Adsorption Efficiency Research Articles

Phenyl-extended resorcin[4]arene opens up a new avenue for highly efficient iodine adsorption

Phenyl-extended resorcin[4]arene opens up a new avenue for highly efficient iodine adsorption

Harvesting Zr-based metal-organic frameworks by continuous-flow synthesis as efficient adsorbents for eliminating nitrogen-containing compounds in liquid fuel

This work designed a continuous-flow tubular reactor for rapidly and scalably harvesting the metal-organic framework (MOF) of UiO-66(Zr)-NH2. The experimental conditions, including temperature (110–140 °C), holding time (10–30 min), and CH3COOH/H2N-BDC molar ratio (100–250), were carried out to survey their impacts on the product yield and quality. The highest yield and production rate of ∼72% and ∼1.55 g h−1 were obtained at 130 °C, 20 min, and CH3COOH/H2N-BDC ratio 200. The temperature and modulator content significantly influenced MOFs’ crystal morphology, crystallinity, and porosity. Besides, the adopted method also successfully produced UiO-66 and UiO-67 MOFs with high production rates. The adsorptive denitrogenation (ADN) performances were carried out using liquid fuel models containing quinoline (QU) and 2-methyl pyrrole (MP). In batch mode adsorption, the UiO-66-NH2-130-200 sample showed the highest adsorbing quantities of ∼199 and ∼163 mg g−1 for QU and MP, respectively. Furthermore, the prepared MOFs efficiently removed NCCs from liquid fuel under a continuous fixed-bed column process. These demonstrate that modulator-assisted continuous-flow synthesis can be a potential strategy for the scalable harvest of Zr-MOFs with good qualities and high performance in getting rid of NCCs from liquid fuel.

Study on the Phosphate Compound Adsorption onto MgO-KOH/Biochar Adsorbent as Binding Agent in Diffusive Gradient in Thin Film (DGT) Technique for Bioavailable Phosphate Detection

Phosphate compounds, particularly bioavailable forms like PO₄³⁻, are critical contributors to eutrophication. In this study, MgO-KOH/biochar was used as a binding agent in the Diffusive Gradient in Thin Films (DGT) technique to enhance phosphate detection. The adsorbent was synthesized from biochar derived from palm oil waste, activated with KOH to increase surface area, and combined with MgO for enhanced adsorption efficiency. The adsorption process followed a pseudo-second-order kinetic model, indicating that chemical interactions dominated the adsorption mechanism. Under different pH levels and phosphate concentrations, the material showed a good selectivity for orthophosphate, achieving an adsorption capacity of approximately 100 mg/g. Characterization via FTIR, XRD, and SAA confirmed the successful synthesis of MgO-KOH/biochar and its structural properties, which contributed to its performance. Additionally, the MgO-KOH/biochar DGT device demonstrated better efficiency in adsorbing PO₄³⁻ compared to conventional ferrihydrite-based DGT systems, positioning it as a highly effective tool for monitoring bioavailable phosphates in aquatic environments. Copyright © 2024 by Authors, Published by BCREC Publishing Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Simulation and modeling of methylene blue dye removal by an agri-food waste (Peanut shells)

Our study explores the potential of utilizing peanut shells, an abundant and low-cost food waste, as a natural adsorbent for the removal of industrial dyes, specifically methylene blue. We conducted a detailed investigation of the adsorption process, which revealed that it conforms to both Langmuir and Freundlich isotherms, indicating the ability of peanut shells to adsorb methylene blue effectively. To optimize the adsorption yield, we employed a Box-Behnken experimental design. This approach allowed us to assess the impact of several key factors, including the mass of the adsorbent, dye concentration, pH, temperature, stirring rate, and the ionic strength of salts in the solution. The mathematical model and simulation of the adsorption process helped us identify the best conditions for maximizing the dye removal. Our experiments resulted in a maximum adsorption efficiency of 97%, achieved under optimal conditions: 1.5 g of adsorbent, a methylene blue concentration of 40 mg/L, pH 11, temperature of 65°C, 0 mg/L ionic strength, and a stirring rate of 165 rpm. These findings suggest that peanut shells are a viable, eco-friendly alternative for dye removal, offering a sustainable solution for wastewater treatment and contributing to waste reduction.

