Adsorption Kinetic Studies Research Articles

Magnetic activated carbonaceous materials from sugarcane bagasse: Preparation, characterization, and hexavalent chromium removal

The presence of hexavalent chromium (Cr (VI)) in effluents remains a global concern due to its toxic properties. Even though adsorption has been employed for its removal from water, developing sustainable materials with higher adsorption capacities is still pivotal to tackling such contamination. In this study, two magnetic carbons (MC) were produced by hydrothermal carbonization (HTC) of sugarcane bagasse in the presence of iron (III) nitrate at 230 and 270 °C. Both MCs were thermochemically activated at 500 and 700 °C using KOH (1:2; w:w). The materials were characterized in terms of composition, structure, morphology, texture, and surface properties and then evaluated in adsorption studies of Cr (VI). After HTC, some iron phases such as α-Fe2O3, γ-Fe2O3, and Fe3O4 were observed, while thermochemical activation additionally revealed Fe0 and Fe4[Fe(CN)6]3. Activation increased the amount of meso- and macropores, specific surface area, pHzpc, surface hydrophilicity, and carbon and nitrogen contents. The adsorption kinetics study indicated that the pseudo-second-order model describes better the behavior of the materials. The investigation of adsorbent dose showed that doses below 1.00 g L−1 were more efficient in Cr (VI) removal. MC-230 and MC-270 thermochemically activated at 700 °C exhibited the highest Cr (VI) adsorption capacities (10.5 and 15.5 mg g−1, respectively). Therefore, the improved adsorption capacity for Cr (VI) of the materials thermochemically activated at 700 °C was mainly due to their enhanced textural properties.

The Adsorption Isotherm and Kinetics Studies of Cu(II) and Cr(III) Metal Ions from Aqueous Solutions on Activated Biosorbent of Coffee Pulp Waste

The Adsorption Isotherm and Kinetics Studies of Cu(II) and Cr(III) Metal Ions from Aqueous Solutions on Activated Biosorbent of Coffee Pulp Waste

Adsorption Isotherm, Kinetic and Thermodynamic Studies for Removal of Fluoride Ions from Drinking Water Using Modified Natural Pumice

This study aimed to modify pumice using aluminum chloride as an adsorbent for defluoridation. Batch and column experiments were carried out to evaluate the effects of pH, initial fluoride concentration, contact time, dose, and temperatur. The modified pumice adsorbent showed good fluoride removal in both batch and column studies. Fluoride up-take was observed to be effective >7%, at pH 6.5-7.5, and adsorption equilibrium time was observed at 60 min. the adsorption results were modelled using kinetic and isotherm models. Experimental data indicated that fluoride adsorption follows the second pseudo-order kinetics model (R2 > 0.99) and fits well with both the Freundlich and Langmuir isotherm models, which showed favorability for the adsorption of fluoride with a maximum capacity of 0.083 mg/g. The negative values of ∆Ho and ∆Go indicate that the adsorption process was feasible, exothermic, and spontaneous. The column performance showed the best fluoride uptake efficiency, with a breakthrough capacity of 0.48 mg/g. The %R was approximately %100 using0.1M NaOH. Fluoride levels in real wells water decreased dramatically (e.g. 4.1-0.88, 7.1-1.54, and 6.2-1.46 mg/L). The results revealed that modified pumice has the potential for fluoride removal from drinking water.

Adsorption Kinetics Studies for Groundwater Remediation: A Study on Environmental and Economic Sustainability

Adsorption Kinetics Studies for Groundwater Remediation: A Study on Environmental and Economic Sustainability

Efficient Capture of Phosphate From Aqueous Media Using Bimetallic La‐Zr‐MOF

ABSTRACTDeposition of excessive phosphate in natural water column caused several issues, like the eutrophication and destruction of aquatic ecosystems. Adsorption has been an effective and convenient method for phosphate elimination. Herein, a novel bimetallic metal–organic framework adsorbent, namely, La‐Zr‐MOF, was prepared, and the morphology, crystallite, characteristic functional groups, specific surface area, and composite material surfaces were analyzed using XRD, FT‐IR, SEM‐EDS, and BET. The adsorption performance of the adsorbent was systematically evaluated by batch adsorption experiments, and the adsorption thermodynamic and kinetic properties were analyzed. The results reveal that La‐Zr‐MOF exhibits a high selectivity and sorption performance for phosphate, and the adsorption of La‐Zr‐MOF follows the Langmuir and pseudo–second‐order models; the phosphate removal procedure is a chemisorption accompanied by an endothermic reaction, and the maximum capacity was 127.7 mg g−1. Combined with batch adsorption experiments, kinetic and thermodynamic studies and various characterization analyses together revealed the phosphate removal mechanism, mainly ligand exchange and electrostatic interactions.

