Adsorption Kinetic Parameters Research Articles

A Sustainable Solution for the Adsorption of C.I. Direct Black 80, an Azoic Textile Dye with Plant Stems: Zygophyllum gaetulum in an Aqueous Solution.

The presence of pollutants in water sources, particularly dyes coming by way of the textile industry, represents a major challenge with far-reaching environmental consequences, including increased scarcity. This phenomenon endangers the health of living organisms and the natural system. Numerous biosorbents have been utilized for the removal of dyes from the textile industry. The aim of this study was to optimize discarded Zygophyllum gaetulum stems as constituting an untreated natural biosorbent for the efficient removal of C.I. Direct Black 80, an azo textile dye, from an aqueous solution, thus offering an ecological and low-cost alternative while recovering the waste for reuse. The biosorbent was subjected to a series of characterization analyses: scanning electron microscopy (SEM), thermogravimetric analysis (TGA), Brunauer-Emmett-Teller (BET) method, X-ray diffraction (XRD), and infrared spectroscopy (IR) were employed to characterize the biosorbent. Additionally, the moisture and ash content of the plant stem were also examined. The absorption phenomenon was studied for several different parameters including the effect of the absorption time (0 to 360 min), the sorbent mass (3 to 40 g/L), the pH of the solution (3 to 11), the dye concentration (5 to 300 mg/L), and the pH of the zero-charge point (2-12). Thermodynamic studies and desorption studies were also carried out. The results showed that an increase in plant mass from 3 to 40 g/L resulted in a notable enhancement in dye adsorption rates, with an observed rise from 63.96% to 97.08%. The pH at the zero-charge point (pHpzc) was determined to be 7.12. The percentage of dye removal was found to be highest for pH values ≤ 7, with a subsequent decline in removal efficiency as the pH increased. Following an initial increase in the amount of adsorbed dye, equilibrium was reached within 2 h of contact. The kinetic parameters of adsorption were investigated using the pseudo-first-order, pseudo-second-order and Elovich models. The results indicated that the pseudo-first-order kinetic model was the most appropriate for the plant adsorbent. The isotherm parameters were determined using the Langmuir, Frendlich, Temkin, and Dubinin-Radushkevich models. The experimental data were more satisfactory and better fitted using the Langmuir model for the adsorption of dye on the plant. This study demonstrated that Zygophyllum gaetulum stems could be employed as an effective adsorbent for the removal of our organic dye from an aqueous solution.

Application of zirconium aspartic acid metal-organic framework (MIP-202(Zr)) for high efficient ruthenium adsorption from aqueous solutions

The zirconium metal – organic framework MIP-202(Zr), based on L-aspartic acid, was prepared by hydrothermal method and used for study of ruthenium adsorption from aqueous solutions. The obtained material was characterized by X-ray diffraction (XRD), infra red spectroscopy (IR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The batch adsorption experiment was performed for determination of adsorption equilibrium, kinetics and thermodynamics parameters to Ru(III) from aqueous solution on MIP-202(Zr). The data of ruthenium sorption onto MIP-202(Zr) were fitted and analyzed by the Langmuir, Freundlich and Temkin equilibrium isotherm models, while the Langumir adsorption isotherm models fit the best. Kinetic data were analyzed by four kinetic models, and ruthenium sorption on MIP202(Zr) can be describes the best by intra particle diffusion (Weber Morris). Analysis of thermodynamic properties of ruthenium ions sorption onto MIP-202(Zr) shows that the sorption process has a spontaneous and endothermic nature and is energetically beneficial.

