Sulfide Ion Concentration Research Articles

A rapid and sensitive paper-based sensor for sulfide ion detection in Chinese liquors

The accurate monitoring of sulfide ion concentrations is vital for ensuring food safety, but current detection methods are often cumbersome and confined to laboratories. This study introduces an innovative paper-based colorimetric sensor that leverages the peroxidase-like activity of cobalt tetrasulfonate phthalocyanine (CoTsPc) for rapid, sensitive, and selective sulfide ion quantification. The underlying mechanism relies on the interaction between cobalt and sulfide ions, modulating the catalytic efficiency of CoTsPc and triggering a visible color change when 3,3′,5,5′-tetramethylbenzidine (TMB) and hydrogen peroxide are present. By controlling solvent evaporation, the reaction kinetics are standardized, enabling reproducible and accurate colorimetric measurements. Experimental results show that adding sulfide ions to the TMB-H₂O₂ reaction system causes a gradual decrease in color intensity on the paper substrate. This change verifies effectiveness of the sensor, highlighting its potential for reliable sulfide ion detection in food safety applications, while providing a simple and portable alternative to conventional methods.

Microbial green synthesis of luminescent terbium sulfide nanoparticles using E. Coli: a rare earth element detoxification mechanism

BackgroundRare-earth sulfide nanoparticles (NPs) could harness the optical and magnetic features of rare-earth ions for applications in nanotechnology. However, reports of their synthesis are scarce and typically require high temperatures and long synthesis times.ResultsHere we present a biosynthesis of terbium sulfide (TbS) NPs using microorganisms, identifying conditions that allow Escherichia coli to extracellularly produce TbS NPs in aqueous media at 37 °C by controlling cellular sulfur metabolism to produce a high concentration of sulfide ions. Electron microscopy revealed ultrasmall spherical NPs with a mean diameter of 4.1 ± 1.3 nm. Electron diffraction indicated a high degree of crystallinity, while elemental mapping confirmed colocalization of terbium and sulfur. The NPs exhibit characteristic absorbance and luminescence of terbium, with downshifting quantum yield (QY) reaching 28.3% and an emission lifetime of ~ 2 ms.ConclusionsThis high QY and long emission lifetime is unusual in a neat rare-earth compound; it is typically associated with rare-earth ions doped into another crystalline lattice to avoid non-radiative cross relaxation. This suggests a reduced role of nonradiative processes in these terbium-based NPs. This is, to our knowledge, the first report revealing the advantage of biosynthesis over chemical synthesis for Rare Earth Element (REE) based NPs, opening routes to new REE-based nanocrystals.

Highly efficient visible light active iron oxide-based photocatalysts for both hydrogen production and dye degradation

Photocatalysis is essential for wastewater cleanup and clean energy, and in this current study, we have synthesized nanomaterials (iron oxide-based) for photocatalytic pollution degradation and hydrogen production. The performance of aluminium oxide/ferric oxide (Al2O3/Fe2O3), samarium oxide/ferric oxide (Sm2O3/Fe2O3) and yttrium oxide/ferric oxide (Y2O3/Fe2O3) were compared for the production of hydrogen (H2) and degradation of dye under natural sunlight. Various characterisation equipment was used to characterize these photocatalysts’ structure, morphology, elemental content, binding energy and band gap. The hydrogen recovery efficiency of iron oxide-based photocatalysts from sulphide-containing wastewater is assessed. Y2O3/Fe2O3 has shown the highest hydrogen production of 340 mL/h. The influence of operating factors such as sulphide ion concentration, catalyst quantity, and photocatalyst photolytic solution volume on hydrogen production is studied. The optimal values were 0.25 M, 0.2 g/L, and 1L, respectively. The developed photocatalyst passed multiple cycles of stability testing. Fe2O3 has shown the highest Rhodamine B (RhB) dye degradation efficiency of 94% under visible light.

Understanding the different effects of fouling mechanisms on working and reference electrodes in fast-scan cyclic voltammetry for neurotransmitter detection.