Ag@AgCl/carbon nitride/graphene oxide three-dimensional nanocomposite constructed for efficient removal of organic dyes by synergistic adsorption-photocatalysis

The efficient removal of dye pollutants from wastewater is a significant and hotspot research. In this manuscript, Ag@AgCl nanoparticles were anchored on three-dimensional carbon nitride/graphene oxide (CN/GO) using an in-situ photoreduction strategy, and thus a novel (Ag@AgCl/CN/GO) was achieved. The results showed that the Ag@AgCl/CN/GO was a highly efficient adsorption and photocatalytic material for the removal of dye pollutants. The maximum adsorption capacity of malachite green (MG), methylene blue (MB), rhodamine B (RhB) and crystal violet (CV) can be reached as 324, 216, 148 and 112 mg g−1, and the photocatalytic degradation rate were 95 %, 83 %, 76 % and 93 % under irradiation for 60 min, which were greatly higher than some comparisons reported. The improved visible light, enhanced absorption and electron transfer in the Ag@AgCl/CN/GO three-dimensional structure were responsible to the highly efficient removal of dyes. Furthermore, the Ag@AgCl/CN/GO showed a good reusability in the cycling test. The constructed nanocomposite will be attractive for removing pollutants in wastewater.

Simplex-lattice design and decision tree optimization of endophytic Trichoderma-multi-walled carbon nanotube composite for enhanced methylene blue removal

This study investigates a novel approach for enhancing methylene blue (MB) removal from water using a composite of endophytic Trichoderma mate and multi-walled carbon nanotubes (MWCNTs). For the first time, a unique combination of simplex-lattice design and decision tree learning algorithm was employed to optimize MB removal. This innovative approach effectively identified the optimal composite ratio of hyphal mate (0.5354 g/L) and MWCNTs (0.4646 g/L) for maximizing MB removal, which achieved remarkable removal efficiency ranging from 63.50 to 95.78 % depending on the combination used. The DT model further demonstrated promising potential for predicting MB removal efficiency. SEM revealed a unique hybrid material formed by the intertwining or entrapment of MWCNTs within the hyphal network of Trichoderma mate. FT-IR analysis confirmed the presence of novel functional groups on the MWCNTs' surface at 2438.79 and 528.25 cm−1, likely due to interactions with the endophytic fungi's biomolecules. These functional groups presumably act as reducing and stabilizing agents, promoting efficient MB adsorption. This research paves the way for utilizing the combined biological and chemical approach (fungal biomass and MWCNTs) in bioremediation applications. The findings suggest significant potential for practical applications in wastewater treatment, providing an eco-friendly and cost-effective method for dye removal. Furthermore, the proposed method shows promise for scaling up to industrial wastewater treatment and applicability in resource-limited settings, offering a sustainable solution for global water pollution challenges. Further investigations with larger datasets incorporating additional influencing factors are necessary to refine the predictive power of the DT model for practical applications.

Efficient microplastics adsorption in aqueous environments via bidirectional ordered graphene oxide/nanocellulose aerogels

Microplastics not only accumulate various harmful substances but also are ingested by marine organisms and humans, causing immeasurable impacts. Therefore, the removal of microplastics has become a crucial proposition for addressing the issue of microplastic pollution. This study investigated a bidirectional ordered graphene oxide (GO)/nanocellulose aerogels (D-DPGG) to remove microplastics from water bodies. The concentration of microplastics before and after adsorption was measured using a fluorescence spectrophotometer. D-DPGG aerogel exhibited excellent adsorption performance for microplastics (241.56 mg/g) and maintained high adsorption efficiency (>80 %) over 20 cycles of adsorption testing. Additionally, the link between GO and dual-directional treatment significantly improved the aerogel microstructure. It had an apparent layered structure in the transverse direction and improves the mechanical properties. D-DPGG aerogel not only served as an effective solution in adsorption but also held promise as a novel material in directional structural design.

