Waste Sulfuric Acid Research Articles

Defining and classification of the soft projects as a base for their scope planning

On the basis of deterministic model in the form of a system of nonlinear equations it is developed a «soft» model of stationary process of benzene nitration with a mixture of nitric and sulfuric acids in the reactor of ideal mixing, which allows to take into account the effect of uncertainty of input variables of the process on output variables: stationary temperature and conversion degree. The model algorithm is random assignment of input variables: speed and the heat of reaction and heat loss coefficient of the probable range of admissible values and solving the system of equations of the model for given values of regulate parameters and random allowable value of residence time. The model is visualized as a bitmap image of the points on the plane and allows to take into account the uncertainty of input factors, such as the range of the lower and upper boundaries of the bitmap image («thick line»). It was established that a decrease with increasing conversion module and its increase with increasing concentration of the waste sulfuric acid are occurred for the adiabatic and isothermal processes. However, in an adiabatic process, depending on the module, there is a significant increase in temperature significantly superior to the standard values (50-70 °C), even when the module is 12. Increasing the temperature of the mass in inlet from 20 to 40 °C also leads to significant increase in the degree of conversion and temperature the reactor outlet. With increasing the residence time is observed narrowing of the upper and lower boundaries of the fixed conversion rate and leveling of uncertainty.

Cleaning Waste Sulfuric Acid from PVC Gas Analysis Scheme Design and Composition Analysis

HWasu Corporation produces an enormous amount of PVC acetylene gas to wash waste sulfuric acid every year, and the composition of waste acid impurity is complex. The stench restricts the reuse of waste sulfuric acid, This paper establishes the detection scheme which is divide int three parts,respectively: escaping of the exhaust gas, liquid slag washing and washing slag quantitative analysis.Burning waste acid solid content of 11.40%, light component is 97.18%, sulfuric acid content of 79.22%, after washing slag of weight percent is 7.30%, Washing liquid slag quality percentage of 4.10%.Escaping gases mainly contain acetylene, hydrogen chloride, sulfur oxide impurities. Washing slag liquids mainly contain phosphoric acid root, organophosphorus, chloride, calcium, magnesium,iron ions and sulfuric acid root ion. Washing slags mainly contain silicon dioxide, carbon, hydrogen, calcium oxide, magnesium oxide, ferric oxide,and etc. Finally through the balance calculation of data, We can figure out that the experimental data is accurate and reliable for comprehensive utilization of wast sulfuric acid to provide basic theory data.

Systematic Regeneration of Waste Sulfuric Acid in Semiconductor Manufacturing Using Batch Vacuum Distillation

We describe herein a systematic regeneration of waste sulfuric acid produced in semiconductor manufacturing, using batch vacuum distillation (BVD). During the recycling process, dilute sulfuric acid feed was continuously concentrated and fed back to the original wafer washing step. It consisted of a batch tank to charge the feed solution, condenser to capture generated vapor, receiving tank to receive condensed distillate liquid, and vacuum pump to reduce the system pressure. The improper control of the vacuum operation led to incomplete condensation; consequently, the vacuum pump became dysfunctional. The goal of this study was to prevent such mishap. After the feed condition was defined, a basic design was conceived, and the main characteristics of the BVD were determined. The results of sensitivity analyses on the feed and operating conditions have been discussed. The strategies for designing the vacuum pump’s capacity should be changed depending on phase equilibria at the target pressure.

구리이온을 함유한 PCB 폐에칭액의 Cross-flow 나노여과

In this study the nanofiltration (NF) membrane treatment of a sulfuric acid waste solutions containing copper ion () discharging from the etching processes of the printed circuit board (PCB) manufacturing industry has been studied for the recycling of acid etching solution. SelRO MPS-34 4040 NF membrane from Koch company was tested to obtain the basic NF data for recycling of etching solution and separation efficiency (total rejection) of copper ion. NF experiments were carried out with a cross-flow membrane filtration laboratory system. The permeate flux was decreased with the increasing copper ion concentration in sulfuric acid solution and lowering pH of acid solution, and its value was the range of . Total rejection of copper ion was decreased with the increasing copper ion concentration, lowering pH of acid solution and decreasing cross-flow rate. The total rejection of copper ion was more than 70% at the experimental condition. The SelRO MPS-34 4040 NF membrane was represented the stable flux and rejection for 1 year operation.