Isotherm, kinetic, and thermodynamic studies of adsorption of copper (II) and nickel (II) ions using low‐cost treated orange peel from aqueous solutions

AbstractThe aim of this study was to utilize processed orange peel waste (TOP) as an adsorbent to remove Cu(II) and Ni(II) ions from aqueous solutions. As a result of systematic experiments to determine the optimal conditions, it was determined that the most suitable conditions for the effective removal of Cu(II) ions were 400 mg/L initial concentration, 100 min contact time, 0.2 g adsorbent dosage, and a solution pH of 5.92. Similarly, the optimal conditions for the removal of Ni(II) ions were determined by systematic experiments to be 300 mg/L initial concentration, 0.2 g adsorbent dosage, 100 min contact time, and a solution pH of 6.19. The systematic experiments also included further investigation of the surface properties of TOP, and promising results were obtained by tests at three different temperatures (298, 308, and 318 K). The adsorption capacities for Cu(II), Ni(II), and Ni(II) were determined as 72.99, 75.18, and 76.33 mg/g, 42.55, 44.44, and 46.29 mg/g, respectively. Further analysis of the adsorption kinetics revealed that the pseudo‐second‐order model accurately represented the experimental data for both ions. Thermodynamic investigations provided strong evidence that the adsorption process of these noble metal ions on TOP is endothermic and spontaneous. The results of this study emphasize that TOP, with its low cost, easy‐to‐use nature, and high adsorption capacity, can be considered a long‐term solution for environmental remediation and water treatment in sustainable engineering applications.

Kinetic adsorption studies of methylene blue and crystal violet dyes removal in single and competitive systems using lemon peels/activated carbon/alginate composite

Kinetic adsorption studies of methylene blue and crystal violet dyes removal in single and competitive systems using lemon peels/activated carbon/alginate composite

Synthesis and characterization of novel β-cyclodextrin xanthate hydrogel/nickel oxide nanocomposites: adsorption isotherm, kinetic, thermodynamic, photocatalytic activity and reusability studies

Synthesis and characterization of novel β-cyclodextrin xanthate hydrogel/nickel oxide nanocomposites: adsorption isotherm, kinetic, thermodynamic, photocatalytic activity and reusability studies

Adsorption Kinetic, Isotherm and Mechanism Study of Xanthate-Modified Neem Leaf Powder as an Efficient Adsorbent for Methylene Blue Dye

Adsorption Kinetic, Isotherm and Mechanism Study of Xanthate-Modified Neem Leaf Powder as an Efficient Adsorbent for Methylene Blue Dye

Kinetic and Mechanistic Analysis of Phenol Adsorption on Activated Carbons from Kenaf

Activated carbons were prepared from kenaf (Hibiscus cannabinus L.). Carbonization was carried out at 600 °C for 2 h, and activation was performed using air at 600 °C and using CO2 at 750 °C. The activated carbons obtained were treated with HNO3 and H2SO4. The samples were characterized by their chemical and physical structure. The activated carbons obtained were mainly macroporous, and their structure underwent major changes with the activation method and acid treatment. Activated carbons were alkaline and acid-treated carbons were neutral. They were used for phenol adsorption and a kinetic and mechanistic study of adsorption was carried out. The fit to the pseudo-second order and Elovich models was predominant. The rate-limiting step of the process was determined to be diffusion within the pores, as the experimental data fit the Bangham model. DFT simulation showed that the preferred adsorption position involves π-π stacking and that oxidation enhances this interaction. Furthermore, the simulation showed that the interaction of phenol with oxygenated functional groups depends on the type of functional group.

Improving the adsorption properties of low surface area hardwood biochar for the removal of Fe+ and PO₄3- from aqueous solution.

