Intraparticle Diffusion Model Research Articles

Highly porous biomass-derived graphene-based carbons for removal of phenol from wastewater

This study explores the effectiveness of highly porous graphene-based carbons derived from biomass as an adsorbent for removing phenol from aqueous solutions. The graphene-based carbons were extensively characterized using electron microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, and BET analysis. They predominantly consisted of sp2-bonded carbons and demonstrated an exceptionally high specific surface area with an interconnected pore structure. This unique structure enables effective phenol adsorption primarily through favorable π-π interactions, resulting in outstanding adsorption capacity. Both Langmuir and Freundlich isotherm models provided excellent fits to the adsorption data, confirming the favorable phenol adsorption characteristics of the carbons. Furthermore, the adsorption kinetics were well-described by non-linear pseudo-first-order (PFO), pseudo-second-order (PSO), and linear intraparticle diffusion (IPD) models, indicating that phenol adsorption occurs through a physisorption mechanism involving the phenolic ring and the basal plane of the carbon. This study underscores the potential of biomass-derived graphene-based carbon as a cost-effective and efficient adsorbent for phenol removal, offering promising implications for sustainable water treatment solutions.

Removal of Bisphenol S (BPS) by Adsorption on Activated Carbons Commercialized in Brazil.

This study assessed three powdered activated carbons (BETM, COCO, and SIAL) commercialized in Brazil at the bench scale in agitated reactors, analyzing their kinetic behavior and adsorptive capacity for BPS and BPA in ultrapure water. BETM exhibited the highest adsorption capacities (Q0max) for BPS and BPA at 260.62 and 264.64 mg/g, respectively, followed by SIAL, with a Q0max of 248.25 mg/g for BPS and for 231.20 mg/g BPA, and COCO, with a Q0max of 136.51 mg/g for BPS and 150.03 mg/g for BPA. The Langmuir isotherm model can describe the processes well. A pseudo-second-order model can describe the adsorption kinetics, and SIAL carbon had the highest rate constants (7.45 × 10-3 mg/g/min for BPS and 2.84 × 10-3 mg/g/min for BPA). The Weber-Morris intraparticle diffusion model suggests intraparticle diffusion as the rate-limiting step of all adsorption processes. Boyd's model confirmed more than the mechanism actuating in the bisphenol adsorption. The results suggest that adsorbents with basic surfaces, high specific surface areas, and high mesopore volumes tend to remove BPS and BPA efficiently. Therefore, activated carbons can effectively complement the existing treatment in Brazilian water treatment plants (WTPs).

Polystyrene-reduced graphene oxide composite as sorbent for oil removal from an Oil-Water mixture

This study enhanced the adsorptive capacity of polystyrene (PS) by infusing reduced graphene oxide (rGO) nanoparticles obtained from the synthesis of graphene oxide to produce PS-rGO composites via electrospinning method. Physicochemical characterization of as-synthesized rGO and PS-rGO were carried out through scanning electron microscopy, N2 physisorption among others. Oil sorption performance of synthesized rGO in crude oil, vegetable oil, fresh engine oil and used engine oil are 130.96 g/g, 121.77 g/g, 105.01 g/g and 100.56 g/g. Oil sorption capacities of electrospun pure PS in crude oil, vegetable oil, fresh engine oil and used engine oil were 46.32 g/g, 38.54 g/g, 35.14 g/g and 32.57 g/g and those of PS-rGO infused with 4 wt% of rGO were found to be 105.52 g/g, 98.86 g/g, 86.25 g/g and 83.47 g/g for crude oil, vegetable oil, fresh engine oil and used engine oil samples respectively. Pseudo second order (PSO) kinetic model fits the sorption data of the four oil samples on the four composite sorbents produced. Intra-particle diffusion (IPD) model evidently showed that sorption of the four oil samples on the four composite sorbents, occurred in three (3) phases. Composites demonstrate high oil adsorption capacity, and are reusable upto three sorption–desorption cycles.

