Methylene Blue Adsorption Research Articles

Investigation of kinetics and thermodynamics of methylene blue dye adsorption using activated carbon derived from bamboo biomass

This research paper aimed to evaluate the potential of activated carbon (AC) made from non-torrefied and torrefied bamboo biochar samples for the purpose of adsorbing methylene blue solution. The process involved impregnating bamboo biochar with a 5 M potassium hydroxide (KOH) solution at a 1:4 ratio of biochar to KOH, followed by carbonization at 800 °C, 900 °C, and 1000 °C to produce activated carbon samples. The samples were then characterized using techniques such as XRD, FESEM-EDX, FTIR, FE-TEM, and BET analysis to study their respective phase, surface morphology, elemental composition, functional groups, and structural and surface properties. The results showed that the torrefied bamboo AC exhibited a specific surface area of 366 m2/g and a total pore volume of 0.24 m3/g. Kinetic analyses showed adsorption following a pseudo-second-order model, with a capacity of 83.3 mg/g according to the Langmuir model and a favorability constant of 0.52 from the Freundlich model. Thermodynamic studies revealed the process to be spontaneous and endothermic, with changes in enthalpy and entropy of 77,810.73 kJ/mol and 269.9 kJ/mol·K, respectively. These findings highlight the effectiveness of bamboo-derived AC as a sustainable adsorbent for MB dye removal, offering a promising solution for water pollution control.

Enhanced Photocatalytic Activity of V2C MXene-Coupled ZnO Porous Nanosheets with Increased Surface Area and Effective Charge Transfer.

Photocatalysis performs excellently when degrading organic pollutants, but the photocatalytic degradation rate is not high for most photocatalysts due to their narrow sunlight adsorption range and high recombination rate of electron hole pairs. Herein, we use V2C-MXene with a wide sunlight adsorption range to couple ZnO porous nanosheets and form ZnO/MXene hybrids using a facile electrostatic self-assembly method. The ZnO/MXene hybrids acquired demonstrated improved photochemical efficiency in breaking down methylene blue (MB) when contrasted with porous ZnO nanosheets. The degradation rate of MB reached 99.8% under UV irradiation for 120 min after the ZnO/MXene hybrid formation, while 38.6% was attained by the ZnO porous nanosheets. Moreover, photodegradation rate constants (k) were calculated as 3.05 × 10-3 and 5.42 × 10-2 min-1 for ZnO porous nanosheets and ZnO/MXene hybrids, respectively, indicating that the photodegradation performance was enhanced by 17.8 times after the modification of V2C. This was probably because the modification of V2C can increase the specific surface area to provide more sites for MB adsorption, widen the sunlight adsorption range to produce good photothermal effect, and facilitate the transfer of photogenerated carriers in ZnO to promote the reaction of more photogenerated carriers with MB. Hence, this work offers a simple approach to creating effective photocatalysts for breaking down organic contaminants.

Preparation of carboxymethyl cellulose/graphene oxide/ZIF-8 aerogels for efficient methylene blue adsorption

Despite the promising potential of zeolitic imidazole framework-8 (ZIF-8) for dye adsorption, addressing challenges such as aggregation and recycling difficulties remains essential. Herein，a novel three dimensional (3D) carboxymethyl cellulose (CMC), graphene oxide (GO) and ZIF-8 hybrid aerogel (CGZ-3) was prepared via blending ZIF-8 into the CMC-GO matrix. The structure and composition of CGZ-3 were characterized by SEM, FT-IR, TG and XPS. Adsorption experiments were conducted to optimize various parameters affecting the behavior of methylene blue (MB) adsorption. The composite aerogel exhibited an obvious lamellar network structure, with a surface rich in oxygen-containing functional groups such as -OH and -COOH. CGZ-3 demonstrated a rapid adsorption rate for MB, achieving a removal efficiency of 96% within 15 minutes. The entire adsorption process was spontaneous and endothermic, consistent with the pseudo-first-order kinetic model and Langmuir adsorption isotherm model. The maximum theoretical adsorption capacity was 427.35 mg/g at 298 K. Selective adsorptions tests demonstrated high selectivity of the composite aerogel for MB, and dynamic adsorption further confirmed the exceptional adsorption capacity of CGZ-3. After five cycles of adsorption-desorption, the MB removal rate remained above 95%, with an adsorption capacity exceeding 240 mg/g, highlighting the stability and reusability of CGZ-3. Collectively, the CGZ-3 would be a potential material for the adsorptive removal of MB in practical water treatment.

