Elastic heterogeneity governs asymmetric adsorption-desorption in a soft porous crystal.

Metal-organic frameworks (MOFs), which possess a high degree of crystallinity and a large surface area with tunable inorganic nodes and organic linkers, exhibit high stimuli-responsiveness and molecular adsorption selectivity that enable various applications. The adsorption in MOFs changes the crystalline structure and elastic moduli. Thus, the coexistence of adsorbed/desorbed sites makes the host matrices elastically heterogeneous. However, the role of elastic heterogeneity in the adsorption-desorption transition has been overlooked. Here, we show the asymmetric role of elastic heterogeneity in the adsorption-desorption transition. We construct a minimal model incorporating adsorption-induced lattice expansion/contraction and an increase/decrease in the elastic moduli. We find that the transition is hindered by the entropic and energetic effects which become asymmetric in the adsorption process and desorption process, leading to the strong hysteretic nature of the transition. Furthermore, the adsorbed/desorbed sites exhibit spatially heterogeneous domain formation, implying that the domain morphology and interfacial area between adsorbed/desorbed sites can be controlled by elastic heterogeneity. Our results provide a theoretical guideline for designing soft porous crystals with tunable adsorption hysteresis and the dispersion and domain morphology of adsorbates using elastic heterogeneity.

Separation of Mono-/Divalent Ions via Controlled Dynamic Adsorption/Desorption at Polythiophene Coated Carbon Surface with Flow-Electrode Capacitive Deionization.

Capacitive deionization for selective separation of ions is rarely reported since it relies on the electrostatic attraction of oppositely charged ions with no capability to distinguish ions of different valent states. Using molecular dynamic simulation, a screening process identified a hybrid material known as AC/PTh, which consists of activated carbon with a thin layer of polythiophene (PTh) coating. By utilizing AC/PTh as electrode material implementing the short-circuit cycle (SCC) mode in flow-electrode capacitive deionization (FCDI), selective separation of mono-/divalent ions can be realized via precise control of dynamic adsorption and desorption of mono-/divalent ions at a particular surface. Specifically, AC/PTh shows strong interaction with divalent ions but weak interaction with monovalent ions, the distribution of divalent ions can be enriched in the electric double layer after a couple of adsorption-desorption cycles. At Cu2+/Na+ molar ratio of 1:40, selectivity toward divalent ions can reach up to 110.3 in FCDI SCC mode at 1.0 V. This work presents a promising strategy for separating ions of different valence states in a continuously operated FCDI device.

Adsorption Capacity of Carbon-Silica Composites Towards Diclofenac in Poly(acrylic acid) Containing Systems: A Crucial Study on Common Wastewater Contaminants.

Diclofenac is one of the most popular over-the-counter non-steroidal anti-inflammatory drug and poly(acrylic acid) is a frequently used as thickener, filler or stabilizer. For these reasons, they are common organic contaminants in raw wastewater. The purpose of the presented studies was to compare the adsorption capacity of three carbon-silica composites - metal-free C/SiO2, iron-enriched C/Fe/SiO2 and manganese-enriched C/Mn/SiO2 towards diclofenac. The studies were carried out in single, and mixed systems in the presence of poly(acrylic acid) polymer. Adsorption, desorption and kinetics of the adsorption process were investigated. The concentration of diclofenac in the supernatants was determined using high-performance liquid chromatography. The solids were also characterized with an ASAP apparatus using low-temperature nitrogen desorption adsorption isotherms at liquid nitrogen temperature. In addition, potentiometric titrations and electrophoretic mobility measurements, as well as stability tests of the studied suspensions were carried out. The most efficient composite among investigated ones proved to be C/Fe/SiO2 removing diclofenac at the level of 46.68 mg/g for its initial concentration of 90 ppm. The results obtained clearly demonstrated that the carbon-silica composites are effective in separation of drugs from aqueous solutions and can be successfully used in the future for the removal of organic pollutants from water environment.

Novel insights into the dependence of adsorption-desorption kinetics on particle geometry in chiral chromatography.