Nitrogen-doped activated carbon composite electrode for deionization of phosphate removal and DFT model adsorption of phosphates

Phosphate discharge in sewage can result in water eutrophication, posing a threat to aquatic ecosystems. Membrane capacitive deionization (MCDI) has demonstrated outstanding performance and significant potential for salt removal and nutrient recovery. In this study, a nitrogen-doped activated carbon electrode material (NAC) was synthesized through one-step pyrolysis to selectively remove phosphate from MCDI. At a voltage of 1.2V, a flow rate of 20 mL/min, and a pH of 6.51, the phosphate adsorption capacity of the NAC electrode was determined to be 1.60 mg/g. The study revealed that NAC pHpzc increased from 4.14 to 6.44, effectively broadening the pH range for phosphate removal. In the presence of competing ions (NO3−, Cl−, and SO42−) at a concentration of 0.5 M, the electroadsorption capacity of phosphate decreased to 1.21 mg/g, 1.14 mg/g, and 1.02 mg/g, respectively. The kinetic parameters of adsorption indicated that NAC electroadsorbed phosphate through physical adsorption, with the maximum adsorption capacity achieved at 303K. Data from the Freundlich isothermal model suggested that phosphate adsorption by the NAC electrode involves a multilayer adsorption process. A carbon structure model of density functional theory (DFT), incorporating doped nitrogen, was constructed based on XPS analysis. Following nitrogen doping, the electrostatic potential (ESP) of unsaturated carbon atoms became more positive, enhancing the ability of nitrogen-doped activated carbon to adsorb phosphate. This study provides compelling evidence that nitrogen doping facilitates the adsorption of phosphate by carbon materials.

Loofah sponge immobilized ZIF-8 for efficient adsorption removal of U (VI)

Efficient removal of radioactive and toxic uranium (U) from wastewater is highly desired. In this work, a novel adsorbent was prepared via in situ introducing zeolitic imidazolate framework-8 (ZIF-8) onto the hydrolyzed biomass loofah sponge (HLS) for the removal of U (VI). Benefiting from the introduction of ZIF-8, the physical and chemical properties of the composite adsorbent were significantly improved, leading to an enhanced U (VI) adsorption capacity. The results show that the maximum adsorption capacity of the adsorbent toward U (VI) is 244.03 mg/g under the optimal conditions. The adsorption kinetic parameters and isotherm of U (VI) well follow the pseudo second order model and Langmuir model, respectively. Besides, the thermodynamic parameters shows that the adsorption process of U (VI) is a spontaneous process with an exothermic nature. More importantly, the prepared adsorbent has a good reuseability and anti-interference capability during the adsorption of U (VI). This work supplies a new routine to design highly performed adsorbents for the removal of U (VI).

Kinetic and Mechanistic Modelling of Pyrimethanil Fungicide Adsorption onto Soils of Varying Physico-chemical Properties.

Pesticide transport in the environment is impacted by the kinetics of its adsorption onto soil. The adsorption kinetics of pyrimethanil was investigated in ten soil samples of varying physicochemical properties. The highest adsorption was in the soil having the maximum silt and CaCO3 contents, pH and electrical conductance but the lowest amorphous Fe oxides and CaCl2 extractable Mn. Pseudo-second order kinetics and intra-particle diffusion model best accounted the adsorption kinetics of pyrimethanil. The equilibrium adsorption estimated by pseudo-second order kinetics (q02) was significantly and positively correlated with CaCl2 extractable Cu content (r = 0.709) while rate coefficient (k02) had a negative correlation with crystalline iron oxides content (r = -0.675). The intra-particle diffusion coefficient (ki.d.) had inverse relationship with CaCl2 extractable Mn content in soils (r = -0.689). FTIR spectra showed a significant interaction of pyrimethanil with micronutrient cations. Adsorption kinetic parameters of pyrimethanil could be successfully predicted by soil properties. The findings may help to evolve fungicide management decisions.

Effects of TiO2 Nanoparticles Synthesized via Microwave Assistance on Adsorption and Photocatalytic Degradation of Ciprofloxacin.

