Adsorption Kinetic Data Research Articles

Calcium alginate hydrogels reinforced with cellulose nanocrystals for methylene blue adsorption: Synthesis, characterization, and modelling

Water contamination due to the artificial dyes from domestic and industrial wastewater is one of the most crucial environmental issues and problems that the use of an effective adsorbent for dye adsorption seems necessary. In the present study, calcium alginate hydrogels reinforced with cellulose nanocrystals (CA/CNC) as a green and cost-effective adsorbent were utilized for the adsorption of methylene blue (MB). The characterization of CA/CNC hydrogel beads was performed by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and Brunauer–Emmett–Teller (BET). The MB adsorption kinetics data were consistent with pseudo-first-order model (R2 > 0.99). The equilibrium data of MB adsorption was best fitted by the Langmuir isotherm model and showed monolayer adsorption on homogeneous sites. The maximum Langmuir adsorption capacity (qmax) as an index of the adsorption performance was obtained as 676.7 mg g−1. The obtained results were analyzed by response surface methodology (RSM) and artificial neural network integrated with the whale optimization algorithm (ANN-WOA). ANN-WOA was coded using Python programming language. The contact time (min), shaking rate (rpm), and MB dye concentration (ppm) were considered as input factors for both methods. The fit of the predictive model by RSM was good enough with a correlation coefficient of 0.987. The ANN-WOA model with 3:7:1 topology resulted in higher correlation coefficient, lower root mean square error, and lower normalized standard deviation of 0.999, 0.758, and 15.320, respectively. However, evaluating the statistical criteria confirmed that ANN-WOA is superior to RSM for predicting the experimental data. Therefore, this work showed that CA/CNC hydrogels can be considered as a bio-adsorbent with a simple fabrication route and good adsorption capacity to remove MB from contaminated waters.

Cd2+ and Zn2+ Complexes with 2,4,6-Tri(2-pyridyl)-s-Triazine and Terephthalate for Rapid, High-Capacity Adsorption of Congo Red.

Three crystal complexes were designed and synthesised through the solvothermal method, with Cu2+ , Zn2+ , and Cd2+ ions as the metal centres and 2,4,6-tri(2-pyridyl)-s-triazine (TPTZ) and terephthalate (BDC2- ) as the ligands. Their compositions were determined to be Cd(TPTZ)Cl2 (Cd-MOF), {[Zn(TPTZ)(BDC)] ⋅ 3H2 O}n (Zn-MOF), and Cu2 (PCA)2 (BDC)(H2 O)2 (Cu-MOF) (PCA- =2-pyridinium amide), respectively. Cd-MOF can adsorb 90 % of Congo red (CR) in 10 s at room temperature and atmospheric pressure, and CR removal was complete at 20 s over a wide pH range. The adsorption capacity for CR reached 1440 mg g-1 in 5 min. Selective adsorption was demonstrated in mixed dyes. The adsorption kinetic data agree well with the pseudo-second-order kinetic model. The Temkin model was successfully used to evaluate the adsorption isotherms of CR on Cd-MOF at room temperature, suggesting that adsorption occurs through a hybrid of monolayer and multilayer mechanisms.

Predictive Model Based on K-Nearest Neighbor Coupled with the Gray Wolf Optimizer Algorithm (KNN_GWO) for Estimating the Amount of Phenol Adsorption on Powdered Activated Carbon

In this work, the adsorption mechanism of phenol on activated carbon from aqueous solutions was investigated. Batch experiments were performed as a function of adsorbent rate, solution temperature, phenol initial concentration, stirring speed, and pH. The optimal operating condition of phenol adsorption were: mass/volume ratio of 0.6 g.L−1, temperature of 20 °C and stirring speed of 300 rpm. The equilibrium data for the adsorption of phenol were analyzed by Langmuir, Freundlich, and Temkin isotherm models. It was found that the Freundlich and Temkin isotherm models fitted well the phenol adsorption on the activated carbon and that the adsorption process is favorable. The Langmuir equilibrium isotherm provides a maximum adsorption of 156.26 mg.g−1 at 20 °C. The pseudo-first-order, pseudo-second-order, intraparticle diffusion, and Boyd models were used to fit the kinetic data. The adsorption kinetics data were well described by the pseudo-second-order model. The kinetic was controlled by the external diffusion by macropore and mesopore, as well as by the micropore diffusion. The thermodynamic study revealed the exothermic and spontaneous nature of phenol adsorption on activated carbon with increased randomness at the solid-solution interface. On the other hand, a very large model based on the optimization parameters of phenol adsorption using k-nearest neighbor coupled with the gray wolf optimizer algorithm was launched to predict the amount of phenol adsorption. The KNN_GWO model showed an advantage in giving more precise values related to very high statistical coefficients (R = 0.9999, R2 = 0.9998 and R2adj = 0.9998) and very low statistical errors (RMSE = 0, 0070, MSE = 0.2347 and MAE = 0.2763). These advantages show the efficiency and performance of the model used.

