Continuous Adsorption Research Articles

Continuous Removal of Dyes from Wastewater Using Banana-Peel Bioadsorbent: A Low-Cost Alternative for Wastewater Treatment

Methylene blue is a widely used dye that can have severe negative impacts on the environment and human health. Adsorption is an effective method for removing it from wastewater, but the high cost of traditional adsorbents has motivated the research into low-cost alternatives derived from waste biomass. Designing a dye-removal process requires the knowledge of breakthrough curves. This paper assesses the use of banana peel as an adsorbent in a continuous process for the removal of methylene blue. The adsorption efficiency of lab-scale continuous systems using a stock solution of 0.5 g L−1 methylene blue was analyzed. The best performance was found at pH 6, with a particle size of 0.08–0.3 mm and a fixed bed height of 7.5 cm. The total adsorption capacity was 22.11 mg/g based on experimental data and 25.40 mg/g based on mathematical modeling (Thomas model). The saturation time was 53 h. According to the results, the process conditions and adsorbent characteristics have a critical role in the design of continuous adsorption systems. However, further research is needed to generalize conclusions about the process and include additional experimental data under different operating conditions.

Mechanistic insight into the enhanced NO reduction by CO over a pre-reduced CuxOy-CeO2 multiphase catalyst

The CuxOy(9)-CeO2(1) catalyst contained with the low-valent Cu species was synthesized by a two-step method and employed for NO reduction by CO (NO+CO reaction), which was distinguished from the traditional CuxCe1−xO2 solid solution oxide catalyst because it was a variety of interaction of composite heterogeneous catalyst rather than pure solid solutions or loaded catalysts. The CuxOy(9)-CeO2(1)-pre catalyst after CO pretreatment showed almost 100% NO conversion and also early 100% selectivity to N2 at 150 °C in a reaction atmosphere with a CO to NO concentration ratio of 10, which were markedly superior to CuxOy(9)-CeO2(1)-no pre without CO pretreatment, Cu2O, and CeO2 catalysts. The analysis showed multi-electron cycling systems, including the transformation between Cu+ and Cu0, Cu+ and Cu2+, and the interaction between Cu+/Cu2+ and Ce3+/Ce4+ conducive to improving the REDOX performance of the catalyst. In addition, CO pretreatment was beneficial to producing and stabilizing surface synergistic oxygen vacancies (SSOVs) in the Cu-□-Ce system to promote activity. The in-situ DRIFTS analysis revealed that the NO+CO reaction followed the Mars van Krevelen (MvK) mechanism with Cu+ as the core species. During CO pretreatment, CO would react with the lattice oxygen on the catalyst surface to form the apparent surface oxygen vacancies (SOVs, created on a single metal atom) and SSOVs (mainly on a multi-metal catalyst) for continuous adsorption and reaction. NO could adsorb on oxygen vacancies and dissociate into [N] and [O] atoms, which interacted with CO and eventually generated N2 and CO2, respectively, or filled oxygen vacancies to complete the catalytic cycle. In this process, the formation of SSOVs and the adsorption and dissociation of NO on oxygen vacancies played essential roles.

A green aluminum-based metal organic framework outperforms its polymorph with MIL-53 type topology in o-xylene purification

Investigation of structure–property relationships for xylene separation using polymorphic metal–organic frameworks (MOFs) as adsorbent is highly desirable but the practice remains a vacancy. Herein, we report a comprehensive performance comparison between two polymorphic aluminum-based MOFs (MIL-53-TDC and CAU-23) for selective adsorption of o-xylene (OX) over m-xylene (MX) and p-xylene (PX) in liquid phase. Although containing the same chemical compositions and similar 1D channels, MIL-53-TDC and CAU-23 exhibit distinct pore geometries (square shape VS pseudo-square shape) and pore sizes (8.5 Å VS 6.8 Å). It was found that CAU-23 exhibited much higher OX uptake (1.90 mmol g−1) and selectivity (αOX/PX: 10.4; αOX/MX: 7.6) in liquid-phase competitive adsorption in comparison to MIL-53-TDC. The enhancement of OX preference by the efficient pore confinement in the narrow channel of CAU-23 was confirmed by the theoretical calculations. By virtue of the multiple hydrogen bonding interactions in the confined environment, CAU-23 exhibited excellent preferential OX uptake over other isomers in liquid phase, outperforming most of the reported sorbents. Further, the continuous adsorption–desorption experiments as well as recycling experiments demonstrated exceptional separation performance of CAU-23 under dynamic conditions. Therefore, the excellent separation performance combined with the facile green low-cost synthesis suggest an impressive potential of CAU-23 for practical application.

