Inlet Concentration Research Articles

Adsorptive abatement of Pb2+ and crystal violet using chitosan-modified coal nanocomposites: A down flow column study

Every moment huge amounts of industrial wastewater are contaminating our surface/groundwater sources by discharging into the environment directly. This crude wastewater is the most problematic subject because it is the matrix of hazardous toxicants, which can drastically damage public health-safety. So, it is urgent to purify before discharging/reusing. This study focused on the recent improvement and latent implication of Activated Chitosan-Modified Coal(ACMC) bionanocomposite filter. Here, we briefly described how ACMC was produced and its potential application in the removal of Pb2+ and Crystal Violet (CV) effectively from wastewater. However, the influence of different parameters like initial concentration (20–40 ppm), volumetric flow rate (4–6 mL/min) and bed height (0.4–1.0 cm) were investigated appropriately meanwhile the adsorbent amount was (1.0–2.0 g). The adsorption efficiency and removal percent were strongly correlated with inlet concentration, flow rate, and bed height. The highest removal capacity and percentage were found nearly (243.08 and 238.51)mg/g additionally (78.48 and 82.50)% for Pb2+ and CV. Finally, three well-known column adsorption models namely Thomas, Yoon-Nelson and Adam-Bohart model were applied for the fitting of experimental data which exhibited a decent agreement with all three models that are also suitable for the description of breakthrough curve (BTC) and supports the Langmuir isotherm by following second-order reversible reaction kinetics. Thus this new class of ACMC nanoadsorbents could be beneficially used for the real-time bulk scale industrial wastewater treatment as a suitable replacement of hazardous fossil-based synthetic ones for sustainable environmental protection.

Numerical study of falling film dehumidification performance on corrugated plates

Due to a number of benefits, liquid desiccant dehumidification has received a lot of attention lately. In comparison to previous improvement strategies, corrugated plates have demonstrated higher efficacy in liquid desiccant dehumidification. This study employs computational fluid dynamics to examine the dehumidification performance of falling film liquid desiccant dehumidification on over sinusoidally shaped corrugated plates. The effects of plate geometries, solution parameters, and moist air (concentration of humidity, temperature, and flow rate) were discussed. Additionally, a mass transfer correlation was proposed based on the current numerical data. It is indicated that the corrugated plate significantly enhances dehumidification performance due to the liquid film waves intensification, mass transfer area expansion, and induction of vortexes close to the gas-liquid interface. The most effective falling film dehumidification is achieved using a corrugated plate with a wavelength of 5.0 mm and an amplitude of 0.5 mm. By raising the solution or air inlet temperature, the dehumidification rate is reduced while being strengthened by raising the solution or air inlet concentration, velocity, or air humidity. While decreasing when solution intake concentration or air velocity rises, the efficacy of dehumidification rises as solution velocity does. The proposed mass transfer correlation accurately predicts 93.3 % of the 45 data, with an error of 11 % or less. In the current parameter scopes, the magnitude has a more significant effect on Shair than the wavelength. Adjustments to air velocity and solution concentration can cause significant fluctuations in Shair, while air and solution temperature have little effect on Shair.

Long-term phosphorus removal by Ca and Fe-rich drainage filter materials under variable flow and inlet concentrations

Phosphorus (P) losses from tile-drained agricultural fields may degrade surface water quality by accelerating eutrophication. Among the different edge-of-field technologies, compact filter systems using different filter materials have been identified as potentially effective solutions for removing P from drainage water before discharge downstream.This study investigated the long-term (>696 days) P removal efficiency of 5 different filter materials in a column setup, using artificial drainage water (pH 6). Filter materials included two iron-based granulates (calcinated diatomaceous earth (CDE), ferric hydroxide granules (CFH)), and three calcium-based granulates (seashells, limestone, calcinated silicate/calcium oxide (Filtralite-P)). Experiments were performed under variable flow rates (0.037 and 1.52 L h−1; hydraulic retention time of 26–43 min and 18–30 h) and inlet P concentrations (0.14 and 0.7 mg L−1). An overall analysis revealed that the Fe-based materials achieved higher P retention than Ca-based materials. In particular, CFH was capable of retaining 99 and 98 % of the high and low inlet P concentrations, respectively. Conversely, limestone retained only 25 % of the high P load. CDE performed moderately well, independently of the inlet P concentration. Filtralite-P and Seashells performed well at high inlet P concentration but relatively poorly at low P concentration. The sensitivity of filter material P removal efficiency to variations in P loading was generally lowest for CFH and highest for limestone.

