Sips Model Research Articles

Efficient and Selective Removal of Palladium from Simulated High-Level Liquid Waste Using a Silica-Based Adsorbent NTAamide(C8)/SiO2-P.

In order to realize the effective separation of palladium from high-level liquid waste (HLLW), a ligand-supported adsorbent (NTAamide(C8)/SiO2-P) was prepared by the impregnation method in a vacuum. The SiO2-P carrier was synthesized by in situ polymerization of divinylbenzene and styrene monomers on a macroporous silica skeleton. The NTAamide(C8)/SiO2-P adsorbent was fabricated by impregnating an NTAamide(C8) ligand into the pore of a SiO2-P carrier under a vacuum condition. The adsorption performance of NTAamide(C8)/SiO2-P in nitric acid medium has been systematically studied. In a solution of 0.2 M HNO3, the distribution coefficient of Pd on NTAamide(C8)/SiO2-P was 1848 mL/g with an adsorption percentage of 90.24%. With the concentration of nitric acid increasing, the adsorption capacity of NTAamide(C8)/SiO2-P decreases. Compared to the other 10 potential interfering ions in fission products, NTAamide(C8)/SiO2-P exhibited excellent adsorption selectivity for Pd(II). The separation factor (SFPd/other metals > 77.8) is significantly higher than that of similar materials. The interference of NaNO3 had a negligible effect on the adsorption performance of NTAamide(C8)/SiO2-P, which maintained above 90%. The adsorption kinetics of Pd(II) adsorption on NTAamide(C8)/SiO2-P fits well with the pseudo-second order model. The Sips model is more suitable than the Langmuir and Freundlich model for describing the adsorption behavior. Thermodynamic analysis showed that the adsorption of Pd(II) on NTAamide(C8)/SiO2-P was a spontaneous, endothermic, and rapid process. NTAamide(C8)/SiO2-P also demonstrated good reusability and economic feasibility.

Synthesis of Activated Biochar from the Bark of Moringa oleifera for Adsorption of the Drug Metronidazole Present in Aqueous Medium

Moringa oleifera seeds, in particular, have been used for water and wastewater treatment due to their ability to remove many pollutants. Therefore, the present work aims to produce bioadsorbent materials by pyrolysis using biomass from the seed shell of Moringa oleifera to remove the drug Metronidazole present in an aqueous medium. The biochars produced were activated with phosphoric acid (H3PO4) and potassium hydroxide (KOH) to compare the material’s modifications and adsorption mechanisms with the biochar in nature (BCM). The biochars were characterized by Point-of-zero charges (pHpzc), Scanning Electron Microscopy (SEM), X-ray Diffractometry (XRD), Fourier transform infrared spectroscopy (FTIR), and Raman spectroscopy. The studies showed that the adsorption behavior varied with the pH of the solution. The adsorption study verified that the activated biochars presented better results, so in the kinetic study, the adsorption behavior occurred rapidly in the initial minutes until stabilizing within 3–4 h, better fitting the Elovich model. Isotherm models were tested, where the experimental data were adjusted to the Sips model, with an adsorption capacity of 18 mg g−1 for acid-activated biochar (BCH3PO4) and KOH-activated biochar (BCKOH) with 366.49 mg g−1. The results showed that biochars, especially BCKOH, become viable for production because they are a low-cost material and highly effective in removing drugs.

Study on the removal efficacy and mechanism of phosphorus from wastewater by eggshell-modified biochar.