One-pot synthesis of transition metals-doped LiAl-LDHs to improve lithium adsorption performance and stability

Transition metal doping of Li/Al-LDHs can alter the interlayer spacing and surface charge of LDHs, thereby enhancing adsorption performance and stability. To investigate the rules and mechanisms governing the enhancement of stability and adsorption capacity of Li/Al-LDHs through transition metal element doping, several transition metal elements (Co, Zn, Mn, Zr, and Ni) were selected, and the five types of transition metal-doped Li/Al-LDHs and one undoped Li/Al-LDHs were synthesized by a one-pot method. Compared to the original Li/Al-LDHs, the Co-doped Li/Al-LDHs exhibited higher adsorption capacity, lower dissolution loss, and greater stability. Additionally, after Co doping, the lattice constant of Li/Al-LDHs decreases, effectively reducing the intercalation energy and increasing lithium diffusion efficiency. When used for lithium adsorption, Co-Li/Al-LDHs exhibited a Li+ capacity of 12.6 mg/g and reached saturation adsorption within 90 min. Notably, Co-Li/Al-LDHs achieved a high Li+ adsorption capacity (6.46 mg/g) in East Taigener salt-lake brine. After 10 cycles, the adsorption capacity did not show any significant change, and after 336 h adsorption-desorption cycles (200 rmp, oscillation), the total Al dissolution loss was only about 0.035 ‰, demonstrating that Co doping can enhance the interlayer binding force of Li/Al-LDHs, thereby reducing the decomposition of the layered structure in solution, lowering aluminum dissolution loss, and improving structural stability. The results show that doping with transition metals can reduce the Al dissolution rate of LDHs, and Co-Li/Al-LDHs can be used as an efficient adsorbent for lithium extraction from salt lake and have higher stability.

3D Graphene-like Carbon Structures from Poly(Acrylic Acid): A Novel Synthetic Route.

Emerging contaminants, such as the hormone 17α-ethynylestradiol (EE), in aquatic environments pose a serious risk to both human and environmental health, making efficient removal essential. This study evaluated the effectiveness of three-dimensional porous carbon structures derived from poly(acrylic acid) (PAAc, Carbopol 990) as adsorbents for removing EE from aqueous solutions. Activated carbon materials were prepared using varying ratios of KOH as an activating agent (PAAc:KOH; 1:0 AAC, 1:1 AC1, 1:2 AC2, and 1:3 AC3). Adsorption tests were conducted by adding 10 mg of the adsorbent to 40 mL of an EE solution (100 ppm, 20% acetonitrile in water). Analyses including TGA, XRD, and Raman spectroscopy were performed to evaluate the materials' structural properties and adsorption capacities. Among the materials, AC3 exhibited the highest adsorption capacity for EE (238 mg g-1), followed by AC2 (153 mg g-1) and AC1 (82 mg g-1). The superior efficiency of AC3 can be attributed to its larger surface area and pore volume, enabling greater interaction with EE molecules. These materials demonstrated higher adsorption capacities compared to commercial activated carbons and single-walled carbon nanotubes. This work opens new possibilities for developing efficient adsorbents, contributing to more effective and sustainable solutions for water purification and environmental protection.

