Adsorption Of Methylene Blue Dye Research Articles

One-step synthesis of a sustainable carbon material for high performance supercapacitor and dye adsorption applications

The sustainable transformation of bio-waste into usable, material has gained great scientific interest. In this paper, we have presented preparation of an activated carbon material from a natural mushroom (Suillus boletus) and explor its properties for supercapacitor and dye adsorption applications. The produced cell exhibited a single electrode capacitance of ∼247 F g−1 with the energy and power density of ∼35 Wh kg−1 and 1.3 kW kg−1, respectively. The cell worked well for ∼20,000 cycles with ∼30% initial declination in capacitance. Three cells connected in series glowed a 2.0 V LED for ∼1.5 min. Moreover, ultrafast adsorption of methylene blue dye onto the prepared carbon as an adsorbent was recorded with ∼100% removal efficiency in an equilibrium time of three minutes. The performed tests indicate that the mushroom-derived activated carbon has the potential to become a high-performance electrode material for supercapacitors and an adsorbent for real-time wastewater treatment applications.

Assessing cationic dye adsorption mechanisms on MIL-53 (Al) nanostructured MOF materials using quantum chemical and molecular simulations: Toward environmentally sustainable wastewater treatment

The escalating levels of environmental pollutants, particularly cationic dyes, present a significant ecological threat. Cationic dyes such as rhodamine B (RB) and methylene blue (MB) are extensively used in diverse industrial applications and are known to exert detrimental effects on the environment. The focus of this study revolves around comprehensively examining the adsorption mechanisms associated with the binding of cationic dyes, namely, RB and MB, onto pristine and carboxylic acid (CXA)-modified MIL-53 (Al) nanostructures. By employing quantum mechanics and molecular simulations, this research elucidates the molecular-level behavior of materials and dyes during the adsorption process. The findings demonstrate that incorporating CXA groups enhances MIL-53 (Al)'s adsorption capacity for both RB and MB dyes. Furthermore, the simulations unveil that RB and MB dye adsorption onto the unmodified and modified MIL-53 (Al) materials occurs primarily through electrostatic, van der waals interactions, π-π stacking, and hydrogen bonding. Notably, RB dye exhibits superior reactivity and stability compared to MB dye, owing to its higher adsorption energy. This study provides valuable insights into cationic dye adsorption on nanostructured MIL-53 (Al), emphasizing the suitability of CXA-modified MIL-53 (Al) nanostructures for cationic dye removal from contaminated wastewater. The outcomes of this investigation hold the potential for developing cutting-edge technologies exhibiting superior efficiency and effectiveness for removing cationic dyes, thereby contributing to environmental preservation and public health. Ultimately, this study highlights the prospects of leveraging quantum mechanics and molecular simulations to anticipate the behavior of nanostructured materials and optimize their properties for wastewater treatment.

Synthesis of Reduced Graphene Oxide from Cellulose and its Applications for Methylene Blue Adsorption

This paper reports the synthesis and its application to the adsorption of methylene blue dye using graphene-oxide (GO) and reduced graphene-oxide (RGO). Among carbon-based nanomaterials, graphene and its derivatives have received remarkable attention due to their unique thermal, mechanical, and electronic properties and two-dimensional structure. The GO was synthesized by the modified Hummers method (chemical exfoliation) of graphite flake. This reaction produced graphite oxide (GrO) as an intermediate material. The synthesized materials, namely graphite, graphene oxide, and reduced graphene oxide, were characterized by XRD, FTIR, and Raman spectroscopy. These materials were tested to evaluate their adsorption capacity, concentration, contact time, and adsorbent weight on methylene blue, which was analyzed using a UV-vis spectrophotometer. The XRD pattern showed the formation of 2θ peaks at 24° to 26o for graphite, graphene oxide, and reduced graphene oxide, respectively. Furthermore, characterization by FTIR showed the appearance of O-H groups with peaks of 3358 cm-1 and 3342 cm-1 for graphene and reduced graphene oxides. Raman characterization indicated that reduced graphene oxide has a wavelength at the D-band peak of about 1375 cm-1 and the G-band peak reaching 1597 cm-1 with an ID/IG intensity ratio of 0.8. The adsorption test of methylene blue showed that reduced graphene oxide had the best adsorption capacity with an adsorbent, concentration, optimum time, and highest adsorption capacity value of 25 mg, 30 ppm, 45 minutes, and 15.642 mg/g. The adsorption process followed the Langmuir isotherm rule, as evidenced by the R2 value of 0.9881.

