Search Results (32)

Unmanned aerial vehicles, also termed as unarmed aerial vehicles, are used for various purposes in and around the environment, such as delivering things, spying on opponents, identification of aerial images, extinguishing fire, spraying the agricultural fields, etc. As there are multi-functions in a single UAV model, it can be used for various purposes as per the user’s requirement. The UAVs are used for faster communication of identified information, entry through the critical atmospheres, and causing no harm to humans before entering a collapsed path. In relation to the above discussion, a UAV system is designed to classify and transmit information about the atmospheric conditions of the environment to a central controller. The UAV is equipped with advanced sensors that are capable of detecting air pollutants such as carbon monoxide (CO), carbon dioxide (CO₂), methane (CH₄), ammonia (NH₃), hydrogen sulfide (H₂S), etc. These sensors present in the UAV model monitor the quality of air, time-to-time, as the UAV navigates through different areas and transmits real-time data regarding the air quality to a central unit; this data includes detailed information on the concentrations of different pollutants. The central unit analyzes the data that are captured by the sensor and checks whether the quality of air meets the atmospheric standards. If the sensed levels of pollutants exceed the thresholds, then the system present in the UAV triggers a warning alert; this alert is communicated to local authorities and the public to take necessary precautions. The developed UAV is furnished with cameras which are used to capture real-time images of the environment and it is processed using the YOLO V3 algorithm. Here, the YOLO V3 algorithm is defined to identify the context and source of pollution, such as identifying industrial activities, traffic congestion, or natural sources like wildfires. Full article

The development of sustainable waste management for environmental remediation has highlighted the potential of biochar produced from agricultural wastes as an effective adsorbent for gas pollutant capture. This work focuses on the production and activation of biochar derived from pistachio shells for CO₂ and H₂S adsorption. Adsorbents were obtained by pyrolysis and subsequently activated through two methods: chemical activation with KOH and physical activation with CO₂. Adsorption studies were conducted to evaluate the influence of these activation methods on textural properties and adsorption capacities. Chemical activation enhanced microporosity and increased the specific surface area (531 m²/g), resulting in a better performance, obtaining adsorption capacities of 87 mgCO₂/g_adsorbent and 9.6 mgH₂S/g_adsorbent. Non-linear kinetic models were identified as the most suitable for fitting CO₂ adsorption data, with the Avrami model presenting the best fit results. Dynamic H₂S adsorption tests revealed the influence of moisture present in the adsorbent, favoring H₂S dissociation and thus improving capture processes, especially when chemical activation biochar is employed. This enhancement is attributed to the greater development of active centers on its surface, including micropores and heterogeneous atoms introduced though impregnation. Full article

The gas sweetening process is essential for removing harmful acid gases, such as hydrogen sulfide (H₂S) and carbon dioxide (CO₂), from natural gas before delivery to end-users. Consequently, chemical absorption-based acid gas removal units (AGRUs) are widely implemented due to their high efficiency and reliability. The most common solvent used in AGRU is monodiethanolamine (MDEA), often mixed with piperazine (PZ) as an additive to accelerate acid gas capture. The absorption performance, however, is significantly influenced by the solvent mixture composition. Despite this, solvent composition is often determined through trial and error in experiments or simulations, with limited studies focusing on predictive methods for optimizing solvent mixtures. Therefore, this paper aims to develop a predictive technique for determining optimal solvent compositions under varying sour gas conditions. An ensemble algorithm, Extreme Gradient Boosting (XGBoost), is selected to develop two predictive models. The first model predicts H₂S and CO₂ concentrations, while the second model predicts the MDEA and PZ compositions. The results demonstrate that XGBoost outperforms other algorithms in both models. It achieves R² values above 0.99 in most scenarios, and the lowest RMSE and MAE values of less than 1, indicating robust and consistent predictions. The predicted acid gas concentrations and solvent compositions were further analyzed to study the effects of solvent composition on acid gas absorption across different scenarios. The proposed models offer valuable insights for optimizing solvent compositions to enhance AGRU performance in industrial applications. Full article

