Kinetic Model Research Articles

Valorization of Eggshell as Renewable Materials for Sustainable Biocomposite Adsorbents—An Overview

The production and buildup of eggshell waste represents a challenge and an opportunity. The challenge is that uncontrolled disposal of generated eggshell waste relates to a sustainability concern for the environment. The opportunity relates to utilization of this biomass resource via recycling for waste valorization, cleaner production, and development of a circular economy. This review explores the development of eggshell powder (ESP) from eggshell waste and a coverage of various ESP composite sorbents with an emphasis on their potential utility as adsorbent materials for model pollutants in solid–liquid systems. An overview of literature since 2014 outlines the development of eggshell powder (ESP) and ESP composite adsorbents for solid–liquid adsorption processes. The isolation and treatment of ESP in its pristine or modified forms by various thermal or chemical treatments, along with the preparation of ESP biocomposites is described. An overview of the physico-chemical characterization of ESP and its biocomposites include an assessment of the adsorption properties with various model pollutants (cations, anions, and organic dyes). A coverage of equilibrium and kinetic adsorption isotherm models is provided, along with relevant thermodynamic parameters that govern the adsorption process for ESP-based adsorbents. This review reveals that ESP biocomposite adsorbents represent an emerging class of sustainable materials with tailored properties via modular synthetic strategies. This review will serve to encourage the recycling and utilization of eggshell biomass waste and its valorization as potential adsorbent systems. The impact of such ESP biosorbents cover a diverse range of adsorption-based applications from environmental remediation to slow-release fertilizer carrier systems in agricultural production.

A Reformulation of the Laminar Kinetic Energy Model to Enable Multi-mode Transition Predictions

AbstractThe paper describes the development of a novel transition/turbulence model based on the laminar kinetic energy concept. The model is intended as a base framework for data-driven improvements. Starting from a previously developed framework, mainly aimed at separated-flow transition predictions, suitable terms for model generalization are identified and reformulated for handling different transition modes, namely bypass and separated-flow modes. The ideology for the definition of new terms has its roots in mixing phenomenological and correlation-based arguments, ensuring generality and flexibility and allowing a variety of lines of action for improving model components via machine-learning approaches. The model calibration, carried out with reference to flat plate test cases subjected to different pressure gradients and freestream turbulence levels, is discussed in detail. Although the constructed model is calibrated on a group of classic flat plat cases, the validation campaign, mostly carried out on gas turbine cascades, demonstrates its ability to predict transitional flows with engineering accuracy. Finally, while the model is not specifically developed for natural transition predictions, satisfactory predictions are obtained in scenarios with low freestream turbulence for flat plate and airfoil flows.

Removal of Pb(II) and Cd(II) from a Monometallic Contaminated Solution by Modified Biochar-Immobilized Bacterial Microspheres.

Lead (Pb) and cadmium (Cd) are toxic pollutants that are prevalent in wastewater and pose a serious threat to the natural environment. In this study, a new immobilized bacterial microsphere (CYB-SA) was prepared from corn stalk biochar and Klebsiella grimontii by sodium alginate encapsulation and vacuum freeze-drying technology. The removal effect of CYB-SA on Pb(II) and Cd(II) in a monometallic contaminated solution was studied. The results showed that the removal of Pb(II) and Cd(II) by CYB-SA was 99.14% and 83.35% at a dosage of 2.0 g/L and pH = 7, respectively, which was 10.77% and 18.58% higher than that of biochar alone. According to the Langmuir isotherm model, the maximum adsorption capacities of Pb(II) and Cd(II) by CYB-SA at 40 °C were 278.69 mg/g and 71.75 mg/g, respectively. A combination of the kinetic model, the isothermal adsorption model, scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS), X-ray photoelectron spectroscopy (XPS) and Fourier-transform infrared spectroscopy (FTIR) analyses showed that the main adsorption mechanisms of CYB-SA encompass functional group complexation, ion exchange, electrostatic attraction and physical adsorption. The findings of this study offer practical and theoretical insights into the development of highly efficient adsorbents for heavy metals.