Removal of Dibenzofuran from aqueous solution by sugarcane bagasse-based biochar

Dibenzofuran (DBF) has been considered an environmental risk due to its high toxicity and risks to human health and ecosystems. Among wastewater treatment technologies, the adsorption process has emerged as a potential solution to remove organic pollutants efficiently, including dibenzofuran, in wastewater. The study aims to investigate the feasibility of sugarcane bagasse-based biochar for DBF removal through adsorption. Biochar characteristics showed a high specific surface area of up to 498.97 m2/g and abundant functional groups on the material surface, resulting in high removal performance of DBF with average adsorption efficiency and adsorption capacity reaching maximum values of 98.43% and 96.77 mg/g, respectively. The optimum parameters were suggested for DBF removal: pyrolysis temperature of 700oC, contact time of 50 min, biochar dosage of 0.5 g/L, and DBF concentration of 40 mg/L. Furthermore, the results of adsorption kinetics and adsorption isotherms indicated that the adsorption process benefits DBF removal. Pseudo-second-order model and Langmuir model can describe the DBF removal process due to the best fit to experimental data (R2 > 0.98). Based on these findings, sugarcane bagasse-based biochar could be utilized efficiently to remove DBF from wastewater.

Removal mechanisms of pentachlorophenol in a horizontal-flow anaerobic immobilized biomass reactor (HAIB) inoculated with an indigenous estuarine sediment microbiota: adsorption and biodegradation processes.

Pentachlorophenol (PCP) is a highly toxic and carcinogenic compound with significant environmental impact, necessitating effective treatment technologies. This study evaluates PCP removal mechanisms, including adsorption and biodegradation, during the startup of a horizontal-flow anaerobic immobilized biomass reactor (HAIB), and examines the impact of PCP concentration on microbial diversity using denaturing gradient gel electrophoresis (DGGE). The primary mechanism for PCP removal in the HAIB was adsorption, effectively described by the Freundlich isotherm model. Adsorption efficiency ranged from 86 to 104% for PCP concentrations between 0.2 and 5.0mg/L, and 46% to 64% for concentrations between 0.098 and 0.05mg/L. Additionally, PCP degradation intermediates such as 2,3-DCP and 2,6-DCP were detected, indicating that biodegradation also occurred in the HAIB. Organic matter degradation averaged 81 ± 9%, and methane content in the biogas averaged 46 ± 9%, confirming the anaerobic process. No inhibition of microbial activity was observed due to PCP toxicity, even at a PCP load of 5mg PCP/g STV per day. While the archaeal community showed only slight changes, with similarity coefficients ranging from 88 to 95%, the bacterial community was significantly affected by PCP, with similarity coefficients ranging from 18 to 50%. Bacterial groups were responsible for the initial PCP degradation, while the archaeal community was involved in metabolizing the resulting byproducts. The use of indigenous inoculum from the Santos-São Vicente estuary demonstrated its potential for effective PCP removal. Polyurethane foam proved to be an effective support material, enhancing the adsorption process and reducing PCP toxicity to the microbial consortium. This study provides valuable insights into PCP adsorption and biodegradation mechanisms in HAIB, highlighting the effectiveness of indigenous inoculum and polyurethane foam for PCP removal.

Layered Perovskite La2Ti2O7 Nanostructures for Photocatalytic Degradation of Congo Red Dye Pollutant

AbstractIn photocatalytic innovation, there has been a lot of interest in creating broad spectral responsive photocatalysts to get superior catalytic performance. In this study, we synthesized highly visible‐light responsive La2Ti2O7 perovskite photocatalysts by the probe ultrasonication procedure followed by high‐temperature calcination. Such materials are characterized using UV‐vis diffuse reflectance spectra, powder X‐ray diffraction, X‐ray photoelectron spectroscopy, and scanning electron microscopy to illustrate the optical absorption activities, crystalline properties, chemical composition, and microscopic features. La2Ti2O7 extends optical absorption towards the visible light spectrum and narrows the band gap. The photocatalytic efficacy of the resulting La2Ti2O7 nanostructures was investigated by performing photocatalytic degradation of persistent Congo red (CR) dye while subjected to visible photon illumination using three Osram 150 W tungsten halogen lamp ((λ≥400 nm), 5000 lm nominal luminous flux, 80,600 lx radiation intensity. With effective efficiency, the optimum degradation of the 10 ppm CR dye with a percentage of 95.9 was achieved after 90 min during exposure to the La2Ti2O7 perovskite with a catalyst dosage of 30 mg/100 mL at pH 6. Consequently, La2Ti2O7 nanostructures alone depicted 19.8 % adsorption efficiency for CR dye. In addition, OH⋅ and holes were important in degrading CR dye, which included many different reaction pathways. The treated solution can also demonstrate the environment's safety for accepting water. In summary, under natural visible light irradiation, the synthesized La2Ti2O7 showed enormous promise for eliminating different organic contaminants using photocatalytic methodology.