The excessive discharge of phosphorus from rural domestic sewage is a problem that worthy of attention. If the phosphorus in the sewage were recovered, addressing this issue could significantly contribute to mitigating the global phosphorus crisis. In this study, corn straw, a common agricultural waste, was co-pyrolytically modified with eggshells, a type of food waste from university cafeterias. The resulting product, referred to as corn straw eggshell biochar (EGBC) was characterized using SEM, XRD, XPS, XRF, and other methods. Batch adsorption experiments were conducted to determine the optimal preparation conditions of EGBC and to explore its adsorption characteristics. EGBC showed strong adsorption effectiveness within a pH range of 5-12. The adsorption isotherm closely followed the Sips model (R2 > 0.9011), and the adsorption kinetics were more consistent with the pseudo-second-order model (R2 > 0.9899). The process was found to be both spontaneous and endothermic. Under optimal conditions, the phosphorus adsorption capacity of EGBC was measured to be 288.83 mg/g. This demonstrates the high efficiency of EGBC for phosphorus removal and illustrates an effective method of utilizing food waste for environmental remediation. PRACTITIONER POINTS: Biochar prepared from waste eggshell was used to removal and recovery phosphorus in wastewater treatment. EGBC has an impressive adsorption capacity that can reach up to 288.83 mg/g. EGBC has excellent adsorption and filtration capabilities, and there is a sudden increase in concentration at 900 min in the breakthrough curve of EGBC. EGBC has good regeneration performance, with an adsorption effect of 65% and an adsorption capacity of 121 mg/g after four desorption and regeneration cycles.

Zirconium-loaded zeolite composites for selective sorption of 1-hydroxyethylidene-1,1-diphosphonic acid (HEDP) from water: Performance and mechanism

Three zirconium-loaded zeolite (Zr-Z) composites—namely, Zr4+-Z, ZrO2-Z, and ZrMo2O8-Z—were prepared by co-precipitation of Zr4+, ZrO2, and ZrMo2O8, respectively, with artificial zeolite, and these composites were used for the efficient removal of a representative phosphonate, i.e., 1-hydroxyethylidene-1,1-diphosphonic acid (HEDP). The adsorption efficiency of the three composites for HEDP at an initial concentration of 2 mg/L was more than double that of artificial zeolite. Pseudo-second-order kinetics could fit the adsorption process of the three composites well. The heterogeneous adsorption by Zr4+-Z, ZrO2-Z, and ZrMo2O8-Z was determined by using the Sips model. And the theoretical maximum HEDP-adsorption capacities of Zr4+-Z, ZrO2-Z and ZrMo2O8-Z were 3.52 mg P/g, 3.38 mg P/g and 3.77 mg P/g, respectively, at 308 K. At pH 4–9, the three Zr-Z composites could achieve efficient and stable HEDP adsorption. Among Co-existing ions (Cl−, HCO3−, NO3−, SO42−, Ca2+, Mg2+), 50 mM HCO3− hindered adsorption due to its competition with HEDP. The characterization results show that the adsorption mechanism involved hydrogen bonds, electrostatic attraction, and ligand exchange. In addition, the reusability and column adsorption performance of the Zr-Z composites were explored for the efficient removal of the organic phosphonate HEDP from wastewater in practical applications.

Influence of terephthalate anion in ZnAl layered double hydroxide on lead ion removal: Adsorption, kinetics, thermodynamics and mechanism

In this work, layered double hydroxides (LDHs) intercalated with carbonate (ZnAl-CO3) and terephthalate (ZnAl-TA) anions were synthesized for the removal of lead (Pb2+) ions from aqueous solutions. ZnAl-TA showed better Pb2+ removal performance than ZnAl-CO3. In the kinetic study, the Elovich model obtained the best fit; the Weber-Morris model showed that intraparticle diffusion is not a limiting step in the process. The Sips model fitted better to the adsorption isotherms, with a maximum adsorption capacity of 124 mg.g−1. The thermodynamic study showed that the process is spontaneous and endothermic. In the regeneration of ZnAl-TA, the use of NaCl as a desorption eluent showed less Zn2+ leaching and greater desorption efficiency compared to acid eluents. The adsorption capacity of Pb2+ in the presence of other ions followed the order Ni2+ > Ca2+ > Cd2+ > Mg2+ > Cu2+. The ZnAl-TA adsorbent reached 88% of its initial efficiency after 3 cycles with high stability. From post-adsorption XRD, FTIR, and XPS analyses, Pb2+ was removed predominantly by chelation, surface complexation, and precipitation. In general, the ZnAl-TA adsorbent proved to be an efficient sorbent material for Pb2+ removal from aqueous effluent.

