Adsorption Of Methylene Blue Dye Research Articles

Synthesis and characterization of a new natural saccharide polymer (n-LTP) for adsorption of Methylene blue dye from an aqueous solution

ABSTRACT In this study, a new natural polysaccharide material, i.e., n-LTP, was synthesized by mixing Linum usitatissimum seed oil cake, Trigonella foenum-graecum and Plantago physilium husk in a 1:1:1 ratio for adsorption of Methylene blue. BET, FTIR and SEM reveal the presence of various organic and inorganic groups besides heterogeneous surfaces of the adsorbent having a surface area of 384 m2/g. It is observed that at pH values of 12, contact time of 100 min, n-LTP dose of 1.5 mg, with dye concentration of 70 ppm at 50 °C, nearly 88% of adsorption take place. Experimental data shows that the Freundlich isotherm (R2 = 0.96) and pseudo-first-order kinetic model (R2 = 0.9538) fit best to the process. A thermodynamic study showed that the process was spontaneous, endothermic and feasible. Electrostatic, π -π and hydrogen bonding interactions are involved in MB dye adsorption on n-LTP as confirmed by a surface complexation model (SCM). Overall, results of the study explored the potential f n-LTP for removal of MB dye from contaminated water. This study is novel as till now, to the best of our knowledge, no work has been reported on MB adsorption using n-LTP as Q5 an adsorbent specifically.

Premise setting for sustainable developing adsorption in environmental remediation using graphitic carbon nitride@agar-derived porous carbon composite

In the adsorption process for wastewater treatment, the adsorbent plays an important role. A composite adsorptive material composed of graphitic carbon nitride and agar-derived porous carbon (CNPC) was fabricated from simple precursors (melamine, thiourea, and agar) and through a facile procedure with different melamine and thiourea ratios. Characterization of CNPC proved a successful formation of a porous structure consisting of mesopores and macropores, wherein CNPC holds distinctive electrochemical (lowered resistance and higher specific capacity) and photochemical properties (lowered bandgap to 2.33 eV) thanks to the combination of graphitic carbon nitride (CN) and agar-derived porous carbon (PC). Inheriting the immanent nature, CNPC was subjected to the adsorption of methylene blue (MB) dye in an aqueous solution. The highest adsorption capacity was 133 mg/g for CNPC-4 which was prepared using a melamine to thiourea ratio of 4:4 – equivalent to the removal rate of 53.2 % and following the pseudo-I-order reaction rate. The effect of pH points out that pH 7 and 9 were susceptible to maximum removal and pretreatment is not required while the optimal ratio of 7.5 mg of MB and 30 mg of material was also determined to yield the highest performance. Furthermore, the reusability of the material for three consecutive cycles was evaluated based on two methods pyrolysis at 200 °C and photocatalytic degradation by irradiation under visible light. In general, the photocatalytic regeneration pathway is more ample and efficient than pyrolysis in terms of energy efficiency (saving energy over 10 times) and adsorption capacity stability. As a whole, the construction of accessible regenerative and stable adsorbent could be a venturing step into the sustainable development spearhead for industries.

Theoretical and Experimental Analysis of Hydroxyl and Epoxy Group Effects on Graphene Oxide Properties.

In this study, we analyzed the impact of hydroxyl and epoxy groups on the properties of graphene oxide (GO) for the adsorption of methylene blue (MB) dye from water, addressing the urgent need for effective water purification methods due to industrial pollution. Employing a dual approach, we integrated experimental techniques with theoretical modeling via density functional theory (DFT) to examine the atomic structure of GO and its adsorption capabilities. The methodology encompasses a series of experiments to evaluate the performance of GO in MB dye adsorption under different conditions, including differences in pH, dye concentration, reaction temperature, and contact time, providing a comprehensive view of its effectiveness. Theoretical DFT calculations provide insights into how hydroxyl and epoxy modifications alter the electronic properties of GO, improving adsorption efficiency. The results demonstrate a significant improvement in the dye adsorption capacity of GO, attributed to the interaction between the functional groups and MB molecules. This study not only confirms the potential of GO as a superior adsorbent for water treatment, but also contributes to the optimization of GO-based materials for environmental remediation, highlighting the synergy between experimental observations and theoretical predictions in advances in materials science to improve sustainability.