A Detailed Reaction Mechanism for Thiosulfate Oxidation by Ozone in Aqueous Environments.

The ozone oxidation, or ozonation, of thiosulfate is an important reaction for wastewater processing, where it is used for remediation of mining effluents, and for studying aerosol chemistry, where its fast reaction rate makes it an excellent model reaction. Although thiosulfate ozonation has been studied since the 1950s, challenges remain in developing a realistic reaction mechanism that can satisfactorily account for all observed products with a sequence of elementary reaction steps. Here, we present novel measurements using trapped microdroplets to study the pH-dependent thiosulfate ozonation kinetics. We detect known products and intermediates, including SO32-, SO42-, S3O62-, and S4O62-, establishing agreement with the literature. However, we identify S2O42- as a new reaction intermediate and find that the currently accepted mechanism does not directly explain observed pH effects. Thus, we develop a new mechanism, which incorporates S2O42- as an intermediate and uses elementary steps to explain the pH dependence of thiosulfate ozonation. The proposed mechanism is tested using a kinetic model benchmarked to the experiments presented here, then compared to literature data. We demonstrate good agreement between the proposed thiosulfate ozonation mechanism and experiments, suggesting that the insights in this paper can be leveraged in wastewater treatment and in understanding potential climate impacts.

Interplay of Nav1.8 and Nav1.7 channels drives neuronal hyperexcitability in neuropathic pain.

While voltage-gated sodium channels Nav1.7 and Nav1.8 both contribute to electrogenesis in dorsal root ganglion (DRG) neurons, details of their interactions have remained unexplored. Here, we studied the functional contribution of Nav1.8 in DRG neurons using a dynamic clamp to express Nav1.7L848H, a gain-of-function Nav1.7 mutation that causes inherited erythromelalgia (IEM), a human genetic model of neuropathic pain, and demonstrate a profound functional interaction of Nav1.8 with Nav1.7 close to the threshold for AP generation. At the voltage threshold of -21.9 mV, we observed that Nav1.8 channel open-probability exceeded Nav1.7WT channel open-probability ninefold. Using a kinetic model of Nav1.8, we showed that a reduction of Nav1.8 current by even 25-50% increases rheobase and reduces firing probability in small DRG neurons expressing Nav1.7L848H. Nav1.8 subtraction also reduces the amplitudes of subthreshold membrane potential oscillations in these cells. Our results show that within DRG neurons that express peripheral sodium channel Nav1.7, the Nav1.8 channel amplifies excitability at a broad range of membrane voltages with a predominant effect close to the AP voltage threshold, while Nav1.7 plays a major role at voltages closer to resting membrane potential. Our data show that dynamic-clamp reduction of Nav1.8 conductance by 25-50% can reverse hyperexcitability of DRG neurons expressing a gain-of-function Nav1.7 mutation that causes pain in humans and suggests, more generally, that full inhibition of Nav1.8 may not be required for relief of pain due to DRG neuron hyperexcitability.

Quantification of the Contribution of Heterogeneous Surface Processes to Pollutant Abatement during Heterogeneous Catalytic Ozonation.

Heterogeneous surface processes such as adsorption and oxidation with surface-adsorbed reactive oxygen species (ROSad, e.g., adsorbed oxygen atom (*Oad) and hydroxyl radicals (•OHad)) have been suggested to play an important role in pollutant abatement during heterogeneous catalytic ozonation (HCO). However, to date, there is no reliable method to quantitatively evaluate the contribution of heterogeneous surface processes to pollutant abatement (fS) during HCO. In this study, we developed a method by combining probe compound-based experiments with kinetic modeling to distinguish heterogeneous surface processes from homogeneous bulk reactions with aqueous O3 and ROS (•OH and superoxide radicals (O2•-) in the abatement of various pollutants (e.g., atrazine, ibuprofen, tetrachloroethylene, and perfluorooctanoic acid) during HCO with reduced graphene oxide. The results show that the pollutants that have a low affinity for the rGO surface (e.g., ibuprofen and tetrachloroethylene) were essentially abated by homogeneous bulk reactions, while the contribution of heterogeneous surface processes was negligible (fS < 5%). In contrast, heterogeneous surface processes played an important or even dominant role in the abatement of pollutants that have a high surface affinity (e.g., fS = 32-82% for atrazine and perfluorooctanoic acid). This study is a critical first step in quantitatively evaluating the role of heterogeneous surface processes for pollutant abatement during HCO, which is crucial to understanding the mechanism of HCO and designing catalysts for effective pollutant abatement.