Adsorption of Safranine-T dye using a waste-based zeolite: Optimization, kinetic and isothermal study

The global issue of water resource pollution due to wastewater containing dyes is a significant environmental concern. The proper treatment of these harmful wastewaters is a great challenge due to their characteristic structural complexity and low biodegradability. The present work reports the application of a Linde Type-A (LTA) zeolite synthesized from a hazardous aluminum waste as an adsorbent to remediate Safranine-T dye from aqueous solutions. The optimal experimental conditions (agitation rate and zeolite dosage of 147 rpm and 21.5 g/L, respectively) were determined through a central composite rotational design (CCRD), and enabled a removal efficiency of 98.12 % of the textile dye. The model that showed the best fit to the experimental data and better explained the adsorption mechanism, according to the isothermal studies, was the Sips model. The kinetics followed the pseudo-first order model and revealed that Safranine-T dye removal was achieved in a contact time of just one minute. The waste-based LTA zeolite exhibited highly promising adsorbent properties with an efficient and extremely fast adsorption capacity. Its use as a treatment agent for dye-contaminated wastewater can significantly contribute to sustainability and the circular economy.

Rapid and effective antibiotics elimination from water by Fe-BTB MOF: An insight into adsorption mechanism

Tetracycline (TC) and sulfamethoxazole (SMZ) are common antibiotics utilized in human and veterinary medicines to overcome bacterial infections. However, due to their poor metabolism, they can easily be excreted into wastewater or sewage, leading to bioaccumulation and posing a risk to the local environment. This research studied the removal of SMZ and TC using a novel Fe-BTB MOF. The results showed that the Fe-BTB MOF achieved excellent adsorption capacities of 649 and 276 mg g−1 for SMZ and TC, respectively, within 1 h. The kinetics and equilibrium adsorption data correlated well with the pseudo-second-order and Sips models, respectively, suggesting favourable chemical adsorption for SMZ and TC over the MOF. Adsorption experiments, spectroscopic findings, and theoretical calculations suggest that π-π stacking, electrostatic, and hydrogen bond interactions played the main role in the adsorption mechanism. Fe-BTB regeneration was satisfactory for its use in treating antibiotic-contaminated wastewater, allowing its reuse for at least four cycles. Furthermore, water samples from different sources (tap, streams, sea, lake) were also used to confirm the excellent adsorptive performance of this Fe-BTB MOF in practical application.

Advanced thermodynamic approach to adsorption of charged adsorbates from aqueous electrolyte solutions

This study present estimation of the thermodynamic parameters and the influence of ionic activity coefficient on the thermodynamic equilibrium constant of adsorption of phosphates on fly ash. The adsorption was conducted over a wide range of initial phosphate concentrations at different pH values pH = (3; 7; 10). The adsorption results were treated using the Langmuir, Freundlich and Sips adsorption isotherms, which provide information about the maximum adsorption capacity. The Langmuir and Sips isotherms were a satisfactory fit to the adsorption data, especially at pH = 3, with an acceptable regression coefficient over the entire concentration range, Langmuir (r2 = 0.9737) and Sips (r2 = 0.9969). The estimated maximum phosphate sorption capacity of fly ash was 6.21 ± 0.68 (mmol·g−1) according to Langmuir and 4.19 ± 0.16 (mmol·g−1) according to the Sips model, at pH = 3.0. However, there is no data in the published literature for estimating the thermodynamic parameters of the phosphate adsorption process using thermodynamic models for activity coefficients. Novel approach of this paper was determination of the thermodynamic equilibrium constant and Gibbs free energy, using the Pitzer ion-interaction model to predict the nature of adsorption. The Pitzer-ion interaction model was used for the mixed ionic systems, taking into consideration the effect of other present ions besides phosphates in the equilibrium solution resulting from fly ash desorption. The procedure for comprehensive estimation of the ion activity coefficient at maximum adsorption capacity and the dimensionless thermodynamic equilibrium constant using Langmuir's and Sips’s constants was presented. The calculated value of the phosphate activity coefficient in the equilibrium solution was γH2PO4,e = 0.7003 ± 0.0027 and the converted molar activity coefficient was γH2PO4,e = 0.6903 ± 0.0027. The estimated values of Gibbs free energy were: ΔGL = −6.788 ± 0.521 kJ·mol−1 based on Langmuir equilibrium constant and ΔGa = −7.707 ± 0.527 kJ·mol−1 based on activity and thermodynamic equilibrium constant. According to Sips model, the adsorption process is even more spontaneous, with the Gibbs free energy calculated using the phosphate activity coefficient and the thermodynamic equilibrium constant, ΔGa = −9.707 ± 0.617 kJ·mol−1. Consideration of the ionic activity coefficient is particularly important for large, charged adsorbates at higher concentrations, as the absolute difference in free energy for adsorption is app. 12 %. The scientific contribution is reflected in obtaining the necessary and more accurate information for the improvement of adsorption processes and possibly for the upgrading of fly ash in overall wastewater treatment technology.