High-efficient removal of methylene blue by zirconium-based organic frameworks modified with 1,3,5-benzenetricarboxylic acid: Characterization, performances, and mechanisms

The vast discharge of methylene blue (MB) dye in industrial effluent, risks the ecological environment, thus making its removal unavoidable. Recently, metal organic frameworks (MOFs) due to their larger pore volume, surface area and easy synthesis have proved to be exceptionally promising materials for contaminant treatment. Based on 1,3,5-benzenetricarboxylic acid (BTC) as a modifier, a new composite material consisting of BTC and Zr-based MOF (UIO-66-BTC) was fabricated for the effective removal of MB from the effluent. Its synthesis and efficient application has been confirmed by characterization analysis. The influencing factors, adsorption isotherms, and adsorption kinetics of MB adsorption by adsorbent were studied. It was demonstrated that the removal rate of MB adsorption by UIO-66-BTC reached 98.45% and the adsorption amount reached 393.80 mg g−1 at temperature (298 K), pH 7, adsorbent dosage (0.5 g L−1), MB initial concentration (200 mg L−1), and contact time of 720 min, respectively. The maximum adsorption of MB by UIO-66-BTC was 20.827 times higher than that of UIO-66 (18.908 mg g−1). The experimental data fits with the pseudo-second-order kinetic model and Langmuir isotherm, implying that the adsorption process is a monolayer chemisorption process. The thermodynamic and regeneration experiments showed that the spontaneous process enhanced the adsorption of MB at lower temperatures and the adsorption efficiency of MB remained above 68% after five successive cycles. The mechanism of MB adsorption on adsorbents is mainly based on electrostatic interactions, pore filling, hydrogen bonding and π-π interactions. It is concluded that this new adsorbent can be effectively used to treat MB in effluents.

Covalent crosslinking tetraethylenepentamine/cellulose composite aerogels with adsorbability for dye elimination

The cellulose-biomass material possesses a distinctive structure, distinguished by its eco-friendliness, degradability, renewability, cost-effectiveness, and efficacy as a bio-absorbent. In this groundbreaking study, we synthesized cellulose aerogels for the first time using a combination of sol-gel processing, straightforward chemical crosslinking, and freeze-drying. The functionalized materials exhibit an intricately interconnected three-dimensional porous structure achieved through covalent crosslinking with tetraethylenepentamine (TEPA). The resulting aerogel demonstrated a highly porous structure (exceeding 90%), low density (91.89–114.87 mg/cm3), and abundant surface amine groups advantageous for removing organic dyestuffs. To comprehensively assess the impact of the fabricated aerogel on methylene blue and crystal violet adsorption behavior, a detailed investigation was conducted, considering variables such as cellulose content (1.0–3.0 wt%), TEPA/EtOH/H2O volume ratio (1.0–3.0/5.0/3.0), contact time (0–300 min), and initial dye concentration (25–200 mg/L). As a result, the nitrogen-rich aerogel (with 2 wt% cellulose and TEPA/EtOH/H2O ratio of 2.0/5.0/3.0) exhibited dye adsorption following a pseudo-second-order kinetic model, with adsorption isotherms aligning with the Freundlich model. Thermodynamic assessments indicated that the adsorption process is a spontaneous endothermic reaction. Consequently, these eco-friendly cellulose sponges emerge as promising adsorbents for effective wastewater treatment, highlighting their potential as a sustainable solution in environmental remediation.