Hydrogen sulfide is present in active or extinct volcanic areas (mofettas). The habitable premises in these areas are affected by the presence of hydrogen sulfide, which, even in low concentrations, gives off a bad to unbearable smell. If the living spaces considered are closed enclosures, then a system can be designed to reduce the concentration of hydrogen sulfide. This paper presents a membrane-based way to reduce the hydrogen sulfide concentration to acceptable limits using a cellulosic derivative–propylene hollow fiber-based composite membrane module. The cellulosic derivatives considered were: carboxymethyl–cellulose (NaCMC), P1; cellulose acetate (CA), P2; methyl 2–hydroxyethyl–cellulose (MHEC), P3; and hydroxyethyl–cellulose (HEC), P4. In the permeation module, hydrogen sulfide is captured with a solution of cadmium that forms cadmium sulfide, usable as a luminescent substance. The composite membranes were characterized by SEM, EDAX, FTIR, FTIR 2D maps, thermal analysis (TG and DSC), and from the perspective of hydrogen sulfide air removal performance. To determine the process performances, the variables were as follows: the nature of the cellulosic derivative–polypropylene hollow fiber composite membrane, the concentration of hydrogen sulfide in the polluted air, the flow rate of polluted air, and the pH of the cadmium nitrate solution. The pertraction efficiency was highest for the sodium carboxymethyl–cellulose (NaCMC)–polypropylene hollow fiber membrane, with a hydrogen sulfide concentration in the polluted air of 20 ppm, a polluted air flow rate (Q_H2S) of 50 L/min, and a pH of 2 and 4. The hydrogen sulfide flux rates, for membrane P1, fall between 0.25 × 10⁻⁷ mol·m²·s⁻¹ for the values of Q_H2S = 150 L/min, C_H2S = 20 ppm, and pH = 2 and 0.67 × 10⁻⁷ mol·m⁻²·s⁻¹ for the values of Q_H2S = 50 L/min, C_H2S = 60 ppm, and pH = 2. The paper proposes a simple air purification system containing hydrogen sulfide, using a module with composite cellulosic derivative–polypropylene hollow fiber membranes. Full article

Temperature and humidity, along with concentrations of ammonia and hydrogen sulfide, are critical environmental factors that significantly influence the growth and health of pigs within porcine habitats. The ability to accurately predict these environmental variables in pig houses is pivotal, as it provides crucial decision-making support for the precise and targeted regulation of the internal environmental conditions. This approach ensures an optimal living environment, essential for the well-being and healthy development of the pigs. The existing methodologies for forecasting environmental factors in pig houses are currently hampered by issues of low predictive accuracy and significant fluctuations in environmental conditions. To address these challenges in this study, a hybrid model incorporating the improved dung beetle algorithm (DBO), temporal convolutional networks (TCNs), and gated recurrent units (GRUs) is proposed for the prediction and optimization of environmental factors in pig barns. The model enhances the global search capability of DBO by introducing the Osprey Eagle optimization algorithm (OOA). The hybrid model uses the optimization capability of DBO to initially fit the time-series data of environmental factors, and subsequently combines the long-term dependence capture capability of TCNs and the non-linear sequence processing capability of GRUs to accurately predict the residuals of the DBO fit. In the prediction of ammonia concentration, the OTDBO–TCN–GRU model shows excellent performance with mean absolute error (MAE), mean square error (MSE), and coefficient of determination (R²) of 0.0474, 0.0039, and 0.9871, respectively. Compared with the DBO–TCN–GRU model, OTDBO–TCN–GRU achieves significant reductions of 37.2% and 66.7% in MAE and MSE, respectively, while the R² value is improved by 2.5%. Compared with the OOA model, the OTDBO–TCN–GRU achieved 48.7% and 74.2% reductions in the MAE and MSE metrics, respectively, while the R² value improved by 3.6%. In addition, the improved OTDBO–TCN–GRU model has a prediction error of less than 0.3 mg/m³ for environmental gases compared with other algorithms, and has less influence on sudden environmental changes, which shows the robustness and adaptability of the model for environmental prediction. Therefore, the OTDBO–TCN–GRU model, as proposed in this study, optimizes the predictive performance of environmental factor time series and offers substantial decision support for environmental control in pig houses. Full article