Aqueous arsenic (III) removal using a novel solid waste based porous filter media block: Traditional and machine learning (ML) approaches

Arsenic (As) contamination of groundwater is one of the main obstacles preventing people from having easy access to potable water. Gypsum-based a porous filter media block (PFMB) made with moringa bark was proposed to remove arsenic (III) from aqueous solutions. The adsorption isotherms using Langmuir (R2 = 0.976) and Freundlich (R2 = 0.967) and kinetics using pseudo-first and second order and intraparticle diffusion models were achieved. The removal rates of PFMB using 10 g/L in batch experiments were found to be 98.4 % and 94.2 % for 0.50 and 1.0 ppm, respectively. The efficiency was evaluated by varying the material composition, pH, and experimental conditions using a machine learning model with an R2 = 0.95. A new approach to forecasting adsorption capacity based on material composition and experimental data allows the effective determinate to be found from a wider perspective. The model explanation with shapley additive value (SHAP) and partial dependence plots (PDP) showed the initial concentration, and time were the most influential factors in the adsorption process. Arsenic (III) adsorption on the innovative composite material appears promising, which will ensure the reuse and effective disposal of solid waste. ANN can be used to evaluate and predict new conditions without lab experimentation.

Modification of PVA Nanofiber by Simple Hot Water Treatment and Application on the Removal of Malachite Green Dye From Aqueous Solutions.

In this study, the crosslinking of PVA nanofiber was increased using solvent vapor treatment. Then, Fe3O4 nanoparticles were synthesized by a simple hot water technique and composited with the nanofiber. The study focuses on applying the modified PVA nanofibers to remove malachite green (MG) from water using different pH, contact times, and dye initial concentrations. The surface morphology of the nanofiber was determined using SEM, FTIR, and XRD techniques. SEM showed that the crosslinking was increased, and Fe3O4 nanoparticles appeared as agglomerates on the surface of the nanofiber. The removal percentages at optimal pH and contact time were 99.76%, and 99.5%, respectively. Thereafter, kinetics was studied by the linear pseudo-first order, pseudo-second order, Elovich equation, and Intraparticle diffusion models. Results demonstrated that the adsorption kinetics follow the pseudo-second order. Moreover, the adsorption isotherm was discussed using Langmuir and Freundlich equations. The Langmuir equation best described the adsorption with R2 value of 0.9771, and the maximum removal was 128.205 mg/g. As a result, the MG dye molecules covered the PVA nanofiber/Fe3O4 nanoparticles in a monolayer and homogenous coverage. The results of this study are significant for industries' wastewater treatment as they provide a potential solution for the removal of MG dye from textile, paper, cosmetics, food, and aquaculture industries' wastewater.

Thiol-functionalized cellulose adsorbents for highly selective separation of palladium over platinum in acidic aqueous solutions

The selective separation of palladium (Pd) over platinum (Pt) remains a challenge in metal recycling, because of their similar electronic configuration and chemical properties. This study explored their selective separation using three new adsorbents by grafting sulfur-donor ligands onto cellulose, namely 2-aminothiophenol (Cell-AP), 2-mercaptopyridine (Cell-MP), and 2-mercaptobenzothiazole (Cell-MBT). These adsorbents exhibited excellent adsorption capacity for Pd(II), reaching 163.3 ± 2.5 mg/g (at pH 1), 92.5 ± 1.2 mg/g (at pH 1), and 27.5 ± 0.5 mg/g (at pH 2.5), respectively. Isotherm studies showed that the adsorption process followed Freundlich isotherm, indicating a multilayer adsorption that takes place on a heterogenous surface. Kinetic results fit best with pseudo-second-order and intra-particle diffusion model, suggesting that the rate-limiting process involves chemisorption and intra-particle diffusion. Thermodynamic studies showed that adsorption by Cell-AP and Cell-MP was a spontaneous exothermic reaction. The materials also showed superior selectivity of Pd(II) over Pt(IV) with a maximum separation factor (SFPd/Pt) of 64.50, which improves over most previous studies. The mechanism of selectivity was further investigated by XPS, FTIR, SEM and DFT calculations, which showed that PdCl42- has smaller size, shorter HOMO-LUMO gap, and lower binding energy to ligands as compared to PtCl62-. This was used to explain the higher affinity for Pd(II) over Pt(IV) of these sulfur-modified adsorbents. This work provides a practical approach for the selective separation of Pd over competing ions that could improve the efficiency for overall metal recovery or recycling processes.