The existence of slow adsorption-desorption kinetics in chiral liquid chromatography is common knowledge. This may significantly contribute to worsening the efficiency and kinetic performance of a chromatographic run, especially when high flow rates are employed. Many attempts and protocols have been proposed to access this term, the so-called c ads , but they are based on different (theoretical) assumptions. As a consequence, no official method is available for the estimation of the adsorption-desorption kinetics term. In this work, a novel approach to access c ads is presented. This procedure combines experimental results obtained with kinetic and thermodynamic measurements. The investigations have been performed on two zwitterionic teicoplanin chiral stationary phases (CSPs) based on 1.9 µ m fully porous and 2.0 µ m superficially porous particles (FPPs and SPPs), using Z-D,L-Methionine as probe molecule. Kinetic studies have been performed through the combination of both stop-flow and dynamic measurements, while adsorption isotherms have been calculated through Inverse Method. This study has confirmed that, on both particle formats, analyte diffusion on the surface of the particle is negligible, meaning that adsorption is localized, and it has been demonstrated that adsorption-desorption kinetics is strongly dependent on particle geometry and, in particular, on the loading of chiral selector. These findings are fundamental not only to unravel novel aspects of the complex enantiorecognition mechanism but also to optimize the employment of CSPs for ultra-fast and preparative applications.

Heat and mass transfer simulation of the microwave-assisted toluene desorption for activated carbons regeneration.

The low cost and high efficiency of microwave-assisted regeneration render it a viable alternative to conventional regeneration methods. To enhance the regeneration performance, we developed a coupled electromagnetic, heat, and mass transfer model to investigate the heat and mass transfer mechanisms of activated carbon during microwave-assisted regeneration. Simulation results demonstrated that the toluene desorption process is governed by temperature distribution. Changing the input power and flow rate can promote the intensity of hot spots and adjust their distribution, respectively, thereby accelerating toluene desorption, inhibiting readsorption, and promoting regeneration efficiency. Ultimately, controlling the input power and flow rate can flexibly adjust toluene emissions to satisfy the processing demands of desorbed toluene. Taken together, this study provides a comprehensive understanding of the heat and mass transfer mechanisms of microwave-assisted regeneration and insights into adsorbent regeneration.

Sorption and mobility assessment of tembotrione in soils of upper, trans and middle Gangetic plain zones of India.

The presence of undesired agrochemicals residues in soil and water poses risks to both human health and the environment. The behavior of pesticides in soil depends both on the physico-chemical properties of pesticides and soil type. This study examined the adsorption-desorption and leaching behavior of the maize herbicide tembotrione in soils of the upper (UGPZ), trans (TGPZ) and middle Gangetic plain zones of India. Soil samples were extracted using acetone followed by partitioning with dichloromethane, whereas liquid-liquid extraction using dichloromethane was used for aqueous samples. Residues of tembotrione and its metabolite TCMBA, {2-chloro-4-(methylsulfonyl)-3-[(2,2,2-trifluoroethoxy) methyl] benzoic acid}, were quantified using liquid chromatography-tandem mass spectrometry. The data revealed that tembotrione adsorption decreased with increasing pH and dissolved organic matter but increased with salinity. The maximum adsorption occurred at pH 4, 0.01 m sodium citrate and 4 g/L NaCl, with corresponding Freundlich constants of 1.83, 2.28 and 3.32, respectively. The hysteresis index <1 indicated faster adsorption than desorption. Leaching studies under different flow conditions revealed least mobility in UGPZ soil and high mobility in TGPZ soil, consistent with groundwater ubiquity scores of 4.27 and 4.81, respectively. Soil amendments decreased tembotrione mobility in the order: unamended > wheat straw ash > wheat straw > farm yard manure > compost. The transformation of tembotrione to TCMBA and its mobility in soil columns were also assessed.

Adsorption-desorption and leaching behavior of benzovindiflupyr in different soil types.

Benzovindiflupyr is a succinate dehydrogenase inhibitor fungicide that targets mitochondrial function for disease control. In this study, we investigated the adsorption-desorption and leaching behavior of benzovindiflupyr in eight soil types using the batch equilibrium method and the soil column leaching method. A Freundlich model (r2 > 0.9959) was used to better characterize the adsorption-desorption process in eight soil types, with adsorption coefficients (KF-ads) ranging from 2.303 to 17.886. KF-ads was significantly and positively correlated (p < 0.05) with the organic carbon content. High temperatures and increased initial pH of aqueous solutions led to a decrease in benzovindiflupyr adsorption in the soil. The adsorption was also influenced by factors such as ionic strength, humic acid, surfactant type, microplastic type, and particle size and concentration. Moreover, benzovindiflupyr exhibited low leachability in all four soils selected, but different leaching solutions affected the risk of benzovindiflupyr migration to groundwater. Overall, this study provides insights into the adsorption characteristics of benzovindiflupyr in different soils and provides key information for environmental risk assessment.

Adsorption-desorption behavior of florpyrauxifen-benzyl on three microplastics in aqueous environment as well as its mechanism and various influencing factors.