Facile synthesis of magnetic ZnAl layered double hydroxides and efficient adsorption of malachite green and Congo red

Excessive dye effluent has contaminated the ecosystem, and it is challenging to effectively remove dye from the aqueous system. In the present work, magnetic Zn-Al layered double hydroxides (MZA) was synthesized via co-precipitationmethod for the adsorption of malachite green (MG) and Congo red (CR) in the aqueous solution. The successful synthesis of MZA was characterized by SEM-EDS, XRD, FT-IR BET and VSM. The batch experiments were conducted to investigate the effect of various adsorption parameters on the adsorption capacity of MG and CR by MZA, such as MZA dosage, solution pH, etc. Further adsorption studies, kinetics, isotherm, and thermodynamic were performed to explore the adsorption behavior of MG and CR on MZA. The maximum adsorption capacity at 298 K for MG and CR on MZA were 850.93 and 279.09 mg/g, respectively. Adsorption kinetics followed the pseudo-second-order model. Adsorption thermodynamics showed spontaneous, endothermic for MG and CR adsorption on MZA. The electrostatic attraction, hydrogen bonding, and molecular intercalation mainly occurred during adsorption process. In addition, MZA exhibited higher adsorption capacityafter 4 cycles of continuous adsorption–desorption. In conclusion, MZA might be a potential adsorbent for purifying wastewater containing MG and CR.

Surface chemistry regulation of nanoparticle coatings on activated carbons for rapid and long-lasting adsorption of organic pollutants

The nature of activated carbons (AC) to possess large specific surface areas and highly developed internal channels, is beneficial to absorb a variety of organic pollutants for practical applications in widespread areas, such as odor removal, flue gas cleaning and water purification. However, the domination of water affinity on AC could promote the adsorption to saturation in a short period, hindering the adsorptive performance on organics and reducing the service life severely. Thus, a simultaneous demonstration of the remarkable adsorptive property along with moisture resistance is of great significance. In this work, the superhydrophobic ACs with selective adsorptive property were fabricated via the combination of pretreatment to roughen the surface and grafting of propyl trimethoxysilane on superhydrophobic nanoparticles. The design was verified by the theoretical calculation of density functional theory accompanied with surface grafting ratio, and the as-prepared ACs presented favorable damp- and water-proof ability in the long term, showing only 11.8% weight increment for up to 180 days in high humidity. More importantly, superhydrophobic ACs exhibited effective capture of organics for continuous adsorption under aqueous phase and humid conditions, with removal efficiency over 90%.

In suit establishment of Ti3C2 MXenes exchanger via Na+, K+ and NH4+ intercalation: Exceptionally UO22+ loading capability and hijacking mechanism