Fast-scan cyclic voltammetry (FSCV) is a widely used technique for detecting neurotransmitters. However, electrode fouling can negatively impact its accuracy and sensitivity. Fouling refers to the accumulation of unwanted materials on the electrode surface, which can alter its electrochemical properties and reduce its sensitivity and selectivity. Fouling mechanisms can be broad and may include biofouling, the accumulation of biomolecules on the electrode surface, and chemical fouling, the deposition of unwanted chemical species. Despite individual studies discussing fouling effects on either the working electrode or the reference electrode, no comprehensive study has been conducted to compare the overall fouling effects on both electrodes in the context of FSCV. Here, we examined the effects of biofouling and chemical fouling on the carbon fiber micro-electrode (CFME) as the working electrode and the Ag/AgCl reference electrode with FSCV. Both fouling mechanisms significantly decreased the sensitivity and caused peak voltage shifts in the FSCV signal with the CFME, but not with the Ag/AgCl reference electrode. Interestingly, previous studies have reported peak voltage shifts in FSCV signals due to the fouling of Ag/AgCl electrodes after implantation in the brain. We noticed in a previous study that energy-dispersive spectroscopy (EDS) spectra showed increased sulfide ion concentration after implantation. We hypothesized that sulfide ions may be responsible for the peak voltage shift. To test this hypothesis, we added sulfide ions to the buffer solution, which decreased the open circuit potential of the Ag/AgCl electrode and caused a peak voltage shift in the FSCV voltammograms. Also, EDS analysis showed that sulfide ion concentration increased on the surface of the Ag/AgCl electrodes after 3 weeks of chronic implantation, necessitating consideration of sulfide ions as the fouling agent for the reference electrodes. Overall, our study provides important insights into the mechanisms of electrode fouling and its impact on FSCV measurements. These findings could inform the design of FSCV experiments, with the development of new strategies for improving the accuracy and reliability of FSCV measurements in vivo.

Colorimetric and absorbance based sensor for sulfide and bicarbonate ions by dye doped polymer composite

We have developed a simple, rapid and cost-effective Dual-channel “colorimetric and absorbance” sensor using polyvinylpyrrolidone (PVP) capped Rhodamine6g (Rh6G) dye composite. Dye-doped polymer composite probe (PVPRH) exhibit intense, narrow absorption properties and long-term stability than the bare Rh6G. The probe’s colorimetric relationship with pH was demonstrated by absorption titration. The PVPRH provides a sensitive dual channel method for the determination of sulfide and bicarbonate with colorimetric response and absorption quenching. The synthesized probe, as a two-faced, exhibited remarkable colorimetric responses from orange to pale yellow in the presence of S2- and orange to soft pink in the presence of HCO3- ion, which can be observed by the naked eye also. Under optimal conditions, the relative absorption intensity decreases with increasing ion concentration of sulfide and bicarbonate ions. This trend is observed within the probe solution concentration range of 5 mM to 50 mM. The Dye-doped polymer composite probe is easy, cost effective, rapid, and has real time detection capability for sulfide and bicarbonate ions. The composite probe is stable and optically modified and can be successfully used for detections of S2- and HCO3- ions as strip senor.

Folic acid-derived luminescent carbon dots: Effect of Ag inclusion and switch ON sensing of sulfide ions

One of the aesthetic concerns of the scientific community is to ensure all people have access to safe drinking water. Sulfide ion is considered as a public health risk-worthy constituent in water. The present work investigates the effect of localized surface plasmon resonance (LSPR) of silver nanoparticles (AgNP) on the photoluminescence response of folic acid-derived carbon nanodots (CD) and their application towards sulfide ion detection. Herein, CD are grown on the surface of AgNP, causing an absorption band centered at ∼ 400 nm due to LSPR. AgNP effectively quench the luminescence of CD through the static quenching mechanism. The Ag-CD system is designed as a simple and selective sensor for sulfide ions in water in a linear range of 0.8–1.5 µM with a Limit of Detection (LOD) of 50 nM and a Limit of Quantification (LOQ) of 170 nM. The ion selectivity for sensing was carried out in accordance with the Hard and Soft – Acids and Bases theory and its predictions. The practical applicability of the sensor was tested by determining the spiked sulfide ion concentrations in pond water and tap water, which produced an adequate outcome.

