Methylene Blue Capacity Research Articles

Investigation on novel chitin and chitosan from dung beetle Heteronitis castelnaui (Harold, 1865) and its potential application for organic dyes removal from aqueous solution

Chitosan, a natural polysaccharide, has attracted considerable attention as an environmentally friendly and highly efficient adsorbent for dye removal. It is usually produced by deacetylation or partial deacetylation of chitin. However, conventional sources of chitin and chitosan are limited, prompting the need for alternative sources with improved adsorption capabilities. Herein, this study focuses on exploring a novel chitin and chitosan source derived from the dung beetle and evaluates its potential for organic dye removal from aqueous solutions. The research involves the extraction and characterization of chitin and chitosan from dung beetle Heteronitis castelnaui (Harold, 1865) using various analytical techniques, including SEM, FT-IR, TGA, XRD, NMR, deacetylation degree and elemental analysis. The chitosan obtained was used for the formation of hydrogels with sodium alginate via cross-linking with calcium chloride. And then the prepared hydrogels were evaluated for its adsorption capacity through batch adsorption experiments using methylene blue as a model pollutant. The adsorption capacity for methylene blue was 1294.3 mg/g at room temperature with solution pH = 12, MB concentration of 1800 mg/L. Furthermore, the kinetics of the adsorption process were analyzed using pseudo-first-order and pseudo-second-order models to understand the rate of adsorption. The maximum adsorption capacities were determined using Langmuir and Freundlich isotherm models. This study provides valuable insights for the development of sustainable dye adsorption technologies, specifically investigating a novel chitosan source derived from the dung beetle.

Waste newspaper as cellulose resource of activated carbon by sodium salts for methylene blue and congo red removal

The work was aimed at evaluating the adsorptive properties of waste newspaper (WN) activated carbons chemically produced using sodium salts for methylene blue (MB) and congo red (CR) removal. The activated carbons, designated as AC1, AC2, AC3 and AC4 were prepared through impregnation with NaH2PO4, Na2CO3, NaCl and NaOH, respectively and activation at 500 °C for 1 h. The activated carbons were characterized for surface chemistry, thermal stability, specific area, morphology and composition. The AC1 with a surface area of 917 m2/g exhibits a greater MB capacity of 651 mg/g. Meanwhile, a greater CR capacity was recorded by AC2 at 299 mg/g. The pseudo-second order model fitted well with the kinetic data, while the equilibrium data could be described by Langmuir model. The thermodynamic parameters, i.e.., positive ΔH°, negative ΔG° and positive ΔS° suggest that the adsorption of dyes is endothermic, spontaneous and feasible at high solution temperature. To conclude, WN is a potential cellulose source for producing activated carbon, while NaH2PO4 activation could be employed to convert WN into activated carbon for effective dye wastewater treatment.

Two‐Dimensional Copper‐Based Metal‐Organic Framework for Efficient Removal of Methylene Blue from Wastewater

AbstractMetal‐organic frameworks (MOFs) can effectively remove methylene blue (MB) from wastewater due to their abundant adsorption sites and multi‐level pores. In this paper, a copper‐based MOF: {[Cu ⋅ (L) ⋅ (H2O)] ⋅ (DMF)}n (1) (H2L=2‐hydroxyterephthalic acid; DMF=N,N‐dimethylformamide), was synthesized by hydrothermal synthesis method. X‐ray single crystal diffraction showed that a two‐dimensional structure was formed by the carboxyl group of L2− in 1 took μ2‐η1 : η1 bridged two adjacent Cu(II). In this two‐dimensional structure, the coordinated water molecules and hydroxyl group on L2− were distributed on the surface of 1. Thus, it had abundant adsorption sites. The transmission electron microscopy (TEM) of copper‐based MOF nano adsorbent showed that the particle diameter of the nano adsorbent prepared by a cell fragmentation apparatus was about 50 nm. The performance of the copper‐based MOF nano adsorbent in adsorbing MB indicated that the optimal adsorbent dosage was 0.20 g/L and the solution pH was 6. Under the optimal experimental conditions, its maximum adsorption capacity for MB was 143.3 mg/g, which was superior to most MOFs adsorbents. The adsorption thermodynamic analysis showed that the copper‐based MOF nano adsorbent at 25–45 °C was an exothermic (ΔH<0), and spontaneous (ΔG<0) process.