Climate change and environmental degradation pose a threat to Europe and the world. The mechanism that will address these challenges is the European Green Deal, which envisions transforming the EU into a modern, resourceful, economical and competitive economy, aiming for zero greenhouse gas emissions. Landfill gas generated in a landfill waste deposit poses a threat to the environment and people. In this aspect, its capture, treatment and safe neutralization or use for energy purposes are important. Treatment of landfill gas, which is the fuel for gas engines in cogeneration units, is crucial for their proper operation and the quantity and quality of electricity and heat generated. The purpose of this study was to perform research to determine the hydrogen sulfide content of landfill gas and the actual efficiency of hydrogen sulfide removal from the gas using activated carbon. The tests performed constitute the basis for the reliable operation of gas engines in cogeneration installations and are dedicated mainly to the operators of these installations. Accordingly, three measurement campaigns were carried out, each with 42 measurements, the first for the “raw” gas obtained directly from the landfill, the second for the gas before entering the carbon filter and the third after its treatment. In addition, surface analysis was performed, and the elemental composition of the “fresh” molded activated carbon constituting the filter material was determined using a scanning electron microscope with an EDS system. The results showed a high elemental content of carbon in the test sample at 92.78%, while the efficiency of hydrogen sulfide removal from landfill gas by activated carbon, calculated from the measurements, was 97.05%. The obtained test results confirmed the validity of using impregnated activated carbon to remove hydrogen sulfide from landfill gas and its high adsorption efficiency, which can consequently result in reliable operation of the gas engine in the cogeneration unit and ultimately fit in with the objectives of the European Green Deal. The research results are an incentive for operators of cogeneration installations to systematically examine the quality of landfill gas and the efficiency of biogas purification devices. Full article

The article is devoted to the issues of the utilization of hydrogen-containing gas wastes in oil refining deep processing. Gas wastes consist of hydrogen, methane, ethane, propane, butane, other saturated and unsaturated C5-C7 hydrocarbons, sulfur compounds, carbon monoxide, carbon dioxide, nitrogen and oxygen. The use of a hybrid power plant for efficient conversion of the potential energy of the gas mixture into electrical and thermal energy is proposed. It is shown that gas waste from oil production has a net calorific value comparable to the calorific value of natural gas (46 and 49 MJ/kg, respectively). Fuel gas is a valuable product that can be used after desulfurization instead of burning in the atmosphere. The article proposes the developed composition of the adsorbent for hydrogen sulfide capturing, including 40% wt. bentonite, 40% wt. calcium oxide, 10% wt. zinc oxide and 10% wt. manganese oxide. The capture rate was 98.3%. A comparison of various types of fuel for a hybrid power plant with a high-temperature fuel cell and an assessment of the efficiency of using gas waste from oil refineries was carried out. It is shown that fuel gas from oil production waste has a high potential for use in power plants due to its high calorific value and a number of other advantages compared to natural gas. Full article

Production of renewable fuels from gasification is based on catalytic processes. Deep desulfurization is required to avoid the poisoning of the catalysts. It means the removal of H₂S but also of organic sulfur species. Conventional cleaning consists of a several-step complex approach comprising catalytic hydro-treating followed by H₂S removal. In this work, a single-stage process using a zinc and nickel oxide sorbent has been investigated for the removal of organic sulfur species present in syngas. The process is called reactive adsorption and comes from the refinery industry. The challenge investigated by CIEMAT was to prove for the first time that the concept is also valid for syngas. We have studied the process at a lab scale. Thiophene and benzothiophene, two of the main syngas organic sulfur compounds, were selected as target species to remove. The experimental study comprised the analysis of the effect of temperature (250–450 °C), pressure (1–10 bar), space velocity (2000–3500 h⁻¹), tar components (toluene), sulfur species (H₂S), and syngas components (H₂, CO, and full syngas CO/CO₂/CH₄/H₂). Operating conditions for removal of thiophene and benzothiophene were determined. Increasing pressure and temperature had a positive effect, and full conversion was achieved at 450 °C, 10 bar and 3500 h⁻¹, accompanied by simultaneous hydrogen sulfide capture by the sorbent in accordance with the reactive adsorption desulfurization (RADS) process. Space velocity and hydrogen content in the syngas had little effect on desulfurization. Thiophene conversions from 39% to 75% were obtained when feeding synthetic syngas mimicking different compositions, spanning from air to steam-oxygen-blown gasification. Toluene, as a model tar component present in syngas, did not strongly affect the removal of thiophene and benzothiophene. H₂S inhibited their conversion, falling, respectively, to 2% and 69% at 350 °C and 30% and 80% at 400 °C under full syngas blends. Full article