Competitive Effect of Zinc and Cadmium on the Biosorption of Chromium by Orange Waste

Batch experiments were conducted to test orange waste (OW), an agricultural solid waste byproduct from the orange juice manufacturing industry, as adsorbent for binary solutions of Cd2+-Cr3+ and Zn2+-Cr3+. Fourier transform infrared spectroscopy (FTIR) and the point of zero charge (pHpzc) were used to identify the functional groups on the OW surface involved in biosorption. The biosorption equilibrium data for both binary-metal solutions were obtained and fitted to various isotherm models. The extended Sips and the non-modified Redlich-Peterson isotherm models gave the best fit for the experimental data. According to the extended Sips model, the maximum biosorption capacity of OW was 0.573 mmol·g−1 for Cd2+, 0.453 mmol·g−1 for Zn2+, and 1.96 mmol·g−1 for Cr3+. The sorption capacity dropped to 0.061 mmol·g−1 for Cd2+ and to 0.101 mmol·g1 for Zn2+ in their binary systems with Cr3+ for the higher initial metal concentrations in the solution. However, the maximum sorption capacity of chromium was only slightly affected by the presence of Cd2+ or Zn2+. For both binary systems, the presence of a second metal ion in the solution always conduces to a reduction in the sorption of the other metal in the solution. The presence of Cr3+ decreased the sorption of Cd2+ and Zn2+ more than vice versa. Conclusively, effective removal of Cr3+ ions from an aqueous solution can still be achieved in the presence of Cd2+ or Zn2+.

New insight into impact of humidity on direct air capture performance by SIFSIX-3-Cu MOF.

Removal of CO2 from air is one of the key human challenges in battling global warming. SIFSIX-3-Cu is a promising metal-organic framework (MOF) suggested for carbon capture even at low CO2 concentrations. However, the impact of humidity on its performance in direct air capture (DAC) is poorly understood. To evaluate the MOF performance for DAC application under humid conditions, we investigate the adsorption of H2O, CO2, and N2 using density functional theory (DFT), grand canonical Monte Carlo (GCMC), and molecular dynamics (MD) simulations. The simulation results show a higher tendency of SIFSIX-3-Cu towards H2O adsorption rather than CO2 (and N2). The results agree with the adsorption isotherms for the pure compounds from the Sips model. The extended Sips model shows 1.34 mmol g-1 CO2 adsorption at the atmospheric pressure and 298 K for the CO2/N2 mixture containing 400 ppm CO2, and low CO2 adsorption (less than 0.75 mmol g-1) at a low relative humidity (RH) of 20%. This finding highlights the efficiency of SIFSIX-3-Cu for DAC in dry air and the negative impact of humidity on the CO2 selective adsorption. Therefore, we suggest to consider the impairing of humidity effects when designing a SIFSIX-3-Cu-based CO2 separation process and removal of any water vapor before introduction of the air to SIFSIX-3-Cu.

Facile synthesis of a 3D magnetic graphene oxide/Fe3O4/banana peel-derived cellulose composite aerogel for the efficient removal of tetracycline.

