with a high arsenic content was studied, with enargite (Cu3AsS4) as the main mineral phase. The objective was to evaluate the effect of pretreatment on copper extraction efficiency prior to leaching. Three key variables were investigated: curing time (0, 5, 10, and 15 days), H2SO4 dosage (0, 70, 140, and 210 kg/t), and FeCl3 concentration (0, 0.5, 1, and 1.5 M). The sample was characterized both before and after pretreatment, revealing the formation of new species such as CuSO4·5H2O and Cu2Cl(OH)3 under optimal conditions of 15 days curing time, 70 kg/t of H2SO4, and 1 M FeCl3. Copper extraction solely through curing reached 20.79%. The analysis suggests that curing time is the most influential factor in the process, accounting for 46% of the overall contribution. In comparison, sulfuric acid and ferric chloride contribute less, with 20% and 10% contributions, respectively.

Evaluation of selected minerals and health risk and proximate analysis of wasawasa (a street food)

This study was carried out to determine the proximate composition and the potential heavy metal health risk that may be associated with the consumption of wasawasa, a dish made from locally milled yam peels, by examining the presence of six metals (iron, nickel, chromium, sodium, and magnesium and potassium) in samples procured. Sixteen (16) samples of ready-to-eat wasawasa were collected from Aboabo, Manhyia, Sawaba, Asawase, Adenyase, and Ayigya in Kumasi, since these are the communities where wasawasa is mainly produced, sold, and consumed. The samples were digested with a nitric, perchloric, and sulfuric acid mixture and analyzed using a microwave plasma atomic emission spectrometer (Agilent 4210 MP-AES). The average concentrations of metals were Na (8506.88 mg/kg), Mg (222.63 mg/kg), Fe (84.45 mg/kg), Cr (2.31 mg/kg), K (1702.08 mg/kg, and Ni (1.12 mg/kg). Proximate analysis was used to determine Protein, fat, ash, moisture, and fiber content of the local wasawasa, which were found to be 15.667 %, 0.45 %, 1.00 %, 27.54 %, and 0.41 %, respectively. The hazard index of the heavy metals (Fe, Ni and Cr) for both adults and children were each greater than one, indicating the population is likely to experience non-carcinogenic effects from the consumption of wasawasa.

Enhanced bioethanol production from Compositae plant stalks: Integrating dry acid pretreatment and fungal mediated biodetoxification

Compositae is an important economic plant with relatively high contents of water-soluble sugars in stalk section. The pretreatment of Compositae plant stalks quickly converts the water-soluble sugars into high titers of furan aldehydes, which inhibits the viability of consequent fermentation strains. This study used the typical Compositae plant stalks of sunflower, Jerusalem artichoke, and stevia as feedstocks for dry acid pretreatment under high solids loading, then a unique solid-state biodetoxification method was applied to degrade these high-titer inhibitors. The results showed that temperature and sulfuric acid concentration were two key parameters for enhancing pretreatment efficiency. Enzymatic hydrolysis yield of the above pretreated stalks reached up to 79.68%, 66.75% and 74.05%, respectively. For pretreated Jerusalem artichoke stalk, it contained 37.36% of cellulose, 2.72% of xylan, 3.04% of glucose, 11.64% of xylose, 20.54% of lignin, and some inhibitors (3.80% of acetate, 0.24% of HMF and 0.23% of furfural). After biodetoxification, 100% of furfural, 40% of HMF, and 36% of acetate were quickly removed by Amorphotheca resinae ZN1, which resulted in 55.57 g/L ethanol production (equivalent to 7.1% by volumetric percentage) with the yield of 55.54% from 73.59 g/L of glucose and 40.69 g/L of xylose by simultaneous saccharification and co-fermentation (SSCF). This study provides a combinational approach of dry acid pretreatment and biodetoxification for Compositae plant stalks biorefinery.