The treatment of gaseous contaminants, such as hydrogen sulfide (H₂S), is often carried out with adsorbent materials that are disposed of after saturation. The reuse of such materials promotes sustainability and the reduction in unnecessary waste. Granular activated carbon (GAC) is a well-known adsorbent used to capture gaseous H₂S which can be reused. It is hypothesized that it can also concentrate contaminants for future treatment, thereby reducing secondary treatment costs. Cyclic adsorption/desorption experiments were completed with samples of GAC to investigate the feasibility of implementing the concept of repeated H₂S adsorption/desorption in the construction of a pilot odor control device. A column filled with GAC was exposed to a stream of H₂S gas and then heated to 500 °C to regenerate the carbon. The concentration of H₂S at the inlet and outlet of the column was measured at regular intervals. Three samples of GAC had an average adsorption efficiency of 82% over the course of three cycles and were regenerated to 70% of initial adsorptive capacity after one cycle, and 60% after two cycles. These results indicate that after being saturated with H₂S, GAC can be regenerated at high temperatures, evidence that H₂S may become concentrated during the process. Additional characterization experiments confirmed that the sulfur content of the carbon increased after adsorption and decreased after thermal regeneration. The procedures demonstrated in this experiment were further utilized with a pilot device designed to provide a low-cost method for reducing odors in landfill gas. Full article

This paper presents the preparation and characterization of composite membranes based on chitosan (Chi), sulfonated ethylene–propylene–diene terpolymer (sEPDM), and polypropylene (PPy), and designed to capture hydrogen sulfide. The Chi/sEPDM/PPy composite membranes were prepared through controlled evaporation of a toluene dispersion layer of Chi:sEPDM 1;1, w/w, deposited by immersion and under a slight vacuum (100 mmHg) on a PPy hollow fiber support. The composite membranes were characterized morphologically, structurally, and thermally, but also from the point of view of their performance in the process of hydrogen sulfide sequestration in an acidic media solution with metallic ion content (Cu²⁺, Cd²⁺, Pb²⁺, and/or Zn²⁺). The operational parameters of the pertraction were the pH, pM, matrix gas flow rate, and composition. The results of pertraction from synthetic gases mixture (nitrogen, methane, carbon dioxide) indicated an efficient removal of hydrogen sulfide through the prepared composite membranes, as well as its immobilization as sulfides. The sequestration and the recuperative separation, as sulfides from an acid medium, of the hydrogen sulfide reached up to 96%, decreasing in the order: CuS > PbS > CdS > ZnS. Full article

An energy production system that combines biomass and fuel cells produces much energy with minimal environmental impact. However, the hydrogen sulfide (H₂S) contained in gasified biomass degrades fuel cell performance, thus negating the advantages of this combination. In this study, the removal of H₂S by adsorption after biomass gasification was investigated. Metal oxides with high adsorption performance are common H₂S adsorbents. However, they have a significant environmental impact in terms of metal depletion, which is an environmental impact indicator. Therefore, neutralized sediment materials from mine drainage treatments can be used as H₂S adsorbents. A previous study found that the adsorption performance of H₂S adsorbents is equivalent to that of metal oxides, especially in the high-temperature zone (300 °C), and the environmental impact is considerably lower than that of metal oxides. However, because the neutralized sediment is a powder (Φ 4.5 μm on average), there is a possibility that the gas will not flow due to the pressure drop when it is used in a large adsorption column. Therefore, in this study, we propose the use of granulated neutralized sediments for practical plant operations. No studies have investigated the adsorption performance of granulated neutralized sediment through experiments or quantitatively investigated the effect of using waste material as a H₂S adsorbent to reduce the environmental impact of hydrogen production. Based on these data, the sulfur capture capacity of the granulated neutralized sediment was experimentally investigated. The extent to which the environmental impact of the hydrogen production system could be reduced when granulated neutralized sediment was used as the H₂S adsorbent was assessed. Note that the granulated neutralized sediment is formed with about a Φ 0.56–1.25 mm diameter. The granulated neutralized sediment exhibited approximately 76.8% of the adsorption performance of zinc oxide (ZnO) on a conventional adsorbent. In terms of the LCA, the global warming potential (GWP) and the abiotic depletion potential (ADP) were improved by approximately 0.89% (GWP) and 55.3% (ADP) in the entire hydrogen production process. This study demonstrated that the use of waste materials can significantly reduce the environmental impact on the entire system. Full article

