Continuous Flow System Research Articles

Continuous-flow degradation of Orange I using CoFe2O4-loaded activated carbon catalyst: Optimization of reaction parameters and toxicity prediction

Orange I (OI) azo dyes produce toxic aromatic compounds in water, making solutions an important issue. In this study, we employed the urea combustion method to load CoFe2O4 particles onto activated carbon (CFO-AC-500). Subsequently, the catalyst was incorporated into a column continuous flow device, testing the effects of multi water parameters and toxicity, and predicting the degradation process on the catalytic degradation of OI for peroxymonosulfate (PMS) activation. In CFO-AC-500/PMS continuous reactor, it showed a satisfied OI removal of more than 82 % of the OI at a flow rate of 73.6 mL/min in 240 min. Also, response surface methodology (RSM) was employed to optimize the operating conditions, with model fitting results demonstrating that the OI removal rate could reach 95.07 % under specific conditions. ESR analyses revealed that the degradation of OI was primarily governed by free radicals (SO4•-, HO• and O2•-) and non-radical pathways (1O2). The biological toxicity of degraded OI was significantly reduced. This innovative CFO-AC-500/PMS continuous flow system can provide an effective new method for the degradation of difficult-to-treat pollutants in practical applications.

Intermittent Flow Control Schemes for Heat Stress Mitigation in Lactating Sows on a Floor Cooling Pad

The Purdue hog cooling pad has previously been demonstrated to mitigate heat stress in lactating sows by conductively transferring heat from a sow to cool water running through an integral heat exchanger. Coolant effectiveness, which describes how much heat is removed per volume of water flushed through the cooling pad, is used to compare the operation under varying conditions. Past studies have indicated that the intermittent flow of cooling water achieves a greater coolant effectiveness than continuous flow operational schemes. An electronic control system was implemented with the current cooling pad design to allow for the automated control of a solenoid valve to create the intermittent flow conditions. All testing was performed using 18 ± 1 °C inlet water. Potential control schemes were categorized into two groups, temporal and temperature threshold. The temporal schemes opened the solenoid for 30 s, enough time to flush the entire contents of the cooling coils, before closing for 3, 6, or 9 min. The temperature threshold control schemes utilized feedback from thermal probes embedded beneath the surface of the cooling pad to open the solenoid for 30 s, when a maximum surface temperature was detected. Trigger temperatures of 28.0, 29.5, or 31.0 °C were used. The temperature threshold control schemes achieved greater heat transfer rates (348, 383, 268 W) compared to the temporal control schemes (324, 128, 84 W). The cooling effectiveness for all control schemes ranged from 46.6 to 64.7 kJ/L. The tested intermittent flow control schemes in this study achieved greater cooling effectiveness than continuous flow systems from previous studies (time: 51 kJ/L; temperature: 61 kJ/L; steady: 5.8 kJ/L), although the temporal control schemes exhibited lower heat transfer rates (time: 180 W; temperature: 330 W; steady: 305 W).

Toxicity of crude oil: a systematic review of the acute impacts on Cnidaria

Cnidarians are ecosystem engineers that play a fundamental role in food webs. However, they are increasingly threatened by anthropogenic activities, such as oil spills, which can cause acute sublethal effects and in some cases, mortality. The literature on this theme is limited and fragmented, with diverse objectives and methodologies, making it challenging to identify consistent patterns and knowledge gaps. This article aims to provide a systematic review of the acute impacts of crude oil and petroleum hydrocarbons on members of the Phylum Cnidaria, to synthesize and integrate the available data. The research followed the PRISMA 2020 guidelines, and employed the search terms: “crude oil” AND “acute” AND (Cnidaria OR coral), along with the names of each Cnidarian class. The search was restricted to articles published in English from 2013 to 2023, excluding studies that did not directly address the core topic. The number of records collected was relatively low, with only 30 articles identified from 20 studies. The highest number of publications occurred in 2022, and the USA was the most represented country. The Class Anthozoa, particularly corals (Order Scleractinia) was the most studied. Research focused on the effects of crude oil on gametes, embryos, larvae and adults, with most studies examining adult organisms. The majority (56.6%), utilized mixtures of crude oil hydrocarbons, while a smaller proportion (36.6%) focused on pure aromatic hydrocarbons. Most experiments employed Water Accommodated Fractions (36.6%) and continuous flow system (20%). The most common exposure durations (30%) were 96 and 48h, with exposure times ranging from 18h to several days. There was significant variation in methodological approaches, underscoring the need for standardized protocols. Research on adult cnidarians primarily assessed health and morphology, lethality, genetic alterations, and symbiont efficiency. In contrast, studies on early life stages focused on lethality, larval metamorphosis and settlement. Overall, the results indicate that responses vary considerably, particularly concerning exposure time and oil concentration, with sublethal effects at different levels. Further studies incorporating a broader range of species, novel approaches, and the combined effects of elevated temperature and UV radiation are crucial to advancing our understanding of oil impacts on cnidarians.