Biochar produced from wood residues may provide a new method and material for managing the environment, particularly in terms of carbon sequestration and contaminant remediation. Additionally, biochar produced from wood residues is free of chemical fertilizers, likewise in rice straw, wheat straw, corn straw, etc. This study investigated the removal of iron from aqueous solutions by a novel low-cost and eco-friendly biochar made from hardwood trees and modified by adding MgCl2 for effective phosphate removal. Optimal adsorption conditions were determined through studies of adsorption time, pH, and adsorbent dosage. Batch equilibrium isotherm and kinetic experiments and pre/post-adsorption characterizations using FESEM-EDS, XRD, and FTIR suggested that the presence of carboxyl group elements and colloidal and nano-sized MgO (periclase) particles on the biochar surface were the main adsorption sites for aqueous iron and phosphate respectively. In this study, the HW and MgO-HW biochar showed excellent Dubinin-Radushkevich isotherm (D-R) maximum adsorption capacities of 289.45 and 828.82mg/g for iron and phosphate. The kinetic study for iron and phosphate adsorption was described well by pseudo second-order model and pseudo second-order model respectively. The HW biochar and the prepared MgO-HW biochar exhibited commendable iron adsorption (98.25%) performance at 10 pH units and phosphate (96.22%) at pH 6 respectively. Thus, this research reveals a waste-to-wealth strategy by converting hardwood waste into mineral-biomass biochar with excellent Fe and P adsorption capabilities and environmental adaptability.

Kinetic study of paraquat adsorption on alginate beads loaded with montmorillonite using shrinking core model

Water contamination by pesticides threatens clean water availability, highlighting the need for advanced sustainable sanitation systems. Adsorption using biopolymers and minerals is prominent. Understanding process kinetics and influencing parameters is crucial for optimizing contaminant-adsorbent contact time for safe water disposal. The adsorption kinetics of Paraquat (PQ) at three initial concentrations (C0 = 19, 38, and 50 ppm) were studied using alginate-montmorillonite (Alg-Mt) beads with varying clay contents and a 30-min gelation time. The beads were characterized by elemental analysis, TG/DTG, FTIR, XRD, SEM, and EDX. The Shrinking Core Model (SCM) was applied to the experimental data to determine if the diffusion of PQ within the beads depended on clay content. The effective diffusion coefficient (Dp) in the adsorbent increased from 7 × 10−12 to 1 × 10−10 m2 s−1 with increasing clay content, suggesting that diffusion into the interior depended on interaction with the mineral.This investigation also demonstrated that the synthesis of beads at different gelation times does not impact either the adsorption capacity or the adsorption rate of the herbicide on the materials. These results indicate that diffusion depends solely on the interaction of the cationic herbicide with the clay encapsulated within the bead hydrogel.

Kinetic and isotherm adsorption studies of Zn (II) ions on hydroxyapatite nanoparticles: Linear and nonlinear analyses

Kinetic and isotherm adsorption studies of Zn (II) ions on hydroxyapatite nanoparticles: Linear and nonlinear analyses

A facile and green synthesis of corn cob-based graphene oxide and its modification with corn cob-K2CO3 for efficient removal of methylene blue dye: Adsorption mechanism, isotherm, and kinetic studies

In recent years, the treatment of synthetic dyes has become an environmental concern. In this study, a single step calcination process was used to develop the inventive, simple, and inexpensive adsorbent CC-GO/CC-K2CO3 composite. The composite was employed for the treatment of methylene blue (MB), a cationic dye. Several characterization methods including powder XRD, FTIR, XPS, BET, FESEM, EDX, Raman, and HRTEM techniques were utilized for the analysis of the composite. The surface area and mean pore diameter of CC-GO/CC-K2CO3 were 32.651 m2 g−1 and 3.71 nm, respectively. The adsorption experiment showed that optimal parameters for the removal of MB dye are at an adsorbent dose of 60 mg, initial dye concentration of 80 mg/L, contact time of 150 min, and pH value of 12 at room temperature. Under optimized conditions, CC-GO evidences a removal efficiency of 70.34 ± 1.36 % while after incorporation with CC-K2CO3 the removal capacity sharply increases up to 98.10 ± 0.4 %. Kinetic and isotherm models were used to analyze the removal rate constant and equilibrium adsorption capacity under various adsorption environments. The adsorption study was found to follow the models of pseudo-second order kinetic and Freundlich isotherm. The CC-GO/CC-K2CO3 composite has the maximum adsorption capacity (MAC) of 160.77 mg/g established by the Langmuir isotherm. The prepared composite has demonstrated the capacity to be recycled up to three times with a gradual decrease in its adsorption behavior, exhibiting removal efficiency of 61.66 ± 2.04 %.A cost estimation study of the composite was also performed to assess its cost effectiveness.