Effect of permeable spacer structure on energy loss and mass transfer in reverse osmosis membrane modules

This study used numerical simulation to investigate the effects of a novel permeable cylindrical-flow distributor on energy loss and mass transfer in reverse osmosis (RO) membrane modules. The analysis focused on variables, such as Reynolds number, inlet concentration and flow incidence angle, influencing the improvement of water production efficiency in RO membranes and the reduction of concentration polarisation on the membrane surface. The membrane surface shear stress, vorticity, permeate flux and concentration polarisation factor were used to describe these effects. To better explain the performance of the permeable flow distributor, the viscous resistance coefficient (Du) in the porous media model was used to measure the permeability of the flow distributor. Furthermore, a produced water energy consumption factor (JCP) was defined to represent the energy required for unit water production. The results indicate that the permeable flow distributor significantly reduces pressure loss in the membrane channels, avoiding the high energy consumption associated with traditional flow distributors in RO processes. The Du exhibits an optimal value in the range of 1e8 to 1e10, which maximises the JCP, leading to a 32.9 % improvement compared to traditional impermeable flow distributors. This achievement enables energy-efficient and effective desalination of seawater.

Indoor air VOCs biofiltration by bioactive coating packed bed bioreactors

Bioactive coatings are envisaged as a promising biotechnology to tackle the emerging problem of indoor air pollution. This solution could cope with the low concentrations, the wide range of compounds and the hydrophobicity of some indoor air VOCs, which are the most important bottlenecks regarding the implementation of conventional biotechnologies for indoor air treatment. A bioactive coating-based bioreactor was tested in this study for the abatement of different VOCs (n-hexane, toluene and α-pinene) at different empty bed residence times (EBRT) and inlet VOC concentrations. The performance of this reactor was compared with a conventional biofilm-based bioreactor operated with the same microbial inoculum. After an acclimation period, the bioactive coating-based bioreactor achieved abatements of over 50% for hexane, 80% for toluene and 70% for pinene at EBRTs of 112–56 s and inlet concentrations of 9–15 mg m−3. These results were about 25, 10 and 20% lower than the highest removals recorded in the biofilm-based bioreactor. Both bioreactors experienced a decrease in VOC abatement by ∼25% for hexane, 45% for toluene and 40% for pinene, after reducing the EBRT to 28 s. When inlet VOC concentrations were progressively reduced, VOC abatement efficiencies did not improve. This fact suggested that low EBRTs and low inlet VOCs concentration hindered indoor air pollutant abatement as a result of a limited mass transfer and bioavailability. Metagenomic analyses showed that process operation with toluene, hexane and pinene as the only carbon and energy sources favored an enriched bacterial community represented by the genera Devosia, Mesorhizobium, Sphingobacterium and Mycobacterium, regardless of the bioreactor configuration. Bioactive coatings were used in this work as packing material of a conventional bioreactor, achieving satisfactory VOC abatement similar to a conventional bioreactor.

Oxyanion Removal from Impaired Water by Donnan Dialysis Plug Flow Contactors.

