SO2 In Water Research Articles

Research on Ozone-Enhanced Oxidation of Industrial Zinc Sulfite from Flue Gas Desulfurization

ABSTRACT This study investigates the air oxidation and ozone-enhanced oxidation of zinc sulfite. Zinc sulfite was prepared by reacting pure or industrial zinc oxide with SO2 in water. The oxidation experiments were conducted under constant temperature conditions, with slurry, oxygen, and ozone concentrations in the ranges of 0.5–4%, 10–60%, and 1100–1920 ppm, respectively. The experiments involved determining the zinc ion concentration, sulfite concentration, dissolved oxygen, ozone concentration in the exhaust gas, and total organic carbon value for analysis of the oxidation process. The findings revealed that the mass transfer rate of O2 and/or O3 determined the reaction rate in the main stage of the oxidation process, while ozone affected the non-mass transfer control stage, resulting in an average enhancement of 15% in the oxidation rate. Furthermore, ozone causes organic matter attached to industrial zinc sulfite particles to fall off into the solution, significantly improving the oxidation ratio of industrial zinc sulfite.

Integrated Absorption–Adsorption Process for Waste-Free Decontamination of Gases from Sulfur Dioxide, Part 2: CFD Modeling and Experimental Investigation of a Bubble-Cap Tray

There are many technologies for removal of sulfur dioxide (SO2) from flue gases. They are intrinsic part of the efforts for sustainability of energy production as they reduce the harmful impact of fossil fuel combustion on the environment by minimizing one of the main air pollutants. A wide range of methods use alkaline absorbents. In most cases, the products obtained from the absorption process have to undergo further oxidation, which increases the cost of carrying out the process. As a final result, the sulfates obtained (Na2SO4 and CaSO4) have limited practical application and there is a problem with their disposal. Scientific and engineering efforts have been directed towards the development of a practically waste-free technology for gas purification from SO2. An absorption–adsorption method is proposed, which comprises absorption of SO2 in water with simultaneous adsorption of the resultant sulfurous acid (H2SO3) from the aqueous solution with a synthetic anion-exchange resin. Regeneration of the adsorbent is accomplished with a dilute solution of ammonia (NH3), followed by decomposition of the resulting ammonium sulfite ((NH4)2SO3) with nitric acid (HNO3). The products of the processes are pure gaseous (liquefied) SO2 and an aqueous solution of ammonium nitrate (NH4NO3). Sulfur dioxide has a wide range of applications in the chemical industry; ammonium nitrate is a product with a variety of commercial uses as well, the most common of which is as a soil fertilizer. The new absorption–adsorption method offers a practically waste-free technology. The basic unit of this technology is a bubble-cap tray column where the absorption–adsorption process is carried out in an aqueous suspension of a synthetic anion-exchange resin. This work presents a CFD simulation of the flow on the bubble-cap tray. A physical model of the column is constructed, which contains a bubble-cap tray fabricated by 3D printing. As a result of this experimental study, new data on the tray pressure drop, gas holdup, and the kinetics of the absorption–adsorption process were obtained.

Water-soluble dual lysosome/mitochondria-targeted fluorescent probe for detection of SO2 in water, food, herb, and live cells

In this paper, we present a new donor-π bridge-acceptor type fluorescent probe, MIB, which bears two organelle-targeted groups, namely positively charged benzothiazole group for mitochondria and morpholine moiety for lysosomes. In aqueous solution, the nucleophilic addition of HSO3- (as SO2 donor) to MIB blocked its long-range π-conjugation and ICT process and resulted in significant optical signal changes (blue-shifted UV absorbance and fluorescence), which enabled colorimetric and ratiometric fluorescent detection of HSO3- with high selectivity and sensitivity (detection limit of 63.15 nM). MIB offers obvious advantages of good water-solubility, fast response time (within 1 min), unique dual lysosome/mitochondria targeting capability and has been applied to the sensing of endogenous and exogenous SO2 in live cells through fluorescent imaging. In addition, the proposed probe has been utilized for the determination of bisulfite in real water, food and herbal medicine samples, showing good recovery (91.45 % − 109.3 %) and precision.

Reduction of Ionic Silver by Sulfur Dioxide as a Source of Silver Nanoparticles in the Environment.