Hydrogen sulfide is a toxic and corrosive gas; thus, in order to mitigate its environmental impact, its capture and removal from various emitting sources, natural and anthropogenic, is of a necessity. In this work, recent advances (2020–2022) proposed by a series of investigations are reviewed. Adsorption using metal-oxide-based adsorbents appeared to be the most popular technology, whereas solvent absorption is used to co-absorb both toxic H₂S and CO₂. The uses of the various membrane technologies for H₂S removal are also described. Full article

Recirculating aquaculture systems (RAS) are efficient at solid waste capture and collection but generate a concentrated waste stream. Anaerobic digestion (AD) could be one potential treatment option for RAS facilities. However, the concentration of organic matter in the sludge can significantly affect the biogas quality from AD. This study evaluated the effect of fish sludge (FS) solid concentration on biogas quality. Three FS treatments consisted of different initial total solid concentrations (1.5%, 2.5%, and 3.5%) from a mixture of sludge produced by Atlantic salmon (Salmo salar) and rainbow trout (Oncorhynchus mykiss). Methane (CH₄) production was measured, quantified, and normalized on a volatile solids (VS) basis. The highest solid concentration treatment produced 23% more CH₄ than the lowest solid concentration (519 mL/g VS versus 422 mL/g VS, respectively). Peak CH₄ production occurred on Day 7 for the lowest FS concentration (78.2 mL/day), while the highest FS concentration peaked on Day 11 (96 mL/day). Peak hydrogen sulfide (H₂S) concentrations ranged from 1803–2074 ppm across treatments, signifying the requirement of downstream unit processes for H₂S removal from biogas. Overall, this study demonstrated that increasing the FS concentration can significantly enhance CH₄ production without affecting the stability of the digestion process. Full article

Metal-based adsorbents with varying active phase loadings were synthesized to capture hydrogen sulfide (H₂S) from a biogas mimic system. The adsorption–desorption cycles were implemented to ascertain the H₂S captured. All prepared adsorbents were evaluated by nitrogen adsorption, Brunauer–Emmett–Teller surface area analysis, scanning electron microscopy–energy-dispersive X-ray spectroscopy, and Fourier transform infrared spectroscopy. From the results, modified adsorbents, dual chemical mixture (DCM) and a core–shell (CS) had the highest H₂S adsorption performance with a range of 0.92–1.80 mg H₂S/g. After several cycles of heat/N₂ regeneration, the total H₂S adsorption capacity of the DCM adsorbent decreased by 62.1%, whereas the CS adsorbent decreased by only 25%. Meanwhile, the proposed behavioral model for H₂S adsorption–desorption was validated effectively using various analyses throughout the three cycles of adsorption–desorption samples. Moreover, as in this case, the ZnAc₂/ZnO/CAC_OS adsorbents show outstanding performances with 30 cycles of adsorption–desorption compared to only 12 cycles of ZnAc₂/ZnO/CAC_DCM. Thus, this research paper will provide fresh insights into adsorption–desorption behavior through the best adsorbents’ development and the adsorbents’ capability at the highest number of adsorption–desorption cycles. Full article

This study reports on the synthesis of bi-metal compound (BMC) adsorbents based on commercial coconut activated carbon (CAC), surface-modified with metal acetate (ZnAc₂), metal oxide (ZnO), and the basic compounds potassium hydroxide (KOH) and sodium hydroxide (NaOH). The adsorbents were then characterized by scanning electron microscopy and elemental analysis, microporosity analysis through Brunauer–Emmett–Teller (BET) analysis, and thermal stability via thermogravimetric analysis. Adsorption–desorption test was conducted to determine the adsorption capacity of H₂S via 1 L adsorber and 1000 ppm H₂S balanced 49.95% for N₂ and CO₂. Characterization results revealed that the impregnated solution homogeneously covered the adsorbent surface, morphology, and properties. The adsorption test result reveals that the ZnAc₂/ZnO/CAC_B had a higher H₂S breakthrough adsorption capacity and performed at larger than 90% capability compared with a single modified adsorbent (ZnAc₂/CAC). Therefore, the synthesized BMC adsorbents have a high H₂S loading, and the abundance and low cost of CAC may lead to favorable adsorbents in H₂S captured. Full article