In the last twenty-five years, extensive work has been done on ion exchange membrane bioreactors (IEMB) combining Donnan dialysis and anaerobic reduction to remove trace oxyanions (e.g., perchlorate, nitrate, chlorate, arsenate) from contaminated water sources. Most studies used Donnan dialysis contactors with high recirculation rates on the feed side, so under continuous operation, the effective concentration on the feed side of the membrane is the same as the exit concentration (CSTR mode). We have built, characterized, and modelled a plug flow Donnan dialysis contactor (PFR) that maximizes concentration on the feed side and operated it on feed solutions spiked with perchlorate and nitrate ion using ACS and PCA-100 anion exchange membranes. At identical feed inlet concentrations with the ACS membrane, membrane area loading rates are three-fold greater, and fluxes are more than double in the PFR contactor than in the CSTR contactor. A model based on the nonlinear adsorption of perchlorate in ACS membrane correctly predicted the trace ion concentration as a function of space-time in experiments with ACS. For PCA membrane, a linear flux dependence on feed concentration correctly described trace ion feed concentration as a function of space-time. Anion permeability for PCA-100 was high enough that the overall mass transfer was affected by the film boundary layer resistance. These results provide a basis for efficiently scaling up Donnan dialysis contactors and incorporating them in full-scale IEMB setups.

Optimization of effecting parameters for flue gas desulfurization in a self‐priming venturi scrubber using response surface methodology

AbstractHydrogen sulfide (H2S), a highly poisonous and corrosive gas, is regarded as a hazardous air pollutant with significant effects on human health. Hence, reduction of hydrogen sulfide (H2S) gas from the atmosphere is very essential. In the present work, self‐priming venturi scrubber is employed to extract H2S gas from the air. Response surface methodology (RSM) with a central composite design (CCD) has been selected to investigate maximizing the H2S removal efficiency by optimizing the process variables. Experiments were carried out by altering the throat gas velocity, outer cylinder liquid level and inlet concentration of H2S. The analysis of variance (ANOVA) test showed that the parameters had a significant effect on the efficiency of H2S removal. A quadratic equation has been developed that accurately predicts the percentage of removal efficiency. The appropriateness of the generated model has been verified by the value of higher R2 resulting from the regression analysis. According to the observations, the velocity of throat gas has the highest effect on the H2S removal efficiency, whereas inlet H2S concentration has the least effect.

Adsorption equilibrium of activated carbon amid fluctuating benzene concentration in indoor environments

Adsorption is commonly employed to remove volatile organic compounds (VOCs) from indoor air. However, the reversibility of this process has been rarely explored in prior research. Meanwhile, some previous research indicated partial reversibility in adsorption and desorption processes, which has not been described in traditional adsorption equilibrium models. In this study, we measured benzene adsorption and desorption isotherms on 6 activated carbons within two concentration ranges: 0–3 ppm and 0–6 ppm. The results showed that the adsorption process was partially reversible and the desorption isotherm was hysteretic for all the samples. Different carbons exhibited distinct isotherm patterns, yet the desorption isotherms in the experimental concentration range can be calculated from the adsorption isotherms using the same empirical equation. In addition, we measured the breakthrough curves using the oscillating benzene concentration (6 ppm to background) on the test columns. Reversible adsorption was observed at low degrees of saturation of the test column. Especially for microporous activated carbon, desorption could be sustained for several hours with purging even at the breakthrough rate of about 10%. An adsorption equilibrium model incorporating partially reversible adsorption and hysteretic desorption isotherm was developed based on the experimental data, which allows a preliminary interpretation of the measured breakthrough curves at fluctuating inlet concentrations.

Experimental and Modeled Results Describing the Low-Concentration Acetone Adsorption onto Coconut Shell Activated Carbon