Synergistic effect of adsorption and photolysis on methylene blue removal by magnetic biochar derived from lignocellulosic biomass

In this study, magnetic biochar was synthesized by doping Fe3O4 onto the biochar surface followed by analysis of its properties. The efficiency of methylene blue (MB) removal through the combined processes of adsorption and photolysis was assessed. The presence of Fe3O4 on the biochar surface was confirmed using Raman spectroscopy and X-ray photoelectron spectroscopy. The magnetic biochar, after MB adsorption, showed a magnetism of 39.50 emu/g leading to a 97.07 % recovery rate. The specific surface area of biochar was higher (380.68 m2/g) than that of magnetic biochar (234.46 m2/g), and the maximum adsorption capacity of MB was higher in the biochar (0.03 mg/g) than that in magnetic biochar (0.02 mg/g) under the optimal conditions for MB adsorption. The MB adsorption experiments using biochar or magnetic biochar were optimally conducted under 10–20 mg/L MB concentration, 1 g biochar dosage, pH 12, 200 rpm rotation speed, 25 °C temperature, and 30 min duration. Under dark conditions, biochar had a higher MB removal rate, at 83.91 %, compared to magnetic biochar, at 78.30 %. Under visible light (λ > 425 nm), magnetic biochar effectively removed MB within 10 min, highlighting the synergistic effect of adsorption and photolysis. MB is physically and chemically adsorbed by the monolayer on the surface of EB and EMB according to adsorption behavior.

Effect of dissolution for black carbon on the adsorption capacity for methylene blue: Equilibrium, kinetics and thermodynamics

Black carbon was widely researched due to its significant role on the global carbon cycle and contaminant transport, and most people were concerned about the property of the dissolved black carbon from black carbon. In this work, we focused on the research of the residual those of black carbon. Two kinds of black carbon originated from peanut shell and bamboo were prepared and the corresponding residual black carbons were also obtained by the ultrasonic dissolution process. It was found the chemical and structure properties of residual black carbon changed a lot compared to black carbon. Using methylene blue as a target contaminant, the adsorption capacity of methylene blue by the residual black carbon was greater than that of black carbon. The adsorption capacity of black carbon-bamboo for methylene blue increased from 11.1 mg/g to 16 mg/g after the dissolution process, and the adsorption capacity of black carbon-peanut shell for methylene blue increased from 14 mg/g to 23 mg/g. The various influencing factors, such as the pH, initial concentration, temperature and adsorbent dosage, were systematically studied. The black carbons derived from peanut shell before and after the ultrasonic dissolution process both showed greater adsorption capacities for methylene blue. To further elucidate the methylene blue adsorption process, different kinds of isotherm and kinetics models were applied to simulate the experimental data. The results indicated that the Langmuir isotherm model was suitable to all the carbons before and after the ultrasonic dissolution process, and the pseudo-second-order model showed great simulation for the adsorption of methylene blue. In addition, the analysis of the thermodynamic study revealed that the adsorption processes of methylene blue were endothermic and spontaneous. Overall, results obtained from this work revealed the black carbon after been dissolved showed better adsorption capacity for contaminant.

Two-Dimensional Cu-Based MOF for Selective Staining of the Cellular Nucleus through Fluorescence Imaging and Selective Sorption of Dye Molecules in Aqueous Medium.