Deep insights into kinetics, optimization and thermodynamic estimates of methylene blue adsorption from aqueous solution onto coffee husk (Coffee arabica) activated carbon

In the current study, an attempt was made to synthesize coffee husk (CH) activated carbon by chemical modification approach (sulphuric acid-activated CH (SACH) activated carbon) and was used as a valuable and economical sorbent for plausible remediation of Methylene blue (MB) dye. Batch mode trials were carried out by carefully varying the batch experimental variables: SACH activated carbon (SACH AC) dosage, pH, initial dye concentration, temperature, and contact time. The optimum equilibrium time for adsorption by SACH activated carbon was obtained as 60 min, and the maximum adsorption took place at 30 °C. Morphological and elemental composition, crystallinity behaviour, functional groups, and thermal stability were examined using SEM with EDX, XRD, FTIR, BET, TGA, and DTA and these tests showed successful production of activated carbon. The outcomes showed that chemical activation enhanced the number of pores and roughness which possibly maximized the adsorptive potential of coffee husk. The Box-Benken design (BBD) was used to optimize the MB dye adsorption studies and 99.48% MB dye removed at SACH AC dosage of 4.83 g/L at 30 °C for 60 min and pH 8.12, and the maximum adsorption was yielded for sulphuric acid-activated coffee husk carbon carbon with 88.1 mg/g maximum MB adsorption capacity. Langmuir- Freundlich model deliberately provided a better fit to the equilibrium data. The SACH AC-MB dye system kinetics showed a high goodness-of-fit with pseudo second order model, compared to other studied models. Change in Gibbs's free energy (ΔGo) of the system indicated spontaneity whereas low entropy value (ΔSo) suggested that the removal of MB dye on the SACH activated carbon was an enthalpy-driven process. The exothermic nature of the sorption cycle was affirmed by the negative enthalpy value (ΔHo). The adsorptive-desorptive studies reveal that SACH AC could be restored with the maximum adsorption efficiency being conserved after the fifth cycles. Overall, the outcomes revealed that sulphuric acid-activated coffee husk activated carbon (SACH AC) can be used as prompt alternative for low-cost sorbent for treating dye-laden synthetic wastewaters.

Effect of Microwave-Assisted CO2 Pyrolysis on the Production of Activated Carbon from Confiscated Cigarettes

Confiscated cigarettes are a significant problem worldwide, and in Malaysia, the Royal Malaysian Customs Department (RMCD) Perlis had confiscated 1.5 billion sticks of cigarettes from 2016 to 2019 and the cost of disposal reached RM1.2 billion. Confiscated cigarettes are commonly disposed by incineration which can cause environmental pollution. In this study, the cigarette tobacco was converted into activated carbon (AC) via microwave-assisted CO2 pyrolysis. The tobacco was first carbonized at 300℃, followed by carbon dioxide (CO2) activation under microwave heating. The highest yield, 31% was obtained at 616W for 6 min. The BET surface area for tobacco, char and the best AC produced were 1.99, 1.21 and 1.69 m2/g, respectively. Response surface methodology (RSM) of dye removal from AC showed that the optimum condition with the best adsorption properties was achieved at 364 Watt for 2 minutes, which resulted in 87.4% removal of methylene blue (MB). Due to the low surface area, the capability of the AC to adsorb MB dye might be assisted by a diversified factors that contributes to the adsorption mechanism. Modelling of the adsorption data also showed that the adsorption process occurs in multilayers of the adsorbent, best fit to the Freundlich isotherm. Microwave-assisted CO2 pyrolysis shows potential in the production of AC from tobacco and could be further improved to increase the surface area.

