2B Dye Research Articles

Transforming waste to purity: 3D electro-Fenton process boosted with pistachio shell-derived iron-biochar electrode for methyl violet 2B dye catalytic removal

Traditional degradation methods with typical catalysts which have limited negatively charged surfaces are not effectively degrade cationic dyes. A multi-functional iron-biochar was prepared from waste pistachio shells (Fe@PSB) that offers enhanced dye removal due to abundance of negatively charged sites for the degradation of the carcinogenic dye known as methyl violet 2B (MV 2B) in a cutting-edge three-dimensional electrochemical Fenton system (3DEF) with graphite (GP) cathode and Titanium (Ti) anode (3DEF-Ti/GP). Catalytic properties of Fe@PSB were explored for MV 2B dye degradation at broad acidic pH range. At optimum operating conditions of the current of 2.0A, pH 5.0, and Na2SO4 dose of 0.2M, nearly 98.8% of 10mg/L MV 2B dye removal was attained in 60min of electrolysis time. Commercial particle electrodes did not perform as well for the MV 2B dye degradation. The catalytic mechanism of 3DEF-Ti/GP system was investigated by quenching experiments which revealed that the hydroxyl radical (•OH) was responsible for the oxidation of dye molecules. Fe@PSB significantly performed up to four successful cycles. Liquid chromatography-mass spectrometry analysis revealed that de-methylation was the primary degradation pathway. This unique approach not only valorizes agricultural waste but also paving the way for greener environmental solutions.

Nano-synthesis, characterization, theoretical, biological and catalytic studies of Mn(II), Cu(II), Cd(II), and Th(IV) complexes based on antipyrine azo dye ligand

The design and detailed characterization of the azo dye ligand obtained from the reaction of 4-aminoantipyrine diazonium salt with 3-hydroxybenzaldehyde (HL) and its novel metal chelates with Mn2+, Cu2+, Cd2+ and Th4+ ions have been presented. Utilizing modern spectroscopic and analytical techniques, these complexes were found to adopt an octahedral geometry, demonstrate inner sphere d2sp3 hybridization for Th(IV) complex and outer sphere sp3d2 hybridization for other complexes. Particle sizes calculated using the Debye-Scherrer equation on XRD patterns were 32.05 nm for Mn(II), 34.07 nm for Cu(II), 30.90 nm for Cd(II), and 22.05 nm for Th(IV). These substances' anticancer activity was assessed on human lung cancer cells (A-549) and pancreatic carcinoma cell lines (PANC-1). Cd(II) complex exhibited higher cytotoxicity against the A-549 cell line than the reference drug vinblastine sulfate which revealing its potential application as a new anticancer agent. Quantum chemical computations using the DMOL3 module's density functional theory (DFT) and molecular docking studies with the Schrödinger suite demonstrated significant inhibitory effects of the free organic compound and Cu(II) chelate on the FGFR1 protein, crucial for cell development and differentiation. Additionally, the study examined the catalytic activity of HL and its metal chelates in the oxidative degradation of methyl violet 2B dye in presence of H2O2. The order was followed by the pseudo-first-order rate constants: Th(IV) chelate (0.9556 min⁻¹) > HL (0.4911 min⁻¹) > Cu(II) chelate (0.5979 min⁻¹) > Mn(II) chelate (0.2645 min⁻¹) > Cd(II) chelate (0.2280 min⁻¹).

Green synthesis of Fe[sbnd]Ni[sbnd]Sn trimetallic oxides from Moringa oleifera for photocatalytic degradation of Reactive Red 6B dye