A two-dimensional copper-based metal-organic framework, [Cu(C23H14O6)(C10H8N2)2]·H2O·DMSO, 1, was synthesized using pamoic acid (C23H16O6) and 4,4'-bipyridine (C10H8N2) as an organic ligand and Cu(II) as a metal ion. Single-crystal structure X-ray diffraction studies of the as-synthesized compound showed a two- dimensional structure with free hydroxyl groups. Upon excitation at 370 nm, the aqueous dispersion of [Cu(C23H14O6)(C10H8N2)2]·H2O·DMSO, 1, showed emission centered at 525 nm resulting from the intraligand energy transfer. Fluorescence microscopic experiments using a human epithelioid cervix carcinoma HeLa cell line were carried out, clearly showing that our compound selectively stained the cellular nucleus. To utilize the porous nature of [Cu(C23H14O6)(C10H8N2)2]·H2O·DMSO, 1, its dye sorption behavior in aqueous solution was determined, and a high affinity for methylene blue (MB) dye was confirmed. Our synthesized compound sorbed 88% MB dye with an initial concentration of 32 mg L-1, and its sorption capacity for MB was found to be 29.79 mg g-1. The possible mechanism of the dye sorption behavior was discussed in terms of the size and charge of dye molecules with respect to molecular-level interactions between the framework and the dye molecules.

Synthesis and application of biochar from agricultural by-products. Effect of pyrolysis temperature on the acid-base properties of biochar

Biochar was synthesized from banana peels using the pyrolysis method in a nitrogen gas environment. The pyrolysis temperature ranged from 100°C to 500°C with a heating rate of 5°C per minute and a pyrolysis time of 1.5 hours. The influence of the pyrolysis temperature on the acid-base properties of the biochar surface was evaluated through characteristic SEM and BET measurements. Boehm titration showed a gradual decrease in the total acid functional groups and an increase in the total base functional groups with the increasing pyrolysis temperature. Methylene Blue (MB) was used as a model substance to investigate the adsorption properties of the synthesized biochar. The Langmuir and Freundlich models were employed to describe the adsorption equilibrium. The kinetics of MB adsorption followed a pseudo-second-order kinetic equation. The adsorption capacity of MB by biological charcoal was influenced by the acid-base properties of the material, indicating the impact of the pyrolysis temperature.

MnO2 decoration onto the guava leaves: A sustainable and cost-effective material for methylene blue dye removal

Excessive number of dyes in water is becoming the main cause of water pollution, which is very important to remove because it is harmful. Dye contaminated water is being treated by various methods. Adsorption method can be considered best for the study of dye removal due to several technological reasons. The adsorption method has also been emphasized in this study. In the present work, a nano-bio-composite was fabricated by growing manganese oxide nanoparticles on abundant cellulosic guava leaf powder. This allows nanocomposite to be prepared in large quantities at nominal cost. The characterization technique confirmed the irregular growth of manganese oxide nanoparticles onto the guava leaf powder. The electrostatic and non-electrostatic interactions was confirmed in between manganese oxide nanoparticles and the carbon structure of guava leaf powder. The massive functional groups were found to be in the prepared nano-bio-composite. The grain size of prepared material was in nano range. The developed nano-bio-composite was used to remove methylene blue from water. This showed a very good adsorptive capacity for methylene blue. The analyzed adsorption data was modelled through isotherms, kinetics and thermodynamics models. The nature of the adsorption process was determined to be spontaneous and exothermic. The reusability test was carried out for five adsorption-desorption cycles. The reusability results suggested the better removal efficiency (%) in the first two cycles with only 20 % reduction in removal efficiency (%). The leaching test result revealed the good stability of MnO2/GL at neutral pH. It was a unique and cheap adsorbent of its kind, which had not been noticed anywhere before.