Effect of Reaction Pathways on the Kinetic Modeling of Aquathermolysis of Heavy Oils

Effect of Reaction Pathways on the Kinetic Modeling of Aquathermolysis of Heavy Oils

Harnessing Moringa oleifera root powder (MORP) for the sustainable remediation of heavy metal contaminated water.

Heavy metal environmental pollution is rapidly increasing due to the increase in industrialization and urbanization. Industrial processes, such as paint production, mining, and raw materials producing industries release effluents rich in heavy metals, like Pb2+, Cd2+, Cu2+, and Cr3+. These heavy metals are dangerous because they persist in nature, are non-biodegradable and they have high tendency to accumulate in the environment and in living organisms who are exposed to them. This work studied the removal of heavy metals (Cu, Pb, Cr, and Cd) from aqueous solution using Moringa oleifera root powder (MORP) as the adsorbent. The MORP was characterized by SEM, FTIR, BET, and XRD. Batch adsorption experiments carried out investigated the effects of adsorbate concentration, adsorbent dosage, agitation time, pH and temperature on adsorption. The optimum parameters are: contact time (90 min); pH (9); adsorbent dose (0.6); metal ion concentration (30 mg L-1) for Cr and 40 mg L-1 for the rest; and temperature (50 °C) for Cu and Pb, and 70 °C for Cr and Cd. These experimental data were analyzed with 5 isotherm models (Temkin, Flory-Huggins, Langmuir, D-R and Freundlich). The result obtained fitted best to Temkin isotherm in comparison to others. Kinetic studies revealed that the pseudo-second order kinetic model best described the adsorption (with high R2 values ranging from 0.9810-0.9976) compared to pseudo-first order and intra-particle diffusion kinetics model. Results of the thermodynamic study showed that the sorption process was endothermic for Cu and Pb, but exothermic for Cd and Cr. The adsorbent showed good adsorptive tendencies toward the ions studied, and could be applied on an industrial scale for the remediation of metal contaminated water.

Physicochemical Characterization and Thermodynamic Analysis of Avocado Oil Enhanced with Haematococcus pluvialis Extract

The consumption of fatty acids offers significant health benefits; however, they are prone to degradation by environmental factors. One method to preserve these fatty acids is the addition of synthetic antioxidants. This study focuses on the determination of peroxide and MDA formation rates at temperatures of 25 °C, 45 °C, and 65 °C. The oxidative stability of cold-pressed avocado oil was evaluated using pure astaxanthin, TBHQ, and H. pluvialis extract at concentrations of 100, 500, and 1000 ppm. Kinetic models and thermodynamic analysis were applied to determine the oxidation rate and compare the antioxidant effects of H. pluvialis extract with astaxanthin and TBHQ. The Arrhenius model was used to estimate activation energy (Ea), enthalpy, entropy, and free energy. Avocado oil with 500 ppm of H. pluvialis extract showed antioxidant effects comparable to TBHQ and pure astaxanthin. The activation energy of plain avocado oil was 40.47 kJ mol−1, while with H. pluvialis extract, it was 54.35 kJ mol−1. These findings suggest that H. pluvialis extract offers effective antioxidant properties and could serve as a natural alternative to synthetic antioxidants in food applications, despite the limitations of unprotected astaxanthin.

