Pseudo-second Order Model Research Articles

Rapid adsorptive removal of emerging and legacy per- and polyfluoroalkyl substances (PFASs) from water using zinc chloride-modified litchi seed-derived biochar

The present study successfully synthesized a novel biochar adsorbent (M−L−BC) using litchi seed modified with zinc chloride for PFASs removal in water. M−L−BC greatly enhanced removal of all examined PFASs (>95 %) as compared to the pristine biochar (<40 %). The maximum adsorption capacity was observed for PFOS, reaching 29.6 mg/g. Adsorption kinetics of PFASs followed the pseudo-second-order model (PSO), suggesting the predominance of chemical adsorption. Moreover, characterization and density functional theory (DFT) calculations jointly revealed involvement of surface complexation, electrostatic interactions, hydrogen bonding, and hydrophobic interactions in PFAS adsorption. Robust PFAS removal was demonstrated for M−L−BC across a wide range of pH (3–9), and coexisting ions had limited impact on adsorption of PFASs except PFBA. Furthermore, M−L−BC showed excellent performance in real water samples and retained reusability after five cycles of regeneration. Overall, M−L−BC represents a promising and high-quality adsorbent for efficient and sustainable removal of PFASs from water.

Al(III)-based MOF for tetracycline removal from water: Adsorption performance and mechanism

The high concentration of pharmaceuticals in water systems can harm the ecosystem and human health. Tetracycline (TC) is a human and veterinary antibiotic widely used for bacterial infections. The excessive use of TC has resulted in a risk to health and the environment since TC has been found in various water ecosystems. Then, this study focuses on effectively removing tetracycline from water solutions using an Al(III)-based MOF CYCU-3. The material showed high adsorption in the pH range of 4–9 with an equilibrium time of 120 min and outstanding cyclability. The maximum adsorption capacity was 428.1 mg g−1. The experimental data were fitted into Pseudo-Second Order (PSO) and Temkin models, suggesting physicochemical interactions. The thermodynamic study proved the exothermic nature of the process. The adsorption mechanism was proposed based on the experimental analysis, Fourier-transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and theoretical calculations. It was proposed that cation-π, π-π interactions, and hydrogen bonding played the main role in adsorption. CYCU-3 displays higher adsorption capacity compared with some representative porous materials. Therefore, CYCU-3 can be considered a suitable adsorbent for the treatment of water contaminated with pharmaceuticals.

Photocatalytic degradation of methamidophos in water using zinc oxide as a photocatalyst

Conventional agriculture and the need to satisfy the demand for food, cause different types of pesticides to be used indiscriminately, causing them to be dispersed into ecosystems by wind and water currents, representing a serious environmental problem. For this reason, it is important to apply effective technologies for the elimination of pesticides from water bodies. In the present research, heterogeneous photocatalysis using ZnO as a photocatalyst was applied to evaluate the degradation of methamidophos in contaminated water prepared in ultrapure water and river water. Considering the working parameters of 3 g/L of zinc oxide, a concentration of 50 mg/L of methamidophos, with constant agitation of 300 rpm, temperature 25 ± 2 °C and a natural pH, methamidophos degradation percentages of 86.66 % and 57.96 % were achieved in ultrapure water and river water, respectively. The chloride, sulfates, nitrates, and nitrites anions present in the river water could be responsible for the decrease in the effectiveness of the photocatalytic process. The mathematical models that best describe the degradation process were the pseudo-second order model and the Elovich model.

Methylene Blue Adsorption Kinetics Investigation by Coconut Shell Activated Carbon Adsorbent Using Fractional Power, Avrami and Bangham Models

Methylene blue is not easily biodegradable, and its persistence in water can contribute to long-term contamination if not properly treated. Numerous adsorption kinetic study successes were achieved utilizing activated carbons of coconut shell, especially the Pseudo-First and Pseudo-Second order models with little/no regards to the unique behavior described by the Avrami, Bangham and the Fractional Power kinetic models. The parameters in those models are determined to describe the sorption mechanism. Avrami model fitting results suggests a complex adsorption process, which does not follow the first-order kinetic. Obtained results show that the Fractional Power model best described the Coconut Shell-Activated Carbon Methylene blue bio-sorption process at constant adsorption capacity of 15937.8 mg/g. Findings show that Bangham kinetic model does not fit the experimental data for Methylene blue sorption from aqueous solution. Methylene blue exposure issues like gastrointestinal discomfort, skin and eye irritation, and imbalances in the populations of various species in aquatic ecosystems due to impacts on their growth, reproduction and survival, may be solved using a very effective adsorbent, such as the Coconut Shell -Activated Carbon used here.