Green algae Ulva lactuca-derived biochar-sulfur improves the adsorption of methylene blue from water

The present investigation explores the efficacy of green algae Ulva lactuca biochar-sulfur (GABS) modified with H2SO4 and NaHCO3 in adsorbing methylene blue (MB) dye from aqueous solutions. The impact of solution pH, contact duration, GABS dosage, and initial MB dye concentration on the adsorption process are all methodically investigated in this work. To obtain a thorough understanding of the adsorption dynamics, the study makes use of several kinetic models, including pseudo-first order and pseudo-second order models, in addition to isotherm models like Langmuir, Freundlich, Tempkin, and Dubinin–Radushkevich. The findings of the study reveal that the adsorption capacity at equilibrium (qe) reaches 303.78 mg/g for a GABS dose of 0.5 g/L and an initial MB dye concentration of 200 mg/L. Notably, the Langmuir isotherm model consistently fits the experimental data across different GABS doses, suggesting homogeneous adsorption onto a monolayer surface. The potential of GABS as an efficient adsorbent for the extraction of MB dye from aqueous solutions is highlighted by this discovery. The study’s use of kinetic and isotherm models provides a robust framework for understanding the intricacies of MB adsorption onto GABS. By elucidating the impact of various variables on the adsorption process, the research contributes valuable insights that can inform the design of efficient wastewater treatment solutions. The comprehensive analysis presented in this study serves as a solid foundation for further research and development in the field of adsorption-based water treatment technologies.

Analysis of Methylene Blue Adsorption onto the Modified <i>Teucrium polium</i> by the Kinetic and Isotherm Nonlinear Models

Analysis of Methylene Blue Adsorption onto the Modified <i>Teucrium polium</i> by the Kinetic and Isotherm Nonlinear Models

Earth-abundant quaternary chalcogenide copper zinc tin sulfide-based nanocomposites CZTS-gCN and CZTS-GO (graphene oxide) as photocatalysts for degradation of methylene blue

This study explores the potential of Cu2ZnSnS4 (CZTS) as an environmentally friendly and nontoxic semiconductor photocatalytic material with a narrow band gap. The research focuses on investigating, photocatalytic degradation of Methylene Blue (MB) using CZTS-based nanocomposites prepared through hydrothermal approach. The experiments conducted in this study aim to determine the kinetics of photodegradation and adsorption of MB. Several models are applied to the experimental data to understand the underlying principles governing photocatalysis. The CZTS-gCN and CZTS-GO nanocomposites are thoroughly characterized using various analytical techniques such as X-ray diffraction for phase purity and crystallite size, Scanning Electron Microscopy, and other characterization are also employed to observe the morphology, phase structure, optical band gap, recombination of charge carriers The study discusses a potential method for enhancing the photocatalytic performance of the CZTS nanocomposite under light conditions. The photodegradation rate of MB dye is evaluated, showing a remarkable 64% degradation.

Multifunctional bionanohybrids of graphene oxide/β-cyclodextrin for applications in methylene blue adsorption, solvent response, and smart light-driven

In this study, a multifunctional graphene oxide/β-cyclodextrin bionanohybrids (BWGO) was prepared successfully. The structure, morphology, adsorption capacity, solvent response, and light-driven properties of the BWGO were systematically investigated through the in-situ formation of an asymmetric gradient structure. The maximum adsorption value of BWGO based on bio-nanohybrids was 81.27 mg·g−1 for methylene blue (MB), which fitted the Langmuir isotherm in accordance with the pseudo-secondary kinetic model. Additionally, the host–guest interaction model of between BWGO and MB (in ratios of 1:1 or 1:2) was proposed by ROESY. Remarkably, the BWGO exhibited not only unique and exceptional responses to organic hazard solvents, self-driven, and photothermal responses, but also demonstrated controllable object loading and shape memory useful for soft grasping. More importantly, the related mechanisms of adsorption and behaviors driven by multiple stimuli (solvent, light) were elucidated through the host–guest interaction, wrinkled structure, gradient solvent swelling effects, and conformational changes in the macromolecular chain. This work not only introduces the multifunctional bionanohybrid materials with a wrinkled structure for the adsorption of organic dyes, but also opens avenues for potential applications in smart windows, soft grasping, and biomimetic industrial materials.