Many initiatives have incorporated graphene oxide (GO) and biomass into aerogels for wastewater treatment. We report on the facile fabrication of a magnetic GO/Fe3O4/banana peel-derived cellulose (bio-cellulose) aerogel using an ultrasound-assisted mechanical mixing method and freeze-drying technique for the removal of tetracycline (TC). The component materials and composite aerogel were characterized using Fourier-transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRD), Raman spectroscopy, field-emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDX), nitrogen adsorption-desorption analysis, and vibrating sample magnetometry (VSM). The effects of solution pH and adsorbent dose on the adsorption performance of the synthesized adsorbents were investigated. The adsorption behavior at the equilibrium of the GO/Fe3O4/bio-cellulose aerogel was studied and analyzed using four well-known non-linear models: Langmuir, Freundlich, Sips, and Temkin. The results showed that the experimental data fitted well with the Freundlich and Sips isotherm models. The maximum adsorption capacity achieved from the Sips model was 238.7 mg g-1. The adsorption kinetics were studied and proved to follow the Elovich kinetic model with an initial rate of 0.89 g g-1 min-1. These results confirm the favorable adsorption of TC on the heterogeneous surface that exhibits a wide range distribution of adsorption energies of the desired GO/Fe3O4/bio-cellulose aerogel. The experimental findings demonstrate that the aerogel possesses the notable features of environmental friendliness, cost-effectiveness, and comparatively high TC adsorption capacity. Therefore, utilizing biomass to develop the structure of the magnetic GO-based composite aerogel is significantly promising for antibiotic-containing wastewater treatments.

Eco-friendly biosorbent for lead removal: Activated carbon produced from grape wood

This study looked into the removal of heavy metals from aqueous systems using carbon obtained from grape wood, an agricultural waste. Activated carbon was created by pyrolyzing and activating grape wood. Characterization of the material showed a highly porous structure with a large number of surface oxygen groups. In batch investigations, optimal conditions (pH 5, 25 °C, 100 mg L−1 starting Pb2+) resulted in an all-out lead uptake capability of 135.7 mg g−1. In 60 min, over 90% of the material was removed at a pseudo-second-order rate of 1.894 × 10−4 g mg-1 min-1. Adsorption had an all-out capability of 293.7 mg g−1, which was in line with the Sips model. Positive enthalpy (70.88 kJ mol−1) and entropy (0.2546 kJK−1mol−1) values from the thermodynamic analysis suggested chemisorption. Using HCl, the adsorbent could be renewed up to five times.

Natural chalcone dye-functionalized magnetite nanoparticles: Synthesis, characterizations and performance for the removal of methylene blue and the antibacterial activity

In the present research work, we report the co-precipitation synthesis of size‐controlled of uncoated (Magn) and natural chalcone dye-functionalized superparamagnetic magnetite nanoparticles (Magn_NCD NPs) and the study of their efficiency for the adsorption of methylene blue (MB) as well as their antibacterial activity. The NCD was isolated from Acacia cyanophylla and characterized by using IR, UV–visible and 1H NMR spectroscopies. For the functionalized NPs, the size-control was achieved by varying the pH (pH5 for the sample Magn_NCD5 and pH8 for the sample Magn_NCD8) of the reaction medium. The powders consisted of almost spherical NPs with an average particle size of ∼8, ∼3 and ∼7 nm, for Magn, Magn_NCD5 and Magn_NCD8, respectively. Adsorption study of the MB onto the NPs was conducted by varying the NPs’ nature, the pH, the NPs’ dosage, the MB concentration and the contact time. Regarding the effect of the NPs’ nature on the removal of MB, the smallest NPs (Magn_NCD5) were noticeably more performant. For these NPs, the removal efficiency was found to increase with the increase of pH in the pH range 3–9. Additionally, the adsorption kinetics was studied by the three most applicable kinetic models. The pseudo-second order kinetic model was better suited to the experimental adsorption data. Moreover, the adsorption isotherms were analyzed using the Langmuir, Freundlich, Sips and Redlich–Peterson models. The experimental data were best fitted to the Sips model with an extremely high correlation coefficient. Based on this model, the maximum adsorption capacity was calculated (qm = 125 mg.g−1). The reusability of Magn_NCD5 was also tested. These NPs showed a good reusability; After 5 regeneration-reuse cycles, the decrease in MB removal % was less than 8%. Finally, the antimicrobial activity was carried out against P. aeruginosa (gram-negative) and E. faecalis (gram-positive) bacteria. The Magn_NCD5 showed more zone of inhibition in E. faecalis (19 mm) than P. aeruginosa (14 mm).

Effective adsorptive removal of a cationic dye from aqueous solutions using a biosorbent derived from Sargassum sp.