One-step synthesis of short columnar α-calcium sulfate hemihydrate from titanium white waste acid

The waste sulfuric acid solution emerged as a main emission substance from titanium dioxide production is called titanium white waste acid (TWWA). The disposal of TWWA has been a concern due to its potential impact on the environment. A green way including one-step preparation and purification stages of α-calcium sulfate hemihydrate (α-HH) from TWWA and lime mud via a neutralization reaction in the hydrothermal pressure apparatus was developed. The preferred experimental conditions were obtained, i.e., lime mud/TWWA/sodium citrate ratio: 16/16/1, 140 ℃, 0.5 MPa, reaction time: 10 min. The recovery rate of α-HH in the whole process was 89.5%. The method presented high efficiency and selectivity in conversion to a short-columnar-shaped α-HH under addition of 3.40 × 10−2 mol/L sodium citrate as a crystal modifier. The structure and composition of the obtained α-HH products were confirmed by XRD, TGA, and SEM. Compared with titanium gypsum, the obtained short columnar α-HH with hexaprismatic morphology showed excellent mechanical properties. According to GB/T 9776 − 2008 “Calcined gypsum”, the compressive strength of 7 days of the cemented short-columnar α-HH was about 6.35 MPa, which it meets the strength requirements for building gypsum.

Study on recovering the scattered metals from coal gangue by low-temperature activation and two-stage selective leaching

As metal deposits are developed on a large scale and at high intensity, the strategic metals under “protective measures” will inevitably face resource depletion. It becomes particularly important to sustainably and stably maintain the supply of strategic metals. A method is proposed to selectively extract Li and Ga from coal gangue through a process of ammonium sulfate roasting followed by stepwise leaching. Li and Ga in coal gangue are converted into metal sulfates or ammonium sulfates through low-temperature roasting, and then selectively extracted through a water-acid combined stepwise leaching process. Under the conditions of 450 °C and 2 h, with a coal gangue to ammonium sulfate ratio of 1:2.5, the leaching rates of lithium and gallium reach 88.35 % and 90.28 %, respectively. During the roasting process, ammonium sulfate decomposes into ammonium hydrogen sulfate, which enters the core through the pores of gangue and reacts with kaolinite to enhance activation. Li is converted into lithium sulfate ammonium and extracted through aqueous solution leaching, while metal gallium is first converted into gallium sulfate ammonium and then, with increasing temperature, into ammonium sulfate and extracted through dilute acid leaching.

Optimization of struvite from sewage sludge ash as phosphorus source.

Phosphorus is an essential macronutrient for crop production. Struvite precipitation and reuse from phosphorus-rich sewage sludge are cost-effective measures to improve phosphorus utilization efficiency and decrease its negative environmental impact. In this study, the objectives were to optimize the phosphorus extraction (using sulfuric acid) and recovery (as struvite) processes and determine the most appropriate process conditions using RSM. This was done by evaluating the effect of different parameters such as acid concentration (mol/l) (0.02 to 0.8), H2SO4/ISSA ratio (liquid/solid) (20 to 150ml/g), and time (0.5 to 4h) for leaching tests and N: P ratio (1 to 2), Mg: P ratio (1 to 2), and pH (8 to 11) for struvite precipitation. The optimization of the factors affecting PO43--P extraction from SSA by acidic leaching showed that applying 0.5mol/l H2SO4 and 57ml/g L/S ratio at 2h achieved the highest PO43--P extraction (99.8%). The extraction of phosphorus also leached heavy metals; however, using a cation exchange resin, it was possible to effectively remove heavy metals from P-rich solutions. The optimal phosphorus recovery as struvite (98.5%) was achieved at the lowest pH and N/P ratio, while an increase in Mg/P ratio from 1 to 2 positively affected phosphorus recovery. The obtained struvite had a high content 94.6%, and the heavy metal content in struvite was lower than the value of standard, so that the obtained struvite sample can be used as fertilizer.

Proton transport mechanisms in aqueous acids: Insights from abinitio molecular dynamics simulations.

The solvation and transport of protons in aqueous solutions of phosphoric acid (PA), sulfuric acid (SA), and nitric acid (NA) were studied using abinitio molecular dynamics simulations. Systems with acid-to-water ratios of 1:1 and 1:3 were examined to understand the similarities and differences in transport mechanisms. The solvation structure of H3O+ in these systems is similar to that in slightly acidic water, with variations in the strength of hydrogen bonds (H-bonds) accepted by acid molecules. In aqueous PA systems, strong H-bonds between PA molecules are slightly affected by water, leading to significantly greater H3O+ diffusion compared to aqueous SA and NA systems. This enhanced diffusion is attributed to the participation of PA molecules in H3O+ transport, where the PA molecule can shuttle a proton for H3O+, facilitating a large displacement via collective proton hopping. This shuttling mechanism is prominent in aqueous PA but rare in aqueous SA and absent in aqueous NA. Moreover, the decomposition of H3O+ diffusion into vehicular and structural components indicates that the higher diffusion in aqueous PA is primarily due to the structural mechanism with the aid of PA molecules. In the aqueous NA systems, the vehicular diffusion is dominant at low water contents and the increase in water content improves the structural diffusion by forming connected H-bonds within water molecules. Our findings elucidate the role of acid molecules in proton transport within their aqueous solutions, thereby advancing the fundamental understanding of proton transport mechanisms.