10.5937/mmeb1403141m = Treatment of waste sulfuric acid copper electrolyte

The aim of this paper was to investigate the possibility of using the copper anodes with high nickel content for electrolytic treatment of waste sulfuric acid copper electrolyte. Nickel content in each anode was about 10 wt. %. Lead, antimony, and tin content was within the limits ranged from 0.1 to 1.4 wt. %. Copper mass content in anodes was in the range from 86 to 90 wt. %, and was mathematical deference to 100 wt. %. Electrolytic processing was done in galvanostatic conditions at the current density of 250 A/m2, electrolyte temperature of 63 ± 2 ° C, duration of each test of 72 h. The mass of each anode was about 7 kg. The waste sulfuric acid electrolyte with concentration of 30 g dm3 Cu2+ ions and 225 g/dm3 SO4 2- ions was used as the working solution. Changing the anode mass, changing the content of copper and nickel ions in the working solution and the mass of obtained cathode deposit were the subject of discussion in this paper. The difference in weight of anode at the beginning and end of the process confirmed that the anodes are dissolved during the process. A significant reduction of Cu2+ ions concentration was achieved as well as an increase in concentration of Ni2+ ions in the working solution. Mass of cathode deposit, obtained during electrolytic refining of anode with the smallest impurity content, was greater than the mass of dissolved correspondent anode for about 2%. Mass of cathode deposit, obtained by refining the anode with the content of Pb + Sn + Sb from 1.5 to 3.5 wt. %, was less than the mass of dissolved correspondent anode by about 2 %.

Dewatering of sludge obtained by neutralisation from sulfuric-acid waste solutions

The aim of this paper was to investigate the possibility of removing the liquid phase from the sludge using the mechanical dewatering methods. The sludge was obtained by neutralization of sulfuric acid waste solution from the process of copper electrolysis, using 1M Ca (OH)2 with and without addition of FeCl3 and AlCl3 as coagulants. Classical method of filtration by gravity and vacuum filtration method were used for tests of sludge dewatering process in the laboratory conditions. Solution volume, amount of sample, dewatering duration was measured during the experiments. The obtained results, presented in this paper, showed that using the vacuum filtration method, high of sludge sample was reduced for 75%, which is almost three times higher value compared to the results obtained using the gravity filtration. Data relating to the time of filtration, using different methods, show that in application of vacuum filtration method the dewatering time is almost 200 times faster compared to the time dewatering with gravity filtration. The shortest settling time was registered for the sludge that was obtained by neutralization process without coagulants addition.

Thermochemical destruction of asbestos-containing roofing slate and the feasibility of using recycled waste sulfuric acid

In this study, we have investigated the feasibility of using a thermochemical technique on ∼17% chrysotile-containing roofing sheet or slate (ACS), in which 5N sulfuric acid-digestive destruction was incorporated with 10–24-h heating at 100°C. The X-ray diffraction (XRD) and the polarized light microscopy (PLM) results have clearly shown that raw chrysotile asbestos was converted to non-asbestiform material with no crystallinity by the low temperature thermochemical treatment. As an alternative to the use of pricey sulfuric acid, waste sulfuric acid discharged from a semiconductor manufacturing process was reused for the asbestos-fracturing purpose, and it was found that similar removals could be obtained under the same experimental conditions, promising the practical applicability of thermochemical treatment of ACWs. A thermodynamic understanding based on the extraction rates of magnesium and silica from a chrysotile structure has revealed that the destruction of chrysotile by acid-digestion is greatly influenced by the reaction temperatures, showing a 80.3-fold increase in the reaction rate by raising the temperature by 30–100°C. The overall destruction is dependent upon the breaking-up of the silicon-oxide layer – a rate-limiting step. This study is meaningful in showing that the low temperature thermochemical treatment is feasible as an ACW-treatment method.