The nanocomposite FeNiSn trimetallic oxides were synthesized using an aqueous Moringa Oleifera leaf extract. The prepared nanocomposite was analyzed using SEM, FTIR, XRD, N2 adsorption-desorption, Zeta potential, and UV–vis analysis. A common Azo dye named Reactive Red 6B (RR-6B), widely applied in the dyeing industry and causing environmental pollution, was selected to examine the photodegradation of FeNiSn trimetallic oxides nanocomposite under sunlight irradiation, and it was shown that this dye could be successfully degraded by prepared nanocomposite. Effects of parameters such as inorganic salt concentration, H2O2 concentration, contact time, pH, and impact of different concentrations of catalyst and dye were examined to find out degradation conditions. This prepared nanocomposite was applied for the photodegradation of RR-6B dye, and 95 % degradation efficiency was obtained at pH 4, 10 mg of catalyst concentration, 10 ppm of dye concentration, and contact time of 2 h. Degradation kinetics were carried out using Langmuir-Hinshelwood and first-order reaction models. These results showed a facile technique for forming nanocomposite to efficiently degrade organic contaminants from wastewater, which directly impacts industrial wastewater treatment. The antibacterial activity was performed using the Time assay kill method for Gram-positive S. aureus and Gram-negative E. coli bacteria. The results of antibacterial activity showed an inhibition effect on bacterial growth by trimetallic oxides NPs, suggesting their potential use in antimicrobial coatings and materials. These findings underscore the practical applications of our research, demonstrating its relevance and potential impact in real-world scenarios.

Chitosan-triphosphate/food grade algae/montmorillonite clay for adsorptive removal of methyl violet 2B dye removal: Behnken design optimization

Chitosan-triphosphate/food grade algae/montmorillonite clay for adsorptive removal of methyl violet 2B dye removal: Behnken design optimization

Enhancing methyl violet 2B pollutant removal from wastewater using Al-MOF encapsulated with poly (itaconic acid) grafted crosslinked chitosan composite sponge: Synthesis, characterization, DFT calculation, adsorption optimization via Box-Behnken Design

In this research, aluminum metal-organic framework encapsulated with poly (itaconic acid) grafted crosslinked chitosan composite sponge (Al-MOF@PIC) was prepared. SEM, FTIR, XPS, XRD, and BET techniques were employed to thoroughly characterize the synthesized material and establish its structure and characteristics. The study discovered that the Al-MOF@PIC is an efficient way to remove dyes, which constitute a significant number of contaminants in industrial wastewater. Subsequently the adsorption of methyl violet 2B (MV-2B) dye, the surface area, pore size, and pore volume of the adsorbent decreased from 1860.68 m2/g, 1.62 nm, and 1.52 cc/g to 1426.45 m2/g, 1.11 nm, and 0.92 cc/g, individually. This modification suggested that a portion of the MV-2B dye had been removed by adsorption over the adsorbent's pores. The excellent adsorption capacity of the material was further confirmed by batch adsorption tests, which displayed a maximum adsorption capability of 646.76 mg/g for the elimination of MV-2B dye. The high adsorption energy of 26.8 kJ/mol designates that chemisorption is primarily responsible for MV-2B dye adsorption against the sponge adsorbent. The Al-MOF@PIC composite sponge demonstrated exceptional reusability over six cycles, demonstrating its strength and durability. The Al-MOF@PIC composite sponge successfully removes MV-2B from water by pore filling, π-π stacking, hydrogen bonding, and electrostatic interactions, which are the key mechanisms behind the adsorption of the dye pollutant. Its potential for practical applications is further demonstrated using Box Behnken-design (BBD) to optimize the adsorption consequences.

Pyrolyzed coal base high surface area and mesoporous activated carbon for methyl violet 2B dye removal: Optimization of preparation conditions and adsorption key parameters

Herein, a low-grade Malaysian coal namely Merit Karpit coal (MRTKC) was transformed into high surface area mesoporous activated carbon (MRTKC-AC) via pyrolysis-assisted ZnCl2 activation. A numerical optimization approach rooted in the Box-Behnken design (BBD) was employed to determine the best operational conditions such as A: dosage of MRTKC-AC (ranging from 0.02 to 0.1 g/100 mL), B: the pH of the solution (varying from 4 to 10), and C: the contact time (ranging from 5 to 25 min). A notable surface area of 1229.1 m2/g and a distinctive mesoporous structure with an average pore diameter of 2.9 nm was achieved at optimum impregnation ratio (1 MRTKC: 2 ZnCl2), heating temperature 500 °C, and residence time 60 min. Moreover, the application of MRTKC-AC was evaluated through the removal of methyl violet (MV) from the aqueous environment. The comprehensive equilibrium and kinetic adsorption analyses showed that the adsorption of MV by MRTKC-AC matched closely to the Langmuir isotherm model, while the kinetic behavior was suitably described by the pseudo-second order model. Thus, the maximum adsorption capacity (qmax) for MV dye onto MRTKC-AC was ascertained to be a substantial 238.6 mg/g. The MV dye adsorption mechanism onto MRTKC-AC surface indicates various dye–adsorbent interactions: electrostatic attraction, p–p interaction, and H-bonding. This work shows that Malaysian low-rank coal is an economical precursor for producing low-cost and efficient mesoporous activated carbon with substantive surface area.