Polar VOCs represented by ketones deteriorate indoor air quality and affect human health. Adsorption by activated carbons can effectively remove harmful gases, but relatively little is known about the adsorption capacity of polar VOCs at a low concentration level. So, this paper adopted acetone as the typical polar VOC to test its adsorption on the coconut shell activated carbon and developed a prediction model to estimate the breakthrough time. The results will help users master the acetone adsorption behavior under realistic conditions and thus estimate the service life of the filters. The adsorption test of acetone with concentrations of 0.5, 1.0, 2.0, 3.0, and 4.0 ppm was carried out. Four adsorption isotherms, namely, Langmuir, Freundlich, Dubinin–Radushkevich, and Temkin, were used to fit the data. The Freundlich model fitted best when was used to determine the equilibrium capacity of acetone. An approach based on the Thomas model was proposed to predict the acetone breakthrough curve. The mass transfer coefficient of acetone adsorption with a relatively high concentration (1.0–4.0 ppm) was calculated based on the Thomas model, and the relationship between the mass transfer coefficient and acetone inlet concentration was established to obtain the mass transfer coefficient of acetone at the predicted concentration. The equilibrium capacity and mass transfer coefficient were substituted into the Thomas model to predict the breakthrough curve of acetone at a lower concentration. The results showed that the shape of the predicted curve was much closer to the measured data of acetone adsorption. The relative deviation between the predicted service life and measured data was 10%, indicating that the Thomas model was suitable for predicting acetone adsorption at low concentrations.

Rapid and convenient synthesis of “green” ammonium-modified chitosan composite sponge with the existence of ascorbic acid for highly efficient removal of Congo red (CR)

In this study, a new green composite sponge made of chitosan and modified with ammonium ascorbate (ACS-CIT) was synthesized in just 10 min. Compared with CS-CIT (sponge prepared from acetic acid), ACS-CIT exhibits significantly enhanced adsorption performance for CR, with the saturated adsorption capacities increased from 353.667 to 1261.639 mg·g−1. The adsorption mechanism can be summarized as the generation of more hydrogen bonds, electrostatic attraction, and intra particle diffusion, revealing the addition of ascorbic acid introduced more hydroxyl groups, thereby enhancing the hydrogen bonding force, and the ammonium modification of chitosan improved the electrostatic attraction of the material, resulting in a significant increase in its adsorption capacity. Additionally, the prepared ACS-CIT showed excellent CR removal performance even in the presence of multiple interfering factors coexisting in the simulated wastewater, and the adsorption capacity remained stable after at least five cycles. Furthermore, the maximum bed capacity of ACS-CIT for CR is 1152.829 mg·g−1 under the given conditions of a flow rate of 1 mL·min−1, inlet concentration of 150 mg·L−1, a bed height of 1 cm respectively, and the breakthrough curve followed the Thomas model. The results indicated the eco-friendly and recyclable ACS-CIT is a promising adsorbent for CR dye removal in water.

Regeneration of coked catalysts via ozonation: Experimental study of diffusion–reaction mechanisms at pellet and reactor scales

This work focuses on regeneration of coked catalysts using ozonation as an alternative process to typical coke combustion with oxygen. Different samples of coked ZSM-5 zeolites obtained during catalytic pyrolysis of polyethylene at 450 °C were exposed to an ozone enriched stream in a fixed-bed reactor. The influence of main operating parameters (time of exposure, temperature, O3 inlet concentration and gas volumetric flowrate) were studied by evaluating coke removal efficiency and by observing regeneration behavior both at pellet and reactor scales. These experimental results led to a better insight of the diffusion–reaction phenomena occurring during the process. Diffusion limitations were illustrated thanks to an innovative method, the analytical acquisition of carbon radial profiles on catalyst pellets, while the apprehension and quantification of competing reactivity (thermal, catalytic and oxidation) gave a better understanding of the ozonation process. Time of exposure and temperature were found to significantly affect carbon removal efficiency, while inlet ozone concentration and flowrate influence were respectively moderate and null in the investigated range. Similarly to combustion, coke ozonation is driven by a balance between diffusion and reactivity, leading to the appearance of a mix of known regeneration regimes depending on the operating conditions: homogeneous and shrinking-core.

