Sulfuric Acid Residue Research Articles

Preparation of Oxidized Pellets from Sulfuric Acid Residue Containing Zinc and Lead by Chlorination Roasting and Its Mechanism of Dezincing and Lead Removal

The utilization of sulfur acid residue is an urgent problem confronting sulfuric acid production enterprises, especially the application of sulfur acid residue (SAR) containing lead and zinc. A method combining chlorination roasting using CaCl2 with pelletizing for processing SAR containing lead and zinc was used in this study, and the effect of calcium chloride on pelletizing performance was studied; in addition, the removal behavior of lead and zinc was also studied by using polarized light microscopy (Zeiss double Axioskop 40A), X ray diffraction, SEM and EDS. The results showed that CaCl2 migrated to the surface of the pellets during drying, and this phenomenon resulted in a lower removal rate of lead and zinc inside the pellets than outside the pellets during the preheating phase. When the roasting temperature was 1220 °C, with an increase in the basicity of pellets, the silicate minerals in the pellets gradually decomposed, the hematite particles were gradually refined, and more lead or zinc minerals were exposed, which further increased the removal rate of lead and zinc in the pellets. Finally, the SAR pellets with Pb and Zn removal rates up to 91.33 and 97.88%, and a compressive strength of 2789 N, could be obtained, which is very beneficial to the sustainable development of sulfuric acid mills.

Optimization of sample preparation conditions in the determination of total arsenic in fish and seafoods by atomic absorption spectrometry with electrothermal atomization

The conditions for sample preparation and determination of total arsenic in fish and seafoods by atomic absorption spectroscopy with electrothermal atomization have been optimized. When using a standard sample preparation procedure (GOST R 53100), a complete decomposition of the organic arsenic compound, arsenobetaine, appeared impossible which leads to underestimated results. A novel sample preparation procedure for the determination of total arsenic, including the addition of concentrated sulfuric acid for complete decomposition of the organic forms of arsenic to inorganic ones is proposed. During the atomization of the sample, an additional stage of drying was introduced with smooth heating from 200 to 250°C, which contributed to a complete removal of sulfuric acid residues from the injected sample volume. The correctness of the proposed methodology was verified using the ICP-MS method and in the analysis of reference samples of fish and seafoods.

Antioxidant activity of polyphenolic compounds obtained from Euphorbia antisyphilitica by-products

In this study, an alternative extraction technique, ultrasound-assisted extraction, was used to extract the polyphenolic fraction from two different residues of the candelilla plant (Euphorbia antisyphilitica). These metabolites were further analyzed to evaluate their bioactivity as antioxidants. In addition, their functional groups were identified by Fourier transform infrared (FTIR) spectroscopy. The antioxidant assays showed statistically significant differences between the phenolic extracts, with citric acid residues (CAR) exhibiting a higher oxidant effect than sulfuric acid residues (SAR). The CAR from San Jerónimo (SJ) cultivar showed decreased IC50 values (179.441 ± 7.92 μL mL−1, DPPH•), and its polyphenolic fraction was able to inhibit lipid oxidation (70.31 ± 2.50%). FTIR analysis subsequently revealed the presence of functional groups related to polyphenolic compounds, such as hydroxy, carbonyl, carbon double bond, and amine groups. In addition, FTIR spectra showed slight differences in phenolic compounds, due to the strong acid treatment involved in the extraction of wax. The present study demonstrated that candelilla by-products from citric acid-wax extraction have a polyphenolic fraction with strong antioxidant activity, which may be useful in food and pharmaceutical products.

Effect of vanadium compounds on the sulfonation of carbon materials

The synthesis of sulfonated carbon materials (SCMs) via the direct sulfonation of carbon nanofibers with sulfuric acid in the presence of vanadium compounds is studied. An efficient sulfiding system (98% H2SO4–NaVO3) providing a high sulfur content in a carbon material without oleum is proposed. It is established that the introduced sulfur exists in samples in the form of sulfo groups located predominantly on the surface. No intrusion of sulfuric acid residues between graphene layers with the formation of clathrates is revealed. It is shown that the surface of a carbon material is partially oxidized with the formation of carbonyl and carboxyl groups. The kinetic activity of the synthesized SCMs in the liquid-phase reaction of acetic acid esterification with ethanol is studied.