Fabrication of engineered biochar-iron oxide from date palm frond for the effective removal of cationic dye from wastewater

Wastewater containing dye is harmful to the environment. Methylene blue (MB) dye can be removed from wastewater using low-cost, renewable adsorbents. In this study, modified biochar (Biochar-FexOy), pristine biochar and FexOy were fabricated, characterized, and investigated for their performance to remove MB dye from wastewater. The Biochar-FexOy (85.1 mg/g) showed increased adsorption capacity in comparison to biochar (60.1 mg/g) and FexOy (50 mg/g) at an optimum pH of 8 due to the increase in surface area, porosity, and deposition of metal ions on its surface for adsorption. The enhanced MB adsorption by the Biochar-FexOy can be attributed to electrostatic attraction, hydrogen bonding, π-π interactions, and possible cationic exchange as evidenced by the result of the FTIR, EDX, and XRD analysis. Moreover, the adsorption of MB dye by the Biochar-FexOy showed an antagonistic effect in the presence of NaHCO3− and NaCl salt but showed a synergistic effect in the presence of Cu (II) ions. The Langmuir and pseudo-second-order isotherm model best describe the adsorption process of MB dye over the Biochar-FexOy. The adsorption capacity was still high after 4 regeneration cycles for the Biochar-FexOy which concludes that modified biochar can be effectively utilized for dye wastewater treatment. Finally, the fixed-bed column adsorption performance demonstrated that Biochar-FexOy could be used to polish real secondary textile industry effluents prior to treatment.

A comprehensive review on adsorption of methylene blue dye using leaf waste as a bio-sorbent: isotherm adsorption, kinetics, and thermodynamics studies.

Water bodies with the dye methylene blue pose serious environmental and health risks to humans. Therefore, the creation and investigation of affordable, potential adsorbents to remove methylene blue dye from water resources as a long-term fix is one focus of the scientific community. Food plants and other carbon-source serve as a hotspot for a wider range of application on different pollutants that impact the environment and living organisms. Here, we reviewed the use of treated and untreated biosorbents made from plant waste leaves for removing the dye methylene blue from aqueous media. After being modified, activated carbon made from various plant leaves improves adsorption performance. The range of activating chemicals, activation methods, and bio-sorbent material characterisation using FTIR analysis, Barunauer-Emmett-Teller (BET) surface area, scanning electron microscope (SEM-EDX), and SEM-EDX have all been covered in this review. It has been thoroughly described how the pH solution of the methylene blue dye compares to the pHPZC of the adsorbent surface. The presentation also includes a thorough analysis of the application of the isotherm model, kinetic model, and thermodynamic parameters. The selectivity of the adsorbent is the main focus of the adsorption kinetics and isotherm models. It has been studied how adsorption occurs, how surface area and pH affect it, and how biomass waste compares to other adsorbents. The use of biomass waste as adsorbents is both environmentally and economically advantageous, and it has been discovered to have exceptional color removal capabilities.

Batch and continuous mode adsorption of methylene blue cationic dye onto synthesized titanium dioxide/polyurethane nanocomposite modified by sodium dodecyl sulfate

In this study, we synthesized and characterized a modified polyurethane (PUF) adsorbent using Sodium Dodecyl Sulfate (SDS) and TiO2-PUF nanocomposite. The adsorption performance of these modified PUF adsorbents was evaluated for the removal of Methylene Blue (MB) dye from wastewater. Optimum values and conditions for the adsorption process were determined based on the maximum dye adsorption (temperature 25 ℃, equilibrium contact time 180 min, adsorbent dose 0.2 g, pH 9 and initial concentration 120 mg/L). The surface-modified PUF adsorbent exhibited significantly enhanced adsorption capacity, increasing from 6.25 to 20.12 mg/g compared to the pure PUF. Langmuir and Freundlich adsorption isotherm models were applied, with the Langmuir model providing the best fit (R2 = 0.99) and a maximum adsorption capacity of 120.48 mg/g of the adsorbent. Thermodynamic studies indicated an exothermic adsorption process, while the pseudo-second-order kinetic model dominated the adsorption kinetics. Continuous experiments at optimized conditions revealed an optimum flow rate of 15 mL/min and a bed height of 2 cm for efficient dye uptake. The adsorbent demonstrated good regeneration and reusability over more than 3 cycles. The modified PUF adsorbent showed great potential for MB dye adsorption. Surface modification significantly improved the adsorption capacity, and the Langmuir model accurately described the adsorption behavior. These findings contribute to our understanding of PUF adsorbents and their applicability for wastewater treatment.