Corrosion Behavior of Stainless Steel in Seawater in the Presence of Sulfide

The effect of temperature (from 288 to 308 K) and concentration of sulfide ions (up to 40 ppm) on the corrosion behavior of AISI 304L and AISI 316L stainless steels in seawater was studied with measurements of open-circuit potential, linear and potentiodynamic polarization, and electrochemical impedance spectroscopy. An increase in temperature and pollutant concentration negatively affects the corrosion stability of stainless steels at the open circuit (the resistance, compactness, and thickness of the surface layer decrease and the corrosion current increases), in the passive region (the passivation current increases, the depassivation potential decreases, and the passive potential region narrows), and in the transpassive potential region (the rate of metal dissolution increases). The occurrence of pitting corrosion on the surface of the samples was confirmed with optical microscopy and a non-contact 3D profilometer. A few large pits (depth 80–100 μm and width 100 μm) were formed on the surface of AISI 304L steel, while several smaller pits (depth 40–50 μm and width 50 μm) were formed on the surface of AISI 316L steel. With increasing temperature and sulfide ion concentration, the width, depth, and density of the pits increased on both steel samples. In the studied temperature and concentration range of sulfide ions, the AISI 316L steels exhibited higher corrosion resistance. Overall, the influence of sulfide ions on steel corrosion was more pronounced than the influence of temperature.

PH, Ion Release Capability, and Solubility Value of Premixed Mineral Trioxide Aggregates

The current study aimed to compare the pH, solubility value, and ion release capability of premixed mineral trioxide aggregates (MTAs) versus conventional pulp capping materials before and after setting. The following materials were used: resin-modified calcium silicate cement (TheraCal LC<sup>®</sup>, TLC), resin-modified calcium hydroxide cement (Ultra-Blend<sup>TM</sup> plus, UBP), and 2 kinds of premixed MTA (Endocem MTA<sup>®</sup> premixed regular 〔EMPR〕 and Well-Root<sup>TM</sup> PT 〔WRP〕). The specimens of each material were prepared before and after setting and were immersed in distilled water. The materials’ pH and solubility value were assessed. Next, three kinds of ion (calcium, sulfide, and strontium) released by pulp capping materials were evaluated via inductively coupled plasma atomic emission spectrometry. In the after-setting group, the pH of TLC and UBP decreased. However, the pH of the premixed MTAs increased with time. TLC released a higher concentration of strontium ion compared with the other materials. Meanwhile, EMPR released a significantly high concentration of sulfide ion (<i>p</i> < 0.05). In the after-setting group, the 2 kinds of premixed MTAs released a significantly higher concentration of calcium ion compared with the other materials (<i>p</i> < 0.05). In the after-setting group, EMPR had a significantly low solubility value (<i>p</i> < 0.05). The Kruskal-Wallis test, followed by the Mann-Whitney U test with Bonferroni correction, was used in statistical analysis. In conclusion, resin-modified calcium silicate cement, modified calcium hydroxide cement, and the 2 kinds of premixed MTAs had an alkaline pH and low solubility value and they released various concentrations of ions after setting.

Pore-Scale Flow Fields of the Viscosity-Lost Partially Hydrolyzed Polyacrylamide Solution Caused by Sulfide Ion