Uranium naturally occurs over four billion tonnes in the seawater, which can be extracted for use as nuclear fuel. Herein, an efficient Ti3C2 MXenes catcher was constructed by a facile and environmental friendly chemistry intercalation strategy and directed at uranium capture. We demonstrate the promising loading capability of MXenes with expansion interlayer spacing due to the intercalation of Na+, K+ and NH4+. We report high sequestration capacity (qm-Na = 1099.40 mg/g and qm-K 876.05 mg/g), large KdU values (104 –105 mL/g, despite the presence of a tremendous excess of Na+, K+, Ca2+ and Mg2+ system). Remarkable, even in the 104-folds of V5+ system, the adsorption efficiency of Na+-MXenes still reached 51.98 %. Real uranium spiked seawater extraction experiments indicated that the sample exhibits promising harvesting uranium performance with ∼ 95.92 ∼ 3643.84 μg/g adsorption capacity after 24 h contact in ∼ 30.34 ∼ 1702.37 μg/L initial concentration. Importantly, the uranyl ion in the exchanged MXenes products could be easily eluted by hydrochloric acid and hydroxide during continuous adsorption–desorption cycles. HRTEM, XRD, FTIR and XPS tests confirmed that ion exchange and surface coordination were the main uptake mechanisms. These advantages of intercalation functionalization method coupled with the very high loading capacity, easy fabrication and environmentally friendly nature providing a new insight for further development of highly efficient uranium enrichment materials.

Modelling of Basic Yellow 28 adsorption onto activated carbon: batch and continuous process

Purpose This study aims to model and investigate Basic Yellow 28 (BY28) adsorption onto activated carbon in batch and continuous process. Design/methodology/approach Batch adsorption experiments were carried out at 25 °C with 50 mg/L BY28 solution at pH 6 with different amounts of activated carbon. Freundlich and Langmuir adsorption isotherm models were used to model batch data. Pseudo-first-order and pseudo-second-order kinetic models were applied with linear regression. The changes of the breakthrough curve with the column height, flow rate, column diameter and adsorbent amount were examined in fixed bed column at room temperature. BY28 adsorption data were modelled by using different adsorption column models (Adams & Bohart, Thomas, Yoon & Nelson, Clark and modified dose–response) with non-linear regression. Findings Freundlich model and pseudo-second-order kinetic model expressed the experimental data with high compatibility. Modified dose-response model corresponded to the fixed bed column data very well. Originality/value Adsorption of Basic Yellow 28 on activated carbon in a fixed bed column was studied for the first time. Continuous adsorption process was modelled with theoretical adsorption models using non-linear regression.

Resin Adsorption of Phenolic Compounds from Olive Leaf and Coffee Residue Extracts: Batch and Packed Column Adsorption Experimental Investigation and Mathematical Modeling

Phenolic compounds are important secondary metabolites often found in nature, and most prominently in plants. Plant biomass residues can be a sustainable source of this high-added-value group of compounds that can be used in the food and cosmetics industries due to their antioxidant properties. Olea europaea is a widely studied source of phenolic compounds, with olive leaves being an untapped solid residue with high phenolic content. Coffee residues after coffee extraction is another biomass residue stream rich in phenols. In this work, phenolic extracts of these two substrates, alongside different fractions produced through ultrafiltration and nanofiltration, were examined in resin adsorption experiments. Amberlite XAD16N was used as adsorbent in both batch and packed column experiments, with the experimental results being fitted with mathematical models for batch kinetics, adsorption isotherms, and column adsorption. The tested adsorbent proved capable of separating the target compounds, exhibiting a capacity of 72 mg of olive leaf phenols from nanofiltration retentate per g of resin in batch adsorption experiments, second order kinetics better described the batch adsorption process, while the use of the Thomas model sufficiently described the continuous adsorption process in packed columns (R2 > 0.9).

Chemical-free fabrication of carbon fiber aerogels from egg boxes for the removal of pharmaceutically active compounds in aqueous solution