In this study, the optimal microwave-assisted sol-gel synthesis parameters for achieving TiO2 nanoparticles with the highest specific surface area and photocatalytic activity were determined. Titanium isopropoxide was used as a precursor to prepare the sol (colloidal solution) of TiO2. Isopropanol was used as a solvent; acetylacetone was used as a complexation moderator; and nitric acid was used as a catalyst. Four samples of titanium dioxide were synthesized from the prepared colloidal solution in a microwave reactor at a temperature of 150 °C for 30 min and at a temperature of 200 °C for 10, 20, and 30 min. The phase composition of the TiO2 samples was determined by X-ray diffraction analysis (XRD) and Fourier-transform infrared spectroscopy (FTIR). Nitrogen adsorption/desorption isotherms were used to determine the specific surface area and pore size distributions using the Brunauer-Emmett-Teller (BET) method. The band-gap energy values of the TiO2 samples were determined by diffuse reflectance spectroscopy (DRS). The distribution of Ti and O in the TiO2 samples was determined by SEM-EDS analysis. The effects of adsorption and photocatalytic activity of the prepared TiO2 samples were evaluated by the degradation of ciprofloxacin (CIP) as an emerging organic pollutant (EOP) under UV-A light (365 nm). The results of the photocatalytic activity of the synthesized TiO2 nanoparticles were compared to the benchmark Degussa P25 TiO2. Kinetic parameters of adsorption and photocatalysis were determined and analyzed. It was found that crystalline TiO2 nanoparticles with the highest specific surface area, the lowest energy band gap, and the highest photocatalytic degradation were the samples synthesized at 200 °C for 10 min. The results indicate that CIP degradation by all TiO2 samples prepared at 200 °C show a synergistic effect of adsorption and photocatalytic degradation in the removal process.

Tailoring Physicochemical Properties of V2O5 Nanostructures: Influence of Solvent Type in Sol-Gel Synthesis.

The influence of different solvents, including aqueous and nonaqueous types, on the physicochemical properties of V2O5 nanostructures was thoroughly investigated. Various characterization techniques, such as XRD, XPS, FTIR, Raman spectroscopy, UV-vis DRS, SEM, TEM, and BET, were employed to analyze the obtained materials. Additionally, the adsorption properties of the synthesized V2O5 nanostructures for methylene blue were examined, and kinetic parameters of adsorption were calculated. The results demonstrate that the morphology of the obtained crystals can be finely controlled by manipulating water concentration in the solution, showcasing its profound impact on both the structural characteristics and adsorption properties of the nanostructures. Furthermore, the structural changes of the resulting V2O5 material induced by solvents show strong impacts on its photocatalytic properties, making it a promising photocatalyst.

Ruthenium sorption onto Fe3O4@MnO2: equilibrium, kinetic and thermodynamic study

Core–shell magnetic adsorbent Fe3O4@MnO2 was prepared and successfully used to ruthenium adsorption from aqueous solutions with 98% efficiency. The adsorption isotherms, kinetic and thermodynamic parameters for Ru(III) sorption onto Fe3O4@MnO2 were studied via a batch adsorption system. Adsorption isotherm models such as: Langmuir, Freundlich and Temkin were tested while the kinetic adsorption data were analyzed by pseudo-first order, pseudo-second order, and Weber-Morris models. It has been found that the adsorption process of Ru(III) onto Fe3O4@MnO2 can be describe by a Freundlich model whereas mechanism of sorption is presented better by kinetic Weber–Morris model. Freundlich adsorption isotherm constant is equal Kf = 30.62 mg/g and heterogenity factor n = 3.58. Sorption rate constant is k3 = 0.288 mg/(g·min1/2) and intraparticle diffusion rate constant C = 0.174 mg/g. Thermodynamic parameters such as free Gibb’s energy change (ΔG°), enthalpy change (ΔH°), entropy change (ΔS°) and energy activation Ea were determined. Calculated value of activation energy is equal 25.75 kJ/mol. The adsorption process of Ru(III) was found to be both spontaneous and thermodynamically preferable.

Adsorption of copper (II) from aqueous solutions using adsorbent obtained with sodium hydroxide activation of biochar prepared by microwave pyrolysis

AbstractMicrowave heating is one of the leading methods that save energy, time, and cost for the conversion of bio-waste into biochar in the agricultural sector. In this study, in the first stage, economical biochar production from pistachio green hulls by microwave heating method is in question. In the second step, sodium hydroxide(NaOH) activation was followed to improve the surface properties of biochar. This adsorbent obtained was applied to remove copper ions(Cu(II)) from wastewater. Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), thermogravimetry differential thermal analysis (TG/DTG), and nitrogen adsorption/desorption methods were used to characterize the biochar samples. In adsorption studies, kinetic, isotherm, and thermodynamic parameters were investigated. Cu(II) adsorption capacity on modified biochar obtained by Langmuir isotherm was found to be 227.27 mg/g. In addition, the mechanism of Cu(II) adsorption on modified biochar has been proposed. Biochar, which is obtained from the green shells of pistachios, which is widely available and grown in Turkey, by microwave method and then NaOH activation, is a potential solution for both the improvement of water pollution caused by heavy metals and the disposal of related wastes with an appropriate method.