The rheology of a partially hydrolyzed polyacrylamide (HPAM) solution plays an important role in its oil recovery during polymer flooding. However, multiple factors in brine, such as sulfide ions, cause a dramatic loss in the viscosity and oil recovery. To better understand the sulfide-induced viscosity loss and the consequent flow mechanisms in pore networks, the morphology of polymer solutions with and without sulfide ion was observed by scanning electron microscopy; and the variations of the pore scale flow fields were demonstrated by a microscopic visualization seepage experiment combined with Micro-PIV (Microscale Particle Image Velocimetry). The results showed that, with the presence of sulfide ion, the microstructure of the polymer changed from a uniform three-dimensional network structure to loose and uneven floccules, which resulted in viscosity loss (over 70% with 5-mg/L sulfide ion). Moreover, higher concentrations of sulfide ions (5 mg/L and 10 mg/L) resulted in earlier shear thinning characteristics than those with lower sulfide concentrations. Due to viscosity loss, the average flow velocity in the main stream of the microscopic seepage experiment increased more significantly than that without sulfide. However, the viscosity loss alone cannot independently explain the severe viscous fingering during the subsequent post-water flooding, which was about five times greater than that of the primary water flooding in terms of the velocity ratio between the mainstream and margin. A further pore-scale flow field analysis exhibited an eccentric and a bimodal velocity distribution in the throat along the radial and axial directions, respectively. The former distribution indicated that the adsorbed polymer on the pore wall was broken through by hydraulic shear due to the collapsed structure caused by sulfide ion. The latter suggested that another sulfide-induced impact was an earlier-occurring non-Newtonian characteristic with a low shear rate. Therefore, instead of viscosity loss, elastic loss is the dominant mechanism affecting the characteristics of the aggregate flow field under the action of sulfide. Microscopic flooding combined with Micro-PIV is a feasible and essential method to reveal pore scale flow mechanisms.

Disinfection of therapeutic water - balancing risks against benefits: case study of Hungarian therapeutic baths on the effects of technological steps and disinfection on therapeutic waters.

Thermal therapeutic pools in most countries are operated in a manner similar to swimming pools: with water circulation, filtration and disinfection. However, in some countries, including Hungary, therapeutic pools are traditionally not treated this way, in order to preserve the therapeutic qualities of the water. However, dilution and frequent water replacement applied in these pools are often insufficient to ensure adequate microbial water quality, posing a risk of infection to the bathers. In the present case study, the impact of water treatment (including chemical disinfection by hypochlorite or hydrogen peroxide) was investigated on the therapeutic components of the water in seven Hungarian spas of various water composition. Microbial quality was improved by both disinfectants, but hypochlorite reduced the concentration of the therapeutic components sulfide, bromide, and iodide ions by 40-99%, and high levels of disinfection by-products were observed. Hydrogen peroxide only affected sulfide ion (91% reduction). Other technological steps (e.g., transport or cooling by dilution) were found to have significant impact on composition, often outweighing the effect of disinfection. The current case study demonstrated that thermal waters may be treated and disinfected with minimal loss of the therapeutic compounds, if an adequate treatment procedure is selected based on the water composition.

Investigating the ability of sulfur oxidizing strains in biodesulfurisation of sulfide-containing streams, screening the most capable strain and determining the optimum condition for elemental sulfur recovery from sulfide using response surface method

Beside numerous chemical methods, biological methods were developed to remove sulfide from streams using Sulfur Oxidizing Bacteria (SOB). Because of the wide variety of such bacteria and deep difference in their capability, the ability of seven well-known SOBs were investigated. According to the results T. versutus and T. aerophilum were selected as capable bacteria for further experiments. The valuable product of sulfide oxidation is elemental sulfur, the production of sulfur in the culture medium was considered as the basis for selecting the appropriate bacteria. Evaluations of bacteria showed that T. aerophilum was not able to produce elemental sulfur and only produced sulfate as its final product. However, by creating oxygen restriction conditions, sulfur production is observed for T. versutus. Therefore, the continuation of experiments on the optimization of sulfur production in the culture medium of T. versutus was investigated. Due to the fact that the amount of dissolved oxygen in bioreactor can be controlled by changing the stirrer speed, the stirrer speed was considered as one of the parameters. In these experiments, sulfide ion concentration and initial agitator speed were considered as variables and sulfur production as a response. Experiments were designed using Design Expert software and RSM method. The results of optimization experiments showed that the concentration of 10000 mg/L of sulfide and the stirrer speed of 130 rpm led to the production of elemental sulfur of 1600 mg/L. Therefore, 40% of the incoming sulfide is converted to sulfur.