Effect of Nanoparticles Deposition on Cooling Performance of Photovoltaic Panels

Abstract The current research aims to investigate the deposition and dispersion of nanoparticles for thermally developing laminar flow inside a cooling channel of a photovoltaic (PV) panel. The particle transport is modeled in an Eulerian-Lagrangian framework using a two-way coupling approach to perform the particle trajectories. In the absence of turbulent fluctuations, Brownian diffusion is the main force that contributes to particles deposition due to the small size of the particles used in the current study (below 100 nm). Several parameters were investigated such as inlet temperature, Reynolds number, nanoparticle size, and concentration in order to record the subsequent effects on the deposition efficiency, heat transfer coefficient, and pressure drop. There is no direct particle deposition model available in commercial computational packages such as Fluent, so a deposition model was developed and programmed in C-language using the User-Defined Functions (UDF) capabilities available in the Fluent solver to model how the particles are affected by wall impacts. Model validation was performed against the experimental studies found in the literature and showed good agreement. The efficiency of particle deposition on the channel wall was found to increase with decreasing nanoparticle size and/or Reynolds number. Furthermore, the deposition efficiency increased with the increase in fluid inlet temperature and nanofluid concentration. Moreover, the heat transfer rate was decreased as a result of decreasing nanofluid concentration caused by nanoparticle deposition on the channel walls, while the pumping power was also decreased due to concentration loss.

Electrochemical oxidation of perfluorooctanesulfonate (PFOS) from simulated soil leachate and landfill leachate concentrate

The near-widespread presence of poly- and perfluoroalkyl substances (PFASs) in humans has generated concerns regarding the potential negative impact of these chemicals on human health, as some PFASs are exceedingly persistent and bioaccumulative. Among the perfluorinated PFASs, which exhibit high polarity and strong carbon–fluorine bonds, perfluorooctanesulfonate (PFOS) is one of the frequently encountered species. In this study, the efficiency of electrooxidation (EO) and its application in groundwater simulation were first evaluated as a realistic approach to PFOS removal. After optimizing EO parameters including the solution pH, current density, and the effects of inlet concentration and the anode material, 83 % total organic carbon (TOC) removal was obtained. In groundwater experiments, in which the infiltration of PFOS from soil layers into groundwater was simulated, 79 % TOC removal efficiency was achieved in the more complex groundwater; moreover, an F− ion concentration of 8.78 mg/L was obtained from the decomposition of PFOS. To increase the realism of the simulation, the leachate process was repeated four times, and the EO process was applied to each sequential leachate. In addition, the process efficiency was studied in real landfill leachate wastewater to which PFOS had been added. Despite the challenging wastewater composition, 84 % TOC removal efficiency was achieved. Together, these results indicate that BDD-anodic oxidation may be a practical method to treat PFOS-contaminated groundwater and wastewater.

Modeling and control of networked kinetic systems with delayed interconnections

The modeling and control of networks of kinetic systems, also called chemical reaction networks (CRNs), containing distributed delays are considered in this paper. The nodes in the network are sub-CRNs with nonnegative nonlinear dynamics, while the interconnections are modeled as linear connecting CRNs. Distributed delays appearing in the system are described as physically motivated connecting sub-CRNs with asymptotically stable linear compartmental dynamics. A control model is given for the studied system class, where the manipulable inputs are selected inlet concentrations, and the control goal is to achieve global stability by ensuring the complex balanced property of the closed loop system. Besides stabilization, the tracking of prescribed setpoints is also solved using a suitable decentralized feedforward-feedback combination. The operation of the proposed method is illustrated through a network containing three sub-CRNs and several linear interconnections.

Hexamethyldisiloxane Removal from Biogas Using a Fe3O4-Urea-Modified Three-Dimensional Graphene Aerogel.