Ammonia gas adsorption study using copper impregnated on mesoporous activated carbon from seaweed waste for indoor air purification

Ammonia (NH3), as a toxic gas, has negative impacts on human health even at low concentration, especially in narrowed spaces. In this study, activated carbon was synthesized from seaweed waste and copper was loaded on its surface (Cu/AC filter) to prepare a cost-effective NH3 adsorbent. Pyrolysis (carbonization) temperature can significantly affect the texture properties of activated carbon, and the best activated carbon sample with BET of 1114 m2/g was obtained through pyrolysis at 500 °C followed by KOH-activation at 750 °C. Different from other lignocellulosic biomass-based activated carbons (mainly microporous structure), the prepared algae-based activated carbons mainly have a mesoporous structure (pore size: 7.0–9.0 nm). Copper-impregnation significantly changed the surface chemistry of activated carbon, thereby greatly increasing the NH3 adsorption capacity (max: 128.6 mg/g). The adsorption performance was primarily determined by chemical adsorption (caused by copper impregnation and related inherent functional groups, including O–H, C–H, O–Si–O and SiO–H), followed by physical adsorption (caused by BET). Isotherm studies indicated that NH3 adsorption on Cu/AC filter followed the Langmuir model, whereas the adsorption kinetics followed the pseudo-second-order model. Furthermore, the adsorption mechanism was controlled by intraparticle diffusion model with initial adsorption behavior. This can be attributed to the mesoporous structures of activated carbon, consequently dramatically improving the diffusion efficiency. In addition, the Cu/AC filter showed good regeneration performance, as it can still remain above 90 % after 5 cycles. Finally, this study demonstrated that the seaweed waste is a good precursor for activation carbon and has great potential as excellent NH3 adsorbent for indoor air purification.

Performance evaluation of calcined eggshell waste (Sorbent) for biogas upgrading: Adsorption isotherms, adsorption kinetics, and fixed bed studies

The use of non-renewable energy resources such as fossil fuels accelerates climate change and environmental degradation necessitating a shift to renewable energy sources. Biogas is a renewable energy resource with great potential. However, its application is limited by the presence of contaminants such as carbon dioxide, which reduces its energy value, and density. Upgrading biogas using locally available materials solves waste management and energy sustainability challenges. In the present study, calcined eggshell waste was employed as an adsorbent for carbon dioxide. The effect of calcination temperature, adsorbent mass and adsorbent particle size was evaluated. The experimental data was fitted to adsorption isotherms, adsorption kinetic models, and breakthrough curves. Eggshells with a particle size of 280 μm, calcined at 850 °C, and mass of 75 g showed the best performance in removing carbon dioxide from biogas. It was noted that data from the experiment fitted Langmuir isotherm with RL 0.00216 while its R2 was 0.97 and Freundlich n = 0.6 while R2 = 0.97. Regarding adsorption kinetics, the intra-particle diffusion model shows good conformity with kid of 34, C of 98, and R2 of 0.977. Breakthrough analysis proved that Yoon Nelson's Model fitted well with the experimental data with an R2 of 0.989. Thus, calcined eggshell waste is a good sorbent for biogas upgrading that can solve the twin challenges of waste disposal and management and energy sustainability.

Zinc oxide nanoparticles encapsulated in alginate beads: a promising and recyclable adsorbent for simultaneous uptake of toxic metals

Heavy metal toxicity is a known problem and various methods are used for treatment. Adsorption has some advantages and it would be promising if environmentally friendly and cheap materials were utilized. Alginate and zinc oxide nanoparticles were selected and composite alginate beads were used for the removal of mixed metals from aqueous solutions. Batch and column experiments were conducted to determine some parameters’ effects and the adsorbent’s real application potential. According to the batch experiments, zinc oxide nanoparticles to alginate ratio of 0.5 g g−1, and pH levels nearby to the neutral range led to better metal removals. 0.5 ml min−1 of flow rate supplied better metal removal efficiencies in columns, with the highest treatment as 86% of Pb2+. Acid treatment can be successfully applied for the regeneration of the adsorbent, at least three times only with a 4% reduction in the adsorption efficiency. Heavy metal uptake was compatible with the pseudo 2nd order model indicating chemisorption as a dominant mechanism. Also, the intraparticle diffusion model illustrated adsorption might govern more than one step. The Langmuir model had the best fit and suggested monolayer covering for Pb2+, 76.3 mg g−1. Alginate-based nanocomposite beads were useful for mixed metal removal and could be used.