Molecularly Imprinted Magnetic Nanocomposite Based on Carboxymethyl Dextrin for Removal of Ciprofloxacin Antibiotic from Contaminated Water.

Broad-spectrum antibiotics from the fluoroquinolone family have emerged as prominent water contaminants, among other pharmaceutical pollutants. In the present study, an antibacterial magnetic molecularly imprinted polymer (MMIP) composite was successfully fabricated using carboxy methyl dextrin grafted to poly(aniline-co-meta-phenylenediamine) in the presence of Fe3O4/CuO nanoparticles and ciprofloxacin antibiotic. The characteristics of obtained materials were investigated using FTIR, XRD, VSM, TGA, EDX, FE-SEM, zeta potential, and BETanalyses. Afterward, the MMIP's antibacterial activity and adsorption effectiveness for removing ciprofloxacin from aqueous solutions were explored. The results of the antibacterial tests showed that MMIP had an antibacterial effect against Escherichia coli, a Gram-negative pathogen (16 mm), and Staphylococcus aureus, a Gram-positive pathogen (22 mm). Adsorption efficacy was evaluated under a variety of experimental conditions, including solution pH, adsorbent dosage, contact time, and initial concentration. The maximum adsorption capacity (Qmax) of the MMIP for ciprofloxacin was determined to be 1111.1 mg/g using 3 mg of MMIP, with an initial concentration of 400 mg/L of ciprofloxacin at pH 7, within 15 min, and agitated at 25 °C, and the experimental adsorption results were well-described by the Freundlich isotherm model. The adsorption kinetic data were well represented by the pseudo-second-order model. Electrostatic interaction, cation exchange, π-π interactions, and hydrogen bonding were mostly able to adsorb the majority of the ciprofloxacin onto the MMIP. Adsorption-desorption experiments revealed that the MMIP could be retrieved and reused with no noticeable reduction in adsorption efficacy after three consecutive cycles.

Enhanced vector transport of microplastics-bound lead ions in organic matter rich water

ABSTRACT Microplastics act as a vector for toxic trace metals and their surface complexation mechanisms under different environmental conditions are poorly understood. The present study evaluates the interaction mechanisms of pristine and aged polyethylene (PE) microplastics with Pb2+ in water environments in the presence of NaNO3 and humic acid (HA). The influence of pH, contact time, and concentration of Pb2+ on the sorption performances of PE microplastics have also been examined at different ionic strengths (0.001–0.1 M NaNO3), pH (2–9), reaction time (48 h), Pb2+ loading concentrations (1–25 mg L−1), and HA concentrations (0.5–2.5 mg L−1). The Pb2+ adsorption onto both pristine and aged microplastic showed a gradual increase with increasing pH, reaching maximum adsorption at around pH 5–6. Adsorption of Pb2+ onto both PE microplastics decreased at higher ionic strengths and increased at higher HA concentrations suggesting the possible hydrophobic and electrostatic interactions between microplastics and Pb2+ ions. Adsorption kinetic data for pristine PE microplastics were well described by fractional power model indicating time-dependent adsorption, whereas aged PE showed rate-limiting chemisorption by fitting with a pseudo-second-order kinetic model. Isotherm equilibrium data for pristine PE microplastics fitted well for the Freundlich model implying favourable physisorption on the heterogeneous surfaces. Both Hill and Freundlich models were the best-fitted models for aged PE microplastics suggesting the involvement of cooperative multilayer physisorption. Desorption of PE microplastics-bound Pb2+ was greatly influenced by the solution pH. The ascertaining facts elucidated the vector potential of PE microplastics for Pb2+, impacting their migration and destination in water systems where the adsorption could be influenced by the pH, ionic strength, and dissolved organic matter of the water system.