Utilization of Ketapang Seed Shells in Reducing Pb(NO<sub>3</sub>)<sub>2</sub> Metal Levels by Adsorption Process

Industrial wastes such as lead metal can cause serious problems because of their toxic nature and can pollute the environment. To reduce levels of lead metal, you can use a natural adsorbent from activated charcoal on the outer shell of ketapang seeds. The ketapang tree is a type of plant that is often found in the surrounding environment because it is used as a shade for the many falling ketapang seeds making waste in the environment to reduce environmental pollution from the falling ketapang can be used as an adsorbent because it contains cellulose and carbon elements. One alternative to reduce lead levels using adsorbents is through the adsorption process which is the process of adsorption of a solid or liquid that involves physical, chemical and electrostatic interactions between the adsorbate and the adsorbent on the surface of the adsorbent. The adsorption process using activated charcoal adsorbent is one of the most frequently used non-polar adsorbents because it has better adsorption power and surface area than other types of adsorbents. This study aims to determine the influencing variables and the optimum condition of the natural adsorbent from the activated charcoal of the outer shell of ketapang seeds on decreasing levels of metal Pb (NO3)2. The research method used is an experimental method with a two-level factorial design. The results showed that the adsorption temperature was the most influential variable in this study with an optimum yield presentation of 66.77%. The activated charcoal produced has a water content of 8%, ash content of 5.2% and an absorption capacity of methylene blue of 698 mg/g.

Studying the kinetics and removal mechanism of the methylene blue dye in a continuous adsorption process using prepared mesoporous materials

ABSTRACT This study investigated the removal of a typical organic pollutant methylene blue (MB) dye from wastewater by a prepared mesoporous SBA-15 adsorbent in a continuous adsorption system (fixed-bed column). The structural and textural properties of the SBA-15 adsorbent were determined using different characterization techniques. The adsorption of continuous system experiments assessed the bed height effect, initial concentration, and flow rate on a breakthrough curve. The kinetic constants and breakthrough curves were obtained using the Thomas and Yan models. The breakthrough results revealed that SBA-15 has an excellent adsorption efficiency for use in the continuous adsorption system. The findings explain that MB removal achieved the maximum uptake (84 mg/g) at 6 cm of bed height, 0.5 mL/min of flow rate, and 30 mg/L initial concentration of MB. SBA-15 can be efficiently regenerated by calcination and re-employed 5 times in a fixed-bed system without a significant loss in its adsorption capacity of MB from MB solutions. As a result, SBA-15 was determined as the appropriate media to be adsorbent for MB. This study suggests that the prepared SBA-15 is feasible to use effectively for MB removal from the wastewater.

Nanofiber films reinforced with biomass extracts and their high efficiency in adsorbing dyes

In this study, polyacrylonitrile (PAN) was used as precursor and calcium Lignesulfonate (CLS) as additive to prepare composite films by electrospinning technology for the adsorption of methylene blue (MB) and Congo red (CR) dyes. The composite films were characterized by Brunauer-Emmett-Taylor analysis, Fourier transform infrared spectroscopy, scanning electron microscopy and energy dispersive X-ray spectroscopy (EDS). The effects of pH value, temperature, concentration and reaction time on adsorption efficiency were investigated. When the content of CLS is 20 wt%, the composite membrane has excellent adsorption performance, and the maximum adsorption capacity of MB and CR are 48 and 23 mg/g.

Zeolite supported zinc oxide nanoparticles composite: Synthesis, characterization, and photocatalytic activity for methylene blue dye degradation

In the first stage of this study, zinc oxide nanoparticles (ZnO-NPs) were synthesized. The synthesized nanoparticles were characterized by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), selected area diffraction (SAED), and X-ray diffraction analyses (XRD). Subsequently, a composite material was obtained by coating ZnO-NPs with zeolite from Rátka, Hungary. The photocatalytic degradation of ZnO-NPs using Hungarian zeolite in the ZnO-Zeolite composite was investigated. The objective was to evaluate the efficacy of the ZnO-Zeolite composite in degrading methylene blue (MB) under ultraviolet-visible spectroscopy (UV). It was observed that the composite materials were influenced by the light source. The degradation rates showed that the ZnO-Zeolite composite with 100 mg L−1 MB achieved the highest photodegradation rate of 96.70 % when exposed to sunlight for 210 min. These findings indicate that the ZnO-Zeolite composite with a 1:5 ratio has the potential to significantly increase the photocatalytic activity, achieving a high yield of 96.70 % compared to raw zeolite. In the last stage of the study, equilibrium, kinetic, and thermodynamic studies were carried out. The photocatalytic maximum adsorption capacity of MB for the ZnO-Zeolite composite was calculated as qm= 41.32 mg g−1. In the adsorption and kinetic studies of the obtained composite, the best results were obtained with the Langmuir adsorption isotherm and pseudo-second-order kinetics. A desorption study has been conducted, and it has been determined that the composite can be reused for up to 7 cycles.