Shelf life and storage stability of cold plasma treated kiwifruit juice: kinetic models

ABSTRACT This study examined the quality changes and shelf life of cold plasma (Cold plasma-optimized, S2: 30 kV/5 mm/6.7 min and Cold plasma-extreme, S3: 30 kV/2 mm/10 min) and thermally-treated (S4: 90°C/5 min) kiwifruit juice packed in glass and polyethylene terephthalate bottles stored at 5, 15, and 25°C. Cold plasma and thermally treated juice samples were analyzed for peroxidase activity, microbial enumeration, bioactive compounds degradation, and sensory quality for up to 120 days. The residual activity of peroxidase enzyme in S2 sample after cold plasma treatment was 23.85%, decreasing with increase in storage time and temperature. After cold plasma and thermal treatment, the aerobic mesophiles and yeasts and molds count were below detectable limits in kiwifruit juice. Aerobic mesophiles and yeasts & molds emerged in S2, S3, and S4 samples stored at 5°C after 70, 70, and 90 days, respectively. The total color change increased with increase in storage time and temperature, whereas ascorbic acid, total phenolic content, total antioxidant capacity, and overall acceptability decreased. The shelf life of S2 in glass bottles was 100, 80, and 60 days at 5, 15, and 25°C based on total color change ≥ 12, ascorbic acid loss ≥ 50%, microbial count ≥ 6 Log CFU/mL, or overall acceptability < 5. Quality indices, including total color change, overall sensory acceptability, and ascorbic acid, were modeled, and zero-order model performed better than first and second-order reaction models. Furthermore, Arrhenius, Eyring, and Ball models were employed to model temperature-dependent reaction rates, and the Ball model performed better. So, the zero-order reaction and Ball model were combined to predict kiwifruit juice’s shelf life.

Study on the adsorption process and kinetic, thermodynamic of bio-based waste cattle hair powder toward acidic complex dye.

In this paper, cattle hair waste (CHW) was collected and physically milled into different meshes of ultrafine cattle hair powder (UCHP). The reuse of CHW reaches the purpose of treating pollution with waste by using bio-base adsorbent. It was characterized by using scanning electron microscope-energy dispersive spectrometer (SEM-EDS), Fourier transform infrared (FT-IR) spectroscopy, X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), differential scanning calorimeter (DSC), and X-ray diffraction (XRD). The adsorption studies were carried out under different conditions of temperature, time, pH, concentration of dye solution, mesh size, and dosage of cattle hair powder, respectively. The pseudo-first and pseudo-secondary kinetics and intra-particle diffusion models were employed to analyze the adsorption kinetic. The Langmuir, Freundlich, and Temkin adsorption isotherm was used to analyze the adsorption isotherm. The results showed that the adsorption capacity of UCHP for acidic metal complex (Trupoxane Brown R6) dyes increased with the decreasing pH solution. The adsorption capacity of 200 mesh UCHP was 379.5mg.g-1 when the adsorption conditions were as follows: 100mL dye solution with the initial concentration of 1000mg·L-1, the dosage of adsorbent was 0.1g, the pH was 3 for 12h at 40°C. The kinetic model fitting results showed that the adsorption of dyes by UCHP conformed to the pseudo-second-order kinetic model. Adsorption thermodynamics study showed that the Langmuir model has the highest fitting result. The amino group contained on the surface of cattle hair powder and the amide bond contained in the molecular chain of peptide chain have better electrostatic adsorption binding force for acid metal complex dyes, and the binding between them is mainly electrostatic attraction. The experimental results show that the ultrafine powder has better adsorption property, which provides a high-value conversion way for recycling waste cattle hair.

Development of a Generic Physiologically Based Kinetic Model for the Prediction of Internal Exposure to Organophosphate Pesticides.