A new explanation for the synergistic promoted mechanism of nitrate and nitrite anion species for the high performance MgO adsorbent

The mechanism of CO2 capture on the nitrate and nitrite anion species synergistic promoted MgO has been rarely studied and still not fully understood. Herein we report a systematic investigation on the CO2 adsorption performance of molten salts-promoted MgO adsorbent to deeply reveal the synergistic promoted mechanism of nitrate and nitrite. A series of MgO-based solid adsorbents were synthesized and applied for CO2 capture using NaNO2/KNO3 as promoters. The addition of mixed nitrate and nitrite promoters greatly enhances the adsorption capacity of MgO, exhibiting CO2 capture up to 10.25 mmol·g−1 under optimal conditions. The MgO-based adsorbent in the form of nanosheets has faster adsorption kinetics and better stability, and the possible reaction mechanism of MgO modified by nitrate and nitrite was proposed. Firstly, NO3– interacts with the lattice oxygen (O12-) of MgO to form NO2– and O22–. Secondly, Mg2+ interacts with the free NO2– to form [Mg···NO2]+ and further overcomes the energy barrier to generate [Mg2+···O2–] ion pairs. O22– is not stable and prone to side reaction. However, NO2– can be converted into O2–, and O2– is further generated to O22–, facilitating regeneration of NO3–. The introduction of molten salt can significantly reduce the reaction energy barrier, and the energy barrier required to generate [Mg2+···O2–] ion pairs is reduced from 6.86 eV to 3.50 eV. Adsorption kinetics studies reveal that the nano-flake MgO facilitates the full contact with the promoter and has faster reaction kinetics in the surface reaction control stage. These insights into the synergistic promoted mechanism of nitrate and nitrite anion species is expected to provide guidance for the further design of the high performance MgO-based CO2 adsorbent.

Metal-modified biochars prepared from blue algae and their ability of adsorbing phosphates from water and utilization as soil amendment

The problem of blue algae accumulation can be alleviated by utilizing blue algae as biomass for resource utilization, which can remove excess phosphates from water to alleviate eutrophication. Herein, Magnesium (Mg) and/or lanthanum (La) were used to modify biochar via high-temperature slow pyrolysis with blue algae as the raw biomass. These modified biochars exhibited abundant carbon (18.0%-50.3%), oxygen content (17.4%-49.1%), along with a high specific surface area (82.26-233.80 m2/g). The surface of metal-modified biochar was enriched with hydroxyl and carboxyl groups and metal elements were efficiently incorporated into biochars. Adsorption kinetic and isotherm experiments were conducted under the optimal pyrolysis temperature of 600 °C, pH of 6.0, and adsorbent dosage of 2.0g/L. The adsorption kinetics studies by metal-modified biochars for phosphate fitted well pseudo-second-order model Redlich-Peterson isotherm model. Biochar modified by Mg and La exhibited the highest removal efficiency (97.8%) for phosphate at adsorption equilibrium. The adsorption mechanism involved the electrostatic interaction between hydroxylated metal oxides and negatively charged phosphate ions and the precipitation of phosphate ions through chemical reactions with metal oxides in the solution. After phosphate adsorption, the pristine and metal-modified biochars derived from blue algae were applied as the soil amendment. Biochar adsorbed phosphate apparently improved the germination rate of seeds facilitated the height, width, weight, and chlorophyll content of vegetable seedlings, and induced oxidative stress, which proved that the biochar recovered after adsorption was a high-quality soil amendment. This study provides a new approach for the treatment of phosphate wastewater and the algae application.

Cost‐Effective Approach for Fabrication of High‐Quality Expanded Vermiculite for Alizarin Red S Removal From Aqueous Media

AbstractVermiculite is extensively utilized for several applications, including as a hydroponic substrate, for soil conditioning, oil cleansing, and addressing trace metal pollution. In this study, the expansion of natural vermiculite was easily achieved by utilizing hydrogen peroxide (H2O2) with the aid of microwave technology. The characterization of expanded vermiculite involved the use of X‐ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), nitrogen adsorption isotherm (BET), and energy dissipation X‐rays (EDX). The vermiculite has been enlarged to have a structure resembling flakes, and its surface area measures 73.9 m2/g. The adsorption of Alizarin Red S onto expanded vermiculite was investigated under varying conditions, such as pH, starting concentration, adsorbent content, and duration of exposure. The enlarged vermiculite achieved a maximum adsorption capacity of 182.5 mg/g for Alizarin Red S. Out of the three adsorption isotherm models, both the Freundlich and Temkin models accurately describe the adsorption of Alizarin Red S onto expanded vermiculite. When studying adsorption kinetics, the second‐order adsorption kinetic model is more appropriate than the first‐order adsorption kinetic model, as indicated by an R2 value of 0.8964.