The natural formation of silver nanoparticles (AgNPs) via biotic and abiotic pathways in water and soil media contributes to the biogeochemical cycle of silver metal in the environment. However, the formation of AgNPs in the atmosphere has not been reported. Here, we describe a previously unreported source of AgNPs via the reduction of Ag(I) by SO2 in the atmosphere, especially in moist environments, using multipronged advanced analytical and surface techniques. The rapid reduction of Ag(I) in the atmospheric aqueous phase was mainly caused by the sulfite ions formed from the dissolution of SO2 in water, which contributed to the formation of AgNPs and was consistent with the Finke-Watzky model with a major contribution of the reduction-nucleation process. Sunlight irradiation excited SO2 to form triplet SO2, which reacted with water to form H2SO3 and greatly enhanced Ag(I) reduction and AgNP formation. Different pH values affected the speciation of Ag(I) and S(IV), which were jointly involved in the reduction of Ag(I). The formation of AgNPs was also observed in the atmospheric gas phase via direct reduction of Ag(I) by SO2(gas), which occurred even in 50 ppbv SO2(gas). The natural occurrence of AgNPs in the atmosphere may also be involved in silver corrosion, AgNP transformation and regeneration, detoxification of gaseous pollutants, and the sulfur cycle in the environment.

A Novel Method for Simultaneous Removal of NO and SO2 from Marine Exhaust Gas via In-Site Combination of Ozone Oxidation and Wet Scrubbing Absorption

The stringent international regulations on marine emission abatement have exerted a huge push on the development of marine desulfurization and denitrification technologies. However, for the traditional vessels driven by large two-stroke diesel engines, simultaneous removal of NOx and SO2 is still a big challenge at present. Here, a one-stage ozone oxidation combined with in-situ wet scrubbing for simultaneous removal of NO and SO2 is proposed. A series of experiments were performed based on a bench-scale reaction system. The results showed that in-situ wet scrubbing could effectively decrease flue gas temperature, and then suppress the thermal decomposition of ozone, which was beneficial for improve oxidant utilization. Meanwhile, the in-situ combination of ozone injection and wet scrubbing was in favor of improving the selectivity oxidation of NO over SO2 by ozone, which was possibly due to the high aqueous solubility of SO2 in water. Aiming to reduce the electric power consumption by an ozone generating system, O3/NO molar ratio was kept as low as possible. A complete removal of SO2 and a high NOx removal efficiency could be achieved through the introduction of other oxidative additives in scrubbing solution. This integrated system designed for marine application was of great significance.

Solubility of SO2 in Water from 263.15 to 393.15 K and from 10 to 300 bar: Quantitative Raman Spectroscopic Measurements and PC-SAFT Prediction

Sulfur dioxide (SO2), a kind of acid gas pollutant, can accelerate the reaction of water and rock when it is cosequestered with CO2. The solubility of SO2 in water is essential to understand the tr...

Assessment of waste hardened cement mortar utilization as an alternative sorbent to remove SO2 in flue gas

Developing efficient low-cost absorbents has been recognized as a prerequisite for industrial application of wet flue gas desulfurization (WFGD). Herein, hardened cement mortar (HCM) particles developed from waste concrete blocks were used as an innovative absorbent for SO2. The results show that the SO2 in flue gas can be completely absorbed by the highly alkaline HCM slurry. Under optimum operating conditions, 0.8 g of SO2 was retained by per gram of HCM. Under acid conditions produced upon dissolving SO2 in water, the Ca-rich compounds in HCM particles can continuously release Ca2+ and OH− into the HCM slurry. The Ca2+ ions released can effectively combine with SO32−, resulting in the absorption of SO2 dissolved in water. The dissolution process of HCM particles is well described by the pseudo-second-order model. The desulphurization byproduct was characterized by X-Ray diffraction (XRD) analysis, scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy and energy dispersive spectrometry (EDS). The results show that the desulphurization product mainly consists of gypsum. The technology developed provides a type of new material for removing SO2 in waste flue gas. It also offers an innovative solution for the disposal of waste concrete which is also a global environmental concern.

Sodium Lactate Aqueous Solution, A Green and Stable Absorbent for Desulfurization of Flue Gas

A novel absorbent sodium lactate (NaLa) aqueous solution (aq) for SO2 absorption is reported. SO2 in simulated flue gas is reversibly absorbed in NaLa aq. The absorption capacity of SO2 in the absorbent increases with increasing NaLa content and SO2 concentration, and decreasing temperature. Compared with the absorbents reported in the literature, the absorption capacity of SO2 in NaLa aq. is much high, for example, 50 wt % NaLa aqueous solution can absorb 0.130 g SO2 / g absorbent at a SO2 concentration of 2.5 vol % and 40 oC. Importantly, NaLa (aq) exhibits high reversibility and long-term stability, indicating a promise for the desulfurization of flue gas. The absorption mechanism is proposed to be the replacement of lactic acid (HLa) by sulfurous acid (H2SO3), which is generated by dissolving SO2 in water.