The presence of pharmaceuticals and personal care products (PPCPs) in aquatic environments extremely concerns to human health and the ecosystem; thus, their removal is essential. This work produced carbon fiber aerogels from egg box waste using a chemical-free fabrication process. The pyrolyzed egg box aerogel (PEBA) exhibited three-dimensional interconnected carbon nanofibers with high surface area and pore volume. The adsorption capacity and removal efficiency of four PPCPs, namely, diclofenac (DIC), caffeine (CF), tetracycline (TC), and ciprofloxacin (CIP), from water were high and comparable to other carbon-based adsorbents, and the adsorption time was much faster (within 20 min). The Redlich-Peterson and the pseudo-second-order models were the best-fitted isotherm and kinetic models, respectively, which imply multilayer adsorption at high concentrations and the chemisorption process. Furthermore, mechanisms responsible for the adsorption of all PPCPs were elucidated. PEBA was applied in the fixed-bed column experiment to mimic the continuous adsorption process. In addition, PEBA was recyclable after low-temperature heat treatment. The adsorption capacity (8.1 mg/g) and removal efficiency (94.03 %) for TC was still high after three cycles. Metabolomics analysis revealed that no secondary pollution is released into water after thermal treatment. Therefore, PEBA has the potential as an efficient adsorbent for removing PPCPs from water.

Hg0 removal performance at low temperature by mesoporous MOF-derived Cr2O3 nanoparticle with enriched metal sites and oxygen vacancy: Mechanism study on the role of oxygen species

The oxidation adsorption of Hg0 by metal oxide is an effective method to remove Hg0. A novel high-performance catalyst Cr2O3-MOF was prepared by direct calcination of MIL-101 (Cr) to improve the mercury adsorption capacity of MOFs at lower temperature ranges, overcome the weak resistance to different flue gas components and increase the recycling capacity. Cr2O3-MOF retains the skeleton structure of MOF with small particle sizes and scattered active sites. The oxygen vacancy (OV) formed after calcination can be filled by free oxygen to adjust the catalytic performance of the surface. Thus, Cr2O3-MOF has a mercury removal capacity to be reached at 100% in a wide temperature range (30–200 °C), especially has the ability of mercury adsorption at room temperature that many MOF adsorbents do not have. After continuous adsorption at 30 °C for 50 h, the mercury removal efficiency was maintained at 90.3%, and it could be recycled. Cr2O3-MOF also has excellent resistance to flue gas components such as SO2, NH3, NO, and H2O. Based on different characterization methods and density functional theory (DFT), the transition state theory explains that adsorbed oxygen (OAds) filled in OV has higher mercury capture activity than that of natural lattice oxygen (OLat) in the adsorbent. More importantly, compared with noble metal supported monatomic catalysts, Cr2O3-MOF has a lower cost with higher mercury removal efficiency, it has more industrial application prospects.

Controlled fabrication of nitrogen-doped porous carbon foam with refined hierarchical architectures for desalination via capacitive deionization

Porous carbon materials have been regarded as a promising alternative to activated carbon for desalination via capacitive deionization (CDI) due to refined architectures and functionalities. However, it is still challenging to obtain a controlled hierarchical pore structure and considerable nitrogen-doped content by convenient method. Herein, nitrogen-doped hierarchical porous carbon foams (NHCFs) with different microstructural features, nitrogen contents and nitrogen species were successfully fabricated via a stepwise pyrolysis carbonization strategy using easily available melamine foam. Due to the synergistic effect of hierarchical porous structure and doped nitrogen, the optimized NHCF sample carbonized at 800℃ (NHCF-800) exhibited a maximum desalination capacity of 30.1 mg g−1 at the optimal operating parameters (500 mg/L NaCl solution, 1.2 V) and an excellent regeneration performance after 50 continuous adsorption–desorption cycles. Furthermore, density functional theory (DFT) was also conducted to elaborate the disparity of sodium adsorption energy among the nitrogen species for in-depth understanding, and it mainly benefits from the ascendency of the pyrrolic-N and pyridinic-N over the graphitic-N dopant. This work paves the way of rational regulation of nitrogen-doped process and hierarchical porous structure carbon as CDI electrode materials for desalination.