Isolation and Characterization of a Strain of <i>Acidithiobacillus ferrooxidans</i>

An acidophilic strain was isolated from drainage in Shanxi coal mine, after 16SrDNA amplification and sequencing analysis, it was identified to be Acidithiobacillus ferrooxidans. The ferrous ion oxidation rate of At.f and pH value were studied during its growth, the results showed that, the strain entering into the exponential growth phase needed about 30 hours, and the oxidation rate was more than 99% after 60 hours. The pH value increased from 2.08 to 2.64 at first 30 hours and then decreased to 2.0, and finally maintained at 2.0 in the whole growth process. The isolated strain provided a potential alternative method to handle the steel-picking sulfuric acid waste liquor.

Treatment of air pollution control residues with iron rich waste sulfuric acid: Does it work for antimony (Sb)?

Antimony (Sb) in air pollution control (APC) residues from municipal solid waste incineration has gained increased focus due to strict Sb leaching limits set by the EU landfill directive. Here we study the chemical speciation and solubility of Sb at the APC treatment facility NOAH Langøya (Norway), where iron (Fe)-rich sulfuric acid (∼3.6M, 2.3% Fe(II)), a waste product from the industrial extraction of ilmenite, is used for neutralization.Antimony in water extracts of untreated APC residues occurred exclusively as pentavalent antimonate, even at low pH and Eh values. The Sb solubility increased substantially at pH<10, possibly due to the dissolution of ettringite (at alkaline pH) or calcium (Ca)-antimonate. Treated APC residues, stored anoxically in the laboratory, simulating the conditions at the NOAH Langøya landfill, gave rise to decreasing concentrations of Sb in porewater, occurring exclusively as Sb(V). Concentrations of Sb decreased from 87–918μgL−1 (day 3) to 18–69μgL−1 (day 600). We hypothesize that an initial sorption of Sb to Fe(II)–Fe(III) hydroxides (green rust) and eventually precipitation of Ca- and Fe-antimonates (tripuhyite; FeSbO4) occurred. We conclude that Fe-rich, sulfuric acid waste is efficient to immobilize Sb in APC residues from waste incineration.

Recovery of high purity sulfuric acid from the waste acid in toluene nitration process by rectification

Waste sulfuric acid is a byproduct generated from numerous industrial chemical processes. It is essential to remove the impurities and recover the sulfuric acid from the waste acid. In this study the rectification method was introduced to recover high purity sulfuric acid from the waste acid generated in toluene nitration process by using rectification column. The waste acid quality before and after rectification were evaluated using UV–Vis spectroscopy, GC/MS, HPLC and other physical and chemical analysis. It was shown that five nitro aromatic compounds in the waste acid were substantially removed and high purity sulfuric acid was also recovered in the rectification process at the same time. The COD was removed by 94% and the chrominance was reduced from 1000° to 1°. The recovered sulfuric acid with the concentration reaching 98.2wt% had a comparable quality with commercial sulfuric acid and could be recycled back into the toluene nitration process, which could avoid waste of resources and reduce the environmental impact and pollution.

Copper-Sulfate Pentahydrate as a Product of the Waste Sulfuric Acid Solution Treatment

The aim of this study is synthesis of copper-sulfate pentahydrate from the waste sulfuric acid solution-mother liquor generated during the regeneration process of copper bleed solution. Copper is removed from the mother liquor solution in the process of the electrolytic treatment using the insoluble lead anodes alloyed with 6 mass pct of antimony on the industrial-scale equipment. As the result of the decopperization process, copper is removed in the form of the cathode sludge and is precipitated at the bottom of the electrolytic cell. By this procedure, the content of copper could be reduced to the 20 mass pct of the initial value. Chemical characterization of the sludge has shown that it contains about 90 mass pct of copper. During the decopperization process, the very strong poison, arsine, can be formed, and the process is in that case terminated. The copper leaching degree of 82 mass pct is obtained using H2SO4 aqueous solution with the oxygen addition during the cathode sludge chemical treatment at 80 °C ± 5 °C. Obtained copper salt satisfies the requirements of the Serbian Standard for Pesticide, SRPS H.P1. 058. Therefore, the treatment of waste sulfuric acid solutions is of great economic and environmental interest.