Biosorption of methylene blue by lentil shell on activation with sulfuric acid, formaldehyde, and calcination: kinetic, isotherm, and thermodynamic study

Lentil shell (LS) on modification with sulfuric acid (LSAC), formaldehyde (LSFM), and on calcination (LSCL) were used for the adsorption of methylene blue dye in the present study. The sulfuric acid treated LS adsorbent has shown maximum adsorption. The batch adsorption experiments were studied with the effect of adsorbent dose (10–60 mg), pH (4–10), dye concentration (10–80 mg/L), contact time (10–60 minutes), and temperature (303–333 K). The maximum removal of methylene blue was found at pH 10 with adsorption time 60 minutes. The maximum adsorption capacity is measured for LSAC, LSCL, LSFM, and LS untreated (LSUN) are 49.56, 45.79, 42.24, and 42.09 mg/g respectively for 60 mg adsorbent dose with 60 mg/L of initial methylene blue dye concentration. The biosorbents were characterized with Fourier Transform Infrared spectra, Scanning Electron Microscopy, Transmission Electron Microscopy, BET-N2 adsorption, and Energy Dispersive X-ray analysis. The adsorption isotherm was studied at the temperature of 303, 313, 323, and 333 K. It was found that the higher temperature suitable for maximum adsorption. Langmuir model and Freundlich model were studied from the obtained results for adsorption mechanism. The pseudo second order kinetic model was found suitable for the present adsorption study in comparison with pseudo first order model and intraparticle diffusion model. The data obtained from the present work showed that LS could be employed as an efficient adsorbent for the adsorption of the dye.

Kinetics and adsorption performance of biosorbent starch/poly(vinyl alcohol)/graphene oxide nanocomposite for the removal of dyes

The present work reports an efficient removal of a cationic dye, methylene blue (MB), and an anionic dye, methyl orange (MO) dye from an aqueous solution using graphene oxide (GO)–based nanocomposite as an adsorbent. GO was investigated as a potential nano-reinforcing filler in starch/poly(vinyl alcohol) (PVA) biopolymer matrix. Bio-nanocomposite based on starch/PVA matrix and GO were prepared by an aqueous casting method. The fabricated nanocomposites were characterized using FT-IR, XRD, Raman, TEM, FE-SEM, tensile study, Brunauer–Emmett–Teller (BET) method, Barrett–Joyner–Halenda (BJH) method, zeta potential, and swelling study. The effect of the various compositions of GO nanofiller in the starch/PVA matrix was highlighted and the impact of GO nanosheets on the properties of the nanocomposites was revealed. The results demonstrated that the starch/PVA matrix with 3 g of GO was found to be the optimal concentration of GO. Batch adsorption experiments were conducted to optimize the operational factors, including adsorbent dosage, pH, and contact time, which were systematically investigated. The kinetics of adsorption followed a pseudo-second-order model, while the Langmuir isotherm model described the equilibrium adsorption capacity. The prepared nanocomposite exhibited a maximum monolayer adsorption capacity of 382 mg g−1 for MB dye and 293.3 mg g−1 for MO dye. Based on the calculated thermodynamic parameters for the adsorption of MB (∆H° = − 16.37 kJ mol−1, ∆S° = − 37.99 J K−1 mol−1 and ∆G° from − 4.39 to − 5.13 kJ mol−1) and MO (∆H° = − 13.72 kJ mol−1, ∆S° = − 31.78 J K−1 mol−1 and ∆G° from − 3.72 to − 4.39 kJ mol−1) dyes onto the nanocomposite material was feasible, exothermic, and spontaneous. A plausible adsorption mechanism was proposed, involving electrostatic attraction, H-bonding, and π-π interactions, which collectively governed the adsorption process. The nanocomposite showed good stability and reusability up to five cycles for the uptake of MB and MO dyes. These findings confirmed the effectiveness of the proposed approach to produce bionanocomposite with enhanced properties, which may be used in water purification technology.