Mercury flows in large-scale gold production and implications for Hg pollution control

Large-scale gold production (LSGP) is one of the five convention-related atmospheric mercury (Hg) emission sources in the Minamata Convention on Mercury. However, field experiments on Hg flows of the whole process of LSGP are limited. To identify the atmospheric Hg emission points and understand Hg emission characteristics of LSGP, Hg flows in two gold smelters were studied. Overall atmospheric Hg emissions accounted for 10%–17% of total Hg outputs and the Hg emission factors for all processes were 7.6–9.6kg/ton. There were three dominant atmospheric Hg emission points in the studied gold smelters, including the exhaust gas of the roasting process, exhaust gas from the environmental fog collection stack and exhaust gas from the converter of the refining process. Atmospheric Hg emissions from the roasting process only accounted for 16%–29% of total emissions and the rest were emitted from the refining process. The overall Hg speciation profile (gaseous elemental Hg/gaseous oxidized Hg/particulate-bound Hg) for LSGP was 34.1/57.1/8.8. The dominant Hg output byproducts included waste acid, sulfuric acid and cyanide leaching residue. Total Hg outputs from these three byproducts were 80% in smelter A and 84% in smelter B. Our study indicated that previous atmospheric Hg emissions from large-scale gold production might have been overestimated. Hg emission control in LSGP is not especially urgent in China compared to other significant emission sources (e.g., cement plants). Instead, LSGP is a potential Hg release source due to the high Hg output proportions to acid and sludge.

The Effect of pH on Bioleaching of Deerni Pyrite Roasting Residues as Magnetic Materials

The experiment focused on the Deerni pyrite roasting residues mainly made of magnetic materials such as hematite and magnetite in Qinghai Deerni Copper Deposit. The method of bioleaching sulfuric acid residue by bacteria was proposed for roasting residues desulfurization and valuable metal extraction. First of all, the study systematically performed multi-elements analysis, which provided scientific and technique basis for extraction of valuable metals. Subsequently, the effect of the pH value on the bacterial growth was investigated. The data revealed that pH at 1.2 was the optimum culture condition for the bacteria. The concentration of the bacteria at the best culture condition reached 8.5×107 cells/mL. Finally, the bioleaching experiments were performed to explore the ability of the NB bacteria to oxidize the Deerni pyrite roasting residues. The study demonstrated that the microorganism was able to effectively extract valuable metals such as copper and zinc. The total Fe and sulfur contents of the bioleaching residues account for 68.38% and 0.39%, respectively. The desulfurization effects are evident and bioleaching residues meet the requirements as magnetic materials in steel making industry.

Oil Crop Biomass Residue-Based Media for Enhanced Algal Lipid Production

The aim of this study was to evaluate the use of hydrolysates from acid hydrolysis of four different oil crop biomass residues (OCBR) as low cost culture media for algae growth. The one-factor-at-a-time method was used to design a series of experiments to optimize the acid hydrolysis conditions through examining the total nitrogen, total phosphorus, chemical oxygen demand, and ammonia nitrogen in the hydrolysates. The optimal conditions were found to be using 3% sulfuric acid and hydrolyzing residues at 90 °C for 20 h. The hydrolysates (OCBR media) produced under the optimal conditions were used to cultivate the two algae strains, namely UM258 and UM268. The results from 5 days of cultivation showed that the OCBR media supported faster algae growth with maximal algal biomass yield of 2.7 and 3 g/L, respectively. Moreover, the total lipids for UM258 and UM268 were 54 and 35%, respectively, after 5 days of cultivation, which suggested that the OCBR media allowed the algae strains to accumulate higher lipids probably due to high C/N ratio. Furthermore, over 3% of omega-3 fatty acid (EPA) was produced for the two algae strains. In conclusion, OCBR media are excellent alternative for algae growth and have a great potential for large-scale production of algae-based ingredients for biodiesel as well as high-value food and pharmaceutical products.

Experimental Study on Removal of Arsenic from Sulfuric-Acid Residue of High-Arsenic

The experimental study on removal of arsenic from sulfuric-acid residue of high-arsenic was conducted in this paper. Reduction roasting–magnetic separation and sulfuric acid leaching were discussed, and the results showed that the harmful impurity arsenic can't be effectively removed by the reduction roasting-magnetic separation process from sulfuric-acid residue. The content of arsenic would be enriched with the growth of magnetic iron grade, while the effect of the arsenic removal was obvious for sulfuric acid leaching. The leach residue, in which the content of arsenic was only 0.24% with 92.29% of arsenic leaching rate was obtained from the raw ore with 2.78% of arsenic by the sulfuric acid leaching process. And the iron grade of sulfuric-acid residue reached 61.88% while content of non-ferrous metal was very Low, which can be used as a raw material of iron-smelting. This study provided a certain amount of technical support for the similar high arsenic sulfuric-acid residue recycling.