Immobilization and Kinetic Properties of ß-N-Acetylhexosaminidase from Penicillium oxalicum

The application of immobilized enzymes often plays a key role in successfully implementing an economically feasible biocatalytic process at an industrial scale. Designing an immobilized biocatalyst involves solving several tasks, from the selection of the carrier and immobilization method to the characterization of the kinetic properties of the immobilized enzyme. In this study, we focused on the kinetic properties of free and immobilized ß-N-acetylhexosaminidase (Hex), a promising enzyme for application in the field of biotechnology, especially for the synthesis of bioactive carbohydrates. Hex was immobilized via covalent binding in methacrylate particles. The effect of immobilizing Hex from Penicillium oxalicum into porous particles on kinetic properties was investigated, and mathematical and experimental modeling showed that the kinetic behavior of the enzyme was significantly influenced by diffusion in the particles. Along with the study on kinetics, a simple method was developed to investigate the reversible inhibition of the immobilized enzyme in a continuous-flow system. The method is suitable for application in cases where a chromogenic substrate is used, and here it was applied to demonstrate the inhibitory effects of N-acetyl-glucosaminyl thiazoline (NAG-thiazoline) and O-(2-Acetamido-2-deoxy-D-glucopyranosylidene)amino N-phenyl carbamate ((Z)-PugNAc) on Hex.

Speech-mediated manipulation of da Vinci surgical system for continuous surgical flow

AbstractWith the advent of robot-assisted surgery, user-friendly technologies have been applied to the da Vinci surgical system (dVSS), and their efficacy has been validated in worldwide surgical fields. However, further improvements are required to the traditional manipulation methods, which cannot control an endoscope and surgical instruments simultaneously. This study proposes a speech recognition control interface (SRCI) for controlling the endoscope via speech commands while manipulating surgical instruments to replace the traditional method. The usability-focused comparisons of the newly proposed SRCI-based and the traditional manipulation method were conducted based on ISO 9241-11. 20 surgeons and 18 novices evaluated both manipulation methods through the line tracking task (LTT) and sea spike pod task (SSPT). After the tasks, they responded to the globally reliable questionnaires: after-scenario questionnaire (ASQ), system usability scale (SUS), and NASA task load index (TLX). The completion times in the LTT and SSPT using the proposed method were 44.72% and 26.59% respectively less than the traditional method, which shows statistically significant differences (p < 0.001). The overall results of ASQ, SUS, and NASA TLX were positive for the proposed method, especially substantial reductions in the workloads such as physical demands and efforts (p < 0.05). The proposed speech-mediated method can be a candidate suitable for the simultaneous manipulation of an endoscope and surgical instruments in dVSS-used robotic surgery. Therefore, it can replace the traditional method when controlling the endoscope while manipulating the surgical instruments, which contributes to enabling the continuous surgical flow in operations consequentially.