KMnO4 modified magnetic hydrochar for efficient adsorption of malachite green and methylene blue from the aquatic environment

This study exploited magnetic citrus peel hydrochar (MHC) modified by KMnO4 (MHC/Mn) for the removal of methylene blue (MB) and malachite green (MG). Effects of initial concentration, pH, dosage, temperature, and ion strength on MHC/Mn adsorption properties were investigated. The adsorption kinetics, isotherm, and mechanism were further explored. The results indicated that Fe3O4 was successfully embedded and MnO2 was coated on MHC after modification. The experiment data were well fitted to the pseudo-second-order kinetic model and Langmuir isotherm model. Thermodynamic parameters showed that the adsorption of MHC/Mn to MB is spontaneous and endothermic, and the adsorption of MG is spontaneous and exothermic. The mechanism of MB and MG interaction with MHC/Mn includes electrostatic interaction, hydrogen bond, surface complexation, and π-π interaction. The maximum adsorption capacity of MB and MG calculated were 175.63 mg/g and 1402.17 mg/g. After four adsorption–desorption cycles, the removal rate of MB and MG were 85.11 % and 69.29 %. MHC/Mn is an economical and environmentally favorable adsorbent for the removal of MB and MG in wastewater.

Ultrasonic-Assisted Nitrate Anion Incorporation in Triaminoguanidium Chloride Based Covalent Organic Polymer for Methylene Blue Dye Adsorption.

Terephthalaldehyde-triaminoguanidium chloride covalent organic polymer, Te-TGCl COP can facilely be incorporated with NaNO3 by sonication. Te-TGCl COP incorporated with NaNO3 via ultrasonication adsorbs Methylene Blue (MB) dye. Te-TGCl COP alone shows negligible adsorption capacity for MB, however, when treated with NaNO3, its adsorption capacity emerges slightly. Moreover, ultrasonication of the NaNO3 treated COP, Te-TG-NaNO3 COP shows dramatic increase in its adsorption capacity for MB (qe for Te-TGCl COP ≈0 mg g-1; for Te-TG-NaNO3=17.65 mg g-1). Emergence of MB dye adsorption property in Te-TG-NaNO3 COP composite may be attributed primarily to the electrostatic interaction of MB dye molecules with nitrate anions and the sonochemical effect caused fibrous morphological structure of the adsorbent material. The kinetics of MB dye adsorption onto Te-TG-NaNO3 COP composite exhibits an excellent fit for the pseudo-second order model, suggesting the rate-determining step to be chemisorption. Homogeneous monolayer adsorption of MB dye onto Te-TG-NaNO3 COP composite can be suggested as the Langmuir isotherm model seemed to be fitted well.

Integration of Sn(IV)porphyrin on mesoporous alumina support and visible light catalytic photodegradation of methylene blue