Structure properties and industrial applications of anion exchange resins for the removal of electroactive nitrate ions from contaminated water.

The presence of nitrates in lakes, rivers, and groundwater is common. Anion exchange resins (AER) are polymeric structures that contain functional groups as well as a variety of particle sizes that are used for removing nitrate ions from solutions. This article provides a concise review of the types and properties of AER, synthesis methods, characterization, and environmental applications of AER. It discusses how different factors affect the adsorption process, isotherm and kinetic parameters, the adsorption mechanism, and the maximum adsorption capacities. Additionally, the present review addresses AER's regeneration and practical stability. It emphasizes the progress and proposes future strategies for addressing nitrate pollution using AER to overcome the challenges. This review aims to act as a reference for researchers working in the advancement of ion exchange resins and presents a clear and concise scientific analysis of the use of AER in nitrate adsorption. It is evident from the literature survey that AER is highly effective at removing nitrate ions from wastewater effluents.

Pyrolyzed bone char for nitrobenzene adsorption: Insight into the physicochemical characterizations and adsorption mechanisms

In this study, the preparation of pyrolyzed bone chars for the removal of nitrobenzene (NB) from the water was examined. Adsorption properties of bone chars prepared at diverse pyrolysis temperatures (300–900 ℃) were investigated for removing NB from aqueous solutions. At higher temperatures (700 and 900 ℃), bone chars showed superior adsorption properties for NB removal, and physicochemical characterizations showed that the pyrolyzed bone chars possessed improved properties and amended porous structure after pyrolysis treatment. Pyrolysis temperatures of > 700 ℃ contributed to the dehydroxylation of hydroxyapatite of bone chars, increasing their NB adsorption performance. Maximum NB adsorption capacity of higher temperature pyrolyzed bone chars calculated from the Langmuir isotherm model was 142.41 and 204.34 mg/g for bone char-700 and bone char-900, respectively, indicating that the bone chars had the potential for enhanced NB adsorption. For adsorption isotherm parameters, two-parameter (Langmuir and Freundlich) models showed satisfactory results of NB adsorption on bone char from aqueous solution. Adsorption kinetic parameters of NB adsorption on bone chars showed pleasing results for the pseudo 2nd order model. This study shows that the pyrolyzed bone char is an efficient adsorbent for removing NB from water.

Experimental and theoretical study on corrosion inhibition and adsorption performance of Ipomoea batatas L. leaf extract for mild steel

Recent years have seen a surge in interest in efficient, green, and eco-friendly corrosion inhibitors, leading to extensive research on plant extracts. This study investigates the active phytochemicals in abundant Ipomoea batatas L. leaves, which were extracted with ultrasonics using an ethanol–water solution and applied to mitigate the corrosion of mild steel (MS) in a 1 M HCl pickling solution. The chemical compositions and corrosion inhibition properties of the leaf extract of Ipomoea batatas L. (IBLE) were explored through multiple experiments, and the adsorption thermodynamic and kinetic parameters were analysed. Electrochemical results indicated that the corrosion inhibition mechanism of IBLE is a geometric coverage effect; IBLE acts as a mixed-corrosion inhibitor; and the inhibition efficiency increases with extract concentration and solution temperature, reaching up to 96.4 % at 318 K. X-ray photoelectron spectroscopy (XPS) results showed the adsorption of C=C, C–N, C–N+, C=N, C=N+, C=O, C=O+, C–O, C–O+, Fe-N and other carbonaceous groups on the steel surface. Surface observation confirmed that IBLE can effectively retard steel corrosion. The adsorption analysis revealed that the protective film is a monolayer that follows the Langmuir isotherm, and the oriented adsorption of active ingredients enhances the order of the MS surface. Density functional theory (DFT) and molecular dynamics (MD) simulations were conducted to examine the relationship between inhibition and adsorption of IBLE. The theoretical calculations confirmed that the active compounds in IBLE can adsorb on the Fe (110) surface through physical patterns and by sharing charges with iron to form coordinate bonds. The adsorption abilities of different ingredients vary, but all exhibit synergistic adsorption effects. IBLE can be considered an efficient and renewable corrosion inhibitor for MS in HCl pickling media.