Investigating the adsorption potential of char derived from waste latex for methylene blue removal

This study presents the adsorption of methylene blue (MB) dye using latex char derived from pyrolysis of latex gloves. The adsorption process was investigated systematically using Response Surface Methodology (RSM) with a Central Composite Design (CCD). The effects of four key variables, namely pH, time, temperature, and adsorbent dosage, were studied using a factorial design enriched with center points and axial points. Experimental data were analyzed using a second-order polynomial regression model to construct a response surface model, which elucidated the relationship between the variables and MB removal efficiency. The study found that the char obtained at 800 °C exhibited the highest adsorption capacity due to its increased carbonization, expanded surface area, and diverse pore structure. Analysis of Variance (ANOVA) confirmed the significance of the quadratic model, with remarkable agreement between predicted and experimental outcomes. Diagnostic plots validated the model's reliability, while 3D contour graphs illustrated the combined effects of variables on MB removal efficiency. Optimization using DoE software identified optimal conditions resulting in a 99% removal efficiency, which closely matched experimental results. Additionally, adsorption isotherms revealed that the Freundlich model best described the adsorption behavior, indicating heterogeneous surface adsorption with multilayer adsorption. This comprehensive study provides valuable insights into the adsorption process of MB dye using latex char, with implications for wastewater treatment and environmental remediation.

Low energy synthesis of crystalline mesoporous aluminosilicate consisting of Na-P1 zeolite derived from coal fly ash

Worldwide every year massive amount of coal fly ash is being generated as by product in the power plants which creates economic, environmental and most importantly health problems. Usually coal fly ash is used in cement production worldwide. At present, in Bangladesh, about 95 % of fly ash remains still unutilized. The alkali activation of fly ash has become a top research topic as it is possible to synthesize low cost and ecologically sound mesoporous zeolite type materials. In the present work, to the best of our knowledge, for the first time in Bangladesh, synthesis and characterization of crystalline mesoporous (H3 type hysteresis) aluminosilicate consisting of Na-P1 zeolite with a high BET specific surface area and a high pore volume from coal fly ash based on hydrothermal alkali activation technique have been successfully done. This product has versatile applications like catalysis, gas separation, water softening, water purification, gas sensing etc. The variable of alkali concentration was studied which has the notable influence on the development of the framework of the pores. The untreated coal fly ash (CFA) and the synthesized modified fly ashes (MFAs) were tested by WDS-XRF, XRD, N2 physisorption, FE-SEM, FT-IR, XPS, EDAX-mapping, particle size analysis and other technologies. The BET specific surface area, total pore volume and average pore diameter of the CFA were only 3 m2/g, 0.01 cc/g and 6.3 nm respectively based on nitrogen gas physisorption technique, whereas, after alkali activation at a specific temperature and time, and then curing, significant and promising increased values of the said parameters of 45 m2/g, 0.11 cc/g and 9.8 nm were obtained respectively. In methylene blue dye adsorption experiment, MFA showed higher adsorption capacity (23.87 mg/g).

Novel Ganga-sand-encapsulated polyaniline granules for effective remediation of textile and pharmaceutical wastewater

ABSTRACT This study presents the use of novel Ganga-sand-encapsulated polyaniline granules for effective remediation of textile and pharmaceutical wastewater. The prepared Ganga-sand-encapsulated polyaniline granules were characterised using scanning electron microscope (morphology) and Fourier transform infrared techniques. The effect of adsorbent dose, contact time, pH and concentration influence on the adsorption performance of Ganga-sand-encapsulated polyaniline granules for the removal of methylene blue dye (textile waste) and doxycycline antibiotic (pharmaceutical waste) was studied. Kinetic and isotherm studies were also carried out to investigate the adsorption process further. The maximum adsorptive removal efficacy of methylene blue and doxycycline was found as 98.2% and 85.1%, respectively, at the optimised condition of adsorbent dose: 8 g/L, time: 120 min, pH: 12 and concentration: 50 ppm. From adsorption kinetics, it was established that the adsorption process followed pseudo-second-order (PSO) rather than pseudo-first-order (PFO). The correlation coefficient values for PFO and PSO models were 0.9012 and 0.9992, respectively, for methylene blue dye adsorption on Ganga-sand-encapsulated polyaniline granules. The adsorption isotherm study established that the adsorption process followed the Langmuir model rather than the Freundlich model. This study found that Ganga-sand-encapsulated polyaniline granules can be a promising adsorbent for textile and pharmaceutical wastewater treatment.