Corn Stover Lignin as a Solid Acid Catalyst for the Esterification of Oleic Acid

AbstractThe catastrophic ramifications of fossil fuels on the environment have prompted the search for renewable energy sources. Over the recent decades, biodiesel has garnered attention as a promising direct alternative to diesel fuel; however, reliance on homogeneous catalysts and the requirement for refined vegetable oil feedstocks present financial and sustainability concerns. Thus, there exists a need for the development of sustainable and cost‐effective catalytic solutions. Herein, the application of lignin, an abundant and renewable biomass, as an effective heterogeneous catalyst is reported for biodiesel production via the esterification of oleic acid. Lignin is extracted from corn straw using sulfuric acid, which endows sulfonic acid groups (0.85 mmol g−1) to its structure allowing it to act as an acid catalyst without additional post‐treatments. Conversion of oleic oil to biodiesel is achieved at 97% using a 1:3 oleic acid to methanol molar ratio with a 5 wt.% catalyst loading at 90 °C after only 30 min. Moreover, the catalyst exhibits a remarkable turnover frequency of 2.61 min−1 proving its efficiency. These findings demonstrate that heterogeneous catalysts can be prepared from biomass waste offering a significantly cheaper and less intensive synthesis process and allowing for a paradigm shift to non‐edible and waste cooking oils.

Investigation of the high temperature leaching of a zinc sulphide concentrate in sulphuric acid solutions

Investigation of the high temperature leaching of a zinc sulphide concentrate in sulphuric acid solutions

Effect of Sulphuric Acid Concentration on Nanocellulose Extraction from Rice Husk

Effect of Sulphuric Acid Concentration on Nanocellulose Extraction from Rice Husk

The Dissolution Behavior of Pyrite and Chalcopyrite During Low-Temperature Pressure Oxidation: Chalcopyrite Influence on Pyrite Oxidation

The research of this paper was carried out on the low-temperature (100 ± 2 °C) pressure (0.2–0.8 MPa) leaching of pyrite, chalcopyrite and their mixture. According to experiments on chalcopyrite dissolution, increasing the oxygen pressure from 0.2 up to 0.8 MPa had a slight effect on chalcopyrite dissolution. Oxygen pressure and initial sulfuric acid concentration in the range of 10–50 g/L had the greatest positive effect on the pyrite oxidation. The SEM and EDX mappings indicate the chalcopyrite and pyrite surfaces to be passivated by elemental sulfur. The oxidation degree of pyrite in its mixture with chalcopyrite increased significantly from 54.5 up to 80.3% in 0–240 min. The reaction time is relative to the dissolution of the individual mineral, while the dissolution of chalcopyrite remained virtually unchanged. The addition of Cu (II) and Fe (III) ions does not influence pyrite dissolution when chalcopyrite is added in a leaching process, which can be explained by the formation of an electrochemical link between the minerals. The positive effect of chalcopyrite addition is associated with a decreased formation of elemental sulfur on the surface of pyrite. The described method can be used for the hydrometallurgical processing of copper raw materials with increased pyrite content, as well as for the pretreatment of copper concentrates with gold-rich pyrite concentrates to increase the recovery of gold and silver.

Corrosion inhibition performance of protein derived carbon quantum dots as corrosion inhibitors on low carbon steel in sulfuric acid solution