Volatile methyl siloxanes (VMS), which are considered to be the most troublesome impurities in current biogas-cleaning technologies, need to be removed. In this study, we fabricated a series of Fe3O4-urea-modified reduced graphene-oxide aerogels (Fe3O4-urea-rGOAs) by using industrial-grade graphene oxide as the raw material. A fixed-bed dynamic adsorption setup was built, and the adsorption properties of the Fe3O4-urea-rGOAs for hexamethyldisiloxane (L2, as a VMS model pollutant) were studied. The properties of the as-prepared samples were investigated by employing various characterization techniques (SEM, TEM, FTIR, XRD, Raman spectroscopy, and N2 adsorption/desorption techniques). The results showed that the Fe3O4-urea-rGOA-0.4 had a high specific surface area (188 m2 g-1), large porous texture (0.77 cm3 g-1), and the theoretical maximum adsorption capacity for L2 (146.5 mg g-1). The adsorption capacity considerably increased with a decrease in the bed temperature of the adsorbents, as well as with an increase in the inlet concentration of L2. More importantly, the spent Fe3O4-urea-rGOA adsorbent could be readily regenerated and showed an excellent adsorption performance. Thus, the proposed Fe3O4-urea-rGOAs are promising adsorbents for removing the VMS in biogas.

Utilization of landscape biomass waste as activated carbon to scavenge oxytetracycline: Attraction mechanism, batch and continuous studies

Oxytetracycline (OXY) is an antibiotic widely used in the livestock industry and its existence in water can cause antibiotic resistance genes. A treatment process in a continuous mode is required to treat a high volume of OXY wastewater. Hence, an effort was made in this study to adsorb OXY from an aqueous solution (batch and continuous modes) using landscape biomass waste-based activated carbon (LBWAC). This adsorbent was produced via potassium hydroxide (KOH) chemical treatment combined with microwave heating under carbon dioxide, CO2 gas. The resulting LBWAC exhibited 973.21 m2/g of BET surface area, 842.18 m2/g of mesopores surface area, 0.3911 cm3/g of total pore volume, and 2.44 nm of average pore diameter. In a batch study, OXY adsorption uptakes increased whilst OXY percentage removal decreased when OXY starting concentration increased from 25 to 300 mg/L. The highest uptakes of OXY occurred at a solution temperature of 60 °C (228.44 mg/g) and a solution pH of 12 (63.22 mg/g). The adsorption system studied obeyed the Langmuir model and pseudo-second-order in isotherm and kinetic studies, respectively. The obtained Langmuir monolayer capacity, Qm was 344.83 mg/g. Mechanism study revealed that O, H, and N elements in OXY molecules react with O, H, and N elements in functional groups on LBWAC’s surface via hydrogen bonds and vice versa. Parameters acquired in the thermodynamic study described the adsorption process as spontaneous, endothermic, and physisorption-controlled. The continuous bed column study revealed that the breakthrough point (Tb), exhaustion time (Tex), and maximum adsorption uptake (qmax) for the OXY-LBWAC adsorption system can be increased by decreasing the starting inlet concentration, decreasing the inlet flow rate and increasing the bed height. The continuous adsorption data fitted Thomas model the best. The LBWAC had a good potential to be applied in a large-scale operation for OXY wastewater treatment.

Experimental investigation on the melting process using freezing concentration for heat source tower heat pump system

Facing with problem of the dilute antifreeze solution in winter, it is necessary for the heat source tower heat pump system to develop a new kind of regenerator to improve the utilization rate of waste liquid. In this article, a solution regenerator unit using freeze concentration with a heat pump system was tested to research variations in the melting process under different operation conditions. From the separation efficiency, the low valve opening degree and high freezing point enhanced the separation process. The maximum separation ratio was all at 50 % valve opening degree operation at each concentration group. As the inlet concentration increased, the separation ratio was downtrend at different opening degree operations. For the icing distribution, the low covering ice area shortened the running time of melting process. The average percentage slope can reflect the influence changes of the ice thickness, the ice covering area and the inlet concentration on the melting process. The average percentage slope was inversely linear with the mass of calculated melted ice. The increase in average percentage slope effectively reduced amount of melting ice.

Methyl-Functionalized Al-Based MOF ZJU-620(Al): A Potential Physisorbent for Carbon Dioxide Capture.