Application of Acid Activated Ouw’s Natural Clay (ONC) on Adsorption of Methylene Blue Dye

The application of natural clay as an adsorbent has been widely used. This is supported by the porous surface texture of the clay. However, some treatments are needed to remove impurities in natural clay before using it as an adsorbent. The common effort is to activate it with acid. This research studied the effect of hydrochloric acid concentration on the adsorption capacity of methylene blue dye. The concentrations of hydrochloric acid used were 2, 3, and 4 M. Characterization was carried out with IR, XRD, and SEM-EDX spectroscopy to see the differences in ONC characters before and after adding hydrochloric acid. The characterization results showed that ONC contained montmorillonite and quartz, and an increase in base distance was directly proportional to the increase in the concentration of hydrochloric acid used. High concentrations of hydrochloric acid caused excessive dealumination and deionization. The dealumination process was supported by IR data where there was a shift in wavenumber in the Al-O stretching vibration region from 796 cm–1 to 794 cm–1; the sharper the vibration in the Si-O region (488-468 cm–1); there was also an increase in the Si/Al ratio of pure ONC from 1.7497 to 2.2970 for 3 M ONC-HCl. The concentration of hydrochloric acid did not significantly affect the capacity of ONC as an adsorbent for methylene blue. The adsorption capacity of pure ONC obtained was 4.97215 mg/g, while for ONC-HCl 3 M was 4.97746 mg/g.

Computational investigations on the performance of transition metal carbide (MXene) for methylene blue dye adsorption and remediation from wastewater

MXenes are receiving a lot of attention as adsorbents for environmental contaminants, due to their distinct characteristics, and the adsorption abilities were toughly influenced by the surface terminal groups. In this research the adsorption ability of free-standing Ti3C2 for methylene blue (MB) dye as a major hazardous contaminant in the watery environment is investigated and compared with the O and OH terminated MXene counterparts using computational material tools. DFT simulations are carried out to explore the structural properties and electronic structures, thermodynamic stability, and adsorption behavior of MB on the considered MXenes surface. The Ti3C2 monolayer is observed to behave as superior adsorbent for MB with strong interaction characteristic which is typical for the chemisorption followed by the Ti3C2(OH)2 and Ti3C2O2 MXenes with hydrogen bonding (strong physisorption) and electrostatics attractions, respectively. Meanwhile the DFTB-MD simulation of MB/MXene in ambient conditions reveals a strong ability of Ti3C2 monolayer in MB adsorption by chemical bond formation between N/C atom of MB and surface Ti atom followed by hydrogen bond formation in MB/Ti3C2(OH)2 system. The superior adsorption behavior of free-standing Ti3C2 monolayer in aqueous solution, make this novel monolayer a promising adsorbent for MB adsorption and removal from watery contaminants. The present findings will be beneficial for the design of suitable nanoadsorbents for remediation of hazardous organic contaminants from wastewater.