Enhancing cationic dye removal via biocomposite formation between chitosan and food grade algae: Optimization of algae loading and adsorption parameters

Herein, a natural material including chitosan (CTS) and algae (food-grade algae, FGA) was exploited to attain a bio-adsorbent (CTS/FGA) for enhanced methyl violet 2B dye removal. A study of the FGA loading into CTS matrix showed that the best mixing ratio between CTS and FGA to be used for the MV 2B removal was 50 %:50 % (CTS/FGA; 50:50 w/w). The present study employed the Box-Behnken design (RSM-BBD) to investigate the impact of three processing factors, namely CTS/FGA-(50:50) dose (0.02–0.1 g/100 mL), pH of solution (4–10), and contact time (5–15 min) on the decolorization rate of MV 2B dye. The results obtained from the equilibrium and kinetic experiments indicate that the adsorption of MV 2B dye on CTS/FGA-(50:50) follows the Langmuir and pseudo-second-order models, respectively. The CTS/FGA exhibits an adsorption capacity of 179.8 mg/g. The characterization of CTS/FGA-(50:50) involves the proposed mechanism of MV 2B adsorption, which primarily encompasses various interactions such as electrostatic forces, n-π stacking, and H-bonding. The present study demonstrates that CTS/FGA-(50:50) synthesized material exhibits a distinctive structure and excellent adsorption properties, thereby providing a viable option for the elimination of toxic cationic dyes from polluted water.

Fabrication of glutaraldehyde crosslinked chitosan/algae biomaterial via hydrothermal process: Statistical optimization and adsorption mechanism for MV 2B dye removal

Fabrication of glutaraldehyde crosslinked chitosan/algae biomaterial via hydrothermal process: Statistical optimization and adsorption mechanism for MV 2B dye removal

Nano‐sized Co(II), Ni(II), and Zr(IV) complexes of quinaldine‐based azo dye for promising therapeutic and catalytic applications: Synthesis, characterization, density functional theory studies and molecular docking

Novel azo dye containing the heterocyclic quinaldine nucleus, 3‐((2‐methylquinolin‐4‐yl)diazenyl)naphthalen‐2‐ol HL, and its Co(II), Ni(II) and Zr(IV) nano‐sized metal chelates have been synthesized and fully characterized by alternative analytical and spectral techniques. The finding indicated that the ligand coordinated as a monobasic bidentate via azo nitrogen and hydroxyl oxygen atom, resulting in octahedral geometry towards Co(II) and Zr(IV) complexes, and square planer geometry towards Ni(II) metal ion. Theoretical studies by DFT/B3LYP/6‐311+G(d,p)/LANLDZ including energetic parameters, geometrical optimization, dipole moment, and HOMO–LUMO energy gap were applied to support the geometrical arrangement of the complexes. The produced complexes were generated at the nanoscale, as evidenced by the average particle size from TEM. The average particle size calculated from TEM images for Co(II), Ni(II), and Zr(IV) complexes is 6.0, 12.0, and 5.5 nm, respectively. The antibacterial activity of the ligand compared with its metal complexes shows enhanced activity over the metal complexes against different types of bacteria. Antitumor efficacy of the compounds was tested against A‐549 and PANC‐1 cells, compared with the vinblastine standard. The cytotoxic efficiency of both Co(II) and Ni(II) complexes exceeded that of vinblastine. The anticancer activity of the Zr complex was then studied using molecular docking to determine the interactions between this molecule and PANC‐1. Docking studies revealed that the Zr complex produces four hydrogen bond contacts with the active amino acid residues Arg 136 and Asp 140, two hydrophobic interactions with Val 50 and Leu 147, and two electrostatic interactions with Arg 136. Also, the catalytic property of the free ligand and nanocomplexes were tested on the oxidative degradation of methyl violet 2B dye in the presence of H2O2. The following arrangement was observed for the pseudo‐first‐order rate constants: Co(II) complex (0.068 min−1) > Ni(II) complex (0.066 min−1) > Zr(IV) complex (0.061 min−1) > HL (0.037 min−1).