Influence of Biofloc Technology and Continuous Flow Systems on Aquatic Microbiota and Water Quality in Japanese Eel Aquaculture

Biofloc technology (BFT) systems heavily rely on microbiota to mitigate ammonia toxicity and manage essential nutrient cycling. Understanding the diversity and functional role of microbiota within BFT-applied aquaculture systems is crucial for ensuring sustainable operations. Though some studies exist on BFT microbiota, research on microbial differences in Japanese eel aquaculture is still limited, hindering the wider application of BFT systems. In this study, we analyzed the characteristics of water quality factors and microbiota in Japanese eel (Anguilla japonica) breeding water, applying the BFT system. Using a metabarcoding approach, the diversity and community structure of aquatic microbiota were compared between BFT and continuous flow (CF) systems. The pH was significantly higher in CF water, while total ammonia nitrogen (TAN) and nitrite (NO2−-N) was higher in BFT water. Alpha diversity was significantly higher in BFT compared to CF systems, and it was correlated significantly with pH and TAN. In both BFT and CF water, the phyla Proteobacteria and Bacteroidota were found to be the most abundant. In the BFT water, a diverse array of bacterial taxa, including BFT-specific clades, were consistently present, while the microbiota in CF water was more variable and contained fewer specific taxa. In addition, bacterial functions related to nitrate reduction, sulfur compound oxidation, and chitinolysis were significantly more abundant in BFT than in CF systems. These findings highlight differences in water quality and microbiota between aquaculture systems, which can inform future research on the use of BFT for sustainable fish farming.

Photosensitizer-Free Benzo[1,4]oxazin-2-one Synthesis by Continuous-Flow Photochemistry.

We report a photosynthetic method for producing 2H-benzo[b][1,4]oxazin-2-ones from aryl azides and α-ketoacids. This method is highly sustainable, requiring only visible light irradiation of the substrates and no external additives. Furthermore, we implemented a continuous-flow system to achieve efficient light irradiation and rapid mixing, significantly improving reaction efficiency and reducing reaction time compared to the batch process. The flow system enabled gram-scale synthesis. We also demonstrated the utility of the products, by employing the benzo[1,4]oxazin-2-one moiety as a directing group for C-H activation on the 3-aryl substituent. This green approach highlights the potential for developing environmentally friendly synthetic processes.

Fibrous catalyst based on atomic Pd and N-doped holey graphene functionalized cotton fiber for continuous-flow reaction

Continuous-flow catalysis bridges the gap between bench-scale laboratories and production-scale factories and thus should be a green and promising technology for the manufacture of value-added chemicals. Here, we present the construction of a continuous-flow catalytic system by integrating a tubular reactor with novel catalytic fibers, which are comprised of single-atomic Pd (Pd1) and nitrogen-doped holey graphene (NHG) functionalized cotton fibers (CFs). Due to the loosely packed structure, highly exposed dual-active sites (i.e., single-atomic PdN4 sites and activated C sites in the NHG carbocatalyst) of the CF@(Pd1/NHG) catalytic fibers, the corresponding flowing system exhibites remarkably high catalytic performance (activity and durability) and processing rate in organic reactions, including oxidative hydroxylation of phenylboronic acid and reduction of nitroarenes. Typically, the processing rate of the catalytic system toward 4-nitrophenol (a representative nitroarene) reduction can reach up to 2.46 × 10−3 mmol·mg−1·min−1, significantly higher than that of those packing catalysts reported in recent years.

Dehydration of turbine engine lubricant oil using cellulose hydrogel

Contamination of oils by water is a recurring problem in the industry and can damage engines and equipment. Oil dehydration systems with hydrogels have shown promise for the removal of free, soluble, and emulsified water. This work evaluates, in an unprecedented way, the dehydration of turbine lubricating oil using a cellulose hydrogel. The synthesis of the hydrogel was confirmed by the formation of specific functional groups. The hydrogel was characterized through high-resolution SEM, EDS, FTIR, BET, TGA, DVS and swelling degree. The oil was evaluated regarding its composition and physicochemical properties. The performance of the hydrogel in the treatment of water-in-oil emulsion was analyzed in batch and continuous flow systems. A fixed bed apparatus was specially designed and sized according to the industry's specifications to simulate on-site application. The batch treatment was evaluated using orbital and full tumbling inversion mixing systems, both reaching removal efficiency of around 47 %. Mixing by full tumbling allowed greater stability of the emulsion and control of the water concentration, but it required a longer time to enable adequate water uptake by the hydrogel. The efficiency of the hydrogel in the continuous flow system was affected by retention time and inlet water concentration. With a retention time of 12 min, it was possible to treat 1 L of oil, reducing the water concentration from 412 ppm to 197 ppm and the turbidity from Haze 6 to Haze 1. Thus, the cellulose hydrogel was efficient in dehydrating turbine lubricating oil, opening up the possibility of expanding its use to industrial facilities.