Treatment of Pyrite Cinders for Arsenic Removal Using Acid Leaching Process

A craft of concentrated acid-heating reinforced leaching process is investigated for the treatment of a high arsenic pyrite cinder, a common by-product in vitriol industry. The pyrite cinder, containing 57.37% Fe, and 2.78% As, was conducted for the acid leaching process. The results demonstrated that iron concentrate with 60.57% Fe, 0.28% As and 96.23% of iron recovery was obtained under the optimal acid leaching conditions(Sulphuric acid concentration is a mass ratio of 20%, a leaching temperature of 60°C, a liquid-solid ratio of 2:1 and a leaching time of 120 min).This craft can be used to utilize pyrite cinder and produce qualified concentrate as iron-bearing feed for steel industry, which will help to solve the pollution of sulfuric acid residue and extend raw material sourcing for Chinese steel industry.

Comprehensive Utilization of Sulfuric Acid Residue with High Content of Copper by Pellet Production-Drying-Chloridizing Roasting

A new technology of pellet production-drying-chloridizing roasting is proposed for comprehensive utilization of sulfuric acid residue with high content of copper, a common by-product in vitriol industry. The sulfuric acid residue, containing 60.27% Fe, and 1.61% Cu, was pelletized with addition of 5% bentonite in pan pelletizer. Green balls after drying with 2.3% of water retention were roasting at 1100 °C for 30 min with 5 wt % of CaCl2addition in tube furnace. The results demonstrate that pellets with 60.58% of TFe, a copper volatite ratio of 97.8% were obtained with simultaneous decrease in the copper content down to 0.035%. Key technique is that CaCl2reacts with copper compounds and the chloride can be volatilized at moderate temperatures. This new technology can be used to fully utilize sulfuric acid residue and produce qualified concentrate as iron-bearing feed for steel industry, which will help to solve the pollution of sulfuric acid residue and extend raw material sourcing for Chinese steel industry.

Comprehensive Utilization of Sulfuric Acid Residue in Small Chemical Enterprise

Sulfuric acid residue is one kind of important secondary resource, its comprehensive utilization has drawn extensive attention. Based on analyzing the chemical composition of sulfuric acid residue, through comprehensive comparison of flotation, gravity separation, magnetized baking, magnetic separation and other joint technical processes, it is showed that the chemical-magnetic separation is reasonable by evaluating the applicable ability. Then introduced a case study on comprehensive utilization of sulfuric acid residue in Shikefeng chemical Co., LTD in Luzhou City, the duplex melting process combined advanced induction furnaces with smelting furnace was put forward. Finally, it's concluded that there are many advantages of the duplex melting process, it’s more suitable for the comprehensive utilization of sulfuric acid residue in small chemical enterprise.

Sulfates as novel steroid metabolites in higher plants

Cardenolide sulfates were identified as a novel type of steroid conjugates representing the most polar 5 α-configurated steroids of the cardenolide complex of Adonis aleppica BOISS. Detailed spectroscopic analysis including IR, DCI- and FAB-MS and high-field NMR measurements as well as chemical reactions resulted in the identification of the major sulfate as uzarigenin-3- O-sulfate ( 1) beside the minor components coroglaucigenin-3- O-sulfate ( 2) and corotoxigenin-3- O-sulfate ( 3). The inorganic sulfuric acid residue could be traced by applying trimethyl- and triethylammonia as DCI-MS reactant gases resulting in ammonium-sulfonate cleavage products. Comprehensive NMR studies led to the assignment of key 1 H resonances of these biogenetically closely related steroids. Definitive evidence for the unusual sulfuric acid semi-ester conjugation came from X-ray diffraction measurements confirming the structure and establishing the absolute configuration of uzarigenin-3- O-sulfate ( 1). Concerning the chemotaxonomy of the genus Adonis, due to these novel cardenolides an exceptional position of Adonis aleppica within the taxon has to be acknowledged.