Microplastics (MPs) and pesticides are two categories contaminants with proposed negative impacts to aqueous ecosystems, and adsorption of pesticides on MPs may result in their long-range transport and compound combination effects. Florpyrauxifen-benzyl, a novel pyridine-2-carboxylate auxin herbicide has been widely used to control weeds in paddy field, but the insights of which are extremely limited. Therefore, adsorption and desorption behaviors of florpyrauxifen-benzyl on polyvinyl chloride (PVC), polyethylene (PE) and disposable face masks (DFMs) in five water environment were investigated. The impacts of various environmental factors on adsorption capacity were evaluated, as well as adsorption mechanisms. The results revealed significant variations in adsorption capacity of florpyrauxifen-benzyl on three MPs, with approximately order of DFMs > PE > PVC. The discrepancy can be attributed to differences in structural and physicochemical properties, as evidenced by various characterization analysis. The kinetics and isotherm of florpyrauxifen-benzyl on three MPs were suitable for different models, wherein physical force predominantly governed adsorption process. Thermodynamic analysis revealed that both high and low temperatures weakened PE and DFMs adsorption, whereas temperature exhibited negligible impact on PVC adsorption. The adsorption capacity was significantly influenced by most environmental factors, particularly pH, cations and coexisting herbicide. This study provides valuable insights into the fate of florpyrauxifen-benzyl in presence of MPs, suggesting that PVC, PE and DFMs can serve as carriers of florpyrauxifen-benzyl in aquatic environment.

Evaluation of highly adsorptive Guefoams (multifunctional guest-containing foams) as a potential sorbent for determination of volatile organic compounds (VOCs) by means of thermal desorption.

The present work delves into the feasibility of employing a novel structured sorbent referred to as GFAD (Guefoam Adsorption Device) for the determination of volatile organic compounds (VOCs) in liquid samples. The chosen method has been static headspace sorptive extraction-thermal desorption gas chromatography mass spectrometry (HSSE-TD-GC-MS). The GFAD comprises an aluminum cellular material with a distinct replication structure and a solid guest phase consisting of activated carbon particles dispersed within the cavities of the cellular aluminum. The extensive specific surface area, robustness, and exceptional thermal conductivity of this pioneering material offer distinct advantages over commercially available polydimethylsiloxane-based Twister® devices. Therefore, the trapping efficiency for volatile organic compounds is enhanced, and it is possible to perform the analysis of concentrated samples. According to computational simulations, it has been demonstrated that GFAD has a high heat conductivity. As a result, the desorption efficiency is improved, and minimal temperature gradients are generated throughout the GFAD during the heating process. Besides, the energy consumption is significantly lowered, thus aligning with environmentally conscientious and sustainable analytical practices.The experimental results give a proof of the suitability of the GFAD for determining gaseous compounds in liquid samples through HSSE-TD-GC-MS. For volatile species, the new material provides higher peak areas and lower limits of detection than a commercially available Twister® device. Furthermore, the GFAD is reusable, its adsorbing properties remaining unchanged during, at least, 100 consecutive analyses. In addition, unlike to the Twister®, no intense siloxane peaks are observed in the chromatograms obtained with the GFAD. The feasibility of qualitative and semi-quantitative analysis with the new accessory has been demonstrated with both standards and a cereal bioethanol real sample.

Effects of Visible Light on Gas Sensors: From Inorganic Resistors to Molecular Material-Based Heterojunctions.

In the last two decades, many research works have been focused on enhancing the properties of gas sensors by utilising external triggers like temperature and light. Most interestingly, the light-activated gas sensors show promising results, particularly using visible light as an external trigger that lowers the power consumption as well as improves the stability, sensitivity and safety of the sensors. It effectively eliminates the possible damage to sensing material caused by high operating temperature or high energy light. This review summarises the effect of visible light illumination on both chemoresistors and heterostructure gas sensors based on inorganic and organic materials and provides a clear understanding of the involved phenomena. Finally, the fascinating concept of ambipolar gas sensors is presented, which utilised visible light as an external trigger for inversion in the nature of majority charge carriers in devices. This review should offer insight into the current technologies and offer a new perspective towards future development utilising visible light in light-assisted gas sensors.

Adsorption of Ciprofloxacin on Clay Minerals in Argentinian Santa Rosa-Corrientes Soils.