Since their introduction into agriculture, the toxicity of organophosphate (OP) pesticides has been widely studied in animal models. However, next generation risk assessment (NGRA) intends to maximize the use of novel approach methodologies based on in vitro and in silico methods. Therefore, this study describes the development and evaluation of a generic physiologically based kinetic (PBK) model for acute exposure to OP pesticides in rats and humans using quantitative structure property relationships and data from published in vitro studies. The models were evaluated using in vivo studies from the literature for chlorpyrifos, diazinon, fenitrothion, methyl-parathion, ethyl-parathion, dimethoate, chlorfenvinphos, and profenofos. Evaluation was performed by comparing simulated and in vivo observed time profiles for blood, plasma, or urinary concentrations and other toxicokinetic parameters. Of simulated concentration-time profiles, 87 and 91% were within a 5-fold difference from observed toxicokinetic data from rat and human studies, respectively. Only for dimethyl-organophosphates further refinement of the model is required. It is concluded that the developed generic PBK model provides a new tool to assess species differences in rat and human kinetics of OP pesticides. This approach provides a means to perform NGRA for these compounds and could also be adopted for other classes of compounds.

Curcumin‐Loaded Co‐Axial Electrospun Chitosan/Polyvinyl Alcohol/Calcium Chloride Nanofibrous Membranes for Wound Healing Enhancement

AbstractNanofibrous membranes were developed by combining chitosan (CS), polyvinyl alcohol (PVA), and calcium chloride (CC) to incorporate curcumin (CCM) through a co‐axial electro‐spinning method to improve CCM bioavailability. The optimal parameters were PVA/CS ratio of 7:3 v/v, PVA/CCM ratio of 8:2 v/v, CC amount of 0.5 g, fiber collection distance of 15 cm, voltage value of 18 kV, and injection flow of 0.1 mL/h (both core and shell layer). The prepared PVA/CCM@CS/PVA/CC nanofiber showed smooth surfaces and uniform bead‐free morphology with core‐shell structure. The average fiber diameter was 301.55 ± 76.77 nm with a narrow distribution. Using the Korsmeyer‐Peppas kinetic release model, the nanofiber membrane effectively released ∼85% CCM at pH 7.4 over 96 h via Fickian diffusion transport mechanism. In vitro antibacterial tests demonstrated that the membrane was efficient against both Gram‐positive (Staphylococcus aureus) and Gram‐negative (Pseudomonas aeruginosa) bacteria. When compared to free CCM, the membrane improved cell survival due to its nontoxic and cytobiocompatible features. In vivo tests found that the membrane significantly improved healing in incised‐wound rats, reducing inflammation, fibroblast proliferation, and collagen deposition. These findings indicate that the novel PVA/CCM@CS/PVA/CC nanofiber membrane, which has numerous biological functions, could be a promising candidate for wound dressing therapeutic applications.

Reduction of 2,4-dichlorophenoxy acetic acid herbicide toxicity from aqueous media by adsorption: Experimental and theoretical study using DFT method

This work studies the possibility of reducing the toxicity of water laden with 2,4-dichlorophenoxy acetic acid (2,4-D) using a commercial activated carbon (AC). Multiple structural and textural characterization techniques including Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM/EDS), point of zero charge (pHzpc) determination, Boehm titration, iodine number, Methylene blue index, and BET analysis measurements were performed on the commercial AC. Various parameters affecting adsorption were studied and well-known isotherms models in their linear and non-linear forms were applied for fitting equilibrium data. The kinetic data was analyzed using intraparticle diffusion, pseudo-first and second-order kinetic models. Density functional modeling (DFT) of 2,4-dichlorophenoxyacetic acid was used to investigate the origin of the reactivity. The AC surface area was found to be 1017 m2⋅g−1. A contact time of 30 min, an AC dose of 4 g⋅L−1 and a pH of 6.2 resulted in a maximum adsorption capacity of 235.55 ± 6.43 mg⋅g−1. The thermodynamic study revealed that the adsorption process was physical, spontaneous and endothermic. The adsorption process was governed by second-order kinetics and controlled by intraparticle diffusion.