The valorization of Prunus mahaleb shell through acid modification for the sorption of Pb2+ removal from aqueous solution

AbstractThis study aimed to investigate the biosorption performance of acid-modified waste Prunus mahaleb (PMA) shells in the removal of Pb2+ ions from aqueous solutions. Changes in the morphological properties and functional components of PMA biosorbent were characterized using SEM–EDX, FT-IR, BET, and PZC analyses. The effect of various parameters such as initial Pb2+ concentration, pH, PMA dosage, contact time, and temperature on biosorption was investigated using a batch biosorption procedure. The maximum biosorption capacity, determined using the Langmuir isotherm, was calculated to be 119 mg g−1. It was found that the biosorption kinetic mechanism followed pseudo-second-order kinetics and intraparticle diffusion model. According to the determined thermodynamic parameters, the biosorption mechanism was found to be endothermic (ΔH° > 0), spontaneous (ΔS° > 0), and entropy-increasing (ΔG° < 0). The outcomes of the experiment were evaluated in comparison to other sorbents that have been previously commonly used in the literature. It was demonstrated that PMA could be a promising, environmentally friendly, cost-effective, and sustainable potential biosorbent for the removal of Pb2+ ions.

Investigation of effectiveness of KOH-activated olive pomace biochar for efficient direct air capture of CO2

The capture of CO2 directly from the air is one of the most promising methods under investigation in recent years to reduce the environmental concentration of this pollutant in order to mitigate its effects on climate change. In this work, the activation of olive pomace biochar with potassium hydroxide, KOH, has been studied for its use as a CO2 adsorbent. The effectiveness of biochar activated with KOH at 750 °C in an inert N2 atmosphere was evaluated, using different mass ratios of biochar/KOH, 1:0.5, 1:1, and 1:2. Various characterisation analyses of the biochar were performed to determine its chemical composition, specific surface area, pore size and volume, structure, morphology, and functional groups. The adsorption isotherm was determined at atmospheric pressure and a temperature of 10 °C. The experimental equilibrium results were fitted to the Langmuir, Freundlich, and Temkin models. Additionally, the kinetic behavior of biochar/KOH as an adsorbent was studied, and dynamic experiments were conducted at atmospheric pressure and 10 °C. The experimental data were fitted to various kinetic models (pseudo-first order, pseudo-second order, Avrami, and Elovich). Furthermore, the mass transfer mechanism during the adsorption process was evaluated using the intra-particle diffusion model. Finally, biochar regeneration was investigated for its subsequent reuse as an adsorbent. For this purpose, complete desorption of the captured CO2 in the biochar was easily carried out by modifying the temperature.

Design and development of rare earth elements anchored pectin/chitosan integrated magnesia hybrid composite for effective defluoridation of water

Fluoride pollution in drinking water is a worldwide concern arises from natural and human actions. The excessive fluoride present in drinking water leads to fluorosis. In this study, dual polysaccharide biopolymers namely pectin and chitosan were incorporated with magnesia followed by imprinted with lanthanum and cerium ions gives PCML (pectin/chitosan/magnesia/lanthanum) and PCMC (pectin/chitosan/magnesia/cerium) hybrid materials for fluoride adsorption investigation. The enhanced defluoridation capacities (DCs) of PCML and PCMC composites were seen as 4.976 and 4.972 mg g−1 by 30 min individually. To decide the impact of various affecting parameters viz., dosage, initial fluoride concentration, pH, contact time and challenging anions were examined in batch method. The pH results show the utmost DCs of PCML and PCMC composites was noted at pH 6 and in co-ions experiments, the significant competition found with bicarbonate ion owing to the superior electronic building of bicarbonate ion. The defluoridation equilibrium data of PCML and PCMC composites follows Langmuir, pseudo-second-order and intraparticle diffusion models. The positive ΔH° value as 3.04 kJ mol−1 for PCML composite and 2.88 kJ mol−1 for PCMC composite were exposed that the endothermic nature of fluoride adsorption occurs onto PCML and PCMC composites. The defluoridation mechanism of PCML and PCMC composites were attained by complexation, ion-exchange and electrostatic interaction. The reusability results shows that the synthesized PCML and PCMC composites can be reused upto six cycles. Field trail result demonstrates the synthesized PCML and PCMC composites were applicable at field conditions by reducing fluoride concentration below 1.5 mg/L.