QUANTITATIVE DETERMINATION OF SULPHATE REDUCING BACTERIA AND HYDROGEN SULPHIDE IN HUMAN SALIVA

"Objectives: Sulphate Reducing Bacteria (SRB) are part of the normal oral microbiota. They have been frequently detected in the oral cavity of individuals with and without oral manifestations. The aim of this investigation was to determine possible correlation between SRB count and their activity in saliva versus some oral health manifestations. Methods: A total of 64 saliva samples were collected from healthy individuals, and patients with several oral manifestations. Detection and count of SRB were performed using documented methods, while sulphide ion concentration which is the metabolic end product of these bacteria was measured using a silver electrode connected to a millivolt meter. Results: SRB were detected in 35.9% of saliva samples investigated. Statistical significance was observed between the detection of these bacteria and various oral conditions. However, count of SRB and the sulphide ion concentration in the tested samples did not have significant correlation with the oral conditions considered. Conclusion: The mere detection of SRB in saliva is of significance in the diagnoses of oral conditions. Enumeration of these bacteria and quantification of their metabolic end product in the same samples were not of diagnostic value."

Analysis of Changes in the Quality of Surface Water after Filling of Hydroelectric Reservoirs in the Amazon, Brazil

We employed statistical techniques to assess the quality of surface water measured before and after filling the reservoirs of four important hydroelectric power plants (HPPs) established in the Brazilian Amazon (Belo Monte, Jirau, Teles Pires, and Santo Antonio do Jari). A cluster analysis efficiently identified distinctions between the dendrograms obtained for the pre- and post-filling phases in the four projects and indicated changes in water quality after the reservoirs were filled. The Mann-Whitney U test (at the 5% significance level) allowed for the identification of parameters that exhibited significant changes after filling the reservoirs. Across the four HPPs, a total of 45 monitoring points and 54 water quality parameters were analyzed. The results revealed 14 parameters that changed significantly at a greater number of monitoring points in more than one HPP, namely water temperature, pH, dissolved oxygen, electrical conductivity, oxidation-reduction potential, transparency, total dissolved solids, chlorophyll-α, thermotolerant coliforms, alkalinity, total phosphorus, and calcium, sulfate, and sulfide ion concentrations. These parameters were identified as the most important for explaining the changes in water quality after filling the reservoirs. All monitoring points located within the reservoirs (41 points) and immediately downstream of the dams (4 points) revealed significant changes in water quality. Thus, changes in the quality of surface water were observed along the entire lengths of the reservoirs, including the initial stretches. This study contributes to the understanding of the temporal and spatial effects of the formation of reservoirs on surface water quality parameters.

Hydrochemical Characteristics of Thermal Water Reservoir in Lądek-Zdrój in Light of Research into the Borehole LZT-1—The Deepest Borehole in the Sudetes (SW Poland)

Lądek-Zdrój is situated within the tectonic unit of the Lądek-Śnieżnik metamorphic complex. Thermal water is captured by five springs and borehole L-2. These waters are characterized by TDS content in the range of 160–230 mg/L and predominance of HCO3− (15–100% meq), SO42+ (10–36% meq), and Na+ (57–91% meq) ions. Increased concentrations of radon, hydrogen sulfide, and fluoride ions (7–13 mg/L) determine the medicinal properties of these waters, classified as thermal waters of Na-HCO3-(SO4), F−, H2S, Rn type, with temperatures of 18 to 30 °C and 41 to 45 °C in springs and in the L-2 borehole, respectively. At the turn of 2018 and 2019, a new borehole LZT-1 was drilled in the area of Lądek-Zdrój. It captured thermal waters with a temperature of 37.4 °C at the outflow. The water temperature at the bottom of the heated borehole reached about 59 °C. The lithology of rocks found in the recharged areas implied that the Ca2+ ions present in the studied waters originated from pyroxenes, amphiboles, calcite, calcium plagioclases, and fluorite. As for Na+ and K+ ions, they originate from sodium plagioclases, microcline, and orthoclase. The probable deposit temperature of waters from this borehole was estimated with the use of chemical geothermometers, as ranging from about 87 °C to 97 °C.