Adsorption of methylene blue dye onto phosphoric acid-treated pomegranate peel adsorbent: Kinetic and thermodynamic studies

The orthophosphoric acid-treated pomegranate peels (POPAC) performance was investigated through batch mode for Methylene Blue dye (MB) adsorption from an aqueous solution. Although chemical activation using various chemical agents has been explored by other research work, but novelty application of H3PO4 in a 1:1 wt percentage for activation exhibits unprecedented performance in enhancing the efficiency of MB dye removal. Dependent parameters were optimized, with pH of the sample, contact interval, initial MB concentration, and dose of adsorbent. Excellent removal efficiency (above 92 %) was observed at pH 8 with a dose of 0.25 g/100 mL for 120 min of contact duration. At the qmax value of 14.03 mg/g, the Langmuir isotherm demonstrated the MB dye monolayer adsorption onto POPAC, elucidating the adsorption mechanism with R2 = 0.9883. The kinetics of MB adsorption fit excellently through the pseudo-second-order model with R2 = 0.9997, and the model's estimated adsorption capacity agreed well with the results obtained from the experimental investigation. Thermodynamic parameters, including ΔGᵒ, ΔH°, and ΔS°, additionally demonstrated the spontaneous as well as endothermic adsorption nature of MB on the POPAC’s surface. Furthermore, regeneration studies using 0.1 M NaOH and 0.1 M HCl solutions show adequate MB dye elimination after three cycles. According to the research findings, pomegranate peel may be an inexpensive, environmentally acceptable, and operative biosorbent to eliminate MB dye from polluted aqueous matrices.

Novel mint-stalks derived biochar for the adsorption of methylene blue dye: Effect of operating parameters, adsorption mechanism, kinetics, isotherms, and thermodynamics

The pyrolysis of mint stalks and lemon peels was performed to synthesize mint-stalks (MBC) and lemon-peels (LBC) derived biochars for adsorbing methylene blue (MB). The preparation, characterization, and application of MBC in adsorption have not been reported in the literature. MBC showed higher surface area and carbon content than that of LBC. The removal ratios of MB were 87.5% and 60% within 90 min for MBC and LBC, respectively at pH 7, temperature of 30oC, adsorbent dose of 0.5 g/L, and MB concentration of 5 mg/L. The optimal MBC dose was 1 g/L achieving a removal efficiency of 93.6% at pH 7, temperature of 30oC, contact time of 90 min, and initial dye concentration of 5.0 mg/L. The adsorption efficiency decreased from 98.6% to 31.33% by raising the dye concentration from 3.0 mg/L to 30 mg/L. Further, the increase of adsorbent dose to 10 g/L could achieve 94.2%, 90.3%, 87.6%, and 84.1% removal efficiencies of MB in the case of initial concentrations of 200 mg/L, 300 mg/L, 400 mg/L, and 500 mg/L, respectively. MBC showed high stability in adsorbing MB under five cycles, and the performed analyses after adsorption reaffirmed the stability of MBC. The adsorption mechanism indicated that the adsorption of MB molecules on the biochar's surface was mainly because of the electrostatic interaction, hydrogen bonding, and π-π stacking. Pseudo-second-order and Langmuir models could efficiently describe the adsorption of MB on the prepared biochar. The adsorption process is endothermic and spontaneous based on the adsorption thermodynamics. The proposed adsorption system is promising and can be implemented on a bigger scale. Moreover, the prepared biochar can be implemented in other applications such as photocatalysis, periodate, and persulfate activation-based advanced oxidation processes.

Potential of easily available low-cost raw cotton for the elimination of methylene blue dye from polluted water

This study centered on exploring the adsorptive potential of the raw cotton for methylene blue dye adsorption. Several laboratory experiments conducted to optimize operational factors like pH, concentration of dye, adsorbent dose, contact time, and temperature. Optimized conditions of the study include an adsorbent dose of 0.35 g, pH of 7, an initial dye concentration of 20 ppm with contact time of 30 min at 20 ºC wherein 83% of adsorption take place. The mean values ± standard deviation from triplicate experiments were used to express the results with P < 0.05. The investigational data fit well with the Langmuir isotherm model having R2 of 0.9477 and pseudo second order kinetic model having R2 = 1. The values obtained for adsorption capacities through non-linear models exhibit a significant degree of similarity with those derived from linear models. Thermodynamic study showed a negative ∆G, positive ∆H and increased ∆S values revealing that the reaction was spontaneous and endothermic in nature. The developed method was also tested with tap water which showed 72% of dye removal and subsequent regeneration of the system led to nearly 79% desorption of the dye. Results of the study revealed that additive salts had a minimum effect on the adsorption process. The originality of this study is that no research has been reported till yet, for adsorption of methylene blue by using low-cost raw cotton specifically in its non-modified form.