Effect of lightweight composite brick’s waste on the removal of malachite green from aqueous solution and phytotoxicity assessment

ABSTRACT This study investigates the removal of malachite green (MG) dye by adsorption process using as adsorbent a waste byproduct from lightweight composite brick production, composed of clay and 5 wt.% argan nut shell and designed as waste bricks (WB). Characterization of the adsorbent (WB) was conducted using several techniques such as XRD, XRF, FTIR, etc. Optimal conditions for the adsorption process of MG dye with WB were carried out, considering adsorbent dose (0.02–0.4 g/mL), pH (2–12), contact time (0–360 min), and MG dye concentration (20–210 mg/L). The obtained outcomes indicated that the optimal parameters for a dye concentration of 20 mg/L are an adsorbent dose of 0.15 g/mL, a pH of 10, and an adsorption time of 180 minutes. Furthermore, kinetic, isotherm, and thermodynamic adsorption have been evaluated. The results highlighted that the pseudo second-order and Langmuir model described accurately the adsorption process with an adsorption capacity of about 2.66 mg/g and 23.48 mg/g respectively. While the thermodynamic study conducted at four temperatures (298 K, 308 K, 318 K, 328 K) revealed that the adsorption process is spontaneous and endothermic in nature. Finally, a phytotoxicity test of malachite green dye solutions was carried out using wheat and lentil seeds confirming the treatment effectiveness of the adsorbent.

Experimental design of polymer synthesis applied to the removal of Cd2+ ions from water via adsorption

Cadmium is a highly toxic metal, and its presence can have adverse effects on both human health and aquatic ecosystems. The efficient removal of cadmium from wastewater is therefore of crucial importance, but traditional methods have proved to be inadequate. Thus, technologies for the treatment of wastewater containing cadmium, including adsorption, have been developed. The aim of this study was the preparation of a polymeric material by the grafting reaction of κ-carrageenan and its use as an adsorbent for cadmium removal. This was performed to study the removal capacity of cadmium ions in synthetic solutions, as well as the effects of pH and ions on adsorption capacity, adsorption kinetics, isotherms, and reusability. Additionally, the disinfectant potential of the solution was evaluated for the inactivation of total coliforms and E. coli in river water. The best adsorption capacity was 75.52 ± 1.325 mg g−1, with the kinetics described by the pseudo-second order model. Maximum adsorption capacity (127.6 ± 1.833 mg g−1) and RL (0.0113) were determined using the Langmuir model, the Freundlich model was the one that best fits the experimental data and indicated cooperative adsorption, and the Dubinin-Radushkevich isotherm was used to obtain the adsorption energy and identify that it is physical. The presence of ions K+, Na+, Mg2+, and Ca2+ in a concentration of 0.5% decreased the adsorption capacity, and that at pH 2.0, the adsorption capacity was drastically reduced. The study indicates that the polymer has potential as an adsorbent for removing cadmium from aqueous solutions and exhibits self-disinfecting properties.

Sono-assisted Adsorption of Methyl Violet 2B Using a Magnetic Kaolin/TiO2/γ-Fe2O3 Nano Composite