Food-grade algae modified Schiff base-chitosan benzaldehyde composite for cationic methyl violet 2B dye removal: RSM statistical parametric optimization

This work aims to apply the use of food-grade algae (FGA) composited with chitosan-benzaldehyde Schiff base biopolymer (CHA-BD) as a new adsorbent (CHA-BA/FGA) for methyl violet 2B (MV 2B) dye removal from aqueous solutions. The effect of three processing variables, including CHA-BA/FGA dosage (0.02–0.1 g/100 mL), pH solution (4–10), and contact duration (10–120 min) on the removal of MV 2B was investigated using the Box-Behnken design (BBD) model. Kinetic and equilibrium dye adsorption profiles reveal that the uptake of MV 2B dye by CHA-BA/FGA is described by the pseudo-second kinetics and the Langmuir models. The thermodynamics of the adsorption process (ΔG°, ΔH°, and ΔS°) reveal spontaneous and favorable adsorption parameters of MV 2B dye onto the CHA-BA/FGA biocomposite at ambient conditions. The CHA-BA/FGA exhibited the maximum ability to absorb MV 2B of 126.51 mg/g (operating conditions: CHA-BA/FGA dose = 0.09 g/100 mL, solution pH = 8.68, and temperature = 25 °C). Various interactions, including H-bonding, electrostatic forces, π-π stacking, and n-π stacking provide an account of the hypothesized mechanism of MV 2B adsorption onto the surface of CHA-BA/FGA. This research reveals that CHA-BA/FGA with its unique biocomposite structure and favorable adsorption properties can be used to remove harmful cationic dyes from wastewater.

Characterization and application of natural Moroccan material for methyl violet 2B dye removal from aqueous solution.

In this paper, a natural Moroccan material from the Nador area in the north east of Morocco was studied as an adsorbent to remove methyl violet 2B dye from aqueous solutions. This material has never been studied before in this region, and it will be used in its raw state. It was collected and characterized by X-ray diffraction, FTIR spectroscopy, scanning electron microscopy, X-ray fluorescence, thermal analysis, N2 gas adsorption-desorption, pHPZC, and Brunauer-Emmett-Teller (BET). The studies are realized with a 500-µm grain size and 182m2/g BET surface area. XRD showed the presence of significant peaks belonging to natural zeolite type clinoptilolite-Ca and minor phases. Several parameters were studied such as contact time, adsorbent mass, initial dye concentration, initial pH solution, the particle size of the material, and temperature. Out of the three isotherm models investigated after 60min of contact time in the experiments, the Langmuir model gave the best fit to the experimental data (R2 = 0.99). The results of kinetic and thermodynamic studies revealed that the adsorption process obeyed pseudo-second-order, spontaneous (ΔG° < 0), endothermic (ΔS° > 0). The adsorption of methyl violet 2B dye is chemisorptions and physisorption. The maximum theoretical adsorption capacity was 30.30mg·g-1 at 23°C for a particle diameter of 500µm. The desorption study shows that the material can be desorbed using solvents. The reuse study indicates that the same amount of natural zeolite can be used several times which makes the process efficient and sustainable. The obtained results indicate that the country of Morocco has natural zeolite among its resources and that it can be used as an efficient adsorbent for the removal of dyes.