The presence of antibiotics in soils is increasing drastically in last decades due to the intensive farming industry and excessive human consumption. Clay minerals are one of the soil components with great adsorption capacity for organic pollutants. The study of interactions between antibiotics and mineral surfaces will give us scientific knowledge of these pollutants through soils. In this work, we study the adsorption of the antibiotic ciprofloxacin in the clay mineral fraction of soils from the Argentinian zone of Santa Rosa (Corrientes), in a collaborative research of experiments and atomistic modelling calculations of the intercalation of ciprofloxacin in the interlayer space of montmorillonite. Adsorption and desorption isotherms were performed and compared with different isotherm models. Additionally, enthalpy, entropy, and free energy were determined from equilibrium constants at a function of temperature. All these experiments and calculations lead to the conclusions that two adsorption types of ciprofloxacin are found on clay minerals: one weakly sorbed that is released during the desorption experiments, and other one strongly joined that remains in the soil.

Unraveling the Impact of Adsorbed Molecules on Photocatalytic Processes: Advancements in Understanding Facet-Controlled Semiconductor Photocatalysts.

This work aims to demonstrate that the Fe2O3 nanocrystals' adsorptive and photocatalytic properties can be adjusted by exposing the crystal facets that are functionalized. To this end, cube- and disc-like structures were synthesized using a metal ion-mediated hydrothermal route. Thereafter, some of the samples were annealed at 500 °C for 3 h. Our paper combines the experimental part with theoretical calculations of the obtained materials' band edge positions. The results reveal that-aside from hematite-the as-synthesized discs also contain γ-FeOOH and ß-Fe2O3 phases, which transform into α-Fe2O3 during annealing. The hydrodynamic diameter, zeta potential, and adsorption kinetics measurements show that the cube-like samples exhibit the highest affinity for cationic, whereas the discs have an affinity for anionic dye. Measurements of the wall zeta potential also reveal that annealing the discs modifies their surface state and ability to adsorb molecules. Photocatalytic tests show that the as-synthesized powders have better photocatalytic performance toward methylene blue decomposition than the annealed ones. The observed small changes in the concentration of the MO during illumination result from the energy band structure of the cube-like crystal orientation.

Non-Markovian Diffusion and Adsorption-Desorption Dynamics: Analytical and Numerical Results.

The interplay of diffusion with phenomena like stochastic adsorption-desorption, absorption, and reaction-diffusion is essential for life and manifests in diverse natural contexts. Many factors must be considered, including geometry, dimensionality, and the interplay of diffusion across bulk and surfaces. To address this complexity, we investigate the diffusion process in heterogeneous media, focusing on non-Markovian diffusion. This process is limited by a surface interaction with the bulk, described by a specific boundary condition relevant to systems such as living cells and biomaterials. The surface can adsorb and desorb particles, and the adsorbed particles may undergo lateral diffusion before returning to the bulk. Different behaviors of the system are identified through analytical and numerical approaches.

Empirical model to assess leaching of pesticides in soil under a steady-state flow and tropical conditions.

Abstract: An empirical model of leaching of pesticides was developed to simulate the concentration of fungicides throughout unsaturated soil. The model was based on chemical reactions and the travel time of a conservative tracer to represent the travel time required for water to flow between soil layers. The model's performance was then tested using experimental data from dimethomorph and pyrimethanil applied to the soil under field and laboratory conditions. The empirical model simulated fungicide concentration on soil solids and in soil solution at different depths over time (mean square error between 2.9 mg2 kg-2 and 61mg2 kg-2) using sorption percentages and degradation rates under laboratory conditions. The sorption process was affected by the organic carbon, clay, and the effective cation exchange capacity of the soil. The degradation rate values of dimethomorph (0.039 d-1-0.009 d-1) and pyrimethanil (0.053 d-1-0.004 d-1) decreased from 0 to 40 cm and then remained constant in deeper soil layers (60-80 cm). Fungicide degradation was a critical input in the model at subsurface layers. The model was determined to be a reliable mathematical tool to estimate the leachability of pesticides in tropical soil under a steady-state flow. It may be extended to other substances and soils for environmental risk assessment projects. Supplementary Information: The online version contains supplementary material available at 10.1007/s13762-023-05038-w.

A review of the polyphenols purification from apple products.