DEVELOPMENT OF THE HANDLING PROCESS OF THE WASTE CONCRETE FINE POWDER USING WASTE SULFURIC ACID

Waste concrete fine powder that is residue after aggregates recycling of demolished concrete is disposed as a low material of value. And Waste sulfuric acid is the waste discharged in large quantities by industrial activity. In this paper, we developed the handling process of waste concrete fine powder using waste sulfuric acid. By using this handling process, plaster of Paris with high purity was separable from waste concrete fine powder. Then, waste sulfuric acid was able to carry out neutralization processing.

Recovery of H 2SO 4 from waste acid solution by a diffusion dialysis method

A diffusion dialysis method using anion exchange membrane was used to recover H 2SO 4 from waste sulfuric acid solution produced at the diamond manufacturing process. Effects of flow rate, operation temperature, and metal ion concentration on the recovery of H 2SO 4 were investigated. The recovery of H 2SO 4 increased with the concentration of H 2SO 4 and operation temperature. It also increased with the flow rate ratio of water/H 2SO 4 solution up to 1, above which no further increase was observed. The flow rate did not affect the rejection of Fe and Ni ions. About 80% of H 2SO 4 could be recovered from waste sulfuric acid which contained 4.5 M free-H 2SO 4 at the flow rate of 0.26 × 10 −3 m 3/h m 3 . The concentration of recovered H 2SO 4 was 4.3 M and the total impurity was 2000 ppm. Preliminary economic evaluation has revealed that the dialysis system is highly attractive one that has payback period of only few months.

Continuous precipitation of calcium sulfate dihydrate from waste sulfuric acid and lime

AbstractPrecipitation of calcium sulfate dihydrate, gypsum, from (i) a pure sulfuric acid/lime suspension and (ii) a waste sulfuric acid/lime suspension in a continuous pilot plant in the temperature range from 40 °C to 80 °C was studied. It was observed that in the case of waste sulfuric acid with a high content of Mg2+ and Fe2+ ions, several hours after the beginning of the precipitation, partial dissolution of the product and modification of the crystals from needle‐ and plate‐like to agglomerated structures occurred. It is suggested that the secondary changes occur due to the increased concentration of Mg2+ and Fe2+ ions in the reactor. Below 60 °C, and above 70 °C plate‐like and needle‐like single crystals respectively were formed. The mean size (d50) of the crystals was found to increase with increasing temperature and decrease with the initial concentration of lime. Gypsum produced between 70 °C and 80 °C is suitable for further processing for construction plaster. In a precipitation process with pure sulfuric acid only single perfect needle‐like crystals occurred. Copyright © 2005 Society of Chemical Industry

Comprehensive utilization of acidic wastewater from 3,3′‐dichlorobenzidine hydrochloride manufacture

AbstractIn the commercial manufacture of 3,3′‐dichlorobenzidine hydrochloride, substantial quantities of acidic industrial effluents were generated. A combination of ultrafiltration and evaporation processes was investigated for the recovery of products and dilute hydrochloric acid. In a novel purification method, waste sulfuric acid is purified and reused four or five times in the hydrazobenzene–benzidine transformation step, resulting in a 75% reduction in the consumption of sulfuric acid, minimization of wastewater discharge and environmental hazards risk and significant economic, environmental and social benefits.© 2001 Society of Chemical Industry

Preparation of Calcium Sulfate Hemihydrate Using Stainless Steel Refinery Sludge and Waste Sulfuric Acid