Facile synthesis of magnetically separable copper ferrite infused sulfonated graphene oxide nanocomposite with antimicrobial evaluation and photocatalytic performance under visible light

AbstractFacile approach has been employed for the synthesis of new copper ferrite impregnated sulfonated graphene oxide (SGO) nanocomposite via co‐precipitation technique. The newly created nanocomposite has exceptional qualities like a strong stability, large surface area, simple as well as effective recoverability. Structure, composition, and morphology of CuFe2O4@SGO nanocomposite were analyzed by fourier‐transform infrared spectroscopy (FT‐IR), scanning electron microscope (SEM), energy dispersive X‐Ray (EDX), X‐ray diffraction (XRD), and thermogravimetric analysis (TGA) techniques. The results presented the decoration of CuFe2O4 nanoparticles decorated uniformly upon the SGO sheets. Presently, photocatalytic efficiency of synthesized nanocomposite has been assessed for the deterioration of methyl violet 2B (MV) dye. On the effectiveness of dye degradation, the impacts of variables including initial dye concentration, catalyst loading, and visible light exposure have been studied. The photocatalytic data show that 97% of dye was degraded in merely 90 min. CuFe2O4@SGO nanocomposite was easily recyclable and hence it shows future scope as an inexpensive and alternate approach for removal of dye. The results of antimicrobial data evaluated that outstanding antibacterial data counter to Escherichia coli, Bacillus subtilis, and excellent antifungal data counter to Candida albicans was perceived.

Coal-Based Activated Carbon via Microwave-Assisted ZnCl2 Activation for Methyl Violet 2B Dye Removal: Optimization, Desirability Function, and Adsorption Mechanism

In this work, activated carbon (referred to as MCAC) was produced by microwave radiation assisted ZnCl2 activation using Malaysian coal (MC) as a precursor. The Brunauer–Emmett–Teller findings indicate that the MCAC has a relatively large surface area (798.18 m2/g) and a mesoporous structure (average pore diameter of 3.67 nm). The removal of Methylene Violet (MV 2B) a cationic dye model, was employed to investigate the adsorption properties of MCAC. A numerical desirability function in the Box–Behnken design (BBD) was employed to optimize the independent crucial adsorption variables as follows: A: MCAC dose (0.02–0.1 g); B: pH (4–10); and C: time (5–25 min). The results of equilibrium and dynamic adsorption showed that the adsorption of MV 2B followed Freundlich and pseudo-second order models, respectively. The maximum amount of MV 2B dye that the MCAC could adsorb (qmax) was 134.1 mg/g. Electrostatic interactions, π-π stacking, H-bonding, and pore diffusion contribute to the adsorption of MV 2B dye onto the MCAC surface. This study demonstrates the potential to utilize MC as a low-cost precursor for the efficient synthesis of MAC and its utility for the removal of pollutants.

Optimization of Preparation Conditions of Poly(m-phenylene isophthalamide) PMIA Hollow Fiber Nanofiltration Membranes for Dye/Salt Wastewater Treatment.

Externally selective thin film composite (TFC) hollow fiber (HF) nanofiltration membranes (NFMs) hold great industrial application prospects because of their high surface area module. However, the complicated preparation process of the membrane has hindered its mass manufacture and application. In this work, PMIA TFC HF NFMs were successfully prepared by the interfacial polymerization (IP) of piperazine (PIP) with 1,3,5-benzenetricarbonyl trichloride (TMC). The effect of the membrane preparation conditions on their separation performance was systematically investigated. The characterized results showed the successful formation of a polyamide (PA) separation layer on PMIA HF substrates by the IP process. The as-prepared HF NFMs' performance under optimized conditions achieved the highest pure water permeability (18.20 L·m-2·h-1, 0.35 MPa) and superior salt rejection in the order: RNa2SO4 (98.30%) &gt; RMgSO4 (94.60%) &gt; RMgCl2 (61.48%) &gt; RNaCl (19.24%). In addition, the as-prepared PMIA HF TFC NFMs exhibited desirable pressure resistance at various operating bars and Na2SO4 feed concentrations. Excellent separation performance of chromotrope 2B dye was also achieved. The as-prepared PMIA HF NFMs thus show great promise for printing and dyeing wastewater treatment.