Polynomial chaos expansions on principal geodesic Grassmannian submanifolds for surrogate modeling and uncertainty quantification

In this work we introduce a manifold learning-based surrogate modeling framework for uncertainty quantification in high-dimensional stochastic systems. Our first goal is to perform data mining on the available simulation data to identify a set of low-dimensional (latent) descriptors that efficiently parameterize the response of the high-dimensional computational model. To this end, we employ Principal Geodesic Analysis on the Grassmann manifold of the response to identify a set of disjoint principal geodesic submanifolds, of possibly different dimension, that captures the variation in the data. Since operations on the Grassmann require the data to be concentrated, we propose an adaptive algorithm based on Riemannian K-means and the minimization of the sample Fréchet variance on the Grassmann manifold to identify “local” principal geodesic submanifolds that represent different system behavior across the parameter space. Polynomial chaos expansion is then used to construct a mapping between the random input parameters and the projection of the response on these local principal geodesic submanifolds. The method is demonstrated on four test cases, a toy-example that involves points on a hypersphere, a Lotka-Volterra dynamical system, a continuous-flow stirred-tank chemical reactor system, and a two-dimensional Rayleigh-Bénard convection problem.

Controlling the optoelectronic properties of nitrogen-doped carbon quantum dots using biomass-derived precursors in a continuous flow system

The synthesis of carbon quantum dots (CQDs) from high molecular weight biomass-derived precursors poses a significant challenge due to the complex molecular structures and low conversion efficiency. This work demonstrates a green, rapid, and sustainable continuous hydrothermal flow synthesis (CHFS) approach for nitrogen-doped carbon quantum dots (NCQDs) from various biomass-derived precursors, including high molecular weight polymeric sources like chitosan, lignin, and humic acid. We find that the precursor structure significantly impacts the size of the fabricated NCQDs and their optical properties. Citric acid, a low molecular weight precursor, yields NCQDs with excitation-independent emission, higher quantum yields, and low non-radiative losses, while NCQDs derived from polymeric precursors exhibit excitation-dependent, red-shifted, and lower efficiency emission. Theoretical calculations, performed to understand the configuration and distribution of nitrogen dopants within the NCQD structure, show that pyridinic and graphitic nitrogen atoms exhibit a strong preference to aggregate near the centre of the edge of the NCQD and not in the vertices nor in the graphitic core, thus affecting the HOMO and LUMO, bandgap, and light absorption and emission wavelengths. The life cycle assessment (LCA) analysis highlights the green and scalable advantages of the CHFS process for producing NCQDs compared to batch methods, making it a sustainable and economically viable approach for large-scale NCQD synthesis from high molecular weight biomass-derived precursors. Hence, the combination of experimental data and theoretical calculations provides a comprehensive understanding of the structure-property relationships in these NCQDs.

Electrochemical Nitrate Reduction to Ammonia on AuCu Single-atom Alloy Aerogels under Wide Potential Window.