ABSTRACT In this study, calcium sulfate(gypsum) powder was obtained using waste sulfuric acid and stainless steel refinery sludge by-produced from chemical reagent and the iron industry, by the neutralization of waste sulfuric acid. As variables for the experiment, the molar ratio of the H2SO4: Ca(OH)2, the pH, the reaction temperature and time, the amount of catalyst were used. The crystal shape and microstructure of obtained powder were observed by XRD and SEM, and the thermal property was investigated by DTA. As the NaCl is added 0–20 wt.% as a catalyst to the H2SO4-Ca(OH)2 system, it can be found that the crystal shape goes through the processes as follows; gypsum dehydrate gypsum → gypsum hemihydrate + gypsum dihydrate → gypsum hemihydrate. And gypsum hemihydrate is δ-type as the result of DTA. As waste sulfuric acid and stainless steel refinery sludge were used, the pH of reacted solution (which was 0.8) was rapidly raised up to 8–9 by the addition of stainless steel sludge and gypsum dihydrate was produced as a by-product. Therefore, it was found that stainless steel refinery sludge is sufficiently applicable for the neutralization of waste sulfuric acid.

Acid recovery from waste sulfuric acid by diffusion dialysis

In the process of sulfuric acid production from pyrite, there is a lot of waste acid produced in fume washing with dilute acid. Acid recovery from this sort of waste sulfuric acid by diffusion dialysis is studied in the paper. The mass transfer dialysis coefficient of sulfuric acid of the membrane AFX is measured, the effect of the flowrate of the feed and ratio of feed to water is investigated, and the two kinds of membrane (AFX and S203) are compared. The results show that diffusion dialysis process can separate the metal cation from sulfuric acid effectively, but it is difficult to separate non-cation impurities as As− and F−. The contrast tests of the two membranes show that the dialysis mass transfer coefficient of the membrane AFX is larger, while capacity of the removing impurities of membrane S203 is somewhat better.

Vapor phase nitration of benzene over solid acid catalysts: III. Nitration with nitric acid (2); mixed metal oxide treated with sulfuric acid and heteropolyacid partially neutralized

Vapor phase nitration of benzene over solid acid catalysts is expected to be a clean process without sulfuric acid waste. In this research we investigated the vapor phase nitration of benzene by dilute nitric acid. We found that the catalytic activity of mixed metal oxides containing TiO 2 or ZrO 2 was improved greatly by the treatment with sulfuric acid at 500°C and that the catalytic activity of heteropolyacid can be increased greatly by partial neutralization with Cs or Tl. The reasons for these enhancements were identified as the increase of acid strength and the active surface area, respectively. The catalytic activity is very stable, especially for the mixed oxide treated with sulfuric acid. The TiO 2(4)–MoO 2(1) after treatment with sulfuric acid at 500°C showed a high activity: 87% yield of nitrobenzene (STY=0.72 kg/kg cat h) for more than 528 h on stream.

Vapor phase nitration of benzene over solid acid catalysts: II. Nitration with nitric acid (1); montmorillonite and mixed metal oxide catalysts

Vapor phase nitration of benzene over acidic catalysts is expected to be a clean process without sulfuric acid waste. We investigated this process over acidic catalysts utilizing diluted nitric acid (dil. HNO 3) as a nitrating agent and found that several solid acid catalysts such as montmorillonite ion-exchanged with a multivalent metal cation and mixed metal oxides containing TiO 2 or ZrO 2 exhibited such high activities as 80–90% yields of nitrobenzene (STY=0.6 g/g cat h) for more than 480 h on-streams. We have estimated that the strong Brønsted acidity is the active site for the vapor phase nitration with nitric acid.

Vapor-phase nitration of benzene over solid acid catalysts (1): Nitration with nitric oxide (NO 2)

Vapor-phase nitration of benzene over acidic catalysts is expected to be a clean process with no sulfuric acid waste. We investigated this process over acidic catalysts utilizing nitric oxide (NO 2) as a nitrating agent, and found that several mixed metal oxides, such as silica–alumina, zinc-oxide–titania, and tungsten-oxides–molybdenum-oxide, exhibited a fairly good activity. Among them, WO 3–MoO 3 is the most active, but this catalyst alone deviated from the linear relationship between the activity and acidity. In order to explain this discrepancy several factors, such as acid amount, acid strength, and BET surface area, are examined in detail.