Hydrophobic hypercrosslinked polymers prepared by secondary pore-forming method as excellent toluene adsorbents

In this work, inspired by molecular imprinting technology, we developed a secondary pore-forming method to chemically etch three hypercrosslinked polymers which are constructed from three novel hexapolar monomers containing imine groups, resulting in three novel hydrophobic porous hyper-crosslinked polymers (HCPs) pGly-TPA, pP-TPA and pBP-TPA. The structures were determined by FT-IR and solid-state 13C NMR spectroscopic techniques. The specific surface areas of pGly-TPA, pP-TPA and pBP-TPA are 694.1, 197.9 and 497.7 m2/g, respectively. All three porous polymers exhibit high hydrophobic properties with wetting angles of much greater than 90°. The breakthrough adsorption experiments revealed that the three prepared polymers exhibited significant adsorption capacity for toluene (322.05 mg/g for pGly-TPA, 114.43 mg/g for pP-TPA and 279.14 mg/g for pBP-TPA), but showed almost no adsorption for ethyl acetate, cyclohexane, and n-hexane, exhibiting certain molecular size and polarity selectivity. The adsorption behaviors of toluene on pGly-TPA, pP-TPA and pBP-TPA can be fit by the Boltzmann model and the Yoon-Nelson model, suggesting that the fixed bed has low mass transfer resistance. The adsorption rate is controlled by both external diffusion and intraparticle diffusion, as shown by the intraparticle diffusion model analysis. In addition, the adsorption capacity of toluene on pGly-TPA is almost unchanged under high humidity (70 %) or five adsorption–desorption processes, which demonstrates exceptional water-resistance and stability. This work is a reference for preparing novel hydrophobic HCPs using the secondary pore-forming method for removing VOCs from humid air.

Photocatalytic degradation of Direct Black 10 B dye in aqueous phase using nanophotocatalyst

ABSTRACT In this study, the photocatalytic degradation of an aqueous solution containing a mixture of Direct Black 10 B dye using titanium dioxide (TiO2) as a catalyst was investigated. The degradation of Direct Black 10 B dye was studied for several parameters, including the catalyst, dosage, initial concentration of dye, and pH. Variable catalyst quantities (0.25, 0.50, 0.75, 1, and 1.25 g), pH (3, 5, 9, and 11), and beginning dye concentration were used in the studies (62.5, 125, 250 and 500 ppm). 0.75 g/litre of catalyst was found to be the ideal dose. The ideal catalyst concentration was determined to be 0.75 g/litre, and the maximal dye decolourization rate was further studied in a basic media, i.e. at pH 9 Blue turned into grey and finally white in the acidic medium, whereas blue turned into pink and then white in the basic medium. After 3 hours 98% of the colour was completely removed at this optimal point. The Langmuir, Freundlich and Temkin isotherms were examined. The langmuier isothers with regression coefficient 0.99 is best fitted as compared to Freundlich and Temkin isotherms. The findings of the kinetic analysis suggest that the Pseudo Second order with regression coefficient 0.9923 is best suited as compared with the pseudo first order and Intra-particle diffusion model.