Corrosion inhibition of mild steel in 1 M HCl by pyrazolone-sulfonamide hybrids: synthesis, characterization, and evaluation

Carbon steel is widely used in the petroleum industry for pipelines, storage tanks, and equipment due to its mechanical properties, and strength. However, challenges such as environmental conditions and corrosive materials can affect its lifespan and require maintenance and repair. This work aimed to prepare pyrazalone-sulfonamide hybrids, and confirmed by mass spectra, FTIR, 1H-NMR, and 13C-NMR. These compounds were examined as mild steel corrosion inhibitors in 1 M HCl solutions at 298–323 K using the gravimetric technique, electrochemical measurements, scanning electronic microscope analysis, and quantum chemical calculations. The values of inhibitory efficiency identified by electrochemical and non-electrochemical techniques exhibit good agreement. At various temperatures and in the 50 to 500 ppm concentration range. During the adsorption process, these substances connect to the Langmuir adsorption isotherm. Some adsorption isotherm and kinetic parameters have been developed and discussed. The metal surface had a thin inhibitory protective layer, according to investigations using energy dispersive X-ray spectroscopy (EDX) and scanning electron microscope (SEM). These findings demonstrated the potential of pyrazolone-sulfonamide as effective organic corrosion inhibitors for carbon steel.

Response surface methodology based modelling and optimisation of anionic dyes adsorption onto nitrate intercalated Zn2Al layer double hydroxide adsorbent

ABSTRACT In the present work, nitrate intercalated zinc aluminium layer double hydroxide (ZA-LDH) nanoparticles in the hydrodynamic particle size range between 210 and 530 nm were synthesised using co-precipitation method under reflux condition and nitrogen atmosphere. The pristine ZA-LDH nanoadsorbent was characterised using X-ray diffraction (XRD), Fourier transformation spectroscopy (FTIR), and field emission scanning electron microscopy (FESEM). The results revealed the formation of single-phase ZA-LDH nanopowder with sheet-like morphology. The optimisation of adsorption kinetic parameters with the fixed dose of 10 mg for 50 ml of 0.03 mg/ml MO and AY dye solution was performed using the Box Behnken design model (BBD). The effects of three independent variables such as incubation time, temperature and pH of the suspended ZA-LDH nanoadsorbents in the MO and AY dye solution on the adsorption kinetics were studied. Optimum values for the maximum adsorption capacity were evaluated that included the incubation time of 52.4 min, the temperature of 35.45 ± 0.55°C, and the pH of 5.75 ± 0.75. According to the BBD model, ZA-LDH nanoadsorbent exhibited the maximum adsorption percentage of 99.84% and 99.99% of corresponding MO and AY dye, respectively. The ZA-LDH adsorbent retained up to 72.3% for the MO and 60.43% for the AY dye of regeneration capacity after 5 cycles of regeneration. The adsorption kinetic and isotherm of the MO and AY dyes onto the ZA-LDH nanoadsorbent were well fitted with pseudo second order kinetic model and Langmuir model, respectively. According to Langmuir isotherm, the maximum adsorption capacities of 601.62 mg/g for the MO dye and 462.48 mg/g for the AY dye onto the ZA-LDH were found and those confirmed the monolayer chemisorption mechanism in this case.