Apple polyphenols are one of the major bioactive compounds in apple products and have strong anti-inflammatory effects and the ability to prevent chronic diseases with health benefits. The development of apple polyphenol products is dependent on the extraction, purification and identification of apple polyphenols. The extracted polyphenols need to be further purified to improve the concentration of the extracted polyphenols. This review, therefore, presents the studies on the conventional and novel methods for polyphenols purification from apple products. The different chromatography methods, as one of the most widely used conventional purification methods, for polyphenol purification from various apple products are introduced. In addition, the perspective of the adsorption-desorption process and membrane filtration technique in enhancing the purification of polyphenols from apple products are presented in this review. The advantages and disadvantages of these purification techniques are also discussed and compared in depth. However, each of the reviewed technologies has some disadvantages that need to be overcome, and some mechanisms need to be further identified. Therefore, more competitive polyphenols purification techniques need to emerge in the future. It is hoped that this review can provide a research basis for the efficient purification of apple polyphenols, which can facilitate their application in various fields.

Temperature-controlled microalgae biofilm adsorption/desorption in a thermo-responsive light-guided 3D porous photo-bioreactor for CO2 fixation.

Microalgae biofilm-based culture provides an efficient CO2 reduction and wastewater treatment method for its high photosynthetic efficiency and density. As supporting substrates for microalgae biofilm, porous materials have a big available adsorption area, but mutual shading makes it difficult to transmit external light to the internal surface for attached cells' photosynthesis. Thus, light-guided particles (SiO2) were introduced into photosensitive resin to fabricate a light-guided ordered porous photobioreactor (PBR) by 3D printing technology in this study. The space utilization of the PBR was significantly enhanced and the effective microalgae adsorption area was increased by 13.6 times. Further, a thermo-responsive hydrogel was grafted onto the surface of the substrate to form a smart temperature-controllable interface that could enhance microalgae adsorption and desorption in both directions. When the thermo-responsive layer received light, it would generate heat due to the hydrogel's photo-thermal effect. And the surface temperature would then raise to 33 °C, higher than the hydrogel phase transition point of 32 °C, making the surface shrinking and more hydrophobicity for microalgae cells attachment. The microalgae cells' adsorption capacity increased by 103%, resulting in a high microalgae growth rate of 3.572 g m-2 d-1. When turning off the light, the surface temperature would cool down to below 20 °C, the surface would shrink. And the biofilm shows a 564.7% increase in desorption ability, realizing temperature-controlled microalgae harvesting.

Combination of adsorption/desorption and photocatalytic reduction processes for PFOA removal from water by using an aminated biosorbent and a UV/sulfite system.

Per- and polyfluoroalkyl substances (PFAS) are stable organic chemicals, which have been used globally since the 1940s and have caused PFAS contamination around the world. This study explores perfluorooctanoic acid (PFOA) enrichment and destruction by a combined method of sorption/desorption and photocatalytic reduction. A novel biosorbent (PG-PB) was developed from raw pine bark by grafting amine groups and quaternary ammonium groups onto the surface of bark particles. The results of PFOA adsorption at low concentration suggest that PG-PB has excellent removal efficiency (94.8%-99.1%, PG-PB dosage: 0.4 g/L) to PFOA in the concentration range of 10 µg/L to 2 mg/L. The PG-PB exhibited high adsorption efficiency regarding PFOA, being 456.0 mg/g at pH 3.3 and 258.0 mg/g at pH 7 with an initial concentration of 200 mg/L. The groundwater treatment reduced the total concentration of 28 PFAS from 18 000 ng/L to 9900 ng/L with 0.8 g/L of PG-PB. Desorption experiments examined 18 types of desorption solutions, and the results showed that 0.05% NaOH and a mixture of 0.05% NaOH + 20% methanol were efficient for PFOA desorption from the spent PG-PB. More than 70% (>70 mg/L in 50 mL) and 85% (>85 mg/L in 50 mL) of PFOA were recovered from the first and second desorption processes, respectively. Since high pH promotes PFOA degradation, the desorption eluents with NaOH were directly treated with a UV/sulfite system without further adjustment. The final PFOA degradation and defluorination efficiency in the desorption eluents with 0.05% NaOH + 20% methanol reached 100% and 83.1% after 24 h reaction. This study proved that the combination of adsorption/desorption and a UV/sulfite system for PFAS removal is a feasible solution for environmental remediation.

Functionalized Ordered Mesoporous MCM-48 Silica: Synthesis, Characterization and Adsorbent for CO2 Capture.