Developing Al-based metal-organic frameworks (MOFs) with moisture-resistance ability is a challenge for carbon dioxide (CO2) capture. Methyl-functionalized Al-based MOF ZJU-620(Al), with excellent chemical-thermal stability and specific surface area of 1347 m2/g, observed here, is a potential adsorbent for CO2 capture with good recyclability and large capacity up to 4.25 mmol/g at 298 K and 1 atm. CO2 molecules are largely trapped on two types of sites. One (site I) is near the AlO6 clusters, and another (site II) is between two parallel benzene rings with a distance of 6.64 Å. ZJU-620(Al) can be used for CO2/N2 (15/85) separation with the excellent selectivity up to 107.20 at 273 K and 31.93 at 298 K, and the separation factor of 13.68. It is also with excellent moisture-resistance ability due to 5% breakthrough time (outlet concentration reached the 5% of inlet concentration) without reduction at 80% relative humidity than under dry conditions. Water molecules occupy a small amount of CO2 adsorption site I, but they almost do not occupy the CO2 adsorption site II due to hydrophobic methyl-functional ligands. Moreover, CO2 can be adsorbed on the ZJU-620(Al) surface through C═O···H binding of water molecules with high affinity. Thus, ZJU-620(Al) is a candidate adsorbent for CO2 capture and separation especially under humidity conditions.

Degradation of binary mixtures of water pollutants in a photocatalytic microreactor: Competitive kinetics with explicit radiation absorption effects

The photocatalytic degradation of 17-α-ethinylestradiol (EE2) and phenol in aqueous solutions was studied using a continuous flow, planar microreactor under simulated sunlight. A TiO2 thin film was employed as photocatalyst. The degradation rates of single compounds and binary mixtures were well described by the Langmuir-Hinshelwood equation, including competitive terms for the companion pollutant and the intermediate products, and the effect of photon absorption by the photocatalyst. The absorbed radiation in the microreactor was calculated from the optical properties of the TiO2 film and the application of the Net Radiation method. The estimation of the kinetic parameters was carried out by numerical integration of coupled mass balance equations for EE2 and phenol employing the Runge-Kutta method, and adjusting the kinetics parameters with a nonlinear least-squares solver. The objective of this routine was to minimize the sum of the squares of the differences between the simulated and experimental outlet concentrations of EE2 and phenol under different operating conditions. Using this approach, intrinsic kinetic parameters were obtained. The model was able to predict the degradation of both organic pollutants under different inlet concentrations, irradiation levels, and fluid flow rates. This methodology can be extended to assess the simultaneous degradation of multi-component systems.

Adsorption of hexavalent chromium by Simarouba glauca in a fixed-bed column: a full-factorial design and mathematical modelling

ABSTRACT Due to its high toxicity and mobility, hexavalent chromium must be adequately eliminated from effluent or wastewater. For Cr(VI) adsorption, it is increasingly becoming customary to use inexpensive, readily accessible plant-based materials. It has been discovered that the popular medicinal herb Simarouba glauca is quite effective at removing Cr(VI) from aqueous media. The first stage of this study examines Cr(VI) adsorption onto S. glauca using the 25 Full Factorial Design technique. It was possible to determine the major effects of S. glauca dosage and how they interacted with pH, temperature, the initial Cr(VI) concentration, and time. The adsorption was predicted adequately with the aid of ANOVA, t-test, Pareto charts, main effect, and interaction plots. The second section of the study focuses on the potential for continuous adsorption of S. glauca in a fixed-bed column. The Cr(VI) inlet concentration (50, 100 and 150 mg/L), flow rate (13 and 21 mL/min), and S. glauca bed height (30, 36, 40 and 45 cm) all had an impact on the breakthrough qualities of the adsorption system. The fixed-bed adsorption models of Thomas, Yoon–Nelson, and Adams-Bohart were used to fit the adsorption data. The Thomas model, with a flow rate of 13 mL/min, a bed height of 45 cm and an inlet concentration of 100 mg/L of Cr(VI), calculated the adsorption capacity to be 611.6 mg/g with a coefficient of 0.99. The findings are consistent with the hypotheses advanced by Thomas and Yoon–Nelson. This study suggests that this technique could be used to treat chromium-contaminated water in industrial settings.