Simulation of the Solubility of SO2 on Water Using CFD Modeling Airlift Reactor

Nowadays, petroleum and power plants emissions are increasingly recognized as a serious, worldwide public concern. In recent years, there has been an increasing interest to find solutions to decrease SO2 and the sulfur dioxide emissions from petroleum and electricity facilities. So far, several attempts have been made to figure out methods, procedures or techniques to lessen the emissions of SO2 which requires high cost to develop these techniques. However, the current research provides a solution to this issue through simulation, which allows new ways to test and diagnose these methods, procedures with low cost and danger. Nevertheless, solubility of SO2 in water may consider as conventional approach while sulfur dioxide of SO2 is a soluble gas in water, which can be oxidized through cloud and fog by producing sulfuric acid. Finally, this paper offers a new way to test SO2 solubility through using CFD modeling Airlift reactors.

On the SO2 problem of solid fuel combustion

Many companies use two-phase absorbents (CaCO3 suspension) for waste gases purification from SO2. A qualitative theoretical analysis of the absorption kinetics in the cases of two-phase absorbent, using the convection-diffusion type of model, is presented. It is shown that the low CaCO3 concentration lead to very small chemical reaction rate and as a result the absorption rate is limited by the physical absorption of SO2 in water, i.e. the process efficiency is very small. An average concentration model for quantitative analysis of the absorption process and an iterative numerical algorithm for the model equations solution is proposed.

Variability of SO2 in an intensive fog in North China Plain: Evidence of high solubility of SO2

A field experiment was conducted in an intensive fog event between November 5 and November 8, 2009, in a heavily SO2-polluted area in North China Plain (NCP), to measure SO2 and other air pollutants, liquid water content (LWC) of fog droplets, and other basic meteorological parameters. During the fog period, the concentrations of SO2 showed large variability, which was closely related to the LWC in the fog droplets. The averaged concentration of SO2 during non-fog periods was about 25ppbv, while during the fog period, it rapidly reduced to about 4–7ppbv. Such large reduction of SO2 suggested that a majority of SO2 (about 70%–80%) had reverted from gas to aqueous phase on account of the high solubility of SO2 in water in the fog droplets. However, the calculated gas to aqueous phase conversion was largely underestimated by merely using the Henry's Law constant of SO2, thus suggesting that aqueous reaction of SO2 in fog droplets might play some important role in enhancing the solubility of SO2. To simplify the phenomenon, an “effective solubility coefficient” is proposed in this study. This variability of SO2 measurement during the extensive fog event provides direct evidence of oxidation of SO2 in fog droplets, thus providing important implications for better understanding of the acidity in clouds, precipitation, and fogs in NCP, now a central environmental focus in China due to its rapid economic development.

SO2 Hydrolysis: Ab initio MD Study of the Formation of Bisulfite Ion

Ab initio molecular dynamics simulations have been performed to study the dissolution of SO2 in water. It has been obtained that the hydrated SO2 is surrounded by the water molecules without any S-H hydrogen bond, restraining the sulfonate anion formation but allowing the bisulfite isomer formation. The metadynamics method has been employed to explore the free energy surface of the SO2 + H2O reaction. The simulations revealed that the hydrated SO2 forms bisulfite anion and hydronium cation after overcoming a ca. 17 kcal/mol free energy barrier. Direct, one-step H2SO3 formation could not been observed, in sharp contrast with earlier cluster calculations. These findings indicate a step-wise H2SO3 formation in water. The presence of the sulfur lone pair represents an important constraint on the mechanism: the nucleophilic H2O attack can occur only from certain angles as shown by the reactive trajectories.

Diffusion Coefficients of SO2 in Water and Partition Coefficients of SO2 in Water–Air Interface at Different Temperature and pH Values

Reversed flow gas chromatography was applied to measure the diffusion coefficient of SO2 in water, the partition coefficient of SO2 in air–water interface, and the rate constant, k R, for chemical reaction between SO2 and water at various temperature and pH values. A linear increment of the diffusion coefficients of SO2 in water with temperature is drawn while the partition coefficients are decreased when temperature increases. Additionally, for each temperature, the diffusion coefficients passed through a maximum as pH increases. Finally, k R is slightly increased with pH and, for the same pH values, k R is higher at lower temperatures.