Electrocatalytic nitrate reduction to ammonia (NO3RR) is very attractive for nitrate removal and ammonia production in industrial processes. However, the nitrate reduction reaction is characterized by intense hydrogen competition at strong reduction potentials, which greatly limits the Faraday efficiency at strong reduction potentials. Herein, we reported an AuxCu single-atom alloy aerogels (AuxCu SAAs) with three-dimensional network structure with significant nitrate reduction performance of Faraday efficiency (FE) higher than 90% over a wide potential range (0 ~ -1 VRHE). The FE of the catalyst was close to 100% at a high reduction potential of -0.8 VRHE, accompanying with NH3 yield reaching 6.21 mmol h-1 cm-2. More importantly, the catalyst maintained a long-term operation over 400 h at 400 mA cm-2 for the NO3RR using a continuous flow system in a H-cell. Experimental and theoretical analysis demonstrate that the catalyst can lower the energy barrier for the hydrogenation reaction of *NO2, leading to a rapid consumption of the generated *H, facilitate the hydrogenation process of NO3RR, and inhibit the competitive HER at high overpotentials, which efficiently promotes the nitrate reduction reaction, especially in industrial applications.

Monometallic/Bimetallic Co‐ZIFs Synthesis, Characterization, and Application for Adsorption of SO2 and CO2 in Continuous Flow System

Monometallic/Bimetallic Co‐ZIFs Synthesis, Characterization, and Application for Adsorption of SO₂ and CO₂ in Continuous Flow System

A High-Performance Microwave Heating Device Based on a Coaxial Structure

Continuous-flow microwave heating stands out for its ability to rapidly and uniformly heat substances, making it widely applicable in chemical production. However, in practical applications, the permittivity of the heated liquid changes dramatically as the reaction progresses, affecting the efficiency and uniformity of continuous-flow heating. Herein, this work presents a novel microwave heating device based on a coaxial structure for high-performance heating. Our approach commenced with the development of a multiphysical field model, incorporating spiraled polytetrafluoroethylene (PTFE) as a water channel and the coaxial waveguide as a container. The analysis shows that the uniform distribution of the sectional electric field of electromagnetic waves in the TEM mode within the coaxial structure can enhance heating uniformity. Then, a continuous-flow microwave heating system for different liquid loads was established, and experimental measurements were conducted. The heating efficiency for all loads exceeded 90%, which basely matched the simulation results, validating the accuracy of the model. Finally, the heating efficiency and uniformity under different permittivity loads were analyzed, as well as the impact of channel radius on heating efficiency. The device exhibits high heating efficiency under different loads, with uniform radial electric field distribution and stable heating uniformity. This continuous-flow microwave device is suitable for chemical research and production because of its high adaptability to the large dynamic range of permittivity, contributing to the promotion of microwave energy applications in the chemical industry.

Magnetic Hydrogel Microbots for Efficient Pollutant Decontamination and Self-Catalyzed Regeneration in Continuous Flow Systems.

The efficient removal of organic pollutants from water is crucial for protecting human health and the ecosystem. While adsorbent-based approaches offer advantages over traditional chemical and thermal methods, they still suffer from slow adsorption kinetics, high energy demand, and limited material lifespan. Herein, an efficient decontamination platform is introduced, using magnetic hydrogel microbots (MHMs) made from picolitre-sized hydrogel droplets coated with multifunctional magnetic nanoparticles. This approach includes 1) dividing a droplet into smaller microbots to enhance their interaction with sample solution and 2) dynamically spinning these MHMs to generate hydrodynamic flows that actively draw pollutants toward the embedded hydrogel for capture. The MHMs show high decontamination effectiveness in both bulk and continuous flow setups, achieving ≈95% removal efficiency within 3min. Further integrating MHMs with a non-pressurized fluidic platform enables energy-efficient continuous flow decontamination, removing ≥95% total organic carbon from a complex pollutant mixture at a flow rate surpassing other recent designs. Additionally, the MHMs facilitate self-catalyzed regeneration using an environmentally friendly H2O2 precursor, allowing for long-term and repeated usage. By enabling the unique divide-and-arrest decontamination of toxic pollutants, the multifunctional design holds tremendous promise for on-site wastewater treatment to ensure safe water access for everyone, even in resource-limited environments.