In Situ Functionalisation and Upcycling of Post‐Consumer Textile Blends into 3D Printable Nanocomposite Filaments

AbstractThe linear lifecycle of the textile industry contributes to the enormous waste generation of post‐consumer garments. Recycling or repurposing of post‐consumer garments typically requires separation of the individual components. This study describes a novel and facile chemo‐thermo‐mechanical method for producing extrudable pellets, involving one‐pot, 2,2,6,6‐Tetramethylpiperidine‐1‐oxyl (TEMPO)‐mediated oxidation of post‐consumer polycotton textiles, followed by mild mechanical treatment, all without isolating the constituents of the polycotton blend. The oxidized blend with high cellulose and carboxylate content of 1221 ± 82 mmol COO− per kg of cotton, is pelletised into a masterbatch and further in situ extruded into nanocomposite filaments for 3D printing. The carboxyl groups introduced on the polycotton‐based filters enable cotton fibrillation into nanoscaled fibers during mechanical treatment and extrusion resulting to a variety of functional and high surface‐finish quality models, including filters and fashion accessories. The electrostatic interactions with positively charged species, such as methylene blue (MB), facilitate their adsorption from water while exhibiting promising adsorption capacities. The adsorption of MB follows the Freundlich model and depends on the printed porosity of the filter. A “trash to treasure” concept for textile waste is further corroborated through the use of the developed 3D printing filament into commodity products.

Furfuryl-pyridinium-functionalization of flaxseed gum for effective methylene blue removal from aqueous solution

This study describes the modification of flaxseed gum (FSG) via furfural to obtain a furfuryl-pyridinium modified adsorbent (Flax-Py) with improved adsorption characteristics towards methylene blue (MB) versus results obtained for unmodified FSG. Materials characterization was achieved via complementary spectral methods (NMR, XPS, FT-IR, Raman, and XRD) as well as thermogravimetric analysis (TGA) and ζ-potential measurements. Synthetic modification of FSG to yield Flax-Py that led to enriched N-content (2.75 atom-% versus 0.76 atom-% for FSG), and the conversion of furfuryl to pyridinium was incomplete (ca. 50 %), where both moieties were identified. The adsorption isotherms at pH 7 showed that FSG possessed favorably high MB adsorption capacity (ca. 540 mg/g); while Flax-Py was notably lower (167 mg/g). Flax-Py facilitated 100% MB removal at low dye concentrations (1-10 mg/L) versus 50 % MB removal for the FSG bioadsorbent. Further, Flax-Py showed moderate loss of adsorption with MB (ca. 12-16% dye removal) after five regeneration cycles. Flax-Py revealed improved settling characteristics (time, density, gelation, and solubility) that facilitate enhanced phase separation of FSG fractions by circumventing the need for centrifugation. The adsorption mechanism was attributed primarily to H-bonding effects with secondary contributions due to electrostatic interactions (negative ζ-potential above pH 4.2). This study successfully modified FSG to obtain an improved adsorbent (Flax-Py) attaining nearly quantitative MB dye removal at environmentally relevant concentrations (< 15 mg/L).

Bioeconomic transformation of bio-oil production wastes: a novel adsorbent material for toxic dye adsorption and optimization of process parameters

In this study, for the first time, an adsorbent material was produced from the waste left behind after the bio-oil production process from Terebinth (Pistacia Terebinthus L.) seeds as part of bioconversion, and the adsorption of the hazardous dyestuff methylene blue from aquatic media was investigated. The characterization of the adsorbent was performed using FT-IR, SEM, and BET analysis. The characterization of methylene blue adsorption was conducted to fully understand its nature, including its kinetics, equilibrium, and thermodynamic works. The maximum adsorption capacity (q max) of the monolayer, as determined from the equilibrium data, was calculated to be 166.07 mg g−1. Additionally, the experimental design method was utilized to determine the optimum conditions of the methylene blue adsorption process under various conditions. This study revealed that activated carbons from Terebinth seeds can be used as an economical and environmentally friendly adsorbent, which is very suitable for the removal of highly toxic dyes.