Magnetic Fe3O4 nanoparticles loaded guava leaves powder impregnated into calcium alginate hydrogel beads (Fe3O4-GLP@CAB) for efficient removal of methylene blue dye from aqueous environment: Synthesis, characterization, and its adsorption performance

In the present work, a novel Fe3O4-GLP@CAB was successfully synthesized via a co-precipitation procedure and applied for the removal of methylene blue (MB) from aqueous environment. The structural and physicochemical characteristics of the as-prepared materials were explored using a variety of characterization methods, including pHPZC, XRD, VSM, FE-SEM/EDX, BJH/BET, and FTIR. The effects of several experimental factors on the uptake of MB using Fe3O4-GLP@CAB were examined through batch experiments. The highest MB dye removal efficiency of Fe3O4-GLP@CAB was obtained to be 95.2 % at pH 10.0. Adsorption equilibrium isotherm data at different temperatures showed an excellent agreement with the Langmuir model. The adsorption uptake of MB onto Fe3O4-GLP@CAB was determined as 136.7 mg/g at 298 K. The kinetic data were well-fitted by the pseudo-first-order model, indicating that physisorption mainly controlled it. Several thermodynamic variables derived from adsorption data, like as ΔGo, ΔSo, ΔHo, and Ea, accounted for a favourable, spontaneous, exothermic, and physisorption process. Without seeing a substantial decline in adsorptive performance, the Fe3O4-GLP@CAB was employed for five regeneration cycles. Because they can be readily separated from wastewater after treatment, the synthesized Fe3O4-GLP@CAB was thus regarded as a highly recyclable and effective adsorbent for MB dye.

Green synthesis of iron oxide nanoparticles using brown Egyptian propolis extract for evaluation of their antibacterial activity and degradation of dyes

Metal oxide nanoparticles have been widely used in antimicrobial agents, anticancer drugs, wastewater treatment, degradation of harmful organic dyes, and other fields. In this study, iron oxide nanoparticles (IONPs) were synthesized using Brown Egyptian Propolis (BEP) extract as a reducing and stabilizing agent. The synthesized BEP-IONPs were then applied for their antibacterial activity and to remove cationic methylene blue (MB) dye from an aqueous solution. The chemical structural, morphological and optical properties of the synthesized BEP-IONPs were characterized using UV-visible spectroscopy, FTIR, XRD, XPS, SEM, TEM, and EDX. GC-MS analysis was carried out to study the chemical composition of the BEP extract. The BEP-IONPs prepared with a ratio of 1:1 and 1:2 (BEP:FeCl3) were found to be spherical, with average particle sizes of around 87 and 194 nm, respectively. The antibacterial activity was tested on gram-negative and gram-positive bacterial strains, including Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, and Bacillus subtilis. The results showed that the synthesized BEP-IONPs have potent antibacterial activity with a zone of inhibition of 23.5 mm for Pseudomonas aeruginosa gram-negative bacteria, and a high MB dye adsorption capacity of up to 92.7% at 210 min. The kinetics of photocatalytic degradation of MB dye by BEP-IONPs was found to follow pseudo-first-order kinetics, with a constant rate of 0.0178 min-1. Finally, the synthesized BEP-IONPs can be used effectively as antimicrobial agents against human pathogens and as photocatalysts for the removal of harmful organic dyes.