Ionic Polarization of Carrageenans with Different Charge Densities As Studied by Electric Birefringence Measurements

Ionic polarizability of the κ-, ι-, and λ-carrageenans have been investigated by the electric birefringence method. These carrageenan samples were selected because they have different numbers of sulfuric acid residues on their linear polysaccharide chains; that is, their charge densities are different from each other. The analysis of both the polymer concentration dependence and the added salt concentration dependence showed that these three carrageenans have almost the same ionic polarizability irrespective of their different charge densities when they were compared in the same conditions. The results were analyzed by using two groups of theories. That is, one is based on the “loosely bound” counterion polarization, and the other is based on the “condensed” counterion polarization. The ionic strength dependence of the experimentally obtained polarizability could be fitted by Manning's and Rau and Charney's “loosely bound” counterion polarization theories.

Comparative study of infrared spectra of proteoglycans

Individual preparations of hyaluronic acid (HUA), of the natural hyaline cartilage complex of protein - chondroitin-keratan sulfate (PCKS), and proteoglycan aggregates (PA) of the same tissue and of two individual fractions of heparin, one of which contains three (HP-3) whereas the other contains four (HP-4) sulfuric acid residues, calculated per aminosugar contained in the fraction [7]. Commercial preparations ("Sigma") of chondroitin-4-sulfate (CS-4), chondroitin-6-sulfate (CS-6), dermatan sulfate (DS), and glucuronic acid also were used. All proteoglycan preparations for spectroscopy were used in the form of normal Na+-salts, and glucuronic acid was given in the form of the K + salt. IR absorption spectra were obtained from dry preparations of the test substances, mixed with KJ3R in the ratio of 1:300. Tablets 13 mm in diameter were pressed under a force of 10 tons in vacuo. The IR spectra were recorded at 20~ on a Perkin-Elmer model 577 spectrophotometer in the region 4000-400 cm -1. The signal to noise ratio was 100:1. The scanning speed was 50 cm -1 .rain -1 [8].

Relationship between binding activity of 67Ga and low sulfated acid glycosaminoglycans

The sulfate content of acid glycosaminoglycan (AGAG) extracted from granuloma which had been produced by turpentine oil was inversely proportional to the amount of 67Ga accumulation in the granuloma. Additionally, the lowest sulfation occurred in granuloma at a peak of inflammation when the uptake of 67Ga had reached a maximum. On the basis of electrophoretic pattern, sulfate content, and specific optical rotation, it was concluded that acid glycosaminoglycans obtained from granuloma are mainly composed of chondroitin sulfate-A, -B, and desulfated heparin, while heparan sulfate was a minor component. From in vitro assays, desulfated acid glycosaminoglycans, especially desulfated-heparin and desulfated-heparan sulfate, were found to have a high affinity to 67Ga. These results suggest that low- or de-sulfation of AGAG is related to the accumulation of 67Ga in inflammatory lesions such as granuloma. Moreover, these results suggest that 67Ga does not bind to glycosaminoglycans via sulfuric acid residues.

Fractionation of the polysaccharides ofChara aculeolata

The carbohydrate complex of the Chara algaChara aculeolata Kutz is peculiar and includes polysaccharides of the types of starch, hemicelluloses, and cellulose and also acid polymers of two types, one of which is esterified with sulfuric acid residues while the other contains D-galacturonic acid as the main component.

A study of heparin fractions

When a complex of a total unfractionated heparin preparation and hexamminecobalt (III) is treated with 2–3 M KCl solution a heparin fraction containing 3 sulfuric acid residues to 1 glucosamine residue passes into solution. A heparin fraction containing 4 sulfuric acid residues to 1 glucosamine residue remains in the precipitate thereby freed from hexammine-cobalt (III). The two fractions were isolated in a chemically individual form.

Anticoagulant ability of heparin fractions

The anticoagulant ability of a heparin fraction containing four sulfuric acid residues per disaccharide structural unit of the macromolecule is 1.40 times greater than that of a fraction containing three sulfuric acid residues per unit.

On the Atomic Absorption Determination of Arsenic

Analytical optimum condition for the determination of arsenic by introducing arsine into an atomic absorption spectrophotometer system equipped with an argon-hydrogen flame was examined. The optimum concentrations of reagents in the prepared solution were 3-5N hydrochloric acid, 0.5-2.0% potassium iodide and 0.1-1.0% stannous chloride. The addition of 0.8-2.0g of zinc powder to 20ml of prepared solution was enough to obtain the highest absorbance of arsenic under 0.5kg/cm2 of arsine gas pressure. The absorbance of arsenic was decreased according to the acidity raised by sulfuric acid residue in prepared solution, but recovered by neutralization with ammonia water. The absorbance was interfered with over 5μg of Se4+ and over 500μg of Sb3+ added to the 20ml of prepared solution containing 1μg of arsenic.