In this study, the efficacy of sono-assisted adsorption for the removal of methyl violet 2B (MV-2B) was investigated. A magnetic adsorbent was synthesized using kaolin and TiO2, designated as KTF. Various analyses including scanning electron microscopy with energy dispersive spectroscopy (SEM–EDS), Brunauer–Emmett–Teller (BET), Fourier transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRD), Zeta potential and vibrating sample magnetometer (VSM) were conducted to characterize the structure of KTF. The BET surface area and pore volume of KTF were determined to be 65.279 m2/g and 0.072 cm3/g, respectively. VSM analysis confirmed the superparamagnetic property of KTF. The effect of contact time, initial MV-2B concentration, KTF amount, temperature, ionic strength and initial pH of the solution on the sono-assisted adsorption of MV-2B was investigated. Sono-assisted removal of MV-2B was achieved at a rate of 85.6% under optimal conditions: original pH, KTF amount of 0.2 g/100 mL, initial MV-2B concentration of 20 mg/L, contact time of 15 min, and temperature of 22 °C. Conversely, lower removal efficiencies were observed with conventional adsorption methods employing shaking (37%) and stirring (60.5%). The kinetics of sono-assisted MV-2B removal followed a pseudo-second order model, while the Freundlich isotherm model exhibited a superior fit (R2 = 0.985) in describing the equilibrium behavior compared to Langmuir and Temkin models.

Adsorption and desorption process for high recovery and purification of anthocyanins from (Clitoria ternatea L) using macroporous resins

The intense coloration of the petals of the butterfly bean flowers (Clitoria Ternatea L.) is attributed to high content of anthocyanins, which are considered as an antioxidant phytochemicals that have many health benefits. In this context, it is so important to implement a new method for the separation and purification of phenolic compounds. Therefore, the objective of this work was to evaluate the adsorption and desorption behavior of anthocyanins extracted from the petals of the butterfly bean flowers, using six different macroporous adsorption resins (XAD 2, XAD 4, XAD 7HP, DAX 8. XAD 1180 N and XAD 16), and to identify the best type of resin for anthocyains recovery from butterfly bean flowers extract. The XAD7HP and DAX8 resins showed high adsorption capacity, (248.55 ± 8.8 mg/g) and (228.84 ± 16.9 mg/g) at pH 5, and the highest recovery values for anthocyanins; (75.66 ± 1.1%) and (52.64 ± 1.2%), respectively. The Langmuir model described better the adsorption isotherm process on DAX 8, in turn, the experimental data of equilibrium were better fitted by Freundlich model for isotherm adsorption of anthocyanin on XAD7HP resin. The pseudo-second order model was the best to fit the experimental data of the adsorption kinetics at the different temperatures used. Both resins XAD 7HP and DAX 8 presented high recovery of anthocyanin, comparing with conventional extracted methods the purified anthocyanin using XAD 7HP and DAX 8 can be used as biological compounds with more purity for food and pharmaceutical applications.

Fabrication and characterization of graphene oxide and reduced graphene oxide decorated diatomite composite materials and their adsorption performance for uranium ions

Abstract In this study, the composite materials based on the incorporation of diatomite of graphene oxide (GO)/reduced graphene oxide (rGO/diatomite) were developed and characterized by different techniques (SEM, XRD, FTIR and BET). Developed composites were used for the first time in the removal of uranium ions from aqueous solutions. In adsorption studies, parameters affecting the adsorption efficiency such as solution pH, temperature, contact time and initial U(VI) concentration were investigated using full factorial experimental design (FFED). ANOVA (analysis of variance) analysis within the 95 % confidence interval of the model applied to control the compatibility of the model and the experimental findings was examined. Langmuir, Freundlich and Temkin isotherms were used to determine the adsorption model and related parameters were calculated. In addition, adsorption thermodynamic parameters such as enthalpy, Gibbs free energy change and entropy were calculated. The uranium removal behaviour on GO/diatomite and rGO/diatomite was better characterized by the pseudo-second order and Langmuir models, indicating that uranium ions were chemically adsorbed onto composite materials. Additionally, it was observed that higher temperatures promoted the uranium removal on GO/diatomite and rGO/diatomite, suggesting that the removal process was a spontaneous endothermic and exothermic reaction, respectively. In addition, the adsorption of U(VI) with GO/diatomite and rGO/diatomite was investigated using density functional theory (DFT) study. Configuration and adsorption energy were determined. The GO/diatomite composite materials can be a promising candidate as an adsorbent for the removal of uranium from aqueous solutions.