Comparison of adsorption potential of methylene blue and 17β-stradiol on biochar, activated biochar and catalytic biochar from lignocellulosic waste

This work compares the adsorption capacity of methylene blue (MB) and 17β-stradiol (17β-S) onto biochar (B), activated biochar (AB) and catalytic biochar (CB), obtained through pyrolysis of residual lignin of the second-generation (2G) ethanol production process from a sugarcane industry. K2CO3 was used as activating agent and catalyst. Biochars were characterized by the techniques of point of zero charge, nitrogen adsorption and desorption, SEM and FTIR. Kinetic, isothermal and thermodynamic adsorption studies were carried out. Biochars behaved according to the pseudo-second order (PSO) kinetic model, with similar removal percentages of MB using AB and CB. In contrast, AB showed significantly higher removal percentages of 17β-S than CB. The Sips model agreed to isothermal adsorption data of 17β-S onto all biochars. For MB adsorption, Freundlich model agreed to data using B and AB, and Langmuir model was more suitable for CB. The process was viable, spontaneous, endothermic and showed increase in entropy, except for 17β-S adsorption onto CB. Consequently, the activated and catalytic pyrolysis processes increased the adsorptive potential of biochar derived from 2G lignocellulosic residue. Finally, CB and AB obtained significant removal percentage values of MB (85.8–99.3 %) and 17β-S (37.6–76.7 %), where CB is favorable due to its simpler preparation steps.

Waste biomass-based graphene oxide decorated with ternary metal oxide (MnO-NiO-ZnO) composite for adsorption of methylene blue dye

In this study, a novel approach for the removal of methylene blue (MB) dye is effectively illustrated by using biomass based composite adsorbent. The investigation employed areca nut husk (AH) to produce graphene oxide (GO) by a single step calcination method. Thereafter, AH-GO was incorporated by using ternary metal oxide (TMO) via hydrothermal treatment. The developed AH-GO@MnO-NiO-ZnO composite was characterized by various analytical techniques, including FT-IR, XRD, FESEM, HRTEM, BET surface area and Raman spectroscopy which exhibited promising properties for dye adsorption. To study the adsorption efficiency of prepared composite, optimization experiments were performed for adsorbent dose, initial dye concentration and contact time. The optimized parameters during adsorption phenomenon were found to be 0.5g/L of dose, 20mg/L of initial concentration and 180min of time exhibiting removal efficacy of 93.05 ± 0.93%. Moreover, adsorption isotherm and kinetic models were analysed to explore the adsorption behaviour of AH-GO@MnO-NiO-ZnO towards MB dye. The adsorption isotherm and kinetic studies followed Langmuir isotherm model and pseudo-second-order (PSO) model respectively. AH-GO@MnO-NiO-ZnO has demonstrated a maximum adsorption capability of 127.06mg/g. These findings collectively underscore the potential of AH-based adsorbent as a viable, inexpensive, and environment friendly for the treatment of wastewater contaminated with MB dye.

Magnetic graphene oxide incorporated with Fe2O3 for the removal of lead (II) ions

The objective of this research work is to synthesise graphene oxide (GO) with iron oxide (Fe2O3) nanoparticles as a magnetic adsorbent for lead ion (Pb2+) removal. In this work, the effect of synthesis parameters of GO/Fe2O3 (Fe2O3 loading weight ratio, synthesis time and calcination temperature) and adsorption parameters (initial Pb2+ concentration, adsorption temperature and contact time) on Pb2+ removal were investigated. The adsorption experiment was carried out in a batch system, and the synthesised GO/Fe2O3 adsorbent was characterised using TGA and N2 sorption-desorption analyses. The adsorption characteristics of Pb2+ using GO/Fe2O3 adsorbent were analysed using adsorption isotherms and kinetic study. The optimal synthesis parameters were found to be a 1:0.5 ratio for GO/Fe2O3, a synthesis time of 60 min and a calcination temperature of 400°C, resulting in a Pb2+ removal rate of 96% and adsorption capacity of 49.85 mg Pb2+/g adsorbent. The GO/Fe2O3 adsorbent synthesised at 400°C and a 1:0.5 ratio exhibits a larger surface area and smaller pore diameter, 98.20 m2/g and 15.67 nm, respectively, compared to other samples. Increasing the synthesis temperature decreases the growth and formation of GO/Fe2O3, reducing the surface area. Experimental results revealed that the adsorption of Pb2+ using GO/Fe2O3 adsorbent fitted the pseudo-second-order kinetic and was best described by the Langmuir isotherm with a high correlation coefficient (R2 >0.99).