Magnetic Carbon Nanocomposites: Preparation from Cellulose via Chemical Activation with FeCl3 and Characterization

We have studied the preparation of magnetic graphitic carbon composites, which combine the adsorption properties of activated carbon with magnetic properties and properties intrinsic to graphite. The preparation method is efficient; it comprises modifying flax shive cellulose with citric acid to enhance the chelating ability of the flax shive cellulose matrix, impregnating the modified cellulose with iron chloride, and pyrolysis in an inert atmosphere to control the composition, morphology, specific surface, and porosity of hybrid carbon materials. The scenario of cellulose matrix pyrolysis was suggested using thermogravimetry. X-ray structural analysis was used to characterize the graphitic composites. The citric acid modification of cellulose helps to prepare a high-graphite (74%) carbon composite where the graphitization level of the graphite structure approaches the graphitization level of commercially available graphite at 700°С. Low-temperature N2 adsorption–desorption and ζ-potential measurements helped to suggest the adsorption mechanism for environmentally hazardous dyes. The greatest equilibrium adsorption of Methylene Blue (MB) and Methyl Orange (MO) dyes was 127.4 and 23.7 mg/g, respectively. The prepared composites can be used as adsorbents and fillers in polymer composite materials.

Nigella sativa-Manganese Ferrite-Reduced Graphene Oxide-Based Nanomaterial: A Novel Adsorbent for Water Treatment.

In this study, a novel nanohybrid composite was fabricated via the incorporation of manganese ferrite (MnFe2O4) nanoparticles into the integrated surface of reduced graphene oxide (rGO) and black cumin seeds (BC). The nanohybrid composite was prepared by a simple co-precipitation method and characterized by several spectroscopic and microscopic techniques. The characterization analysis revealed that the rGO-BC surface was decorated with the MnFe2O4. The strong chemical interaction (via electrostatic and H-bonding) between the integrated surface of rGO-BC and MnFe2O4 nanoparticles has been reported. The prepared composite was highly porous with a heterogeneous surface. The average size of the prepared composite was reported in the ranges of 2.6-7.0 nm. The specific surface area of the prepared composite was calculated to be 50.3 m2/g with a pore volume of 0.061 cc/g and a half pore width of 8.4 Å. As well, many functional sites on the nanohybrid composite surface were also found. This results in the excellent adsorption properties of nanohybrid composite and the effectual elimination of methylene blue dye from water. The nanohybrid was tested for various linear isotherms, such as Langmuir and Freundlich, for the adsorption of methylene blue dye. The Freundlich isotherm was the well-fitted model, proving the adsorption is multilayer. The maximum Langmuir adsorption capacity of nanohybrid composite for methylene blue was reported to be 74.627 mg/g at 27 °C. The adsorption kinetics followed the pseudo-second-order recommended surface interaction between the dye and nanohybrid composite. The interaction between methylene blue and the nanohybrid composite was also confirmed from the FTIR spectrum of the methylene blue-loaded adsorbent. The rate-determining step for the present study was intraparticle diffusion. Temperature-dependent studies of methylene blue adsorption were also carried out to estimate adsorption's free energy, enthalpy, and entropy. The methylene blue adsorption was feasible, spontaneous, and endothermic. A comparison study revealed that the present materials could be successfully prepared and used for wastewater treatment.

Synthesis of zeolitic imidazole framework‐8 derived ZnCo layered double hydroxides for the removal of methylene blue from wastewater

AbstractThe development of highly efficient and cost‐effective materials for water treatment is paramount and the preparation of metal–organic framework‐derived layer double hydroxide (MOF‐LDH) is an area of great interest. In this study, an innovative adsorbent material zeolitic imidazole framework‐8 (ZIF‐8) derived ZnCo layered double hydroxides was prepared by in situ growth for the adsorption of cationic methylene blue (MB) dye from wastewater. Analytical tools such as FTIR, SEM, and XRD were used to characterize the composite material. Different adsorption parameters like initial dye concentration, pH, temperature, contact time, adsorption mechanisms, and density functional theory (DFT) mechanisms were studied which showed that the derived material significantly enhanced the adsorption capacity which was 502.51 mg/g at pH 11. DFT analyses suggested that MB possessed interaction sites favorable to adsorbent material. The adsorption kinetic model showed that pseudo‐second‐order had a good correlation coefficient (R2 = 0.99983) value proposing the chemisorption adsorption phenomenon. Both the Langmuir and Freundlich isotherm models are well fitted in experimental data as both have good correlation coefficient (R2 = 0.99771) and (R2 = 0.99856) values respectively but the best fit of the adsorption isotherm data was achieved with the Freundlich model, indicating multilayer adsorption characteristics. The experimental and theoretical analyses demonstrated that the fabricated adsorbent is a highly efficient material for the adsorption of organic pollutants from an aqueous medium.