Development of Maghemite Nanoparticles to Effectively Adsorb Methylene Blue Dye from Water

Development of Maghemite Nanoparticles to Effectively Adsorb Methylene Blue Dye from Water

Fabrication of date palm kernel biochar-sulfur (DPKB-S) for super adsorption of methylene blue dye from water

A novel form of biochar was created by dehydration of Date palm kernel with 85% sulfuric acid. It was examined how the newly produced biochar (DPKB-S) affected the aqueous solution's capacity to extract Methylene Blue (MB) dye. The prepared DPKB-S was categorized by BET, BJH, FT-IR, SEM, EDX, DSC, and TGA analyses. The ideal pH for the MB dye adsorption by DPKB-S is 8. With 0.75 g L−1 of DPKB-S and an initial concentration of 50 ppm MB dye, Date Palm Kernel Biochar-Sulfur (DPKB-S) had the highest removal percentage of 100%. The Langmuir and Freundlich isotherm models were used to investigate the collected data. Freundlich model is the model that best covers MB dye adsorption in DPKB-S at low concentrations (0.75–1.25 g L−1) and the Langmuir model at high concentrations (1.5–1.75 g L−1). The Langmuir model maximum adsorption capacity (Qm) of the DPKB-S was 1512.30 mg g−1. Furthermore, a variety of error function models were applied to investigate the isotherm models derived data, including Marquardt’s percent standard deviation (MPSD), the sum of absolute errors (EABS), the sum of the errors squared (ERRSQ), root mean square errors (RMS), Chi-square error (X2), the average relative error (ARE), average percent errors (APE), and hybrid error function (HYBRID). Kinetic data were calculated by intraparticle diffusion (IPD), pseudo-second-order (PSO), pseudo-first-order (PFO), and film diffusion (FD) models. A PSO rate model with a strong correlation (R2 = 1.00) largely regulated the adsorption rate. The removal mechanism of MB dye by DPKB-S is based on the principle that these positively charged dyes are attracted by electrostatic attraction forces due to the growth in the number of negatively charged regions at basic pH value. According to the results, DPKB-S shows promise as an affordable and competent adsorbent for the adsorption of MB dye. It can be used frequently without experiencing a discernible decrease in adsorption efficiency.

Adsorption of Methylene Blue Dye and Analysis of Two Clays: A Study of Kinetics, Thermodynamics, and Modeling with DFT, MD, and MC Simulations.

The purpose of this research was to learn more about the primary and secondary properties of Moroccan natural clay in an effort to better investigate innovative adsorbents and gain access to an ideal adsorption system. Scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy analysis (SEM-EDX) and X-ray fluorescence were employed for identification. SEM revealed clay grains, including tiny particles and unevenly shaped sticks. First- and second-order rate laws, representing two distinct kinetic models, were applied in the kinetic approach. Adsorption of dye MB onto natural clay was studied, and the results agreed with the 2 s order model. The significant correlation coefficients support the inference that the adsorption process was governed by the Langmuir model. Subsequent DFT analyses demonstrated that the methylene blue dye's HOMO and LUMO surfaces are dispersed across most of the dye's components, pointing to a strong interaction with the clay. To determine how the dye might be adsorbed onto the clay, we employed quantum descriptors to locate its most nucleophilic and electrophilic centers. Endothermic reactions are evident during the MB adsorption process on clay, as indicated by the positive values of ΔH0 and ΔS0 (70.49 kJ mol-1of RC and 84.19 kJ mol-1 of OC and 10.45 J mol-1 K-1 of RC and 12.68 mol-1 K-1 of OC, respectively). Additionally dye molecules on the adsorbent exhibit a higher order of distribution than in the solution, indicating that the adsorption process is spontaneous.