Efficacy of convective-diffusion models to study the transient behaviour of a sewage-sludge-filled packed column for aqueous phase adsorption of fluoroquinolones: Consideration of pseudo-kinetics driven depletion of species

Ciprofloxacin and ofloxacin belong to a class of antibiotics called Fluoroquinolones (FQs), which have a wide anti-bacterial activity against Gram-positive and Gram-negative bacteria. Since the recent Covid-19 pandemic witnessed a magnanimous rise in the use of antibiotics to prevent secondary bacterial infections, it led to vast production and use of such antibiotics. Ultimately the antibiotics get discharged into the municipal sewer pipes, thereby killing the useful microbial colony. In order to prevent environmental degradation a commercial scale-up of the adsorption of these antibiotics using raw sewage sludge is an absolute necessity.In this study, a continuous adsorption operation is conducted in a packed bed of semi-dried raw sewage sludge to remove the FQs from wastewater. Two transient convective-diffusion models are developed including pseudo-first and second-order kinetics driven depletion terms. The models are optimised using the data collected under various dynamic conditions in order to analyse the performance of the packed bed in terms of bed height, flow rate and initial concentration of the FQs. Damköhler numbers of the FQs are estimated to predict the breakthrough times of both the FQs. The ratios of Damköhler numbers of ciprofloxacin and ofloxacin do not change much with flow rate. In all the experiments, Das << 1 for both the FQs, indicating a faster diffusion process with respect to the rate of pseudo-reaction. Diffusion reaches an ‘equilibrium’ well before the reaction achieves pseudo-chemical equilibrium. Ratios of the Damköhler numbers, meant to represent the first-order and second-order convective-diffusion models for ciprofloxacin to ofloxacin is < 1.

Continuous adsorption of ammonium from primary and digester effluents using biosolids-derived biochar and cation exchange resin

Conventional biological treatment of wastewater can remove ammonium in the form of nitrogen gas, thus the opportunity of recovering the nutrient is lost. This study explored the continuous adsorption of ammonium from wastewater (primary and digester effluents) using biochar and cation exchange resin. The biochar was produced via the pyrolysis of biosolids (stabilised sewage sludge), and its ammonium adsorption performance was compared with a commercial cation exchange resin. Adsorption studies suggested that ammonium removal from synthetic wastewater was higher than from real effluents due to the competitive uptake of other components in the stream. Biochar with 100–500 μm particle size gave an ammonium adsorption capacity of 0.17 and 0.53 mg g−1 for primary and digester effluents, respectively. However, resin outperformed biochar with an estimated adsorption capacity of 17.96 and 28.38 mg g−1 for primary and digester effluents, respectively. Furthermore, the biochar bed was saturated in a few seconds, while the resin bed had a breakthrough time of 3 and 21 h, depending on the conditions applied. Therefore, it was proposed to treat the wastewater with biochar to obtain N-laden biochar and then send the resulting effluent to a series of resin columns for complete ammonium removal. The economic analysis of the process generated a net present value of $6 M and $0.6 M and a payback period of 6 and 10 years using primary and digester effluents, respectively. The profitability result is highly sensitive to the products sale price, the number of regeneration cycles of resin, and biosolids management cost.

Lithium Pyrene Squarate Covalent Organic Frameworks for Efficient Lithium and Magnesium Separation from Salt Water

The increasing pressure for lithium resources from the electric vehicle and nuclear energy industries means that new technologies to separate Mg2+ from Li+ from salt water are in demand. To address this need, we fabricated lithium pyrene squarate covalent organic frameworks (Li-SQCOFs) to separate Mg2+/Li+ mixtures from salt water. We optimized the effect of the electrolyte and the amount of the adsorbent and then carried out a kinetics study on the adsorbent recovery at various pH levels using both batch and continuous flow adsorption methods. Li-SQCOF was found to have excellent selectivity for solutions containing a mixture of Mg2+/Li+ ions. This work represents a unique path for the separation of Mg2+/Li+ through direct adsorption using a covalent organic framework (COF). The COF-supported ultrafiltration bed made in this study gave a Mg2+ separation flux of 60.5 h-1 m-2.