Protein derived carbon quantum dots (PCQDs) were successfully fabricated via a hydrothermal method with shrimp meat as the precursor. Subsequently, their corrosion-inhibiting performance on mild steel (L-steel) in a 0.5 mol/L H2SO4 solution was evaluated. Electrochemical impedance spectroscopy (EIS) tests demonstrated that at a concentration of 250 mg/L, the corrosion inhibition efficiency of PCQDs exceeded 90 %. Potentiodynamic polarization (PDP) tests indicated that when the concentration of PCQDs reached 500 mg/L, the corrosion inhibition efficiency was as high as 97.45 %. Comprehensive characterizations of the PCQDs, including X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), and ultraviolet–visible spectroscopy (UV–Vis), verified the existence of functional groups such as carboxyl, hydroxyl, and aromatic rings within the PCQDs. These groups are conducive to forming a strong adsorption force on the surface of L-steel and creating a protective layer. Surface morphology analyses carried out by scanning electron microscopy (SEM) and atomic force microscopy (AFM) revealed that the surface of L-steel treated with PCQDs was significantly smoother in comparison to untreated samples exposed to acidic conditions. Adsorption studies disclosed a mixed physical and chemical adsorption behavior, and theoretical calculations showed that the N and S atoms in PCQDs preferentially adsorb in a parallel direction. The addition of PCQDs led to a reduction in the diffusion coefficient, indicating that the diffusion of corrosive ions was effectively hindered. The distribution function of PCQDs was 3.48 Å, which suggested that the chemisorption mechanism played a dominant role in the inhibition process.

Understanding the Relationship of Closed Pore Structure in Biomass- derived Hard Carbon with Cellulose Regulating Strategy.

Recycling waste biomass to pyrolytic carbon has become a development direction of sodium-ion batteries (SIBs)anodes. However, it remains a challenge to precisely control the composition and structure of biomass to modify the properties of derived carbon. Herein, a strategy of hydrolyzing cellulose in phellem with sulfuric acid is proposed, which can promote cellulose fracture, reduce the graphitization and increase the content of closed pores in hard carbon. Accordingly, after the regulation of closed pore structure, the reversible capacity increased from 207 to 330 mAh g-1 at 20mA g-1, realizing an increase of ≈130 mAh g-1 in the plateau region and the initial Coulombic efficiency (ICE) is enhanced from 78% to 90%. When applied in full cell with O3-Na[Ni1/3Fe1/3Mn1/3]O2, it showed an energy density of 247Wh kg-1. This strategy has certain universality, and it provides the feasibility to use low-value cellulose-containing biomass to fabricate high-performance hard carbon materials.

Removal of Impurities from Nickel and Cobalt in Mixed Hydroxide Precipitate with Solvent Extraction Using Di(2-Ethylhexyl) Phosphoric Acid

ABSTRACT This study investigates the removal of major impurities, namely Fe, Al, Zn, and Mn, in a solution produced by sulfuric acid leaching of mixed hydroxide precipitate from the Ni and Co via solvent extraction using di(2-ethylhexyl) phosphoric acid (D2EHPA). The results of extraction experiments showed that the extracted Ni, Co, Fe, Al, Zn, Mn, and Mg increased as the equilibrium pH, D2EHPA concentration, and O/A ratio increased. The optimum extraction condition was achieved at a pH of 3.5, a 20% (v/v) D2EHPA concentration, and an O/A ratio of 1, with a complete (>99.9%) extraction of Al, Fe, Zn, and 97.33% Mn with co-extracted Ni and Co of 22.32% and 29.13%, respectively, in a single extraction stage. Complete Mn removal can be achieved in two extraction stages. Co-extracted Ni and Co can be scrubbed out using a mild sulfuric acid solution at a pH of 1.2 with only less than 2% of the Al, Fe, Zn, and Mn co-scrubbed. McCabe-Thiele diagrams of the scrubbing processes were constructed, and the results showed that Ni and Co can be scrubbed out using a mild acidic solution at a pH of 1.2, O/A ratio of 1, and temperature of 40°C for 10 min of mixing. Zn and Mn can be stripped completely using 0.5 M sulfuric acid solution at an O/A of 1 and temperature of 40°C for 10 min of mixing, while Fe and Al remained unstripped. Fe and Al can subsequently be stripped via reductive stripping.

Gypsum Binder With Increased Water Resistance Derived From Membrane Water Desalination Waste

ABSTRACTA method has been developed for separating a mixture of calcium, magnesium and sodium sulfates obtained through the interaction of sulfuric acid and waste from the water purification process generated by using membrane filters. The primary goal of this method is to extract gypsum and produce gypsum‐based binders. Patterns were identified regarding how various types, ratio and quantities of additives: blast furnace slag, granite screenings, portland cement, electric steel smelting slag affect the water‐gypsum ratio, strength properties, and water resistance of high‐strength gypsum binders. It was found that adding a single‐component additive specifically to enhance water resistance does not significantly impact these properties. Complex additives have been developed based on Portland cement, granulated blast furnace slag, electric furnace slag, expanded clay dust, and granite screenings of various fractions. These additives are designed to maximize the water resistance of high‐strength gypsum binder based on synthetic calcium sulfate dihydrate. As a result, the water resistance coefficient increased from 0.45 to 0.52. Additionally, a technological block diagram of the process has been proposed.