Two composite catalysts, designated as SnTTP/SA@Al2O3 and SnTTP@Al2O3, were synthesized by the reaction of Al2O3 and trans-dihydroxo-[5,10,15,20-tetrakis(p-tolyl)porphyrinato]tin(IV) (SnTTP) with and without succinic acid (SA) pretreatment, respectively. Chemically, SnTTP was more tightly incorporated onto the surface of Al2O3 through the anchoring group SA in SnTTP/SA@Al2O3 than that in SnTTP@Al2O3. The SA bridging anchoring groups hindered the dissociation of SnTTP from SnTTP@Al2O3 during photodegradation. Therefore, the strong association between Al2O3 and SnTTP via SA connections not only intensified the quantity of tin porphyrin on the surface of Al2O3 but also accelerated electron movement from the excited SnTTP molecules to the conduction band of Al2O3. The aforementioned mechanism demonstrates a significant improvement in the catalytic photodegradation of methylene blue (MB) dye for SnTTP/SA@Al2O3 compared to SnTTP, Al2O3, and SnTTP@Al2O3 under visible-light irradiation. Within 90 min of using SnTTP/SA@Al2O3 at a rate of 0.0406 min−1, the photodegradation capacity of MB was found to be 98 %. The synergistic effect between Al2O3 and SnTTP improved the catalytic efficiency of SnTTP/SA@Al2O3 compared to that of both SnTTP and Al2O3. This study provides a new direction for the construction of highly efficient porphyrin-based photocatalysts and has significant value for extending their applications in water treatment.

Magnetic, Biocompatible and Biodegradable Carboxymethyl Cellulose‐Based Hydrogel for Cationic Dye Adsorption

AbstractEnsuring the availability of water resources that are both clean and safe is crucial for the preservation of environmental health and the well‐being of humans. Here, we fabricated carboxymethyl cellulose‐based hydrogel nanocomposite using acrylic acid (AA) and 2‐acrylamido‐2‐methylpropane sulfuric acid (AMPS) monomers and Fe3O4 nanoparticles through a free radical crosslinking process for adsorption of dyes from contaminated water. The synthesized nanocomposite hydrogel was characterized using various techniques, including TEM, XRD, FTIR, SEM‐EDS, TGA, and AFM analysis. The swelling capacity of samples in an aqueous medium at multiple pH levels and the presence of different salts were investigated. The adsorption efficiency of methylene blue (MB) and crystal violet (CV), emphasizing the effect of hydrogel concentration and the medium's pH, was studied. It was concluded that the hydrogel sample containing 17 % AMPS and 51 % AA had better swelling capacity and dye removal efficiency. The dye adsorption kinetics data were fitted to pseudo‐first and second‐order kinetic models and the Langmuir and Temkin isotherm models. The maximum adsorption capacity for MB and CV was 53.97 and 53.57 mg/g, respectively. It was revealed that the pseudo‐second‐order kinetic model could best describe adsorption (qe=79.2 mg/g for MB and qe=65.8 mg/g for CV). The intra‐particle diffusion model was found to be the rate‐limiting mechanism of dye adsorption. Thermodynamic studies proposed that the adsorption of MB and CV was spontaneous and endothermic. Additionally, magnetic nanocomposite hydrogel‘s reusability up to four successive cycles further determines its probability of adsorption of dyes from wastewater.

Green synthesis of metal nanoparticles from Codium macroalgae for wastewater pollutants removal by adsorption

AbstractAlgae have adsorption properties and reducing agents due to their rich content. In this study, palladium nanoparticles (Pd NP), platinum nanoparticles (Pt NP), and iron oxide nanoparticles (Fe3O4 NP) were prepared from Codium macroalgae using green synthesis. The structure of the synthesized nanoparticles was elucidated by X‐ray diffractometry, Fourier transforms infrared spectroscopy, Brunauer–Emmett–Teller analysis, transmission electron microscopy, ultraviolet‐visible spectroscopy and scanning electron microscopy‐energy dispersive X‐ray spectrometry and their use as nanoadsorbents for the removal of pollutants from aqueous media was investigated in detail. Naproxen (NPX), an anti‐inflammatory drug, and the dyes methylene blue (MB) and cresol red (CR) were selected as pollutants for this study. Batch adsorption experiments were conducted using both real wastewater obtained from the Organised Industrial Zone of Isparta Province and synthetic water samples prepared with tap water from Burdur Province and pure water. Under optimum adsorption conditions, Pd NP showed significant efficiency in the real wastewater sample, with an adsorption capacity of 37.19 and 50.03 mg g–1 for CR and NPX, respectively, within 150 min. In comparison, Pt NP showed an adsorption capacity of 40.01 mg g–1 for MB within the same timeframe. These findings indicate that while Pd NP showed the highest adsorption capacity for both CR and NPX, Pt NP showed the highest adsorption capacity for MB. The Langmuir model and the pseudo‐second‐order equation were more suitable to describe the adsorption behavior of CR, MB, and NPX. In addition, studies on the desorption and reusability of the nanoadsorbents were carried out under the same optimum experimental conditions.