Adsorption of Orange G Dye on Hydrophobic Activated Bentonite from Aqueous Solution

This report focusses on the modification of physical structure and chemical properties of a bentonite clay from the Hammam Boughrara region of the Maghnia district in western Algeria to maximize its adsorption capacity. The purified bentonite clay (called B) was modified, either by acid activation with 1M sulfuric acid (B-Act), or by intercalation with the cationic surfactant cetytrimethyl ammonium bromide (CTAB), applying a cation exchange capacity (CEC) of 100% (called B-CTAB). Modification of B was also introduced by combining these two steps consecutively, i.e., at first acid activation of B, followed by intercalation with CTAB (B-Act-CTAB). The B-Act-CTAB was obtained by H2SO4 (1M) acid activation, followed by co-adsorption of CTAB with 100% and 300% of the CEC of B-Act as precursor. In particular, a strong increase of surface area and pore volume of the modified bentonites was observed for B-Act (469.83 m²/g and 0.401 cm3g−1), B-Act-CTAB100 (267.72 m²/g and 0.316 cm3 g−1) and B-Act-CTAB300 (111.15 m²/g and 0.171 cm3g−1), compared to B (31.79 m²/g and 0.074 cm3 g−1) and B-CTAB (3.79 m²/g and 0.034 cm3 g−1), respectively. The bentonite-based adsorbents were then used to evaluate the removal efficiency of an organic molecule, the azo dye Orange G (OG), as a model for a Persistent Organic Pollutant. Freundlich, Langmuir and Sips (Langmuir–Freundlich) models were applied to analyze equilibrium isotherms, showing a good correlation between experimental data and the Freundlich model. A good agreement was obtained between experimentally obtained kinetic adsorption data and the pseudo-second-order model, allowing to evaluate rate constants. B-Act-CTAB300 can be applied as a low-cost material for removal of azo dyes, since its adsorption capacity towards OG (102.80 mg/g) exceeds largely that of B-CTAB (31.49 mg/g) and B-Act-CTAB100 (12.77 mg/g).

A novel smart stealth sorafenib delivery system based on the magnetic imprinting material modified by polyethylene glycol

AbstractIn order to improve the solubility and the long‐cycle performance of hydrophobic drug sorafenib (SOR), and to obtain an ideal smart drug delivery system for the effective treatment of liver cancer, S‐SMIP, a pH/GSH double‐sensitive sorafenib stealth imprinting material, was successfully prepared by UV‐initiated surface imprinted polymerization on the basis of polyethylene glycol 2000 (PEG2000) acted as “gate keeper” modified magnetic substrate. The results showed that S‐SMIP had a good adsorption capacity of 260.0 mg g−1 and an excellent selectivity factor α 2.33. S‐SMIP's kinetic adsorption data accorded well with the pseudo‐second‐order model and its mechanism was controlled mainly by chemical adsorption. The drug release experiments in vitro indicated S‐SMIP could not only greatly improve the solubility of SOR, but also had the pH/GSH dual‐sensitive response performance. Compared with the non‐stealth imprinted material SMIP, S‐SMIP still had a better long‐cycle effect on the release of SOR, increasing to160 h from 130 h. So, the target material S‐SMIP could greatly prolong the half‐life of SOR, which provided a good idea for the development of a smart drug delivery system.

Preparation of fluorescently and biologically active chain-like chitosan nanocomposite and its use in separating MBP-tagged proteins and as fluorescent tracer of tobacco

Chain-like chitosan-sodium tripolyphosphate (CS-TPP) nanocomposite was prepared by an aqueous solution route. Then fluorescently active 6-carboxyl luciferin (6-FAM) was modified onto CS-TPP surface to afford CS-TPP-6-FAM nanocomposite (CS-TPP-6-FAM) with fluorescent activity. Onto the surface of CS-TPP-6-FAM was grafted bioactive carboxymethyl β-cyclodextrin (CβCD) to obtain CS/TPP/FAM/CβCD that can separate maltose binding protein tagged (MBP-tagged) fusion proteins from E. coli lysate. Findings demonstrate that CS-TPP-6-FAM-CβCD has an average diameter of 22 nm and a chain length of 70 nm. Its adsorption kinetic data can be described by Langmuir isotherm equation and the pseudo 2nd kinetic model, corresponding to high protein binding capacity for MBP-tagged PYL3. Furthermore, CS-TPP-6-FAM-CβCD dispersed in Hoagland nutrient solution can be adsorbed by tobacco through vascular bundle channels. Therefore, CS-TPP-6-FAM-CβCD could have promising applications in separating MBP-tagged fusion proteins from E. coli lysate and in monitoring the growth of plants as the fluorescent tracer.