Parametric optimization of a hybrid cavitation-based fenton process for the degradation of methyl violet 2B in a packed bed reactor

A unique method for treating wastewater containing a commercial dye (Methyl Violet 2B) has been investigated using a hydrodynamic cavitation-based packed bed reactor (HCPBR) which consists of small glass balls. For the first time, the effects of hydrogen peroxide and iron (II) in HCPBR system were examined. In the current study, the Doehlert matrix-based design was used to optimize variables including solution pH, initial concentration of methyl violet 2B, loading of hydrogen peroxide, and iron. The development of cavity bubbles by glass balls and flow-rate-induced jets is the degrading mechanism used in this reactor. It has been observed that the complete removal of methyl violet 2B was obtained at a Fenton ratio of 0.60 and an acidic pH of 2 based on the optimal variables of the Doehlert matrix. Eventually, the pH of the solution (ranging from 1 to 3) was found to be the most important variable in the effective removal of dye. The total required cost was US $ 0.13/L for the HCPBR system based on glass marbles and US $ 0.11/L for orifice-based hydrodynamic cavitation at an optimized Fenton ratio of 0.60 under the acidic pH of 2. Overall, it was observed that HCPBR system based on glass marbles is an effective and alternative technique for the removal of methyl violet 2B dye based on energy economics and ease of fabrication compared to hydrodynamic cavitation.

Removal of methyl violet 2B dye from aqueous solution by adsorption onto raw and modified carobs (Ceratonia siliqua L.)

&lt;p&gt;In the present study, fruits of Ceratonia siliqua L. (carobs) were used as an alternative low cost biosorbents to remove a cationic dye, methyl violet 2B (MV) which has broad applications in paints, textile and printing ink, from aqueous solutions. The untreated (CRM) and thermal treated carobs (CC) were characterized by BET, FTIR, XRD and SEM techniques. The influences on MV adsorption of various experimental factors such as particle sizes, contact time, stirring speed, adsorbent dose, solution pH, temperature, ionic strength and initial MV concentration were investigated. Adsorption kinetics was found to be best represented by the pseudo second order model. The isotherm analysis indicated that the adsorption data could be represented by the Langmuir model for CRM and CC at 20°C. The maximum adsorption capacity for MV was 62.5 mg/g onto CC and 9.804 mg/g onto CRM. Thermodynamic parameters showed that the process was spontaneous and exothermic.&lt;/p&gt;&#x0D;

Heterogeneous catalytic oxidation of chromotrope 2B with H2O2 and metal complexes supported on aluminum oxide hydroxide as catalyst

AbstractThe heterogeneous catalytic oxidation of Chromotrope 2B (C2B) dye with H2O2 and the aluminum oxide hydroxide (AlOOH) modified with ammonia complexes of CuII, CoII, NiII, and CrIII (AlOOH/[Mn+(amm)m]) as catalysts were studied. The AlOOH/[CuII(amm)4] is the most efficient catalyst and therefore it was chosen as the potential catalyst for the oxidative degradation of C2B in an aqueous solution. The AlOOH/[CuII(amm)4] was characterized by Fourier transform infrared spectroscopy (FTIR), X‐ray diffraction (XRD), scanning electron microscopy (SEM), energy‐dispersive X‐ray (EDX), and transmission electron microscopy (TEM), techniques. The rate of reaction was dependent on the type of the metal complex supported on the AlOOH, initial concentration of the dye and H2O2, catalyst dose, pH, the concentration of NaCl, and temperature. The catalytic activity of the AlOOH/[Mn+(amm)m] according to the kind of metal ion decreased in the order: CuII &gt; CoII &gt; CrIII &gt; NiII. Other catalysts consisting of the AlOOH supported with CuII complexed with ethylenediamine, ethanolamine, 1,3 propanediamine, and 1,4 butanediamine, (AlOOH/[CuII(amine)m]), were also investigated. The activity of the (AlOOH/[CuII(amine)m]) as catalyst according to the type of ligand followed the order: 1,4 butanediamine &gt; 1,3 propanediamine &gt; ethanolamine &gt; ethylenediamine &gt; ammonia. The reaction rate increased with increasing the catalyst dose, concentration of H2O2, C2B, and NaCl, pH, and temperature. Since the reusability results for the AlOOH/[CuII(amm)4] revealed good stability over seven cycles, it can thus be considered a promising and cost‐effective catalyst for the removal of harmful dyes from wastewater.