Removal of methylene blue using magnetic Na-bentonite composite in aqueous Solutions

The present work focuses on the development of a new magnetic composite material that would be practical and effective for the removal of methylene blue (MB) dye from water. This composite material was chemically prepared from bentonite and iron salts. It was characterized by ATR-FTIR, DRX, SEM and EDS. The adsorption study showed a relatively high adsorption capacity of MB on the composite (86.2 mg/g) and an MB removal efficiency of 100%. In a study of the influence of certain operating parameters, the effect of pH and temperature on MB removal efficiency was found to be negligible. However, the results of the kinetic and thermodynamic study showed that MB adsorption follows the pseudo-second- order and Langmuir model. Of the eluents tested, acetic acid proved to be the most efficient, with an MB desorption efficiency of 90%. The results obtained show that magnetic bentonite is an interesting solution for the removal of dyes in water by adsorption.

REVIEW OF THERMODYNAMIC AND PHYSICO-CHEMICAL PARAMETERS INFLUENCING METHYLENE BLUE ADSORPTION ON ACTIVATED CHARCOAL OF NATURAL ORIGIN

Methylene blue (MB) is a phenothiazine derivative used in microbiology, surgery, diagnostics and as a sensitizer in the photo-oxidation of organic pollutants. These numerous uses of methylene blue could lead to its accumulation in wastewater, causing harmful effects on the environment and living beings. To combat these harmful effects, numerous wastewater treatment processes, particularly physicochemical, were implemented. Adsorption techniques are particularly used to find new natural, biodegradable and inexpensive adsorbents to treat colored waste from structures such as medical and pharmaceutical laboratories. The aim of the present study was to carry out a relevant bibliographical review of the physico-chemical and thermodynamic parameters that can influence this adsorption of methylene blue on activated carbons of natural origin. The results showed a remarkable elimination of methylene blue. However, parameters such as particle size, adsorbent mass, pH, contact time, initial methylene blue concentration, agitation speed and temperature showed that the adsorption capacity of MB on biosorbents was influenced by these quantities. Similarly, the positive and negative enthalpy values (ΔH°) indicated that adsorption process could be endothermic or exothermic. Other thermodynamic parameters, such as the negative value of Gibbs free energy (ΔG°) and the positive value of entropy (ΔS°), also showed that the adsorption process was feasible and spontaneous.

Synthesis of 1D magnetic Fe3O4@SiO2/TiO2 nanostir bar photocatalyst for the degradation of MB under UV light

Here, a novel one-dimensional (1D) magnetic Fe3O4@SiO2/TiO2 nanostir bar both with high-efficient adsorption and photocatalysis of Methylene blue (MB) has been explored. Firstly, silicon and titanium precursor were loaded on the surface of Fe3O4 through the static magnetic induced self-assembly. Then the TiO2/SiO2 hybrid shell were formed by the hydrothermal treatment process to achieve the 1D magnetic nanostir bar. The 1D magnetic Fe3O4@SiO2/TiO2 photocatalyst exhibited good adsorption capacity and degradation activity of MB. The adsorption capacity of MB by Fe3O4@SiO2/TiO2(60 %) was 40 mg g−1. The apparent reaction rate constant of Fe3O4@SiO2/TiO2 (60 %) was 0.129 min−1. This work will provide a general strategy to explore other useful 1D magnetic nanomaterials for micro-reaction system.