Colorimetric Determination of Sulfide in Turbid Water with a Cost-effective Flow-batch Porous Membrane-based Diffusion Scrubber System.

A cost-effective flow-batch analysis approach with colorimetric measurement has been developed for sulfide ion determination in turbid water samples without using a conventional pump and valve. Under an acidic condition, sulfide ion was converted to hydrogen sulfide gas and liberated out from other complicated matrices. The porous membrane-based diffusion scrubber was utilized as a gas trapping unit for hydrogen sulfide gas separation/preconcentration. From the correlation of sulfide ion concentration and disappearance of sodium nitroprusside reagent detection by using a homemade LED-photodiode based colorimetry, a linear relationship of sulfide ion concentration and absorbance can be obtained with relative standard deviation (%RSD) less than 5%. The limit of detection was 5.6 μmol L-1. The proposed system was applied for sulfide ion determination in wastewater samples with the recoveries of 91.0 - 105.2%. The proposed system is a robust setup and able to handle turbid water samples without a sample filtering step.

Effect of PbO on cyanidation leaching behavior of bornite

During the cyanidation of gold‑copper ores or concentrates, the presence of cyanide-soluble copper significantly increases the cyanide consumption. However, the consumption of cyanide and dissolved oxygen, the concentration of sulfide ions in the leaching solution decreased with the increase of PbO amount. The SEM-EDS analyzed that there was no obvious corrosion on the surface of the bornite leaching residue in the presence of 1.5 g/L PbO, but the surface was getting very sleek. It was known from thermodynamic calculation that PbO would partially dissolve to form plumbite ions in the alkaline cyanide solution, and plumbite ions would react with sulfide ions to form PbS precipitate. The XPS analysis also proved that a large amount of undissolved PbO and PbS precipitation were adsorbed on the surface of bornite. The adhesion of PbO and PbS on the surface of bornite inhibited dissolution of bornite in the cyanide solution.

Знесірчення промислових сульфідно-лужних розчинів сумішевими сорбентами

Modern methods of purification of hydrocarbons (oil, gas) from sulfur-containing compounds (H2S, RSH, RSSR, naphthenic acids, NaHS, Na2S) have been analyzed, which are based on their alkaline extraction followed by oxidation of air oxygen on homogeneous or heterogeneous catalysts. Despite the promising process of catalytic oxidation of sulfur-containing compounds in technical solutions, it has a number of significant drawbacks, primarily related to the activity of the catalyst and the ability to form a large number of intermediate products of the oxidation. Other known methods for the removal of sulfur-containing compounds from technical solutions are based on the chemical interaction of sulfide alkaline solutions with aqueous solutions of metal salts of III-V analytical groups or their interaction with elemental sulfur to form the corresponding sodium polysulfides. A number of studies have investigated the sorptive extraction of sulfur-containing compounds from technical aqueous solutions or commercial hydrocarbons/diesel fuels using various modifications of activated charcoal, natural sorbents, polymeric organic absorbers or mixed sorbents. However, despite the wide variety of sorptive materials studied, the problem of purification of industrial wastewater from sulfur-containing compounds is not completely solved and, in turn, depends on the chemical structure of the surface of the sorbent, as well as on the objects of purification, pH of media and several other factors. It has been developed an alternative method of purification of aqueous sulfide alkaline solutions/wastewater from sulfide and hydrosulfide ions by their adsorption on pre-regenerated mixed sorbents consisting of activated charcoal (AC) of brand Decolar A and kieselguhr (K) of brands Becogur 200 and Becogur 3500 with mass ratio of 4 : 6. It has been found that the degree of purification of the investigated solutions, which is strongly dependent on the initial concentrations of sulfide and hydrosulfide ions, is 95,7…96,6 % and indicates the high efficiency and possibility of using such technologies in industrial production. Surface study of mixed sorbents (AC+K) after purification of aqueous solutions was performed using X-ray phase analysis. The received data confirms the amorphous composition of the activated charcoal and the presence of the main SiO2 cristobalite, 4,02, on the left side of the diffractogram, as well as a number of peaks of various Na2S modifications.