Simulation of the performance of continuous solar-powered adsorption refrigeration system for optimal use in Zaria, Nigeria

Cooling without electricity is the reason for solar adorption refrigeration systems. The epileptic power supply, especially in developing countries, makes solar refrigeration a very attractive option. This is coupled with the abundance of solar energy, making it a favourable alternative power source amongst other power mixes. This article introduces a solar adsorption refrigerator that continually generates cooling using solar energy as a standalone. Thus, this study aims to simulate and analyse the feasibility of refrigeration from a system that uses a blend of zeolite-based adsorbents and water (H2O) as adsorbate pairs via four solar concentrating collectors, two for adsorption and two for desorption using TRNSYS 16.0 simulation software. Unlike the conventional refrigeration system, the compressor was replaced with a solar concentrating collector while other components, such as the condenser, evaporator, and throttling valves, remained. The findings demonstrate that the technology delivered continuous cooling, and due to the comparatively intense beam radiation during the middle of the day, the cooling rate increased.

Adsorption of Atrazine from Synthetic Contaminated Water Using a Packed-Bed Column with a Low-Cost Adsorbent (Moringa oleifera Lam.)

Atrazine (ATZ) is an herbicide used for increased food production due to its weed and pesticide control capacity in different crops. However, ATZ is a chemical compound that is harmful to the environment and human health, and, unfortunately, it has been detected in surface and groundwater. Therefore, the aim of this paper was to perform the adsorption of Atrazine from a synthetically contaminated water sample using a packed-bed column with a low-cost adsorbent prepared from Moringa oleifera Lam. seeds. The synthesized adsorbent presented an increase in the surface specific area (SBET) of 37% in comparison with the in natura material. The effects of the peristaltic pump flow rate (Q), concentration of the ATZ inlet ([ATZ]inlet) solution, and bed height (H) were studied, with the highest percentage of ATZ removed through the adsorption column (50, 0%) obtained with a packed-bed column with H = 13 cm bed height, Q = 1 mL/min, [ATZ]inlet = 2.0 mg/L, pH = 5.0, a breakthrough time of 25 min, and a saturation time of 420 min. The logistic model was used to best fit the experimental data with an R2 &gt; 0.99, and the Bohart–Adams, Thomas, and Yoon–Nelson models were used to explain and analyze the obtained effects in the continuous adsorption of ATZ. Therefore, the Moringa oleifera Lam. seeds provided a low-cost adsorbent for the continuous adsorption of the herbicide Atrazine in a packed-bed column.

Preparation of biochar@chitosan-polyethyleneimine for the efficient removal of uranium from water environment

A novel chitosan-based composite with rich active sites was synthesized by uniformly dispersing biochar into the cross-linked network structure formed by chitosan and polyethyleneimine. Due to the synergistic effect of biochar (minerals) and chitosan-polyethyleneimine interpenetrating network (amino and hydroxyl), the chitosan-based composite possessed an excellent adsorption performance for uranium(VI). It could rapidly (<60 min) achieve a high adsorption efficiency (96.7 %) for uranium(VI) from water and a high static saturated adsorption capacity (633.4 mg/g), which was far superior to other chitosan-based adsorbents. Moreover, the separation for uranium(VI) on the chitosan-based composite was suitable for a variety of actual water environments and the adsorption efficiencies all exceeded 70 % in different water bodies. The soluble uranium(VI) could be completely removed by the chitosan-based composite in the continuous adsorption process, which could meet the permissible limits of the World Health Organization. In sum, the novel chitosan-based composite could overcome the bottleneck of current chitosan-based adsorption materials and become a potential adsorbent for the remediation of actual uranium(VI) contaminated wastewater.