Alginate coated superparamagnetic iron oxide nanoparticles as nanocomposite adsorbents for arsenic removal from aqueous solutions

Superparamagnetic iron oxide nanoparticles (SPIONs) were synthesized by the hydrothermal method and used for effective removal of arsenite, As(III), in their native and alginate beads-encapsulated (SPIONs-Alg) forms. The size of SPIONs was determined as ∼25 nm, and the structural properties of the adsorbents were validated using FTIR and XRD. The magnetization curve had zero coercivity, indicating superparamagnetism. Furthermore, the effects of pH, contact time, temperature, adsorbent dosage, and initial As(III) concentration on removal efficiency were studied. The optimum removal percentages for SPIONs and SPIONs-Alg were 99% and 90%, respectively, at pH 7, 30 °C, and 6.5 mg/L As (III) concentration.The Langmuir isotherm model (R2 ≥ 0.97 for SPIONs and R2 ≥ 0.99 for SPIONs-Alg) fitted the equilibrium data better than Freundlich. The As(III) adsorption capacity of sorbents was evaluated using the Langmuir adsorption isotherm and found to be 11.89 mg/g and 240.081 mg/g for SPIONs and SPIONs-Alg, respectively. The adsorption kinetic data for both adsorbents showed a better fit to the pseudo-second-order kinetic model (R2 ≥ 0.99). The spontaneity of the adsorption process, the endothermic nature of the sorption reaction, and the adsorbents' affinity for As(III) were determined using the negative ΔG, positive ΔH and ΔS values. SPIONs-Alg (1.5 g/l solid-to-liquid S/L ratio) could be collected easily, recovered using 0.1 M NaOH, and reused for five times (sorption ≥ 97%). The feasibility of SPIONs-Alg as a promising adsorbent for removing As(III) from wastewater is clearly validated.

Bis-Catecholamide-Based Materials for Uranium Extraction.

This work reports the synthesis of formo-phenolic resins containing four catecholamide (CAM) moieties with admixture of phenol, catechol or resorcinol. These chelating resins have been developed to selectively extract U(VI) from seawater. This media is a challenging environment due to a pH around 8.2 and a large excess of alkaline and earth-alkaline cations. From the various sorption experiments investigated, the results indicate that the synthesized material exhibit good sorbent properties for U(VI) with uptake capacity about 50 mg/g for the more promising resins with a pronounced selectivity for uranium even under saline conditions. Thermodynamic and kinetic adsorption data were determined for the best resin (Langmuir adsorption model and pseudo-second order model).

Unveiling interactions of norfloxacin with microplastic in surface water by 2D FTIR correlation spectroscopy and X-ray photoelectron spectroscopy analyses

Microplastics (MPs) has shown adsorption of hydrophilic organic matters (HOMs) in aqueous environments. However, it is still difficult to predict the adsorption behaviors of HOMs by different MPs, especially in authentic water systems. In this study, the adsorption behaviors and mechanisms of norfloxacin (NOR) onto polyamide (PA) MPs were investigated in both simulated and real surface water. The results showed that the adsorption equilibrium of NOR by PA in simulated surface water could be achieved within 15 h, while the adsorption rate of NOR in real surface was slowed down, with the equilibrium time of 25 h. Pseudo-second-order model could well describe the adsorption kinetics data. The experimental maximum adsorption capacity of NOR on PA in real surface water (e. g. 132.54 ug/g) was dramatically reduced by 37.5 % compared with that in simulated surface water (e. g. 212.25 ug/g), and the adsorption isotherm would obey Freundlich model. Besides, the leaching of NOR from the surface of PA could occur obviously at acidic environment. Furthermore, the salinity and natural organic matter exhibited significantly adverse effects on the NOR adsorption. Finally, the results of 2D Fourier transform infrared correlation spectroscopy and X-ray photoelectron spectroscopy indicated that the electrostatic, H-bond and van der Waals interactions were involved in the adsorption. More importantly, the sequential functional groups in the adsorption process followed the orders: 1638 (CO) > 1542 amide II (-NH-CO) > 717 (CH2) > 1445 (CO) > 973 amide IV (CONH). This study could provide an insight into the interactions between PA and NOR in different water environments.