H2-driven biocatalysis for flavin-dependent ene-reduction in a continuous closed-loop flow system utilizing H2 from water electrolysis

Despite the increasing demand for efficient and sustainable chemical processes, the development of scalable systems using biocatalysis for fine chemical production remains a significant challenge. We have developed a scalable flow system using immobilized enzymes to facilitate flavin-dependent biocatalysis, targeting as a proof-of-concept asymmetric alkene reduction. The system integrates a flavin-dependent Old Yellow Enzyme (OYE) and a soluble hydrogenase to enable H2-driven regeneration of the OYE cofactor FMNH2. Molecular hydrogen was produced by water electrolysis using a proton exchange membrane (PEM) electrolyzer and introduced into the flow system via a designed gas membrane addition module at a high diffusion rate. The flow system shows remarkable stability and reusability, consistently achieving >99% conversion of ketoisophorone to levodione. It also demonstrates versatility and selectivity in reducing various cyclic enones and can be extended to further flavin-based biocatalytic approaches and gas-dependent reactions. This electro-driven continuous flow system, therefore, has significant potential for advancing sustainable processes in fine chemical synthesis.

Utilizing MXene-mediated electron transfer pathway to boost peroxymonosulfate activation for water purification

Regulating the performance of manganese oxide catalysts to enhance peroxymonosulfate (PMS) activation for degrading emerging organic pollutants remains a significant challenge. To address this issue, Mn3O4/MXene composites with precisely controlled MXene contents are synthesized by combining hydrothermal and calcining methods, resulting in a significant regulate the pathway of Mn3O4 activation of PMS and a notable enhancement bisphenol A (BPA) degradation efficiency. The normalized first-order rate constant for optimized Mn3O4/MXene composites is 0.0218 g/(m2⋅min), which is 8.4 and 2.0 times higher than those of MXene and Mn3O4, respectively. Moreover, this catalyst exhibits excellent mineralization capacities, achieving up to 88.2 % total organic carbon removal efficiency. Combining with electrochemical and electron paramagnetic resonance analysis, the mechanism of electron transfer processes in this composite is elucidated comprehensively. Moreover, Mn3O4/MXene displays remarkable efficiency in degrading refractory pollutants, including antibiotics, phenols, and dyes. Furthermore, Mn3O4/MXene composites exhibit superior stability, reusability, and resistance to interference, highlighting their versatility in diverse environmental contexts. Notably, the catalyst maintains stable catalytic activity for long-term pollutant removal in a continuous-flow system. This study presents a novel approach for developing composite catalysts, providing new avenues for the treatment of emerging pollutants in wastewater.

Cadmium sequestration with MgCuAl-layered double hydroxide@montmorillonite nanocomposite in batch and circulated fluidized bed column experiments

In this study, montmorillonite cationic clay coated with MgCuAl-Layered double hydroxide nanoparticles was investigated for its capacity to adsorb cadmium ion (Cd2+) from aqueous solutions. Montmorillonite, MgCuAl−LDH, and a novel MgCuAl-Layered double hydroxide@montmorillonite nanocomposite (MCA−LDH@MMt) were characterized using various mechanisms including BET surface areas, XRD, TEM, FTIR, and SEM/EDS analysis. The adsorption behaviour of MCA−LDH@MMt towards Cd2+ ion was studied using batch and continuous flow systems. pH, contact time, initial Cd2+concentration, MCA−LDH@MMt dose and particle size, agitation speed, and temperature were examined in the batch system. The higher removal efficiency of Cd2+was reported at pH 5 at 70 mg/l initial concentration and 0.2 g/100 ml best adsorbent dose with 150 rpm. The adsorption of Cd2+ on MCA−LDH@MMt followed Langmuir model and yielded a maximum adsorption capacity of 129.82 mg/g. While the pseudo-second-order model better simulates the cadmium kinetics data, and adsorption rate parameters values showing that the adsorption process was chemisorption and the rate-determining step of controlling cadmium adsorption onto MCA−LDH@MMt not intra-particle diffusion. A three-phase, commonly known as gas-liquid-solid circulated fluidized bed column was used to continuously eliminate Cd2+. Four influencing parameters were studied: liquid and air flow rate, bed height, and initial Cd2+concentration. The adsorption efficiency of Cd2+in a continuous system increased when the liquid flow rate decreased and the bed height increased. The time required for MCA−LDH@MMt to reach saturation increases as the bed height and the air flow rate increase. Column data were described using Bohart-Adams, Thomas, and Yoon and Nelson models of adsorption for given experimental conditions. The Bohart-Adams could represent the initial regime of the breakthrough curves, while the Thomas model was better at describing the whole curve of metal ion adsorption for a given experimental condition.