Tailoring electrospun nanocomposite fibers of polylactic acid for seamless methylene blue dye adsorption applications.

The introduction of biopolymers, which are sustainable and green materials, desegregated nature's water purification proficiency with science and technology, opens a new sustainable methodology in water reclamation. In order to introduce an efficacious adsorbent system for MB dye-toxic pollutant, adsorption, providing robust mechanical properties and facile processability, a facile system was introduced via electrospinning utilizing polylactic acid (PLA) and Ti3C2Tx, viz., PMX. The addition of 3 wt.% Ti3C2Tx led to a 3-fold substantial augmentation in the uptake capacity of the membrane from 197.28 to 307 mg/g when the adsorbate concentration was 100 ppm. The adsorption followed a PSO behavior, proposing that the rate-limiting stage is chemisorption and data best fitted to Freundlich isotherm, indicating heterogeneous adsorption sites and multi-layer adsorption. Further, biodegradability was studied by simulating natural environmental conditions where the nanofibers exhibited 42-64% degradation after 270 days. Based on the result with PLA, it is anticipated that the prepared fibrous system will introduce a new perspective as a potential candidate for MB removal from wastewater, opening new directions toward the research and development in wastewater treatment with electrospun biopolymer fibers using waste PLA.

Removal of Methylene Blue from Aqueous Solutions Using Date Palm By‐Products from Algerian Sahara: Cultivar Variations Effect

AbstractThis study aims to compare the methylene blue (MB) removal capacity from aqueous solutions of seven natural Date Palm (Phoenix dactylifera L.) By‐products (DPBPS). These include: Leaflets (DPLL), Rachis of leaf (DPRL), Fruit Bunch Stalk (DPFBS), Empty Fruit Bunch (DPEFB), Leaf Base (DPLB), fibrillium (DPF) and Spathe Sheath (DPSS), obtained from three different date palm cultivars: Degla, Ghers and Takermost from Ouargla Oasis in the Algerian Sahara, and to investigate the influence of the palm date nature part and cultivar on MB adsorption. Batch adsorption experiments were conducted at different concentrations; 30, 45, 60, 75, 90, and 105 mg/L of MB with 2.5 g of DPBP of each cultivar. The DPBPS of all cultivars exhibits remarkable adsorption efficiencies for MB removal. The highest maximal experimental adsorption capacities were observed for Degla DPLB (4.192 mg/g), Ghers DPF (4.191 mg/g) and Takermost DPF (4.193 mg/g) with(99.81 %), (99.79 %), and (99.82 %) adsorption rates in their cultivar respectively. Conversely, the lowest maximal experimental adsorption capacities were found for Degla DPLL 4.048 mg/g, Ghers DPEFB (4.12 mg/g) and Takermost DPSS (4.089 mg/g) with 96.40 %, 98.09 %, and at 97.67 % adsorption rates in each cultivar respectively. The equilibrium adsorption data were analyzed using Langmuir and Freundlich models. The results indicated a good fit with the Freundlich model. The studied DPBPS represent natural, low‐cost, and locally available adsorbents that effectively remove MB from wastewater.

Thermodynamic study and the development of a support vector machine model for predicting adsorption behavior of orange peel-derived beads in wastewater treatment