A screening guide for efficient dye adsorbents under continuous flow conditions: a review

A screening guide for efficient dye adsorbents under continuous flow conditions: a review

Sustainable Activated Carbon from Agricultural Waste: A Study on Adsorption Efficiency for Humic Acid and Methyl Orange Dyes

In this study, porous activated carbon was produced from coffee waste and used as an effective adsorbent for the removal of humic acid (HA) from seawater and methyl orange (MO) dye from aqueous solutions. Phosphoric acid H3PO4 was used as an activating agent for the chemical activation of these agricultural wastes. The characterization of the activated carbon obtained using a scanning electron microscope (SEM), Fourier-transform infrared (FTIR) spectroscopy analysis, X-ray diffraction (XRD) and the Brunauer–Emmett–Teller (BET) method revealed that the activated carbon products exhibited high porosity and the formation of various functional groups. The effects of different parameters were examined using batch adsorption experiments, such as the adsorbent masses, pH, initial pollutant concentration and contact time. The results show that the performance increased with an increased adsorbent mass (up to 0.25 g/L) and decreased initial concentration of the adsorbent tested. On the other hand, this study clearly showed that the adsorption efficiency of the MO on the raw spent coffee grounds (SCGs) waste was around 43%, while no removal was observed for the humic acid. The experiments demonstrated that the activated carbon synthesized from the used coffee grounds (the efficiency was compared with commercial activated carbon (CAC) with a difference of 13%) was a promising alternative to commercially available adsorbents for the removal of humic acid from seawater. To understand and elucidate the adsorption mechanism, various isothermal and kinetic models were studied. The adsorption capacity was analyzed by fitting experimental data to these models. The experimental data for methyl orange dyes were analyzed using Langmuir and Freundlich isothermal models. The Freundlich isotherm model provided a superior fit to the equilibrium data, as indicated by a higher correlation coefficient (R2) than that of the Langmuir model. The maximum adsorption was observed at pH 3. The Freundlich adsorption capacity was found to be 333 mg/g adsorbent. The PAC showed a high adsorption capacity for the MO and HA. The PAC showed the highest adsorption capacities for the HA and MO compared with the other adsorbents used (SCGs and CAC) and would be a good material to increase the adsorption efficiency for humic acid removal in the seawater pretreatment process. In addition, the prepared AC BET surface area was 520.40 m2/g, suggesting a high adsorption capacity. This makes the material potentially suitable for various applications that require a high surface area. These results indicate that high-quality sustainable activated carbon can be efficiently produced from coffee waste, making it suitable for a wide range of adsorbent applications targeting various pollutants.