Aqueous benzene, toluene, ethylbenzene and xylene (BTEX) removal using core-shell structure activated carbon ball as a permeable reactive barrier material

Permeable reactive barriers (PRBs) are passive and sustainable treatment systems for remediating the diffusion of contaminant plumes in groundwater. Several conventional reactive materials such as activated carbon (AC) have long been used as reactive media for PRBs. AC, which is known for its high adsorption capability and cost-effectiveness, is commonly used to remove multiple pollutants from groundwater. Unfortunately, among the reactive materials, AC can fill in the barrier and pose practical problems, such as a pressure drop, solid losses during handling, and safe disposal of filled sorbents, because of its low particle strength. In this study, AC balls were prepared using zeolite as the core and powdered AC, quartz, and calcite as the shell. AC ball with excellent mechanical strength and high permeability properties in the form of a core–shell layer is a good alternative to conventional reactive materials. The adsorption characteristics of benzene, toluene, ethylbenzene, and p-xylene (BTEX) from solutions using AC balls were investigated. The adsorption equilibrium is in the order of X > E > T > B. The adsorption capacity for B (4.90 mg/g), T (3.37 mg/g), E (1.16 mg/g) and X (0.46 mg/g) were observed at solution pH = 7. To validate the proposed models, batch experiments indicated that the pseudo-2nd-order (11.61 and 10.54 mg/g) and Langmuir models (8.81 and 5.27 mg/g) were the most suitable for describing the kinetics and equilibrium of benzene and toluene, respectively. Regeneration experiments were performed using chemical extraction (methanol) and microwave (MW) heating. When the AC ball was reused six times, the removal efficiency for benzene was maintained above 81 % using methanol, whereas that for benzene was increased to 91 % using MW. A series of experiments revealed that AC balls have considerable reusability. The AC ball can be effectively used as a medium for the removal of benzene in a continuous flow system such as column and sandbox. Based on these results, AC balls are a potential reactive medium for field-scale PRB practical remediation applications.

Removal of livestock odor gas ammonia, hydrogen sulfide, methanethiol by electron beam in a continuous flow system

Odor is becoming one of the serious environmental issues as the industry develops. Electron beam technology has recently attracted attention as an AOP (Advanced Oxidation Process) for air purification, water treatment, and soil remediation. This work studied the removal of major livestock odor such as ammonia (NH3), hydrogen sulfide (H2S), and methanethiol (CH3SH) using a continuous gas flow electron beam treatment process. The effects of initial odor gas concentration, type of background gas, absorbed dose of the electron beam, voltage of the electron accelerator, and odor gas flow rate on the removal of odor gas were all studied in this continuous gas flow treatment system. As the absorbed dose of electron beam was increased, the removal efficiencies of odor gases NH3, H2S, and CH3SH all increased gradually. As the initial concentration of odor gas was decreased and as the flow rate of odor gas was increased, the removal efficiencies also increased. Regarding background gas, the odor gas removal efficiency was found to be in descending order of O2 > air > N2. The lower the voltage (MeV) of the electron beam, the higher the odor gas removal efficiency. This was attributed to the fact that, to set the same absorbed dose (kGy), as the voltage decreases, the current value (mA) increases. For the byproducts, as the absorbed dose of electron beam was increased, the concentration of byproducts increased. Regarding the gas-phase continuous electron beam treatment reactions, the optimal operating conditions must be derived by considering various operational variables, including the initial concentration, electron beam dose, background gas type, gas flow rate, and electron beam voltage. The results of this study show that, among several possibly relevant variables in removing odor gases in the continuous flow electron beam irradiation process, the current value can be considered one of the most important variables, along with the initial concentration and background gas.