Experimental Modeling Investigations on the Biosorption of Methyl Violet 2B Dye by the Brown Seaweed Cystoseira tamariscifolia

Methyl violet 2B dye is a major contaminant that is detrimental to both humans and aquatic microorganisms, thus it should be eliminated from water. In the current investigation, the biosorption of methyl violet 2B dye onto the brown seaweed Cystoseira tamariscifolia biomass as a sustainable low-cost biosorbent was examined by varying biosorption parameters. Biomass dosage of 7 g/L, pH 6, a temperature of 45 °C, a 60 min contact time, and a 30 mg/L initial dye concentration were determined to be the optimum biosorption conditions. Data obtained were interpreted by thermodynamic, isothermal, and kinetic models. The thermodynamic studies demonstrated that the process of dye biosorption was random and endothermic. The data were best described by Langmuir, Dubinin–Radushkevich, and Temkin models. According to the Langmuir equation, the maximal biosorption capacity (qmax) was 10.0 mg/g. Moreover, the pseudo-second-order mechanism is dominant, and chemical biosorption might represent the rate-controlling stage in the biosorption process. However, intraparticle diffusion revealed a boundary layer effect. A scanning electron microscope, energy-dispersive X-ray spectroscopy, the point of zero charge, and Fourier Transform Infra-Red were applied to characterize the algal biomass, exhibiting its remarkable structural properties and the availability of several functional groups. Additionally, ion exchange, electrostatic force, and hydrogen bonding formation are all proposed as biosorption mechanisms. As a result, C. tamariscifolia was evaluated to be a sustainable biosorbent for dye biosorption from aqueous solutions.

Magnetic chitosan microspheres for the removal of methyl violet 2B from aqueous solutions

This work aimed to evaluate the adsorption capacity of magnetic chitosan microspheres for the removal of methyl violet (MV) 2B dye. For this purpose, magnetite was prepared by chemical precipitation of iron salts in alkaline medium and incorporated to chitosan microspheres which were obtained by the suspension cross-linking technique. The influence of the experimental parameters, such as adsorbent dosage (0.05 to 0.25 g), stirring frequency (100 to 800 rpm), pH (2.0 to 12.0), initial dye concentration (30 to 90 mg L−1), and contact time (5 to 480 min), as well as the equilibrium, kinetics and thermodynamics were also evaluated. Furthermore, five isotherm models and three kinetic models were tested to analyze the experimental data. The results evidenced that the equilibrium was better described by the Langmuir isotherm (qm = 128.84 mg g−1), although the statistical Fisher's test showed that other models could also be applied to describe the experimental results. Kinetics studies showed that the adsorption followed the pseudo-second order model with a significant difference between the tested models and that the adsorption process involves more than one sorption rate. It was also found that the adsorption of MV 2B dye onto magnetic chitosan microspheres was an exothermic (ΔH°ads = −1.70 kJ mol−1) and spontaneous (ΔG°ads = −3.96 kJ mol−1) process. Finally, it can be concluded that the magnetic chitosan microspheres constituted an efficient and inexpensive material for the removal of the MV 2B dye from aqueous solutions.

Application of pyrrolidinomethylcalix[4]arene coated silica adsorbent for the removal of Chicago sky blue 6B dye from water samples: Equilibrium and computational modelling studies

ABSTRACT In this study, silica surface has been coated using pyrrolidinomethylcalix[4]arene through the chemical modification of silanol groups. The pyrrolidinomethylcalix[4]arene-coated silica (PCS) adsorbent was characterized using the Fourier transform infrared and scanning electron microscopic technique. The adsorptive removal efficiency of PCS adsorbent was checked through batch studies with various effective parameters such adsorbent dose, pH, and temperature. During experiments, it has been observed that maximum adsorption was achieved in acidic to neutral pH and 25 mg.L−1 of PCS dose, while the kinetic models demonstrates that the pseudo 2nd order equation was the best fit (R2 0.99). The thermodynamic experiments described that the reaction is exothermic and spontaneous. Furthermore, equilibrium models were applied on experimental data and it has been noticed that the equilibrium data was best-fitted with Langmuir isotherm model (R2 0.99). The DFT analysis of dye molecule is helpful to examine the chemical interaction sites of absorbent and adsorbent using B3LYP/LANL2DZ/6-311++G (d,p) level using G09W software.