This study investigates the use of orange peels as a precursor for synthesizing sodium alginate-encapsulated beads for methylene blue (MB) removal. The prepared beads (BOP1 and BOP2) underwent characterization through FTIR, XRF, SEM and TGA. Subsequently, the impacts of various factors, including temperature, the initial pH, initial concentration, salt and humic acid, are studied. The adsorption isotherms show high adsorbed quantities of 764.92 and 659.78 mg/g for BOP1 and BOP2 respectively, while the obtained data are best described by the monolayer with two energies (MMTE) model, which is then used to perform a thermodynamic study of the MB adsorption mechanism. Additionally, the adsorption kinetics data are modeled using three models, with the PFO model identified as the most appropriate. The regenerated beads demonstrate the ability to be reused up to 7 cycles, The effects of NaCl and humic acid on MB adsorption reveal that NaCl inhibits adsorption due to competition with Na+, while humic acid has no effect. Finally, a support vector machine (SVM) model optimized by the Levy Flight Distribution Optimization (LFD) algorithm is developed and found to be capable of accurately predicting the adsorption behavior of the prepared beads. This model is then used in optimizing the process conditions for maximal MB removal. Overall, this study demonstrates that the prepared beads could be potential low-cost and environmentally friendly adsorbents for wastewater treatment applications.

Exploring the potential of olive pomace derived activated charcoal as an efficient adsorbent for methylene blue dye: a comprehensive investigation of isotherms, kinetics, and thermodynamics

Methylene blue (MB) is a heterocyclic aromatic chemical compound used as a dye in various dyeing processes. The accumulation of such an organic compound poses a significant threat to both the environment and human health. Therefore, numerous biological, physical, and chemical processes have been established to remove MB dye, with adsorption being the most predominant dye-based treatment technology. In this context, the aim of this work was to evaluate the adsorption properties of activated carbon derived from olive pomace against methylene blue. To this end, scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy (EDS), and Fourier transform infrared spectroscopy (FT-IR) analyses were carried out to confirm the adsorption of MB on carbon structures. In addition, the effect of contact time, pH, initial dye concentration, adsorbent dose, and temperature on the adsorption efficiency of MB was investigated. On the other hand, kinetic and isothermal models were used to further understand the adsorption mechanism, which showed a good correlation with the pseudo-second-order kinetic model and the Langmuir isotherm. Finally, thermodynamic analysis showed favorable conditions for physisorption, with the process being both endothermic and spontaneous.

Metal organic framework composite based on CuBTC/SPION for application in methylene blue adsorption

AbstractIn this work, a composite (CuBTC/superparamagnetic iron oxide nanoparticles [SPION]) based on copper, benzene‐1,3,5‐tricarboxylic acid (CuBTC) and SPION was synthesized by electrochemical method for the magnetic separation of methylene blue (MB) from aqueous solutions. The synthesis of the proposed composite was carried out under various experimental conditions from 1.4 to 5.4 V for 1–5 h and subsequently studied using different techniques. Scanning electron microscopy showed a granular structure, whereas Brunauer–Emmett–Teller results revealed a well‐developed surface area of around 182 m2 g−1. Fourier transform infrared confirmed the presence of functional groups characteristic to CuBTC and Fe3O4, whereas X‐ray diffraction revealed the phase structure of CuBTC 1D, CuBTC 3D, and Fe3O4 in the obtained composite. Based on the experimental results, the sample synthesized under a potential of 1.4 V for 5 h was selected for MB adsorption studies in the function of adsorbent mass, contact time, solution pH, ionic strength, initial concentration, and temperature. The maximum adsorption capacity was 681 mg g−1, and the adsorption undergoes the Redlich–Peterson and Sips isotherm model. The results obtained for CuBTC/SPION indicate that the nanocomposite is a promising adsorbent for removing MB in synthetic dye water and wastewater.

Hydrothermal carbonization of biomass waste and application of produced hydrochar in organic pollutants removal