Exploring the performance of magnetic methacrylic acid-functionalized β-cyclodextrin adsorbent toward selected phenolic compounds

In this study, the removal of bisphenol A (BPA), 2,4-dinitrophenol (2,4-DNP), and 2,4-dichlorophenol (2,4-DCP) using a new magnetic adsorbent methacrylic acid-functionalized β-cyclodextrin (Fe3O4@MAA-βCD) was evaluated. The materials were characterized by Fourier transform infrared spectroscopy, scanning electron microscope, transmission electron microscopy, and X-ray diffraction. The batch adsorption experiments optimized and evaluated various operational parameters such as pH, contact time, sorbent dosage, initial concentration, and temperature. The result shows that DNP possessed the most excellent affinity toward Fe3O4@MAA-βCD adsorbents compared to BPA and DCP. Also, BPA showed the lowest removal and was used as a model analyte for further study. The adsorption kinetic data revealed that the uptake of these compounds follows the pseudo-second order. Freundlich and Halsey isotherms best-fitted the adsorption equilibrium data. The desorption process was exothermic and spontaneous, and a lower temperature favored the adsorption. Furthermore, hydrogen bonding, inclusion complexion, and π–π interactions contributed to the selected phenolic compound’s adsorption.

Polyacrylic-Co-Maleic-Acid-Coated Magnetite Nanoparticles for Enhanced Removal of Heavy Metals from Aqueous Solutions

The physicochemical properties of ligand-coated nanoparticles make them superior adsorbents for heavy metals from water. In this study, we investigate the adsorption potential of novel polyacrylic-co-maleic-acid-coated magnetite nanoparticles (PAM@MNP) to remove Pb2+ and Cu2+ from an aqueous solution. We argue that modifying the surface of MNP with PAM enhances the physicochemical stability of MNP, improving its ability to remove heavy metals. The adsorption kinetics data show that PAM@MNP attained sorption equilibrium for Pb2+ and Cu2+ after 60 min. The kinetics data are fitted accurately by the pseudo-first-order kinetic model. The calculated Langmuir adsorption capacities are 518.68 mg g−1 and 179.81 mg g−1 for Pb2+ and Cu2+, respectively (2.50 mmol g−1 and 2.82 mmol g−1 for Pb2+ and Cu2+, respectively). The results indicate that PAM@MNP is a very attractive adsorbent for heavy metals and can be applied in water remediation technologies.

Synthesis and evaluation of a novel polycarbonate grafted poly (glycidyl methacrylate) resin for sorption of 131I

To synthesize Q[A(PC-g-PGMA), Glycidyl Methacrylate (GMA) was grafted onto Polycarbonate (PC) using a radiation-induced grafting technique, followed by amination and quaternization. It was studied how total concentration, monomer concentration, and absorbed dosage affect the degree of grafting (DG). FTIR, SEM, and TGA were used to describe the structure of the resultant Q[A(PC-g-PGMA)]. Q[A(PC-g-PGMA)] was utilized in a batch procedure to investigate the sorption efficiency of 131I in varied concentrations of HCl and/or HNO3 solutions. The results showed that 0.01 M HNO3 is the optimum medium for high retention of 131I, with a maximum capacity of 187 mg/g. The kinetic and isotherm data of 131I adsorption revealed that it followed the Pseudo-second-order and Freundlich models, respectively. The sorption process of 131I was discovered to be endothermic and spontaneous after studying thermodynamic parameters such as enthalpy change (ΔH°), free energy change (ΔG°) and entropy change (ΔS°).

Structural Properties of Graphene Oxide Prepared from Graphite by Three Different Methods and the Effect on Removal of Cr(VI) from Aqueous Solution.

Herein, three types of graphene oxides (GOs, GO-M1, GO-M2 and GO-M3) have been successfully prepared from graphite by three different methods and utilized for the removal of Cr(VI) from aqueous solutions. Further, the effects of initial concentration and pH, adsorbent dosage, contact time and temperature on the adsorption performance of GOs were investigated by batch adsorption experiments. Furthermore, the adsorption mechanisms for Cr(VI) adsorption by GOs are mainly the redox reaction and electrostatic attraction, while there are also pore filling, ion exchange and complexation involved in these adsorption processes. The adsorption kinetic and isotherm data indicate that these adsorption processes of GOs on Cr(VI) are dominantly monolayer chemisorption and equilibrium can be reached in 30 min. The saturation adsorption capacities (Qm, 298.15 K) of GO-M1, GO-M2 and GO-M3 for Cr(VI) are estimated to be 3.5412 mg⋅g-1, 2.3631 mg⋅g-1 and 7.0358 mg⋅g-1, respectively. Moreover, the adsorption thermodynamic study showed that these adsorption processes of Cr(VI) by the three types of GOs at 298.15 K to 323.15 K are endothermic, entropy-driven and thermodynamically spontaneous and feasible. Overall, these findings provided vital insights into the mechanism and application of Cr(VI) removal by GOs.