Hydrothermally Produced Activated Carbon Impregnated with ZnO for the Adsorptive Removal of Toxic Pharmaceutical Contaminants from Aqueous Solution

This research explores the adsorption (AD) of diclofenac sodium (DS) onto a Hydrothermally produced activated carbon impregnated with ZnO (HTC-AC/ZnO) surface, considering various factors such as initial concentration (IC), adsorbent dose, contact time, and pH. The characterization of HTC-AC/ZnO was performed using X-ray diffractometer (XRD), scanning electron microscope (SEM), Fourier-transform infrared spectroscopy (FTIR), and nitrogen physisorption spectroscopy (BET). Tests were conducted with different adsorbent doses (0.5–4 g/L) at 303 K and various initial diclofenac concentrations (ranging from 50 mg/L to 250 mg/L) to observe their effects. Additionally, pH values were altered from 2 to 12 to study their influence on AD. Kinetic studies, thermodynamic studies, and AD isotherm models were examined. The Temkin isotherm model (TIM) was found to be the most accurate for DS-AD on HTC-AC/ZnO. For DS-AD on HTC-AC/ZnO, pseudo-first-order models (PFOM), intraparticle diffusion model (IPDM), and pseudo-second-order models (PSOM) were applied, with a correlation coefficient of 0.945, indicating a good fit for PFOM. The kinetics suggested rapid adsorption. Notably, the HTC-AC/ZnO composite exhibited consistent AD characteristics across four consecutive cycles, with a removal efficiency exceeding 99.38%. This suggests that HTC-AC/ZnO is an appropriate and economically viable adsorbent for the elimination of DS from water-based solutions. The investigation provides compelling evidence that HTC-AC/ZnO is a viable adsorbent for the effective elimination of DS from water sources.

The Effectiveness of Carbonized Neem Leaves Adsorbent for the Removal of Phenol from Synthesized Effluent Using the Batch Process Method

The adsorption of phenol in aqueous solution was investigated using carbonized neem leaves adsorbents. The effect of various factors such as contact time, phenol concentration, pH, temperature, and amount of adsorbent on the adsorption capacity of the adsorbents was determined. The results show that maximum adsorption was obtained at a contact time of 150 minutes, at a phenol concentration of 50 mg/L, optimum adsorption temperature of 45⁰C, pH of 2 and adsorbent dosage of 3 g/L. The equilibrium data was well described by the Freundlich isotherm equation (R2= 0.955 ). This shows a heterogenous adsorption process. The kinetics of the process were explained by the intra-particle diffusion models (R2>0.9). This fitted data indicates a degree of boundary layer control and is not limited to intra-particle diffusion.

Revealing the contribution of Cu(II) and Cu(I) inherent in MOF-199 for efficient thiophene removal at room temperature

Thiophene (C4H4S) removal from coke oven gas is critical to its subsequent high valuable utilization but remains a challenge. MOF-199 was considered as a promising candidate for C4H4S adsorption removal owing to its nature of enriched opened Cu sites. However, the presence of mixed valence of Cu(II) and Cu(I) in MOF-199 makes it puzzling to their respective contribution to the removal of C4H4S. Herein, a series of MOF-199 with different Cu(I) contents were synthesized using different methods, including hydrothermal, solution diffusion, and ultrasonic, and their C4H4S adsorption performance were investigated. The respective contributions of Cu(II) and Cu(I) to the C4H4S removal was systematically discussed. The collected results indicated that although the samples prepared with different methods present a remarkable difference in textural characters, the latter was found to have a negligible influence on the C4H4S removal owing to MOF-199(H) affording an inferior surface area and pore volumes but performing the best C4H4S removal capacity of 53.7 mg S/g. The co-adsorption results of CH3SCH3 and C4H4S indicated that the excellent performance of MOF-199(H) mainly attributed to the presence of Cu(I), which provides active sites for C4H4S adsorption through π complex coordination. Cu(II) species was also found to the C4H4S adsorption via soft-acid-base coordinated interaction, but its contribution is 8.3 mg S/g, only accounting for 15.5 %. Additionally, the adsorption of C4H4S on MOF-199(H) was found to follow the intra-particle diffusion model and the Langmuir models. Moreover, MOF-199(H) also exhibited an excellent regeneration performance due to the weak interaction between C4H4S and their opened Cu sites, the C4H4S adsorption capacity still reaches 50.6 mg S/g after three regeneration cycles, about 94 % of its initial value. The results collected in this study will provide new insights for the manipulation of performance of C4H4S adsorption on the MOF-199.