Facile synthesis of ZnO/RGO/Fe2O3 using macroalgae Caulerpa taxifolia as green reductor and its application as malachite green removal

This study presents the synthesis of a novel ZnO/rGO/Fe₂O₃ composite using Caulerpa taxifolia as a green reductant for the effective removal of Malachite Green from aqueous solutions. Characterization techniques, including FTIR, SEM, and XRD, confirmed the successful incorporation of ZnO and Fe₂O₃ onto the rGO matrix, enhancing its adsorption properties. The composite achieved an exceptional maximum adsorption capacity of 454.5 mg/g at pH 9, significantly outperforming rGO alone and other adsorbents. The adsorption kinetics followed a pseudo-second-order model, indicating chemisorption as the dominant mechanism, with a high correlation coefficient (R² = 0.999). The adsorption isotherms were best described by the Langmuir model, suggesting monolayer adsorption. Thermodynamic parameters revealed that the process was spontaneous and exothermic, with a Gibbs free energy (ΔGo) of -10.93 kJ/mol at 25 °C. The composite's high adsorption capacity, rapid kinetics, and favorable thermodynamics highlight its potential as an efficient and sustainable adsorbent for dye removal. This research offers a promising approach to water treatment, aligning with environmentally friendly practices and providing a viable solution for mitigating water pollution caused by organic dyes. KEY WORDS: Reduced graphene oxide, Water treatment, Caulerpa taxifolia, Isothermal and kinetic studies, Malachite Green Bull. Chem. Soc. Ethiop. 2025, 39(1), 29-47. DOI: https://dx.doi.org/10.4314/bcse.v39i1.3

Preparation of Poly(allylamine Hydrochloride) Grafted Porous Boron Nitride Fibers for Efficient Cr(VI) Adsorption from Aqueous Solution.

Cr(VI) pollution poses great harm to the cyclic utilization of groundwater and surface water resources. Efficient adsorbent materials have great potential to change this situation and assist in the restoration of ecosystems. This work chooses porous boron nitride fibers (pBN) with stable physical and chemical properties as the matrix, 3-aminopropyltriethoxysilane (APTES) as the coupling agent, and uses a one-step crosslinking method to graft poly(allylamine hydrochloride) (PAH) onto pBN, forming pBN-AS@PAH with fascinating Cr(VI) adsorption capacity. PAH is uniformly covered and modified on the surface of pBN, and the composite with high specific surface area (383.33 m2/g), large pore volume (0.37 cm3/g), and abundant amino groups. Its equilibrium adsorption capacity for Cr(VI) can reach up to 123.32 mg/g, and the adsorption behavior follows the quasi second-order kinetic model and Langmuir model, indicating the chemical adsorption process of monolayer. The adsorption style belongs to a spontaneous exothermic process and has the optimal adsorption effect at a pH of ~2. Additionally, after cycling for 5 times, the decrease rate of adsorption capacity is less than 10 %, showing an excellent reusability.

Adsorption of methyl orange and methylene blue on activated biocarbon derived from birchwood pellets

This study explored the adsorption capacity of a physically activated biocarbon derived from the pyrolysis of birchwood pellets (ABPB) towards two dyes - methyl orange (MO, anionic) and methylene blue (MB, cationic), at pH 2, 7 and 11. Compared to mineral commercial activated carbon (CACmineral), ABPB exhibited lower SSA, pores volume and surface; higher external surface and average pore diameter, similar ash content and aromaticity, and stronger hydrophilicity and polarity. The maximum adsorption capacity on ABPB was equal to 220 mg/g for MO and 91 mg/g for MB after 17 h. Batch tests with variable adsorbent amount (0.5–2.5 g/L) showed for both ABPB and CACmineral better results for lower adsorbent dose. Under all tested conditions, ABPB showed higher or analogous adsorption capacity compared to CACmineral. Based on the pKa of MB (3.80) and MO (3.46) and on the pHPZC of ABPB (5.3), the adsorption was favored at pH 2 for MO and at pH 11 for MB. Kinetics analysis and isotherm modelling revealed that, although many different physicochemical interactions occurred between ABPB and the dyes molecules, chemisorption is the rate-controlling step and prevalent mechanism. In conclusion, this study may provide support to further research aimed at exploring the effect of ABPB's physicochemical properties on the efficiency and mechanisms of dyes adsorption.

Loading Self-Assembly Siliceous Zeolites for Affordable Next-Generation Wearable Artificial Kidney Technology.