Adsorption of methylene blue from aqueous solution using poly(2-acrylamido-2-methyl-1-propanesulfonic acid-co-2-hydroxyethyl methacrylate) hydrogel crosslinked by activated carbon

This study aimed to develop an environmentally friendly, inexpensive, and efficient adsorbent for removing methylene blue (MB) dye from wastewater using a three-dimensional porous poly(2-Acrylamido-2-methyl-1-propanesulfonic acid-co-2-Hydroxyethyl Methacrylate), p(AMPS-co-HEMA) composite hydrogel crosslinked with vinyl-functionalized activated carbon (VAC). The surface morphology and chemical structure of the crosslinker were characterized using transmission electron microscopy (TEM), Brunauer-Emmett-Teller (BET) surface area analysis, X-ray spectroscopy (XRD) and Fourier transform-infrared spectroscopy (FT-IR) instruments. The surface morphology, chemical structure and thermal properties of the hydrogel were also characterized using scanning electron microscopy (SEM), FT-IR and thermogravimetric analyzers (TGA). Experimental parameters affecting the adsorption behavior, such as initial dye concentration, time, dosage, pH, and temperature, were systematically investigated. Hydrogel achieved optimal MB removal efficiency (69.53%) at an initial MB concentration of 250 mg/L (1 mg/mL, pH not adjusted) over 24 h. Adsorption kinetics, isotherm, thermodynamic studies, and reusability were investigated. Experimental adsorption isotherm and kinetic data followed the Langmuir model and pseudo-second-order kinetics with a maximum adsorption capacity of 284.90 mg/g hydrogel at 293 K. Thermodynamic findings proved the spontaneity and endothermic behavior of the adsorption process. After 5 adsorption-desorption cycles, the adsorption capacity of the composite hydrogel decreased by only 7.51 mg/g compared to the initial adsorption capacity.

Pb(II) Removal from Aqueous Solutions by Adsorption on Stabilized Zero-Valent Iron Nanoparticles—A Green Approach

Nano zero-valent iron particles (nZVFe) are known as one of the most effective materials for the treatment of contaminated water. However, a strong tendency to agglomerate has been reported as one of their major drawbacks. The present study describes a green approach to synthesizing stabilized nZVFe, using biomass as a porous support material. Therefore, in the first step, biomass-derived activated carbon was prepared by thermochemical procedure from rice straw (RSAC), and then the RSAC-supported nZVFe composite (nZVFe–RSAC) was employed to extract Pb(II) from aqueous solution and was successfully synthesized by the sodium borohydride reduction method. It was confirmed through scanning electron microscopy (SEM) and X-ray diffraction (XRD) characteristics that the nZVFe particles are uniformly dispersed. Results of the batch experiments showed that 6 (g L−1) of this nanocomposite could effectively remove about 97% of Pb(II) ions at pH = 6 from aqueous solution. The maximum adsorption capacities of the RS, RSAC, and nZVFe–RSAC were 23.3, 67.8, and 140.8 (mg g−1), respectively. Based on the results of the adsorption isotherm studies, the adsorption of Pb(II) on nZVFe–RSAC is consistent with the Langmuir–Freundlich isotherm model R2=0.996). The thermodynamic outcomes exhibited the endothermic, possible, and spontaneous nature of adsorption. Adsorption enthalpy and entropy values were determined as 32.2 kJ mol−1 and 216.9 J mol−1 K−1, respectively. Adsorption kinetics data showed that Pb(II) adsorption onto nZVFe–RSAC was fitted well according to a pseudo-second-order model. Most importantly, the investigation of the adsorption mechanism showed that nZVFe particles are involved in the removal of Pb(II) ions through two main processes, namely Pb adsorption on the surface of nZVFe particles and direct role in the redox reaction. Subsequently, all intermediates produced through the redox reaction between nZVFe and Pb(II) were adsorbed on the nZVFe–RSAC surface. According to the results of the NZVFe–RSAC recyclability experiments, even after five cycles of recovery, this nanocomposite can retain more than 60% of its initial removal efficiency. So, the nZVFe–RSAC nanocomposite could be a promising material for permeable reactive barriers given its potential for removing Pb(II) ions. Due to low-cost and wide availability of iron salts as well as rice biowaste, combined with the high adsorption capacity, make nZVFe–RSAC an appropriate choice for use in the field of Pb(II) removal from contaminated water.