Adsorptive performance of a new magnetic hydrochar nanocomposite for highly efficient removal of cadmium ions from water: Mechanism, modeling, and reusability studies

In this study, a novel and effective magnetic watermelon seed hydrochar (MWSHC) was successfully synthesized via hydrothermal carbonization technique and in situ co-precipitation method. The prepared magnetic watermelon seed waste hydrochar has been utilized for the elimination of cadmium ions from the aqueous environment. The structural morphology, surface properties, and thermal stability of MWSHC adsorbent were characterized using FTIR, SEM, XRD, BET surface area, and TGA analysis, which demonstrated the successful synthesis of MWSHC. An extensive study of Cd(II) adsorption was conducted by assessing the influence of contact time, adsorbent mass, pH, initial Cd(II) concentration, temperature, and coexisting cations on the adsorption process of Cd(II). The results revealed that the removal efficiency of Cd(II) was 96.60% achieved at pH 7.0, time: 300 min, and dosage: 0.01 g, T: 298 K. Adsorption isotherm and kinetic parameters were estimated. The results indicated that the Cd(II) adsorption onto MWSHC followed the Freundlich and pseudo-second-order models. Based on the Langmuir equation, the MWSHC has a maximum adsorption capacity of 347.2 mg/g at 298 K. The reusability of magnetic hydrochar nanocomposite was studied, revealing that around 84.4% Cd(II) was still removed after four cycles. In conclusion, the newly- prepared MWSHC adsorbent has the advantages of high adsorption capacity, cost-effectiveness, and easy separation, thus having promising applications in effectively removing cadmium(II) from the aqueous environment.

Removal of aqueous uranyl ions using titania-supported mesoporous silica composite with the synergistic effect of coupled adsorption and photocatalytic reduction of U(VI)

The aim of this study is to determine and compare the adsorption capacities, kinetic and thermodynamic parameters of the adsorption process of uranyl ions from aqueous solution on nanotube titania impregnated mesoporous silica SBA-15 (TNT-SBA-15) and naked SBA-15 (nSBA-15) adsorbents. The TNT-SBA-15 composite containing various molar ratio of nanotube titania to silica (TNT-SBA-15(m:n)) in the matrix was synthesized by the sol–gel/impregnation method using sodium silicate as a silica precursor, sulphuric acid and nanotube titania. Batch adsorption experiments showed that the maximum adsorption capacity (qmax) of the TNT-SBA-15(m:n = 1:1) composite under indoor light be as high as 2.65 mMoleU g−1 that was 1.4 times higher than that of nSBA-15 under the same conditions. Under UV (300 W) illumination the qmax of TNT-SBA-15(1:1) adsorbent reached 3.49 mMoleU g−1 that was 2 times higher than the qmax in the dark. The increase in qmax of the TNT-SBA-15(1:1) composite in the two experiments was attributed to the synergistic effect of coupled sorption and photocatalytic reduction of U(VI) by titania following the deposition of uranium (IV) (hydr)oxide on the surface of the adsorbent. The adsorption process followed a pseudo-second kinetic model. The activation energy was found to be 160 and 135 kJ Mole−1 for the adsorption on nSBA-15 and TNT-SBA-15(1:1), respectively. The isotherm of the adsorption process follows the Langmuir as well as Freundlich models. The adsorption is an endothermic and spontaneous process. Adsorbed TNT-SBA-15 can be easily regenerated in 0.3 M HNO3 solution, and the qmax of the adsorbent was maintained at 95% the initial qmax after three consecutive adsorption–desorption cycles. These results revealed that, though TNT-SBA-15 made from inexpensive reagents could be an effective adsorbent for uranyl removal from wastewater.