The global demand for dialysis among patients with end-stage kidney disease has surpassed the capacity of public healthcare, a trend that has intensified. While wearable artificial kidney (WAK) technology is seen as a crucial solution to address this demand, there is an urgent need for both efficient and renewable toxin-adsorbent materials to overcome the long-standing technological challenges in terms of cost, device size, and sustainability. In this study, we employed screening experiments for adsorbent materials, multimodal characterization, and Monte Carlo adsorption simulations to identify a synthetic self-assembly silicalite-1 zeolite that exhibits highly ordered crystal arrays along the [010] face (b-axis) direction, demonstrating exceptional adsorption capabilities for small molecular toxins such as creatinine and urea associated with uremia. Moreover, this metal-free, cost-effective, easily synthesized, and highly efficient toxin adsorbent could be regenerated through calcination without compromising the performance. The simulated toxin adsorption experiments and comprehensive biocompatibility verification position it as an auxiliary adsorbent to reduce dialysate dosages in WAK devices as well as a potential adsorbent for small-molecule toxins in dialysis. This work is poised to propel the development of next-generation WAK devices by providing siliceous adsorbent solutions for small-molecule toxins.

Pyrene‐Functionalized Silicon Hybrid Porous Polymer for an Efficient Adsorption of Dyes

AbstractPyrene‐functionalized silicon hybrid porous polymer (TAPPy‐HPP). The hybrid polymer was successfully prepared via a Schiff base reaction using tetra(4‐aminophenyl)pyrene (TAPPy) and tetra(4‐formylphenyl)silane (TFS) as the building blocks.. This hybrid polymer was characterized using IR, solid‐state 13C and 29Si NMR, and elemental analysis. Its morphology was analyzed by PXRD and SEM. Thermal analysis using Thermal analysis using TGA shows that the synthetic polymer has greater thermal stability than its monomers at a temperature of 5 % weight loss (Td5 %) of 392 °C. Although TAPPy‐HPP has a Brunauer‐Emmet‐Teller surface area of 45.4 m2 g−1, it adsorbed dyes with high efficiency, particularly the anionic dye Congo Red (CR), with an adsorption capacity of up to 358 m2 g−1. Moreover, TAPPy‐HPP showed excellent recycling and regenerative properties. This polymer is a promising candidate for a fluorescent chemical sensor for the absorption of dyes due to its exceptional physiochemical stability and intense luminescence.

Cnicus Benedictus roots as a low-cost adsorbent for methylene blue dye removal from aqueous solution: kinetic and equilibrium studies

In this research, Cnicus Benedictus roots powder (CBRP) was utilized as a low-cost adsorbent for removing methylene blue (MB) as a cationic dye from aqueous solution. Characterization of CBRP by Boehm titration method, Fourier transform infrared (FT-IR) and environmental scanning electron microscope (ESEM) indicates the presence of different types of functional groups and a very rough surface filled with cavities, suitable for MB adsorption. The effect of various parameters such as CBRP dose (0.2–2 g/1L), contact time (0–180 min), initial pH (1–10), coexisting anions/cations and the initial MB concentration (100–500 mg L−1) on MB adsorption were examined, the results showed that MB uptake depends on the pH of solution, the electrostatic attraction forces, the formation of H-bonds and π–π interactions are the possible CBRP–MB interaction mechanisms. Adsorption kinetic of MB on CBRP was best represented by linear and non-linear form of the pseudo-second order model. The experimental equilibrium data were best described by linear and non-linear forms of Langmuir and Redlich–Peterson isotherm models (R 2> 0.98) with a maximum MB adsorption capacity of 85.47 mg g−1 at 25 °C, the adsorption efficiency R (%) was greater than 90 (%). MB adsorption-desorption experiments showed the reusability of CBRP for five consecutive cycles. According to the obtained results, CBRP can be used as a natural adsorbent material for cationic dyes removal from aqueous solution.