Role of Co and Ni ferrites in the fabrication of Saccharum officinarum bioadsorbents for removing As(III)

Removal of arsenic from drinking water is one of the most significant worldwide concerns. Adsorptive removal of arsenic is highly practical and efficient among the various methods. The green synthesis using sugarcane extract was eco-friendly, and cost-effective and resulted in adsorbents having magnetic behavior and a high capacity for arsenic. In the present study, activated carbon (ACs) of sugarcane and its surface, functionalized with nickel ferrite (AC/NFO) and cobalt ferrite (AC/CFO) were used as biosorbents for the removal of As(III) from aqueous medium. The functionalization was undertaken in a controlled hydrothermal method using Saccharum officinarum (sugarcane) extract as a green source. The morphology, functionality, thermal stability, structure, magnetic behavior, surface area and porosity of adsorbents were confirmed by SEM, FTIR, TGA, XRD, VSM, BJH and AFM. The sorption behavior was determined with the effect of pH, time, concentration, temperature and dose. Pseudo-second order and Langmuir models were found suitable to validate the sorption data. Thermodynamics of the sorption process and the desorption studies suggested that the governing mechanism is chemisorption. The adsorption capacities for AC2, AC2C2 and AC2N2 were 961 µg/g, 1103 µg/g and 1000 µg/g respectively. Among the studied samples, AC2C2 was found as a potential candidate due to its high adsorptive efficiency of 97 % for As(III).

Ultrasound-assisted enhanced adsorption of textile dyes with metal organic frameworks

In this study, ZIF-67 based metal–organic framework (MOF) is used for the adsorption of several synthetic dye effluents (Malachite green (MG), Rhodamine-B (Rh-B), Methylene Blue (MB) and Congo Red (CR)) with intensified adsorption in the presence of ultrasound. The adsorption capacity of ZIF-67 is evaluated for multiple single dye systems and binary dye mixtures. The effect of different operational parameters such as contact time, adsorbent dosage, dye concentration, temperature, pH, binary dye systems, real effluents, and the presence of ultrasound is explored in detail. The adsorption for single dye systems shows the removal efficiencies in the order of MG > CR > Rh-B > MB. The adsorption of CR and MG on ZIF-67 followed Langmuir isotherm which estimated the maximum adsorption capacity of 701 and 3623 mg. g−1 respectively. An optimum adsorbent loading of 1 g.L−1 is effective for the efficient removal of MG and CR. Further, thermodynamic studies indicate that the adsorption process is spontaneous and endothermic. The kinetic models for both dyes suggested a prevailing chemisorption mechanism, in line with the pseudo second-order model (PSOM). For binary dye systems of MG and CR, the selectivity towards maximum adsorption capacity is favored with MG compared to CR. Ultrasound-assisted adsorption intensified the removal efficiency up to ∼ 67 % and ∼ 93 % within 5 min for CR and MG respectively. ZIF-67 is stable over multiple consecutive cycles affirming its reliability for reuse. Maximum removal of dyes was also obtained with real textile dye effluents.

Synthesis and characterisation of novel beta-cyclodextrin based Fe3O4 nanocomposite: adsorption behaviour and photocatalytic dye degradation studies

ABSTRACT Novel Beta-Cyclodextrin-based Fe3O4 nanocomposite has been synthesised through copolymerisation by incorporating Fe3O4 nanoparticles into the polymer matrix. Ultraviolet-Visible (UV-Visible) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, Thermogravimetric (TGA) analysis, Point of Zero Charge, X-ray diffraction (XRD), and Scanning electron microscopy (SEM) analysis have been used to characterise the Fe3O4 Nanoparticles and β-CDHs@Fe3O4 nanocomposite. The synthesised β-CDHs@Fe3O4 nanocomposite has been utilised for the adsorption of methylene blue (MB) dye from aqueous solutions. The maximum percentage removal of MB dye at optimum pH 7 and was found to be 98.51%. The adsorption capacity (qe) of β-CDHs@Fe3O4 nanocomposite has been found to be 268.09 mg/g at optimum dosages 1.2 g/L, pH 7, temperature 25°C, concentration 100 mg/L and an agitation speed of 200 rpm. Adsorption data have been fitted with three isotherm models namely Langmuir, Freundlich, and Temkin, and it was found to be the best fit with the Langmuir isotherm model. Kinetic studies like the pseudo-first order, pseudo-second order, and intra-particle diffusion model were also performed to study the adsorption mechanism. Further, thermodynamic studies demonstrate that the reaction was exothermic and spontaneous. Photocatalytic degradation of MB dye under visible light has also been studied, and 79.01% degradation of the dye was observed. Also, desorption of the nanocomposite was performed, and it was found to be reusable up to 5 times with 90% dye-desorption in the fifth cycle.