Sonicating for the Uptake of Paracetamol from Solution by Activated Carbon from Oak: Kinetics, Thermodynamics, and Isotherms

This inquiry used ultrasonic waves to uptake paracetamol (PA) by using oak-based activated carbon (ACO). The surface of ACO was explored based on FT-IR, SEM, and XRD before and after the adsorption. The kinetic data for PA adsorption onto ACO corresponds to a pseudo-second-order kinetic model. Isothermal models of the Langmuir, Freundlich, D-R, and Temkin were used. The adsorption of PA onto ACO was found to be a monolayer with 96.03% uptake, which corresponds to Langmuir. The thermodynamic experiments revealed the endothermic nature of PA adsorption onto ACO. Under the investigated optimal conditions, the adsorption capacity of PA onto ACO was found to be 97.1 mg. L-1. ACO could be recycled after six regenerations. Ultimately, sonicating has adequate performance for the uptake of PA by ACO.

Evaluation on the performances of adsorption desalination employing functionalized metal-organic frameworks (MOFs)

• Isotherms and kinetics data for water adsorption on functionalized MOFs. • Equations of entropy flow and generation for evaluating AD performances. • Measurement of structural and thermal stabilities of functionalized MOFs. • Calculation of SDWP and PR by temperature-entropy analysis for the first time. • 5%Li-Al-Fum shows minimum entropy generation with higher SDWP. This study focuses on a comprehensive study of MOFs (metal-organic frameworks) plus water systems for adsorption desalination applications. The paper first deals with the modification of parent MOFs such as aluminium fumarate, MOF-801 (Zr) and UiO-66 (Zr) employing MOFs functionalization, alkali ion doping and impregnation of zeolites, and secondly, we focus on their characterizations for understanding both structural and thermal stabilities. Later, water adsorption on these parents and modified MOFs are investigated for a wide range of pressure (0 < P/P s < 1.0) and temperature (30 to 80 °C). Based on experimentally confirmed isotherms, kinetics and MOFs characteristics data, the performance factors such as SDWP (specific daily water production) and PR (performance ratio) are evaluated for various regeneration temperature (55 to 80 °C) and cycle time (100 to 1000 s). Furthermore, the water adsorption characteristics are applied to calculate the entropy flow and generation for each component of AD system. The SDWP is also calculated from the concepts of temperature – entropy diagram. It is found that both OH-UiO-66 (Zr) and 5%Li-Al-FumMOFs provide promising SDWP (> 34 m 3 /tonne of MOFs/day) and 5%Li-Al-Fum shows minimum entropy generation.

Synthesis of Chitosan-TiO2 Nanocomposite for Efficient Cr(VI) Removal from Contaminated Wastewater Sorption Kinetics, Thermodynamics and Mechanism.

A photolysis method was used to prepare a nanocomposite adsorbent (Chitosan-TiO2) and was tested for Cr(VI) removal from aqueous solution. The produce nanocomposite was investigated using, XRD, BET, FTIR, FESEM-EDX and TEM before and after Cr(VI) adsorption. The XRD results shows prepared anatase phase of TiO2 with 12 nm. According to BET measurements, the surface area of the TiO2/chitosan nanocomposite was lower and archived to 26 m2/g, while the TEM and FESEM images show a uniform distribution of TiO2 throughout the chitosan matrix. Adsorption and kinetic experiments were run in batch system under different conditions of pH, contact time, adsorbent dosage and temperature. Experimental Cr(VI) adsorption equilibrium and kinetics data fitted well to Langmuir model. The calculated Langmuir maximum adsorption capacity (qmax) value of nanocomposite was 488 mg/g. Moreover, the highest quantity of Cr(VI) uptake was achieved of pH = 2 and 45℃ and TiO2 and CS-TiO2 had respective removal efficiencies of 94 and 87.5%. The thermodynamic parameters of Cr(VI) adsorption by nanocomposite affirm the spontaneous and endothermic nature of process. Chromium adsorption mechanism by CS-TiO2 nanocomposite were proposed and discussed.