MODEL FOR PREDICTION OF ROTATING STREAM TRAY EFFICIENCY

ABSTRACT Based on the results of the gas flow field, the droplet size distribution and the droplet initial flow rate distribution on a Φ300 mm rotating stream tray (RST), a three-dimensional droplet projection trajectory model, and a mass transfer model have been developed. The calculation of the models was carried out by a finite-difference procedure. The predicted results of the tray efficiency agree quite well with the experimental data measured with absorbing NH3 or SO2 in water on a Φ300 mm RST column and with the industrial data from a Φ3600 mm RST column. Meanwhile, the influence of absorbing system and the RST structure on the tray efficiency is discussed.

Extraction of Anthocyanin Pigments from Purple Sunflower Hulls

ABSTRACTThe anthocyanin pigments in hulls of purple sunflower seeds were extracted using three solvent systems, 50:1:49 ethanol‐acetic acid‐water (EAW), 0.01M acetic acid (AAc), or water containing SO2. Solvent, extraction time, size of ground hulls, pH of extracting solvent, hulls/solvent ratio, and concentration of SO2 in water, were investigated. All were significant factors affecting yield of extracted anthocyanins. EAW and SO2 were more effective extractants than AAc. Optimum conditions from response surface optimization for the extraction with sulphurous water were: SO2 at 200 mg/L, hull size 20 mesh, extraction time 5 min at 22°C, and solvent/hulls ratio = 20.

Selection of SO2 Control for Non-Steady-State Operating Conditions

Most proven SO2 scrubbing processes are applied under quasi-steady-state conditions. Due to the low solubility of SO2 in water, an alkali is added in the suspended or dissolved state and fed proportionally to the quantity of SO2 entering the scrubber. Highly variable gas composition and flow requires careful monitoring and unusual flexibility of the scrubber system. In addition to SO2, concentration of other gases such as oxygen and carbon dioxide can significantly affect the choice of a process. Selection of scrubbing processes and systems is described for two cases: TBRC™ Copper Smelting and Secondary Lead Smelting effluents.

Effect of dissociation on the absorption rate of dilute SO2.

Absorption of dilute SO2 in water, aqueous solutions of H2SO4, NaHSO3 and Fe(II)-edta was theoretically and experimentally investigated. It was found that the dissociation of SO2 in solutions (SO2+H2O→←HSO-3+H+) has a remarkable effect on its absorption rate. The presence of H2SO4 or NaHSO3 prevents the dissociation of SO2, resulting in lower absorption rate than that in pure water. The absorption rate in Fe(II)-edta solution was found to be faster than that into water because of the buffer capacity of Fe(II)-edta solution. The experimental results are satisfactorily explained by the theory of gas absorption accompanied by instantaneous reversible reactions.

Stability Studies with Patulin

Abstract The chemical stability of patulin in a variety of foods and feeds in various solvents and in the presence of SO2 in water was investigated spectrophotometrically. Patulin was found to be completely stable in apple juice and dry corn; however, in wet corn, Durham wheat, and sorghum and in the presence of SO2 in water, patulin was observed to be unstable. Patulin was completely stable over long periods of time in chloroform, benzene, and methylene chloride, but slow decomposition was noted in methanol and water.

The Raman spectrum of sulphur dioxide in different states

AbstractThe influence of the state of matter on the three vibrations of sulphur dioxide has been studied.For that reason the Raman spectra of gaseous SO2 at 12 atmospheres, of liquid SO2 at 40° and 70°, of solutions of SO2 in water and of mixtures of SO2 with CCl4 (and SO3) were investigated.The difference between equation image gas and equation image liquid for the strongest Raman line of SO2, is equal to 6 cm−1. This is to be ascribed to the action of the electrostatic fields of the dipole molecules in the liquid.For solutions in water (at 50°), the dissolved SO2 is in a state comparable with the gaseous one. The concentration of H2SO3 in the solution can only be small.For the mixtures only small displacements of the Raman lines have been The spectrum of the mixtures consists in first approximation of a superposition of the spectra of the two components.The experimental arrangement used, is described in detail.