Diesel removal in non-aqueous phase by fibres from Calotropis procera: kinetic, isothermal and sorption potential evaluation

ABSTRACT Calotropis procera fibres have been proposed for free-phase diesel removal in case of spillage into groundwater. For this, characterizations were carried out using Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FEG-SEM), wettability and contact angle measurements. Sorption oil capacity, kinetic, isothermal and recycling behaviour were evaluated. For initial optimization of the oil sorption capacity, an experimental design (DOE) was applied, with the optimized condition being 60 g L−1 of diesel in water and 0.01 g of fibre. Then, the results clearly indicated that the fibres have a hydrophobic and oleophilic character, quickly reaching more than 71.43 g g−1 of diesel sorption, according to the adjustment (R² > 0.99) of the pseudo-second order and Langmuir models, governed by absorption mechanisms. It should also be noted that at the end of 8 reuse cycles, the fibre presented a total accumulated sorption capacity of about 252.6 g g−1 of diesel. Furthermore, a laboratory-scale experiment was carried out to remove diesel from groundwater in gas station areas, the fibre removed 98.55% to 99.97% of removal efficiencies were achieved of the free phase over time. Therefore, the material demonstrates excellent characteristics for removing diesel spills in groundwater due to its fast, high and stable removal capacity.

Bubble-induced self-assembly synthesis of defective hierarchical boehmite with ultra-high removal efficiency towards Congo red: Preparation and adsorption mechanism

To cope with the increasingly urgent environmental issue and provide promising alternative adsorbents, the synergistic preparation route of dissolution and bubble-induced self-assembly was firstly exploited to guide the reconstruction process of a defective hierarchical porous boehmite-microspheres (BMS) adsorbent in a favorable direction to improve the CR adsorption capacity using aluminium hydroxide industrial waste as raw materials. Multiple non-in-situ physicochemical characterization instruments demonstrate that BMS-4 adsorbent possesses abundant coordinatively unsaturated Al–species, large specific surface area, high porosity, oxygen vacancies and oxygen-containing groups, which promote the maximum adsorption capacities for CR up to 6805.08 ± 5.4 mg g−1. Moreover, the Pseudo-second order model and the Langmuir model are more suitable for describing the behavior of CR adsorption, which proves it is more inclined to be monolayer adsorption and there is no chemical reaction between CR and adsorbent. More importantly, it can be practiced in eight cycles of adsorption tests, achieving ultra-high stability for over 94.46 % of the original adsorption capacity. Combined with density-functional theory (DFT) calculations and experimental results, it is illustrated that the amino protonation is responsible for the additional enhancement of CR adsorption, in addition, oxygen vacancy capture and BMS-4/CR–SO3+–NH3 mechanism for enhanced adsorption of dyes is proposed, both of which show that bubble-induced self-assembly provides a promising route for the preparation of high-performance adsorbents.

Hexavalent chromium scavenging performances of one-pot synthesized hydrous cerium-copper-mixed oxide from contaminated water with plausible mechanism