Using Highly Sensitive Piezo Sensors in an Open System for the Diagnostic Analysis of Skin Volatile Substances

A single sensor with a piezoelectric quartz transducer is considered a platform for simulating an “electronic nose” that performs the function of a sensor array. The analytical task was to detect volatile organic compounds, component-by-component, in biosamples at diagnostically relevant concentrations without selecting mixtures or any sample preparation. We confirmed the fundamental possibility of utilizing a single sensor for the separate detection (recognition) of vapors of organic compounds and various functional states of a body during a short contact (60–80 s) with skin, the most representative and constantly performing bioassay. Modifying the electrodes of bulk acoustic wave piezoelectric quartz resonators with 2–4 μg of the nanohydroxyapatite phase is an essential step in solving the problem. The newly calculated adsorption kinetic parameters can be used to detect biomarkers of many diseases with high reliability, including С3–С5 alcohols, ketones, linear and cyclic amines, acids, aldehydes, etc. The hydroxyapatite sensor can detect molecules pointing to problems with many organs, and any abnormalities in the functioning of the nervous and cardiovascular systems. It can also measure the body’s responses and compensatory mechanisms in relation to stress, hunger, and fatigue. The sensor has a potential as a simple diagnostic and monitoring tool for point-of-care diagnostics of both adults and children.

New insights in the treatment of real oilfield produced water: Feasibility of adsorption process with coconut husk activated charcoal

Naphthenic acids are water-soluble organic compounds (WSO), present in oilfield produced water (OPW), whose removal aims to comply with environmental legislation and ensure the correct disposal of OPW. In this study, the performance of the adsorptive process for the removal of WSO in synthetic (single- and multi-component) and real OPW was evaluated. It was observed that the lower the pH of the sample, the greater the adsorption capacity of WSO. Moreover, the kinetic parameters of adsorption followed the pseudo-second order model while the equilibrium parameters were represented by the isothermal BET (Brunauer, Emmett and Teller) model. In the desorption process followed the second-order model, and the aqueous solution of sodium hydroxide (0.3 and 0.1 M) showed the highest desorption efficiency (~70 %) in the synthetic and real systems, respectively. With this protocol, the adsorbent proved to be effective for the treatment of OPW, without significant loss of efficiency, for up to three consecutive cycles of adsorption-desorption. In addition, after treatment, the real effluent was classified within the legal parameters for offshore disposal, which enhances its industrial application.

Preparation of poly(2‐hydroxyethyl methacrylate)‐grafted chitosan‐montmorillonite superabsorbent nanocomposite for adsorption of bovine serum albumin

AbstractIn this paper, we examined adsorption process of bovine serum albumin (BSA) on [p(HEMA)‐g‐CTS]/MMT ([poly(2‐hydroxyethyl methacrylate)‐graft‐chitosan]/montmorillonite) superabsorbent nanocomposite. [p(HEMA)‐g‐CTS]/MMT superabsorbent nanocomposite was synthesized via free radical polymerization. Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and thermal gravimetric analysis (TGA) techniques, and also swelling test have been utilized for the structural characterization of the synthesized [p(HEMA)‐g‐CTS]/MMT superabsorbent nanocomposite. The influence of numerious adsorption parameters (initial BSA concentration, contact time, pH, sorbent amount, temperature, and ionic strength) on adsorption process were evaluated. Adsorption results showed that the superabsorbent nanocomposite had high affinity to BSA, and maximum adsorption capacity of [p(HEMA)‐g‐CTS]/MMT superabsorbent nanocomposite is 75.8 mg/g. The BSA adsorption results showed that the adsorption kinetics parameters was found to be suitable for the pseudo‐second‐order kinetic adsorption model and the equilibrium BSA adsorption data were explicated according to the Freundlich adsorption isotherm model.

Synthesis, characterization, and performance of chitosan/nylon 6/polyurethane blend for the removal of chromium (VI) and lead (II) ions from aqueous solutions for enhanced kinetic adsorption studies

Abstract Adsorption is vital for the elimination of Cr6+ and Pb2+ ions in the contaminated solution medium. A ternary blend made up of chitosan, nylon 6 and polyurethane foam (CS/Ny 6/PUF) blend in the ratio of 2:1:1 has been investigated. These blends are used as an adsorbent due to the insoluble nature in acidic and basic medium. The adsorption efficacy was analyzed by modifying pH, contact time, and adsorbent dosage. The maximum uptake of metal ions has been exhibited in the pH range 5. An equilibrium adsorption statistic indicated that adsorption isotherm follows the Freundlich model. The adsorption kinetic parameters specified that the adsorption of chromium has shown pseudo-second-order and lead pseudo-first-order reaction.