Utilization of Waste Cotton Fibers by Extracting Nanocellulose Crystals: A Study on Phosphoric Acid Method Compared with Sulfuric Acid Method and TEMPO Oxidation Method

Utilization of Waste Cotton Fibers by Extracting Nanocellulose Crystals: A Study on Phosphoric Acid Method Compared with Sulfuric Acid Method and TEMPO Oxidation Method

Use of nanocelluloses from orange peel and ZnO as hybrid nanofiller in developing functionalized starch nanocomposite for edible coatings

AbstractThis study explores the formulations of orange peel nanocelluloses (NC) with tailored dimensions for the development of functionalized nanocomposites coatings on green chilies. In the present century, the valorization of agro‐waste, specifically orange peel for developing NC facilitated sustainable packaging such as edible films and coatings with improved properties has received importance. As, this approach aligns with the sustainable development goals, including reduced food waste and agro waste. For the work, the derived orange peel celluloses were acid hydrolyzed using sulfuric acid (H2SO4) and hydrochloric acid (HCl) to deliver cellulose nanofibers (CNF) and cellulose nanoparticles (CNP), respectively. The fabricated CNP and CNF were characterized using Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM), and thermogravimetric analysis (TGA). The FESEM morphology showed the formation of CNP with diameter ranges from 42.4 to 108 nm and formation of CNF with diameter ranged from 27.4 to 50.5 nm. The creation of the functionalized nanocomposite was done by reinforcing with hybrid nanofillers consisting CNF, CNP consecutively with ZnO in corn starch for tailormade packaging properties in terms of mechanical, physicochemical, optical, thermal properties, and so on. The results reveal improved tensile strength, and reduced water vapor transmission rates of nanocomposite with the addition of hybrid nanofillers. Additionally, green chilies were coated with the functionalized nanocomposites prepared by different concentrations of nanofillers. The storage analysis was performed in terms of weight loss, total chlorophyll content, and microbiological analysis. The developed coatings were found to be effective in extending the shelf life of green chilies. The control samples showed significantly higher weight loss compared to coated ones. The coated samples showed significantly better firmness and total chlorophyll content after 20 days of storage. In comparison to other coatings, NC and ZnO incorporated starch‐based coating was found to be the most effective in maintaining the quality of fresh green chilies throughout the storage. Thus, incorporating NC and ZnO in starch‐based films and coatings presents a promising avenue for sustainable packaging and preservation.Highlights Agro‐waste orange peel was valorized to develop sustainable food packaging. Orange peel‐based nanocellulose was developed using H2SO4 and HCl. Nanocomposite film was developed using hybrid nanofillers. Nanocomposites provide tailored properties due to the nanofillers. Developed nanocomposite was used as edible coatings on green chilies.

Sulfuric Acid Leaching Recovery of Rare Earth Elements from Wizów’s Phosphogypsum in Poland

Rare earth elements (REEs) are considered vital raw materials for the economy and are on the European Union’s list of critical raw materials (CRMs). Europe is mainly dependent on REE imports. This dependence could be reduced if locally available primary or secondary resources would be processed. In Poland, there are, for instance, over 5 million metric tons of phosphogypsum (PG), a fine powdery byproduct from the fertilizer industry, available near the former Wizów Chemical Plant near Bolesławiec. This material that is considered a waste in Poland contains significant amounts of REEs that could theoretically be recovered and contribute to Europe’s economy. This work is the first systematic analysis of REE leaching studies with sulfuric acid and PG from Wizów. Process parameters such as temperature, particle size, concentration of the leaching solution, and the addition of oxidant and reductant agents were tested to determine the most efficient process. Ultimately, a leaching efficiency of 99% was obtained. Lanthanum exhibited the highest leaching efficiency at almost 100%, followed by Yttrium, Neodymium, Terbium, and Dysprosium. The results of the laboratory experiments are promising and suggest that larger pilot or commercial experiments can be performed next.