ABSTRACT Prolonged use of the chromate [Cr(VI)]-contaminated water originates severe health problems for the public. Thus, the societal urgency is a reusable and cost-effective material for efficient scavenging of Cr(VI) from contaminated industrial wastewater. Aiming this, we had targeted to prepare some cheap and effective materials for scavenging Cr(VI) from the contaminated water. Herein, we report the preparation of hydrous cerium-copper oxide (HCCO) with some tailored compositions and employed toward the abstraction of chromate from water solution. The HCCO (Ce: Cu = 1:4, mole/mole) has shown the highest Cr(VI) scavenging capacity. Experimentally, highest Cr(VI) abstraction efficiency is recorded at pH ~ 3.0 (508.853 mg. g−1 at 303 K). Kinetically, the Cr(VI) scavenging reaction with HCCO surfaces agrees better with the pseudo second-order model (R2 = 0.987) equation and the equilibrium Cr(VI) distribution data explain the Freundlich isotherm model (R2 = 0.998) equation, which anticipates the multi-layered adsorption on heterogeneous sites of the adsorbent. A negative value of the Gibbs free energy change indicates that the Cr(VI) adsorption over HCCO surfaces is spontaneous. The positive enthalpy change indicates the endothermic nature of the said reaction.

Interfacial interactions in aqueous systems of poly(ε-caprolactone)-co-poly(2-hydroxyethyl methacrylate) hydrogel with dye molecules in synthetic wastewaters

The use of dyes is widespread in the textile business, having various detrimental effects on humans and ecosystems. When dying, both cationic and anionic dyes are used. A lot of studies have been conducted in order to find an effective eco-friendly solution to resolve this issue. In this study, we recommend the use of an amphoteric and amphiphilic hydrogel consisting of ε-caprolactone and 2-hydroxyethyl methacrylate which are both biodegradable and cost-effective. The synthesis of this material was confirmed by FTIR, XRD, and SEM. The parameters under which the composite was adsorptively examined were the effects of pH, temperature, and contact time. It was found that the kinetics followed the pseudo fractal-like first order kinetic model for Μethylene Blue, while for Remazol Brilliant Blue R, both the pseudo fractal-like first order and the pseudo-second order models describe the data equally well. Thermodynamic analysis indicated that the adsorption process of both dyes was endothermic and spontaneous. Reuse experiments showed that their removal efficiency was retained at high levels, while stability studies revealed that the hydrogel retains its structural integrity, even at extreme pH values. Finally, the poly(ε-caprolactone)-co-poly(2-hydroxyethyl methacrylate) approach appears to be a viable strategy for removing dye residues from wastewater that is both successful and ecologically acceptable.

Removal of Amoxicillin From Wastewater Onto Activated Carbon: Optimization of Analytical Parameters by Response Surface Methodology.

Antibiotics are widely used in veterinary and human medicine, but these compounds, when released into the aquatic environment, present potential risks to living organisms. In the present study, the activated carbon (AC) used for their removals is characterized by FT-IR spectroscopy, BET analysis and Scanning Electron Microscopy (SEM) to determine the physicochemical characteristics. Response surface methodology (RSM) and Box-Behnken statistical design (BBD) were used to optimize important parameters including pH (2-12), temperature (20-45°C), and AC dose (0.05-0.20g). The experimental data were analyzed by analysis of variance (ANOVA) and fitted to second-order polynomial using multiple regression analysis. The optimal conditions for maximum elimination of Amoxicillin (Amox) are (Dose: 0.124g, pH 5.03 and 45°C) by applying the desirability function (df). A confirmation experiment was carried out to evaluate the accuracy of the optimization model and maximum removal efficiency (R = 89.999%) was obtained under the optimized conditions. Several error analysis equations were used to measure goodness of fit. Pareto analysis suggests the importance of the relative order of factors: pH > Temperature > AC dose in optimized situations. The equilibrium adsorption data of Amox on Activated Carbone were analyzed by Freundlich, Elovich, Temkin and Langmuir models. The latter gave the best correlation with qmax capacities of 142.85mg/g (R2 = 0.999) at 25°C is removed from solution. The adsorption process is dominated by chemisorption and the kinetic model obeys a pseudo-second order model (R2 = 0.999).