Continuous fixed-bed adsorption of reactive azo dye on activated red mud for wastewater treatment-Evaluation of column dynamics and design parameters

Continuous adsorption of Remazol Brilliant Blue (RBB) dye in water onto sulfuric acid activated red mud (CATRM) in a fixed bed column was investigated. Breakthrough curves were obtained experimentally by varying the bed height (Z), influent flow rate (Q), and dye concentration(C0). The adsorption efficiency in the removal of RBB was favored at lower C0, higher Z, and lower Q. The maximum adsorption capacity of the activated red mud bed in the column was obtained at C0 = 70mg/L, Z = 8cm, and Q = 5mL/min and found to be 106mg/g. Important parameters of column dynamics and design such as mass transfer zone (MTZ) and length of unused bed (LUB) were evaluated from the breakthrough curves. The MTZ and LUB have varied with varying Z, which indicated the existence of nonideal conditions. Thomas model was found to be valid to predict the column dynamics and the model parameters were evaluated. Bed depth service time (BDST) model parameters were evaluated to facilitate the determination of packed bed height for the design of packed bed adsorption column. The bed could be regenerated with NaOH solution with desorption efficiency decreasing from 83.8 to 55.72% from the first to third cycle. A fixed bed of CATRM can be effectively used for continuous dye removal from industrial wastewater.

First successful synthesis of an Al-rich mesoporous aluminosilicate for fast radioactive strontium capture

Al-rich zeolites such as NaA (Si/Al = 1.00) have been widely applied to remove radioactive 90Sr2+ because of their high surface charge density enabling efficient ion-exchange of multivalent cations. However, due to the small micropore diameters of zeolites and large molecular size of strongly hydrated Sr2+, Sr2+-exchange with zeolites suffers from very slow kinetics. In principle, mesoporous aluminosilicates with low Si/Al ratios close to unity and tetrahedrally coordinated Al sites can exhibit both high capacity and fast kinetics in Sr2+-exchange. Nonetheless, the synthesis of such materials has not been realized yet. In this study, we demonstrate the first successful synthesis of an Al-rich mesoporous silicate (ARMS) using a cationic organosilane surfactant as an efficient mesoporogen. The material exhibited a wormhole-like mesoporous structure with a high surface area (851 m2 g–1) and pore volume (0.77 cm3 g–1), and an Al-rich framework (Si/Al = 1.08) with most Al sites tetrahedrally coordinated. Compared to commercially applied NaA, ARMS exhibited a dramatically improved Sr2+-exchange kinetics (>33-fold larger rate constant) in batch adsorption while showing similarly high Sr2+ capture capacity and selectivity. Due to the fast Sr2+-exchange kinetics, the material also exhibited 3.3-fold larger breakthrough volume than NaA in fixed-bed continuous adsorption.

Chitosan-Bead-Encapsulated Polystyrene Sulfonate for Adsorption of Methylene Blue and Regeneration Studies: Batch and Continuous Approaches.

Textile industrialization causes water pollution due to the discharge of industrial effluents into the environment. To reduce the impact of industrial effluent, it must be treated in wastewater treatment plants before discharge into rivers. Among all wastewater treatment approaches, the adsorption process is one method to remove pollutants from wastewater, but it has some limitations in term of reusability and ionic selective adsorption properties. In this study, we prepared cationic poly (styrene sulfonate) (PSS)-incorporated anionic chitosan beads synthesized using the oil-water emulsion coagulation method. The produced beads were characterized using FESEM and FTIR analysis. In batch adsorption studies, the PSS-incorporated chitosan beads exhibited monolayer adsorption processes, that is, exothermic processes that occur spontaneously at low temperatures, which were analyzed based on the adsorption isotherms, adsorption kinetics, and thermodynamics model fittings. The presence of PSS enables cationic methylene blue dye to adsorb to the anionic chitosan structure via electrostatic interaction between the sulfonic group and the dye molecule. The maximum adsorption capacity of PSS-incorporated chitosan beads achieved 42.21 mg/g, as calculated from the Langmuir adsorption isotherm. Finally, the PSS-incorporated chitosan beads demonstrated good regeneration with different types of reagents, especially using sodium hydroxide as a regeneration reagent. With the use of sodium hydroxide regeneration of this adsorbent material, a continuous adsorption setup also demonstrated that PSS-incorporated chitosan beads can be reused for methylene blue adsorption for up to three cycle processes.