Functionalization of porous silica with graphene oxide and polyethyleneimine, containing zinc copper ferrite nanoparticles for water treatment and antibacterial application

The article discusses the removal of methylene blue (MB) dye, a common cationic dye used in the textile industry, from aqueous solutions through an adsorption process. The use of porous components as adsorbents are shown to facilitate complete separation after the process is completed. The substrate was synthesized by connecting zinc copper ferrite (ZnCuFe2O4), polyethyleneimine (PEI), and Graphene Oxide (GO) sheets to MCM-48, which is a mesoporous material. The surface of MCM-48 was modified using CPTMS, which created an O–Si–Cl bridge, thereby improving the adsorption rate. The substrate was shown to have suitable sites for electrostatic interactions and creating hydrogen bonds with MB. The adsorption process from the Freundlich isotherm (R2 = 0.9224) and the pseudo-second-order diagram (R2 = 0.9927) demonstrates the adsorption of several layers of dye on the heterogeneous surface of the substrate. The synthesized substrate was also shown to have good bactericidal activity against E. coli and S. aureus bacterial strain. Furthermore, the substrate maintained its initial ability to adsorb MB dye for four consecutive cycles. The research resulted that ZnCuFe2O4@MCM-48/PEI-GO substrate has the potential for efficient and economical removal of MB dye from aqueous solutions (R = 88.82%) (qmax = 294.1176 mg. g−1), making it a promising solution for the disposal of harmful industrial waste.

Enhanced Adsorption of Methylene Blue Dye on Functionalized Multi-Walled Carbon Nanotubes.

Carbon nanomaterials are promising adsorbents for dye removal from wastewater also due to their possible surface functionalization that, in principle, can increase the adsorption rate and provide regeneration. To investigate the real advantages of functionalization, we synthesized and characterized through IR, TGA, TEM, XPS and DLS measurements a multi-walled carbon nanotube (MWCNT) derivative bearing benzenesulfonate groups (MWCNT-S). The obtained material demonstrated to have good dispersibility in water and better capability to adsorb methylene blue (MB) compared to the pristine MWCNT adsorbent. Adsorption kinetic studies showed a very fast process, with a constant significantly higher with respect not only to that of the unfunctionalized MWCNT adsorbent but also to those of widely used activated carbons. Moreover, the adsorption capacity of MWCNT-S is more than doubled with respect to that of the insoluble pristine MWCNT adsorbent, thanks to the dispersibility of the derivatives, providing a larger available surface, and to the possible electrostatic interactions between the cationic MB and the anionic sulfonate groups. Additionally, the reversibility of ionic interactions disclosed the possibility to release the adsorbed cationic pollutant through competition with salts, not only regenerating the adsorbent, but also recovering the dye. Indeed, by treating the adsorbed material for 1 h with 1 M NaCl, a regeneration capacity of 75% was obtained, demonstrating the validity of this strategy.

Sustainable adsorption of methylene blue (MB) dye using individual and combined ratios of Trigonella foenum-graecum (F) seed galactomannan and Linum usitatissimum (L) seed

Abstract This study explores the adsorption of methylene blue (MB) dye from aqueous solution using different forms of fenugreek galactomannan and linseed (both individually and in combination) as an adsorbent. Characterization study of adsorbents reveal the involvement of carboxyl, hydroxyl and amine groups in MB adsorption taking place on the amorphous and porous surface of the adsorbent. BET surface area of the adsorbent (F+L) was found to be 394 m2/g. Different parameters including pH, adsorbent dose, adsorbate concentration, adsorption time and temperature were studied. Results of the study shows 86.62, 86.94, 88.04, 88.24, 88.56 and 89.09% of MB dye adsorption with F, L, F + L (1:1), F + L (1:2), F + L (2:1) and F + L (2:2) under optimized conditions. Maximum adsorption take place at pH 12, i.e., highly basic medium. Isothermal study shows the fitness of the experimental data to Langmuir isotherm model. Kinetic modeling shows that both physical and chemical interactions are involved in dye adsorption. Further, thermodynamic study confirms the spontaneity, endothermicity and feasibility of the process. Overall, current research involves the use of low-cost raw material for MB dye removal that aids in waste management and in promoting sustainability.