Abstract The present research evaluated the potential use of the macroalga Sargassum sp., which was modified with filamentous fungus Cunninghamella echinulata for the biosorption of methylene blue (MB) dye. The modified fungal biomass (FERsarg) was obtained through solid-state fermentation of enzyme (alginate lyase). The FERsarg showed a pHPZC of 7.9, a low mass loss, material micro/mesoporous, and the presence of hydroxyl, carboxylic, phenolic, and carbonyl functional groups. The influence of biomass dosage, solution pH, contact time, initial concentration, and temperature were evaluated for MB biosorption, and the best results were obtained at 2 g L-1 and pH 6. The kinetic study revealed a better fit for the pseudo-second-order model, while the Sips model best described the equilibrium experimental data. The equilibrium was reached within 180 min and showed qmax yielding of 115.49 mg g-1 at 323 K. The thermodynamic understanding of the present research revealed that the biosorbent exhibited spontaneous, exothermic, and physical nature for MB removal. The adsorptive mechanism shows that the process was controlled by electrostatic attraction. Also the feasibility of using residual fermented biomass as a potential adsorbent was applied and discussed, contributing to the concept of minimum waste generation, and supporting the concept of circular bioeconomy.

Linear and Non-linear Regression Methods to Study the Adsorption of Cr(VI) from an Aqueous Solution Using Pomegranate Peel

In this study, the previous data of the adsorption of Chromium (VI) ions on the pomegranate peels (MPGP) as adsorbents were used. linear and non-linear equations for Langmuir, Freundlich, Dubinin-Radushkevich, Tempkin, Redlich-Peterson, Sips, and Toth adsorption isotherm models were applied. The five error functions ERRSQ, HYBRD, MPSD, ARE, and EABS were analyzed for non-linear isotherm equations and in each case a set of isotherm parameters were determined. The algorithms for the simulation of linear and non-linear isotherm models using error functions were achieved with the aid of Microsoft Excel solver Add-Ins for minimizing the respective error function across the concentration range studied. Linear and non-linear methods show comparable data for two-parameter models, also high R2 values were obtained for Langmuir, Freundlich, and Temkin models while the Dubinin-Radushkevich model reveals low R2 values, on the contrary, three-parameter models show different data between linear and non-linear methods with high R2 value for all. Which indicates that the error does not obey the Gaussian distribution.

The Analysis of Consumer Behavior Based on SIPS Model: Taking the Avengers Series as Examples

The Analysis of Consumer Behavior Based on SIPS Model: Taking the Avengers Series as Examples

Performance of Li exchange hierarchical X zeolite for CO2 adsorption and H2 separation

Li exchange hierarchical X zeolite (Li-H-X) was prepared by decationization of X zeolite by NH4Cl solution followed by Li exchange and subsequent calcination. NH4-X and Li-X were prepared to compare the results of Li-H-X. XRD, FE-SEM, EDS, N2 adsorption–desorption, and micro-/mesoporous volume were performed. The higher mesoporosity was confirmed in Li-H-X due to the framework dealumination during decationization. Static and dynamic sorption capacity of sorbents was evaluated to identify the performance of sorbent. The CO2 and H2 equilibrium adsorption capacity of Li-H-X was found to be 9.6 mmol g−1 and 0.78 mmol g−1, respectively, at 298 K and 20 bar, which was 25 % (CO2) and 30 % (H2) higher than Li-X. Static experimental data were validated using the Langmuir, Freundlich, and Sips models. The CO2 & H2 dynamic sorption capacity of Li-H-X sorbent for binary gas (CO2/H2, 25/75 %) was 4.145 mmol g−1 and 0.258 mmol g−1 at 303 K and 10 bar. The higher sorption capacity of Li-H-X was obtained due to large micro-/mesoporous volume of sorbent, which may allow to access unoccupied sites at higher pressure. This result reveals that micro-/mesoporous structure of zeolite adsorbs significantly higher CO2 from binary gas stream, which can use to separate pure H2 from gas stream.