CTAB Surfactant Promotes Rapid, Efficient, and Simultaneous Removal of Cationic and Anionic Dyes through Adsorption on Glycerol/Citrate Polyester

The discharge of dye waste by industries has caused environmental impacts on water properties, aquatic species, and human life. The production of eco-friendly materials for dye removal from wastewater has gained increasing interest, particularly through adsorption, as it is an efficient method for removing pollutants. However, the selectivity and limited adsorption capacity of materials for simultaneously adsorbing cationic and anionic dyes make it challenging to address the prevailing dye effluent issue. In this work, a poly(glycerol citrate) polyester was prepared without a solvent, using microwave heating, and was combined with cetyltrimethylammonium bromide (CTAB) to modulate the simultaneous adsorption of cationic (Rhodamine B, RB) and anionic dyes (acid blue 113, AB and acid red 27, AR). The formation of the polyester was successfully confirmed by ATR-FTIR and the thermal properties were evaluated by TGA and DCS. In the presence of CTAB 5 mM, the material removes almost 100% of the dyes, reaching the kinetics equilibrium in 30 min following the Pseudo-second order model. Additionally, dye adsorption on the polyester in the presence of CTAB was described by the Freundlich isotherm model, indicating a heterogeneous polyester surface that promotes a multi-layer adsorption driven by electrostatic interaction and hydrogen bonds. The material showed an adsorption capacity of 73.7 ± 3.2, 82.1 ± 4.4, and 21.2 ± 0.6 mg/g for RB, AB, and AR, respectively. Our results provide evidence that the poly(glycerol citrate)/CTAB has a higher potential for application in wastewater treatment to remove both anionic and cationic dyes.

Separation studies of 60Co (II) and 134Cs (I) radionuclides from aqueous solution using starch-grafted citric acid-acrylamide/magnesia hydrogel

Abstract In this study, three starch hydrogels composite prepared using different ratios of starch, citric acid, acrylamide, and MgO nanoparticles (referred to as St1-g-(CA-AM), St2-g-(CA-AM), and St3-g-(CA-AM) MgO). These materials were assessed using FT-IR, SEM, and EDX. The adsorption of 134Cs(I) and 60Co (II) onto these materials studied using radiometric analysis. The investigation focused on how temperature, contact duration, initial metal ion concentration, and pH of the solution affected the sorption efficiency. It is found that a pH value of 7 optimized the adsorption reaction, reaching equilibrium after 40 minutes. The kinetics of the adsorption followed a pseudo-second order model. The Langmuir model adequately explained the sorption mechanism, supported by the analysis of isotherm models. The monolayer adsorption capacities for 60Co (II) and 134Cs (I) were 113.38 and 100.2 mg g−1, respectively. The thermodynamic study indicated that the sorption process is both endothermic and spontaneous.

Адсорбционное извлечение аминов из водных растворов

Aquatic biological resources are an important part of the ecosystems of our planet, since they are involved in economic turnover as a source of food. The composition of water, including waste water from enterprises, has a direct impact on the state of aquatic biological resources. To extract and concentrate metals from solutions, hydrometallurgical processes are used – extraction and sorption. Their implementation is possible with the use of special substances – extractants and in a number of processes – sorption materials (Solvent Impregnated Resins (SIR’s) and Levextrel’s) with a mobile phase of the extractant, combining the properties of sorbents and extractants. Despite the advantages of the latter, such as high kinetic parameters, lack of swelling and high values of mechanical strength, they are characterized by the disadvantages of extraction methods – the entrainment of the extractant into the aqueous phase in dissolved and emulsion forms. Under static conditions, the possibility of purification of aqueous solutions containing primary or tertiary amine by adsorption on carbon materials (activated carbon NWC, carbon NWC-T modified with carbon nanotubes, CS-PTFE modified with polytetrafluoroethylene), as well as on styrene-divinylbenzene nonionic copolymer Porolas-T and a natural shell rock adsorbent was studied. The kinetics of adsorption of аmines Primene-JMT and TOA from aqueous solutions by these adsorbents has been studied by the method of a limited volume of solution. Of the known pseudo-first order, pseudo-second order and Elovich models, the pseudo-second order model describes kinetic data more adequately (R2&gt;0.99). The values of the distribution coefficients and the rate constants of adsorption of Primene-JMT and TOA are determined. A block diagram of adsorption purification of aqueous solutions from amines is proposed, the implementation of which will reduce the toxicity of waste solutions and return some of the expensive extractant to circulation.