This novel research, presents the study of utilizing the wild almond shell as biomass waste to fabricate hydrochar using the hydrothermal carbonization (HTC) method based on a central composite design (CCD) with two independent variables (time and temperature) and three responses; productivity, higher heating value (HHV) and norfloxacin (NOR) adsorption capacity. The prepared hydrochar at 200 °C and 8 h was then employed to produce activated carbon (AC) by chemical-thermal activation technique. Hydrochar and AC were characterized using XRD, BET, SEM-EDX, Raman, and FTIR techniques. The pore development, resulting in a rise in the SBET (637.46 m2/g) value occurred after the activation process. Moreover, the results of XRD and Raman analyses revealed a decrease in graphitization degree. The adsorption of norfloxacin, methylene blue (MB), and sunset yellow (SY) by prepared hydrochar and AC were studied to assess the impact of the pH of the solution, initial concentration, temperature, and contact time. The maximum adsorption capacity for NOR, MB, and SY using hydrochar and AC were 85.37, 153.46, 93.35, and 384.1625, 556.465, 264.93 mg/g, respectively. The experimental data for the adsorption of NOR, MB, and SY using hydrochar and AC illustrated a good fit with the PSO model. Besides, the Langmuir and Freundlich models indicated better fitting with empirical data obtained for the adsorption of NOR, MB, and SY, respectively. Thermodynamic study outcomes validated the exothermicity and spontaneity of the adsorption process for both absorbents. This study presents a new opportunity to develop the circular economy by fabrication of sustainable adsorbents with high adsorption capacity for organic pollutants from biomass waste.

Effect of the Photoreduction Process on the Self-Cleaning and Antibacterial Activity of Au-Doped TiO2 Colloids on Cotton Fabric.

This study aims at understanding the effect of the photoreduction process during the synthesis of gold (Au)-doped TiO2 colloids on the conferred functionalities on cotton fabrics. TiO2/Au and TiO2/Au/SiO2 colloids were synthesized through the sol-gel method with and without undergoing the photoreduction step based on different molar ratios of Au:Ti (0.001 and 0.01) and TiO2/SiO2 (1:1 and 1:2.3). The colloids were applied to cotton fabrics, and the obtained photocatalytic self-cleaning, wet photocatalytic activity, UV protection, and antibacterial activity against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) bacteria were investigated. The obtained results demonstrated that the photoreduction of Au weakened the self-cleaning effect and reduced the photocatalytic activity of coated fabrics. Also, an excess amount of Au deteriorated the photocatalytic activity under both UV and visible light. The most efficient self-cleaning effect was obtained on fabrics coated with a ternary TiO2/Au/SiO2 colloid containing ionic Au, where it decomposed coffee and red-wine stains after 3 h of illumination. Adding silica (SiO2) made the fabrics superhydrophilic and led to greater methylene blue (MB) dye adsorption, a faster dye degradation pace, and more efficient stain removal. Moreover, the photoreduction process affected the size of Au nanoparticles (NPs), weakened the antibacterial activity of fabrics against both types of tested bacteria, and modestly increased the UV protection. In general, the photoactivity of Au-doped colloids was influenced by the synthesis method, the ionic and metallic states of the Au dopant, the concentration of the Au dopant, and the presence and concentration of silica.

By-product Eucalyptus leaves valorization in the basic dye adsorption: kinetic equilibrium and thermodynamic study

Abstract Algerian Eucalyptus Leaves (AEL), a natural biodegradable adsorbent abundantly available, was used for the removal of methylene blue (MB) dye. The AEL properties for the removal of MB were investigated under different conditions by varying the AEL amount, MB concentration, pH of the solution and the reaction temperature. Scanning electron microscopy (SEM) and infrared spectroscopy (FTIR) techniques have been used to characterize AEL biosorbent. Experimental results showed that the adsorption of MB dye at the concentration of 50 mg L−1 reached to 91 % at pH 10 with a stirring speed of 200 rpm and after 180 min of reaction time. The experimental data were analyzed using the linear forms of different kinetic models (pseudo-first order kinetic model, pseudo-second order kinetic model, and intra-particle diffusion models). The results demonstrated that the adsorption kinetics of MB was consistent with the pseudo-second order model with R 2 value of 0.9969. The isotherm models Langmuir, Freundlich, Dubinin, Elovich, Brunaut Emmet Teller and Temkin models were also investigated to describe the adsorption equilibrium. The results show that the AEL adsorption is in accordance with Temkin isotherm. The thermodynamic study revealed that the adsorption is spontaneous and exothermic. Therefore, as a cheap green adsorbent with high MB adsorption performance, AEL is expected to become one of the best candidate materials for future industrial wastewater treatment.