Synthesis, Characterization, and Performance of Nano-Metal-Oxide (Al2O3) Blended Biochar for the Removal of Iron from Contaminated Water for Enhanced Kinetic and Adsorption Studies

This paper explored synthesis, characterization, and adsorption modeling for the application of nano-metal-oxide (Al2O3) blended biochar (NMOBC) derived from date palm waste in removing iron (Fe3+) from contaminated water. The pseudo-second-order model provided a goodness-of-fit that was superior to the pseudo-first-order kinetic model based on the value of R2 with all of the initial concentrations. The Elovich kinetic model also presented a good fit, indicating that chemisorption is a predominant mechanism in the adsorption process. The Langmuir, Freundlich, Redlich-Petersons, Temkin, and Sips models provided an exclusive perspective of the adsorption dynamics based on the high value of R2. However, the Sips model suggested the best fit of all of the employed models, with the lowest RMSE value of 0.0239 mg/g and the maximum adsorption capacity of 22.680 mg/g for NMOBC. Both adsorbents were effectively regenerated and reused in multiple cycles, thus leading to sustainable practices. Numerous analytical techniques, including SEM/EDX, FTIR, and BET, were employed in characterizing the structural, morphological, and functional properties of the synthesized NMOBC and BC. Subsequently, it revealed that the adsorption process and the role of various interactions are attributed to surface area, porosity, and ion exchange.

Phyllite/bentonite mixture—an alternative effective buffer material for a geological disposal of radioactive waste

The use of phyllite (Phy) instead of quartz in mixtures with bentonite (B) is recommended as a buffer material for engineering barriers in a geological repository of nuclear waste. The recommendation is based on experimentally determined sorption properties of various Phy/B mixtures. The adsorption capacity of Phy/B mixtures (Phy/B: 75/25, 50/50, and 25/75), the removal efficacy of Eu(III) ions (an analog for fissiongenic lanthanides and actinides), and the rate of their binding reaction were studied using the batch adsorption equilibrium and kinetic experiments at different Eu(III) initial concentrations, solution pH, and solution to adsorbent (L/S) ratio. The adsorption capacity of the Phy/B mixtures increased with the increased bentonite content in the mixture depending on the L/S ratio and solution pH. The highest increase in the adsorption capacity of the Phy/B mixtures compared to phyllite was observed for the Phy/B proportions of 25/75 and 50/50. The rate of the Eu(III) adsorption was the best fitted by the pseudo-second-order kinetic model indicating that the adsorption rate was controlled by chemisorption. The Sips model provided the best correlation of the adsorption experimental data, indicative of more than one adsorption site. The results of this study show the advantage of the Phy/B mixtures in immobilizing Eu and certain fission products by combining adsorption properties of the materials.

Activated Carbon-Incorporated Tragacanth Gum Hydrogel Biocomposite: A Promising Adsorbent for Crystal Violet Dye Removal from Aqueous Solutions.

Biomaterials-based adsorbents have emerged as a sustainable and promising solution for water purification, owing to their eco-friendly nature and remarkable adsorption capacities. In this study, a biocomposite hydrogel was prepared by the incorporation of activated carbon derived from pomegranate peels (PPAC) in tragacanth gum (TG). The hydrogel biocomposite (PPAC/TG) showed a porous structure, a negative surface charge at a pH of more than 4.9, and good stability in aqueous media. The adsorption properties of the PPAC/TG hydrogel biocomposite were assessed for the removal of crystal violet dye (CV) from aqueous solutions using a batch adsorption. The equilibrium adsorption data followed the Sips isotherm model, as supported by the calculated R2 (>0.99), r-χ2 (<64), and standard error values (<16). According to the Sips model, the maximum values of the adsorption capacity of PPAC/TG were 455.61, 470.86, and 477.37 mg/g at temperatures of 25, 30, and 35 °C, respectively. The adsorption kinetic of CV onto the PPAC/TG hydrogel biocomposite was well described by the pseudo-second-order model with R2 values more than 0.999 and r-χ2 values less than 12. Thermodynamic studies confirmed that the CV dye adsorption was spontaneous and endothermic. Furthermore, the prepared hydrogel exhibited excellent reusability, retaining its adsorption capacity even after being used more than five times. Overall, this study concludes that the prepared PPAC/TG exhibited a significant adsorption capacity for cationic dyes, indicating its potential as an effective and eco-friendly adsorbent for water treatment.