Exploring the Mechanisms and Kinetic Modeling of Phenol Amination Using Pd and Rh‐Based Catalysts

AbstractProducing biomass‐derived chemicals to substitute their petrochemical counterparts has long been an aspiration of the green chemistry research community. However, synthesizing secondary amines from biomass precursors presents several challenges related to catalyst nature and the mechanistic understanding of reaction systems. Here, we unravel the mechanistic and kinetic implications of the reductive amination of phenol with cyclohexylamine over Pd/C and Rh/C. A competitive Langmuir‐Hinshelwood reaction model well interpreted the kinetic data, suggesting that support‐metal interfaces serve as active sites for H2, ─NH2 and ═NH activation. The apparent activation energies for imine hydrogenation were 87.6 kJ mol−1 (Pd/C) and 34.5 kJ mol−1 (Rh/C), while ΔHads and ΔSads values confirmed the physicochemical consistency of the model. Moreover, the catalysts demonstrated their high stability to operate for several catalytic cycles, with minor activity losses due to metal leaching and partial sintering of Pd nanoparticles. Despite phenol reductive amination following similar mechanisms on Rh/C and Pd/C, they show differences in selectivity because the hydrogenation of imine is more efficient on Rh0 than on Pd0. This is the first mechanism‐oriented kinetic study for phenol reductive amination; thus, it provides valuable information for process design and scale‐up.

Photocatalytic Degradation of Mancozeb Pesticide Residue using Nanoceria Doped Zinc Oxide Nanoparticles under Natural Solar Irradiation

Introduction: Excessive applications of agrochemicals to meet the high food demand from ever-increasing populations are becoming a major issue for both health practitioners and environmental managers. Chemicals such as ethylene bis-dithiocarbamate pesticide mancozeb (MCZ) are known to have deleterious effects on the ecosystem. AIM: This study, aimed at assessing the suitability of cerium-doped zinc oxide (Ce-ZnO) for efficient degradation of MCZ fungicide. Method: The photocatalysts were synthesized using the coprecipitation method with zinc nitrate hexahydrate, cerium nitrate hexahydrate, and sodium hydroxide. The synthesized nanocomposites were further characterized by Powder X-ray Diffraction (PXRD), Fourier Transform Infrared spectroscopy (FTIR), Scanning Electron Microscopy (SEM), and Energy Dispersive X-ray Spectroscopy (EDAX). The average crystallite size of the as-synthesized particles was found to be 31.42 nm, with very sharp PXRD peaks revealing the pure crystal nature of the particles. The photocatalytic degradation activity was evaluated following a series of experiments under natural environmental conditions. The optimal conditions for the degradation of MCZ fungicide using Ce-ZnO were found to be 10 ppm initial concentration of MCZ, 20 mg dose of the Ce- ZnO photocatalyst, 180 minutes irradiation time, and 10-11 atmospheric UV index. Result: At the optimum conditions, the degradation efficiency was found to be about 90% after 180 minutes. The reported photocatalytic degradation of MCZ using Ce-ZnO fits a pseudo-firstorder kinetic model with an R2 value of 0. 9677. Similarly, the reusability of the as-synthesized photocatalyst was evaluated and found to be active for five rounds with little change in the activity. Conclusion: Thus, the degradation method in the current study can be suitable for the degradation and removal of MCZ in agricultural runoff in the field.

Use of physiologically based kinetic modeling to predict neurotoxicity and genotoxicity of methylglyoxal in humans

This study aimed to evaluate human neurotoxicity and genotoxicity risks from dietary and endogenous methylglyoxal (MGO), utilizing physiologically based kinetic (PBK) modeling-facilitated reverse dosimetry as a new approach methodology (NAM) to extrapolate in vitro toxicity data to in vivo dose-response predictions. A human PBK model was defined based on a newly developed and evaluated mouse model enabling the translation of in vitro toxicity data for MGO from human stem cell-derived neurons and WM-266-4 melanoma cells into quantitative human in vivo toxicity data and subsequent risk assessment by the margin of exposure (MOE) approach. The results show that the MOEs resulting from daily dietary intake did not raise a concern for endpoints for neurotoxicity including mitochondrial function, cytotoxicity, and apoptosis, while those for DNA adduct formation could not exclude a concern over genotoxicity. Endogenous MGO formation, especially under diabetic conditions, resulted in MOEs that raised concern not only for genotoxicity but also for some of the neurotoxicity endpoints evaluated. Thus, the results also point to the importance of taking the endogenous levels into account in the risk assessment of MGO.