Sulfide ion Selective Method of Analysis of Sulfurated Hydrogen in Alkaline Smoked Cigarette Solution

Sulfurated hydrogen commonly called hydrogen sulfide (H2 S) is a clear, colorless, extremely toxic gas that has a rotten egg smell at low concentration. The human nose can detect H2 S at concentrations below 100 parts per billion (ppb). It is found least amount in cigarette smoke that has been the subject of analysis for many analytical chemists. This gases is soluble in alkaline medium and gives free sulfide (S-2 ) ions. Sulfide ion concentration in cigarette smoke solution is found in the range of detection limit of lab made Silver- silver sulfide (Ag/Ag2 S) ion selective electrode (ISE).This project has designed to investigate the amount hydrogen sulfide as a free sulfide (S--)ion in cigarette smoke solution. Silver-silver sulfide ion selective electrode (Ag/ Ag2 S ISE) and Silver–silver chloride (Ag/AgCl) reference electrode are prepared in the lab for determination. Detail protocol of standard addition method with modified Grant’s plot is applied for estimation. Different brand of cigarette samples were collected from different area of Pokhara valley and analyzed. The average amount of H2 S per stick of cigarette smoke is found to vary from 0.0453 mg to 0.0573 mg in different brands. Among them sample no SA-5 shows 0.0453mg per stick of cigarette. This result is minimum in compare to other brands. Similarly, sample no SA- 7 have found 0.0573mg per stick which is higher in compare to other brands.
 Key words: Cigarette smoke, hydrogen sulfide, ion selective electrode, standard addition method, Grant’s plot method,

Performance of Square and Trapezoidal photoreactors for solar hydrogen recovery from various industrial sulphide wastewater using CNT/Ce3+ doped TiO2

CNT/Ce3+ doped TiO2 powder was synthesized using a sol-gel method and characterized by X-ray Diffraction, UV–vis Diffuse Reflectance Spectroscopy, FTIR, EDX, Raman, Transmission Electron Microscopy (TEM), BET and PL. Direct sunlight illumination was used to check the photocatalytic activity of CNT/Ce3+ doped TiO2 for hydrogen production from sulphide wastewater. Sulphide wastewater collected from various industries viz., STP (Sewage Treatment Plant), Refinery (Amine solution) and Tannery (soak pit) were used to test the photocatalytic hydrogen recovery. The suitable industrial wastewater which generates maximum hydrogen was used to check the effect of various operating parameters viz., sulphide ion concentrations, sulphite ion concentrations and catalyst dosage. The maximum hydrogen recovery achieved was found to be 14,500 μmol/h.

Photocatalytic hydrogen production using bench-scale trapezoidal photocatalytic reactor

Hydrogen is the future fuel and energy carrier, which has numerous applications. During combustion, produces only water vapour instead of greenhouse gas emissions. Photocatalytic production of hydrogen as a clean fuel from sulphide wastewater arises as a necessary option that must be considered. Here we report the performance of CNT added CdZnS/Fe2O3 for hydrogen recovery from highly toxic sulphide containing wastewater. The prepared photocatalysts were characterised for XRD (structure), UV-DRS (band gap), HRTEM (particle size), XPS (binding energy), SEM (morphology) and ICP (elemental composition). The photocatalytic hydrogen recovery was performed using novel trapezoidal photocatalytic reactor. The synthesized novel CNT - CdZnS/Fe2O3 nano-photocatalyst has highest production of hydrogen (2679 μmol/h) than plain CdZnS/Fe2O3 (2009 μmol/h).The feasibility studies were conducted to optimize the operating variables viz., S2- (sulphide ion) concentrations, SO32- (sulphite ion) concentrations, catalyst amount, light irradiation and volume of wastewater. Reusability studies under natural solar irradiation were performed and the CNT deposited CdZnS/Fe2O3 photocatalyst was found to be stable upto seven runs.