Engineered biosorbents of pomelo (Citrus maxima (Burm.f.) Merr) peels modified with zinc oxide and titanium dioxide for methylene blue dye sorption

The pomelo-doped zinc oxide beads (PZB), pomelo-doped titanium dioxide beads (PTB), and pomelo-doped zinc oxide and titanium dioxide beads (PZTB) were synthesized for sorbing methylene blue (MB) dye. Their characterizations were explored by X-Ray Diffractometer (XRD), Field Emission Scanning Electron Microscopy and Focus Ion Beam (FESEM-FIB), Energy Dispersive X-Ray Spectrometer (EDX), and Fourier Transform Infrared Spectroscopy (FT-IR). In addition, their sorbent efficiencies for sorbing MB dye were investigated through batch experiments, sorbent reusability studies, sorption isotherms, kinetics, and thermodynamic studies. They were crystalline phases presenting the specific peaks of zinc oxide (ZnO) or titanium dioxide (TiO2). Their surfaces had lamella structures with coarse surfaces, and they also found specific structures of ZnO or TiO2 on the surfaces. Zn–O or Ti–O–Ti was also detected in PZB or PTB or, PZTB depending upon metal oxide types added into pomelo beaded sorbents. For batch experiments, they could adsorb MB dye of more than 86%, and PZTB showed the highest MB dye removal efficiency. In addition, they could be reused for more than three cycles with high MB dye sorptions of more than 72%. They corresponded to Freundlich and pseudo-second-order kinetic models. Moreover, the increasing temperature affected their decreasing MB dye sorptions which were exothermic processes.

V2O5 based nanocomposites with MOF and rGO for the adsorption and photocatalytic degradation of methylene blue dye

In the present work, vanadium pentoxide-metal organic framework (V2O5-MIL 125 MOF) and vanadium pentoxide-reduced graphene oxide (V2O5-rGO) nanocomposites were successfully synthesized using a facile low-temperature hydrothermal treatment. These nanocomposites were used as photocatalysts to study the adsorption capacity and photocatalytic degradation of methylene blue (MB) dye in an aqueous solutions, under dark and UV light conditions. The influence of adsorption on dye removal and its isotherm revealed that both the nanocomposites follow the Freundlich isotherm. The kinetics of adsorption indicated pseudo-second-order behaviour. V2O5-MIL 125 MOF and V2O5-rGO exhibited maximum dye adsorption capacities of 62 and 24 mg/g, respectively. The optimal values for maximum photocatalytic degradation were determined, and the mechanism of degradation was verified using radical scavengers. A 125 W high-pressure mercury vapour light was employed as the light source for all dye degradation studies. Maximum degradation was obtained at neutral conditions (pH 7.4) of the solution, ambient temperature (30±2˚C), and an initial dye concentration of 10 ppm. The synthesized photocatalysts V2O5-MIL 125 MOF and V2O5-rGO exhibited maximum degradation of 87% within 270 min and 82% within 300 min of UV light exposure, respectively. The adsorption and photocatalytic effects of V2O5-MIL 125 MOF and V2O5-rGO were also compared with pure vanadium pentoxide (V2O5), revealing superior activity in both cases.

Comparative study of synthesis methods and pH-dependent adsorption of methylene blue dye on UiO-66 and NH2-UiO-66

Metal-organic frameworks (MOFs) are highly promising adsorbents with notable properties such as elevated adsorption capacities and versatile surface design capabilities. This study introduces two distinct synthesis methods, one lasting 1 h and the other 24 h, for UiO-66 and NH2-UiO-66. While both methods yield structures with comparable crystallinity and morphology, the adsorption performance of the cationic methylene blue dye varies at different pH levels. Despite the 24 h synthesis time being optimal for maximum adsorption in both MOFs, the relative difference in NH2-UiO-66 adsorption percentage at different times suggests reduced dependency on synthesis time for this property. Notably, NH2-UiO-66 exhibits consistent and effective performance across three pH levels, warranting further investigation into its adsorption kinetics and isotherm. The achievement of high adsorption efficiency coupled with a significantly reduced synthesis time underscores the importance of developing simplified synthetic methods, essential for enhancing the practical applicability of MOFs in diverse applications.