Adsorptive Removal of Dye (Methylene Blue) Organic Pollutant from Water by Pine Tree Leaf Biomass Adsorbent

In this laboratory batch adsorption study, the raw pine tree leaf biomass solid waste adsorbent material was used for the removal of methylene blue (MB) dye from water at different physicochemical process conditions. The characteristics of adsorbents were determined for particle size, surface area, the existence of functional group identification, and the morphology of the adsorbent surface. The adsorption was performed at different process conditions, which include solution pH, dye concentrations, adsorbent doses, and temperature, respectively. In this study, it was found that MB dye adsorption increased with increases in solution pH and adsorbate MB dye concentration but decreased with adsorbent doses and temperature at fixed process conditions. The Langmuir isotherm model was best fitted with the experimental equilibrium data, with a higher linear regression coefficient (R2) value of 99.9% among the two widely used Langmuir and Freundlich adsorption isotherm model equations. The maximum Langmuir monolayer adsorption capacity of raw pine leaf was found to be 36.88 mg/g, which was comparable with other reported adsorbent capacities towards methylene blue (MB) dye adsorption. The value of the separation factor, RL, from the Langmuir isotherm model equation gives an indication of favorable adsorption. Thermodynamic parameters such as standard Gibbs free energy change (ΔG0), standard enthalpy change (ΔH0), and standard entropy change (ΔS0) indicated that the methylene blue (MB) dye adsorption by pine tree leaf biomass was spontaneous and exothermic in nature and that the mechanism of adsorption was mainly physical adsorption. Finally, limitations and future studies are also discussed here. The outcome of this batch adsorption study may result in the valorization of locally available large pine tree leaf residue waste, which could be used in water purification.

Eco-friendly synthesis of a novel adsorbent from sugarcane and high-pressure boiler water

ABSTRACT The development of industrial process in line with the circular economy and the environmental, social and corporate governance (ESG) is the foundation for sustainable economic development. Alternatives that make feasible the transformation of residues in added value products are promising and contribute to the repositioning of the industry towards sustainability, due to financial leverage obtained from lesser operational costs when compared with conventional processes, therefore increasing the company competitivity. In this study, it is presented a promising and innovative technology for the recycling of agro-industrial residues, the sugarcane bagasse and the high-pressure water boiler effluent, in the development of a low-cost adsorbent (HC-T) using the hydrothermal carbonization processes and its application in the adsorption of herbicide Diuron and Methylene Blue dye from synthetic contaminated water. The hydrothermal carbonization was performed in a Teflon contained inside a sealed stainless-steel reactor self-pressurized at 200°C, biomass-to-effluent (m/v) ratio of 1:3 and 24 h. The synthesized material (HC) was activated in an oven at 450°C for 10 min, thus being named adsorbent (HC-T) and characterized by textural, structural and spectroscopic analyses. The low-cost adsorbent HC-T presented an 11-time-fold increase in surface area and ∼40% increase in total pore volume in comparison with the HC material. The kinetic and isotherm adsorption experiment results highlighted that the HC-T was effective as a low-cost adsorbent for the removal of herbicide Diuron and Methylene Blue dye from synthetic contaminated waters, with an adsorption capacity of 35.07 (63.25% removal) and 307.09 mg g−1 (36,47% removal), respectively.

Electrospun cellulose acetate/activated carbon composite modified by EDTA (rC/AC-EDTA) for efficient methylene blue dye removal