Diclofenac sodium adsorption in aqueous media by activated carbon obtained from einkorn (Triticum monococcum L.) husk

The uncontrolled release of waste diclofenac with low biodegradability is considered to be a potential threat for the environment and creatures. To find effective solution for this issue, this study reports the adsorption performance of diclofenac sodium salt (DCF) by using activated carbon (EHAC) obtained from einkorn (Triticum monococcum L.) husk in aqueous solution under various circumstances. It was found that DCF adsorption on EHAC was highly solution pH dependent, and DCF adsorption by EHAC decreased with increasing adsorption temperature. Equilibrium data showed that fitted isotherm model with the experiment results of DCF adsorption on EHAC followed the order of Langmuir > Temkin > Freundlich > Dubinin-Radushkevich. Adsorption capacity of EHAC for DCF adsorption in aqueous solution was calculated to be 147.06 mg/g at 25 °C. The adsorption kinetic of DCF adsorption on EHAC was determined to obey the pseudo-second-order kinetic model. By utilizing FTIR and pH data obtained from DCF adsorption on EHAC, DCF adsorption mechanisms with some interactions such as π-π stacking, electrostatic interactions, and hydrogen bonding were suggested at diverse pH values. Additionally, intraparticle diffusion model was applied to kinetic results to further recognize the kinetic mechanism of DCF adsorption on EHAC. Furthermore, thermodynamic parameters for DCF adsorption on EHAC were calculated and evaluated, in which DCF adsorption process by EHAC was determined to be exothermic, spontaneous, and feasible.

Atenolol uptake from pharmaceutical sources onto carbon aerogel prepared by supercritical CO2 drying

Atenolol (ATL) is a popular medication which is widely used to treat hypertension and angina. It is often found in aqueous environments, posing potential risk to human health and ecological well-being. In this study, carbon aerogel was prepared by supercritical CO2 drying of resorcinol–formaldehyde resin subsequently carbonized at 600 °C in an inert atmosphere. This porous material was characterized by SEM, BET, FTIR, and XRD and used for the first time for the removal of ATL from aqueous solutions under varying experimental conditions. Carbon aerogel in the form of microbeads exhibited a relatively high specific surface area of 376.02 m2/g and median pore radius of 9.83 nm. The isotherm models of Langmuir, Freundlich, Temkin, Redlich-Peterson and Brouers-Sotolongo were used to interpret the equilibrium data. Although most of the applied models fitted the data well, the calculated values for maximum sorption capacity (qmax) showed a huge deviation when compared to experimental value of 76.66 mg/g. The pseudo-first and pseudo-second-order kinetic models, Chrastil’s model, and the intraparticle diffusion model were employed for fitting the kinetic data. The rate of the process was rapid with most of the uptake attained in the first 20 min of the contacting. The sorption optimum was achieved at pH pH 9.0 and for sorbent’s dosage of 750 mg/L. Reusability study of the spent aerogel conducted in seven cycles evidenced slight decrease of approximately 1 % in removal efficiency across the cycles indicating that the sorbent maintained its high effectiveness and stability throughout its usage.

Synthesis of MgZnAl Layered Triple Hydroxide Nanoplates as an Efficient Adsorbent for Removing the Acid Yellow 76 Azo Dye

AbstractA simple hydrothermal method was employed for synthesizing MgZnAl layered triple hydroxide nanoplates (MgZnAl LTH) as an efficient adsorbent for removing the Acid Yellow 76 (AY76) azo dye. A batch process was used to perform adsorptions were and investigate the effects of experimental parameters including temperature, adsorbent dosage, solution pH. The best adsorption conditions obtained were pH of 4, MgZnAl LTH dosage of 20 mg and temperature of 55 °C. The kinetics of adsorption was studied using pseudo‐first‐order, pseudo‐second‐order, Elovich, and intraparticle diffusion models. To obtain equilibrium absorption data, Freundlich, Langmuir, and Temkin isotherms were utilized. The findings showed that the adsorption data based on the experiment had a good agreement with the Freundlich model. The highest capacity of adsorption equal to 277.8 mg/g was obtained for the MgZnAl LTH nanoplates toward AY76. Thermodynamic results showed that the process of adsorption of AY76 onto MgZnAl LTH nanoplates had a spontaneous and endothermic nature.