The ordered mesoporous silica MCM-48 with cubic Ia3d structure was synthesized using the cationic surfactant hexadecyltrimethylammonium bromide (CTAB) as a template agent and tetraethylorthosilicate (TEOS) as a silica source. The obtained material was first functionalized with (3-glycidyloxypropyl)trimethoxysilane (KH560); further, two types of amination reagents were used: ethylene diamine (N2) and diethylene triamine (N3). The modified amino-functionalized materials were characterized by powder X-ray diffraction (XRD) at low angles, infrared spectroscopy (FT-IR) and nitrogen adsorption-desorption experiments at 77 K. Characterization from a structural point of view reveals that the ordered MCM-48 mesoporous silica has a highly ordered structure and a large surface area (1466.059 m2/g) and pore volume (0.802 cm3/g). The amino-functionalized MCM-48 molecular sieves were tested for CO2 adsorption-desorption properties at different temperatures using thermal program desorption (TPD). Promising results for CO2 adsorption capacities were achieved for MCM-48 sil KH560-N3 at 30 °C. At 30 °C, the MCM-48 sil KH560-N3 sample has an adsorption capacity of 3.17 mmol CO2/g SiO2, and an efficiency of amino groups of 0.58 mmol CO2/mmolNH2. After nine adsorption-desorption cycles, the results suggest that the performance of the MCM-48 sil KH N2 and MCM-48 sil KH N3 adsorbents is relatively stable, presenting a low decrease in the adsorption capacity. The results reported in this paper for the investigated amino-functionalized molecular sieves as absorbents for CO2 can be considered as promising.

The Study of Optimal Adsorption Conditions of Phosphate on Fe-Modified Biochar by Response Surface Methodology.

A batch of Fe-modified biochars MS (for soybean straw), MR (for rape straw), and MP (for peanut shell) were prepared by impregnating biochars pyrolyzed from three different raw biomass materials, i.e., peanut shell, soybean straw, and rape straw, with FeCl3 solution in different Fe/C impregnation ratios (0, 0.112, 0.224, 0.448, 0.560, 0.672, and 0.896) in this research. Their characteristics (pH, porosities, surface morphologies, crystal structures, and interfacial chemical behaviors) and phosphate adsorption capacities and mechanisms were evaluated. The optimization of their phosphate removal efficiency (Y%) was analyzed using the response surface method. Our results indicated that MR, MP, and MS showed their best phosphate adsorption capacity at Fe/C ratios of 0.672, 0.672, and 0.560, respectively. Rapid phosphate removal was observed within the first few minutes and the equilibrium was attained by 12 h in all treatment. The optimal conditions for phosphorus removal were pH = 7.0, initial phosphate concentration = 132.64 mg L-1, and ambient temperature = 25 °C, where the Y% values were 97.76, 90.23, and 86.23% of MS, MP, and MR, respectively. Among the three biochars, the maximum phosphate removal efficiency determined was 97.80%. The phosphate adsorption process of three modified biochars followed a pseudo-second-order adsorption kinetic model, indicating monolayer adsorption based on electrostatic adsorption or ion exchange. Thus, this study clarified the mechanism of phosphate adsorption by three Fe-modified biochar composites, which present as low-cost soil conditioners for rapid and sustainable phosphate removal.

Simple adsorptive removal of crystal violet, a triarylmethane dye, from synthetic wastewater using Fe (III)-treated pine needle biochar.

Untreated and Fe (III)-treated pine needle biochar (PNB) were evaluated at different pH for the removal of toxic crystal violet (CV) dye from synthetic wastewaters. Adsorption kinetics followed the pseudo-first-order kinetics involving intra-particle diffusion process. The adsorption rate constant increased with Fe treatment of PNB especially at pH 7.0. Adsorption data of CV conformed well to Freundlich adsorption isotherms and both adsorption capacity (ln K) and order of adsorption (1/n) of CV were nearly doubled with Fe (III) treatment of PNB at pH 7.0. Desorption of adsorbed CV from both untreated and Fe (III)-treated PNB could be accounted satisfactorily by third-degree polynomial equations. An increase in ionic strength and temperature enhanced dye adsorption onto untreated and Fe (III)-treated PNB. Adsorption of CV was an endothermic and spontaneous reaction with an increase in entropy of the system. FTIR spectra revealed that C = O of carboxylic acid aryls and C = O and C-O-C in lignin residues of PNB reacted with Fe (III) besides the formation of some iron oxyhydroxide minerals. The changes in FTIR confirmed the possible bonding of positively charged moiety of CV with the untreated and Fe-treated PNB. Scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) revealed the porous surfaces of PNB with clear accumulation of Fe (III) after treatment and deposition of CV dye on surfaces and pores of PNB. Iron (III)-treated PNB at pH 7.0 can serve as an ecofriendly and cost-effective adsorbent for the efficient removal of CV dye from wastewaters.