The present study fabricated regenerated cellulose nanofiber incorporated with activated carbon and functionalized rC/AC3.7 with EDTA reagent for methylene blue (MB) dye removal. The rC/AC3.7 was fabricated by electrospinning cellulose acetate (CA) with activated carbon (AC) solution followed by deacetylation. FT-IR spectroscopy was applied to prove the chemical structures. In contrast, BET, SEM, TGA and DSC analyses were applied to study the fiber diameter and structure morphology, the thermal properties and the surface properties of rC/AC3.7-EDTA. The CA was successfully deacetylated to give regenerated cellulose nanofiber/activated carbon, and then ethylenediaminetetraacetic acid dianhydride was used to functionalize the fabricated nanofiber composite. The rC/AC3.7-EDTA, rC/AC5.5-EDTA and rC/AC6.7-EDTA were tested for adsorption of MB dye with maximum removal percentages reaching 97.48, 90.44 and 94.17%, respectively. The best circumstances for batch absorption experiments of MB dye on rC/AC3.7-EDTA were pH 7, an adsorbent dose of 2 g/L, and a starting MB dye concentration of 20 mg/L for 180 min of contact time, with a maximum removal percentage of 99.14%. The best-fit isotherm models are Temkin and Hasely. The outcome of isotherm models illustrates the applicability of the Langmuir isotherm model (LIM). The maximal monolayer capacity Qm determined from the linear LIM is 60.61 for 0.5 g/L of rC/AC3.7-EDTA. However, based on the results from error function studies, the generalized isotherm model has the lowest accuracy. The data obtained by the kinetic models’ studies exposed that the absorption system follows the pseudo-second-order kinetic model (PSOM) throughout the absorption period.

Chemically Activated Carbon Synthesized from Rice Husk for Adsorption of Methylene Blue in Polluted Water

Rice husk (RH)-based activated carbons (ACs) were successfully manufactured and used as an adsorbent for the removal of methylene blue (MB) dye from polluted water. ACs were created by impregnating RH char with sodium hydroxide and then activating it for 1 h in a nitrogen environment at various activation temperatures. The characteristics of the obtained ACs were confirmed using Brunauer-Emmett-Teller analysis, scanning electron microscopy, X-ray diffraction analysis, and Fourier-transform infrared spectroscopy. The prepared ACs' pore volume and surface area increased with increasing temperature. The maximum specific surface area of the ACs sample was 729.4 m2/g at 900°C activation temperature. Adsorption was used to remove MB dye from polluted water using the obtained product. The effect of experimental parameters like adsorbent dosage, initial MB dye concentration, contact time, temperature, and pH of the MB dye solution was studied. The synthesized ACs were found to remove 80% of the MB dye under optimal conditions of pH (8), initial concentration (50 mg/L), and contact time (120 min). To represent the fitness of the adsorption data, the Langmuir and Freundlich isotherm models were used. The Langmuir model was found to be the best fit to equilibrium data, with R2 = 0.9972. Similarly, using pseudo first-order and pseudo second-order kinetic models, MB dye adsorption on ACs followed the pseudo-second order with an R2 value of 0.99719. The results show that synthesized RH-based ACs have a high potential for use as an effective adsorbent for removing dye from polluted water.

Porous Geopolymer/ZnTiO3/TiO2 Composite for Adsorption and Photocatalytic Degradation of Methylene Blue Dye.

In this study, GP (geopolymer) and GTA (geopolymer/ZnTiO3/TiO2) geopolymeric materials were prepared from metakaolin (MK) and characterized by X-ray diffraction (XRD), X-ray fluorescence (XRF), scanning electron microscopy (SEM), energy dispersive X-rays (EDX), specific surface area (SSA), and point of zero charge (PZC). The adsorption capacity and photocatalytic activity of the compounds prepared in the form of pellets was determined by degradation of the methylene blue (MB) dye in batch reactors, at pH = 7.0 ± 0.2 and room temperature (20 °C). The results indicate that both compounds are highly efficient at adsorbing MB, with an average efficiency value of 98.5%. The Langmuir isotherm model and the pseudo second order kinetic model provided the best fits to the experimental data for both compounds. In the MB photodegradation experiments under UVB irradiation, GTA reached an efficiency of 93%, being higher than that achieved by GP (4%). Therefore, the incorporation of ZnTiO3/TiO2 in the geopolymeric matrix allowed GTA to achieve higher overall efficiency, by combining adsorption and photocatalysis, compared to the GP compound. The results indicate that the synthesized compounds could be used for up to five consecutive cycles for the removal of MB from wastewater through adsorption and/or photocatalysis processes.