Stationary and Dynamic Sorption of 141Ce(III) and 152+154Eu(III) Using Alginate–Gypsum Bio-composite Beads

AbstractThis study introduces a novel Alginate–Gypsum bio-composite, synthesized at a 2:1 weight ratio, as an effective sorbent for Eu(III) and Ce(III) ions in aqueous solutions. Optimal conditions (pH 3, 5-h contact time) yielded 98% sorption efficiency for both ions in single batch systems (50 mg L−1, 20 °C). In binary systems, the composite adsorbed 33.04% of Ce(III) and 47.26% of Eu(III) (mg L−1, 20 °C). Dynamic column system showed 80.297% Ce(III) and 77.5% Eu(III) sorption. The process was endothermic, spontaneous, and best described by a quasi-nth order kinetic model. The sorption process was best described by the quasi-nth order kinetic model, with Eu(III) sorption aligning with the Langmuir and Sips models, and Ce(III) sorption following the Redlich–Peterson and Sips models. Desorption was highly efficient, with up to 99% for Eu(III) and 97% for Ce(III) using 0.1 M EDTA.

Efficient removal of congo red and cytotoxicity evaluation of biosorbents prepared from chitosan-added watermelon pulp

The development of environmentally friendly adsorbents has become increasingly important for treating waste generated by the growing global industry. In this study, new biosorbents were synthesized from an all-natural chitosan and watermelon pulp for the treatment of congo red textile dye from water. Biosorbents were prepared by lyophilizing chitosan-added watermelon pulp (AC-WPC). The prepared biosorbents were characterized by BET, SEM, Zeta Potential and FT-IR analysews. Accordingly, the BET surface area of AC-WPC was 120.92 m2/g. SEM analysis showed that the structures were porous and the results were consistent with the BET analysis. FT-IR analysis confirmed the chemical structures. The isoelectric points of the biosorbents were determined by zeta potential analysis. The AC-WPC biosorbent demonstrated 86% cell viability with cytotoxicity testing. For this reason, it was determined that the AC-WPC biosorbents produced does not cause any serious damage to the cell. Following this, adsorption study of congo red textile dye in water was carried out with these biosorbents. Langmuir and Freundlich isotherms were studied in adsorption experiments, and it was found that the Freundlich isotherms were compatible. Pseudo first and second kinetic models were also studied and found to be compatible with Pseudo Second Kinetic Model. The highest adsorption capacity was observed at 100 mg/l congo red concentration with 98.02% removal and 490.1 mg/g adsorption capacity using AC-WPC. It is thought that these results will potentially contribute to the literature on the removal of textile dyes or other pollutants using chitosan-added watermelon pulp.

Kinetic modeling and optimization of triclosan adsorption onto coconut shell activated carbon

This study investigates the efficacy of activated carbon derived from coconut shells for the removal of Triclosan (TCS) from aqueous solutions. Experimental results demonstrate the impressive efficiency of coconut shell-derived activated carbon in eliminating TCS from water. Statistical analysis underscores the significant role of agitation in enhancing adsorption efficiency, with increased agitation leading to higher contaminant removal rates. Equilibrium is rapidly achieved, with removal efficiencies exceeding 85 %. Kinetic analysis reveals rapid adsorption kinetics, predominantly following the pseudo-second-order model. Additionally, intraparticle diffusion analyses provide insights into TCS diffusion within activated carbon pores, highlighting its dependence on solute concentration. These findings underscore the potential of coconut shell-derived activated carbon as a viable solution for mitigating TCS contamination in water sources, contributing to the development of effective water treatment strategies.