Safranine T Research Articles

Persulfate catalyst synthesized with waterworks sludge for degrading Safranine T in the presence of boron

ABSTRACT Energy conservation and emission reduction are the general trend of the present world. In this study, a catalyst of 3WSH based on the waste recycle of waterworks sludge (WS) and Chinese herbs was prepared using one-step calcination treatment and then characterized by SEM, XRD, XPS, FTIR and BET. The catalytic performance of 3WSHB for activating potassium persulfate (PDS) was evaluated through the degradation of Safranine T (ST) in the presence of boron powder (B). The effects of vital parameters on ST removal were systematically studied, including PDS concentration, 3WSHB dosage, initial solution pH, B dosage, temperature and coexisting cations. The highest efficiency of ST removal was up to 93.0% under the optimal condition with 1.85 mM of PDS, 0.3 g/L of 3WSHB, 0.35g/L of B, 7 of pH. EPR and free radical quenching experiments demonstrated that •OH was the dominant reactive oxygen species for ST degradation in the PDS/3WSHB/B system. Moreover, the intermediates determined by HPLC-MS indicated that the oxidization of benzene ring substituents in ST and a hydrogen abstraction by electron transfer might occur during ST degradation. The dissatisfied reuse performance of 3WSHB might be attributed to its low Fe content and simple reusing way. The results demonstrate the effectiveness of WS recycling and reuse in the field of pollutant remediation.

Photoelectrocatalytic Detection and Degradation Studies of a Hazardous Textile Dye Safranin T.

Herein, we report an electrochemical scaffold consisting of functionalized multiwalled carbon nanotubes (COOH-fMWCNTs) and iron-doped zinc oxide nanoparticles (Fe-ZnO) for the detection of a hazardous textile dye safranin T (ST) and monitoring of its photocatalytic degradation. Prior to the detection and degradation analysis, Fe-ZnO NPs were synthesized by the sol-gel method and characterized by a number of structural and morphological techniques. The carboxyl moiety of COOH-fMWCNTs possessing a strong affinity for the amino functionality of ST led to significant enhancement of the current response at the designed electrochemical platform, whereas the electrocatalytic role, surface area enhancement, and the provision of binding sites of Fe-ZnO led to a further increase in the peak current intensity of ST. Electrochemical impedance spectroscopy showed that the sensing scaffold made of the glassy carbon electrode modified with COOH-fMWCNTs and Fe-ZnO efficiently transfers charge between the transducer and the redox probe. Under optimized conditions, the developed sensor showed a 2.3 nM limit of detection for ST. Moreover, recovery experiments and anti-interference tests qualified the sensing platform for practical applications. The dye was photocatalytically degraded using Fe-ZnO NPs up to 99% in 60 min with a rate constant of 0.068 min-1. The designed sensor was used to probe the degradation kinetics of the target dye, and the results were found consistent with the findings obtained from electronic absorption method. To the best of our knowledge, the present work is the first approach for the efficient detection and almost absolute degradation of ST.

One-Step Synthesis of Al-Doped UiO-66 Nanoparticle for Enhanced Removal of Organic Dyes from Wastewater

In this study, a series of Al-doped metal-organic frameworks (AlxZr(1-x)-UiO-66) were synthesized through a one-step solvothermal method. Various characterization techniques, including X-ray diffraction, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, and N2 sorption measurement, suggested that the Al doping was uniform and barely influenced the crystallinity, chemical stability, and thermal stability of the materials. Two cationic dyes, safranine T (ST) and methylene blue (MB), were selected for investigating the adsorption performances of Al-doped UiO-66 materials. Al0.3Zr0.7-UiO-66 exhibited 9.63 and 5.54 times higher adsorption capacities than UiO-66, 498 mg/g and 251 mg/g for ST and MB, respectively. The improved adsorption performance can be attributed to π-π interaction, hydrogen bond, and the coordination between the dye and Al-doped MOF. The pseudo-second-order and Langmuir models explained the adsorption process well, which indicated that the dye adsorption on Al0.3Zr0.7-UiO-66 mostly occurred through chemisorption on homogeneous surfaces. A thermodynamic study indicated the adsorption process was spontaneous and endothermic. The adsorption capacity did not decrease significantly after four cycles.

Plasmon-dependent photophysical preparation of reversible Au@safranine T core-shell nanostructures with edit and erase features

Core-shell materials have superior properties over their single-component counterparts, and thus how to develop a new type of core-shell structure deserves much hard work. Herein, a plasmon-dependent photophysical (PDPP) process was developed to prepare Au@Safranine T core-shell nanostructures with reversible properties, wherein Safranine T (ST) was at first adsorbed on the surface of negatively charged gold nanospheres (AuNSs) through the electrostatic attraction and then controllably deposited by adjusting plasmonic illumination. The whole PDPP process was monitored in real-time via dark field microscopy (DFM) imaging system, verifying that plasmon-dependent light-matter interaction occurs. The as-prepared Au@ST nanostructures were then successfully applied for a reversible process of edit and erase that was suitable for encryption application with nanosized precision. This research showed that the PDPP process has high promise for developing precise structures of new materials, particularly those through nanoprocessing and nanooperation.

Study of kinetic parameters related to dyes oxidation in ascorbic acid-mediated Fenton processes

Ascorbic acid (AA) is a natural reducer that has been used as a prooxidant additive to improve dyes oxidation via Fenton processes (Fe2+/H2O2 and Fe3+/H2O2). In the present work, low concentration of AA (10 μmol L1) enhanced Bismarck Brown Y (BBY), Safranin T (ST), Rhodamine B (RB), and Reactive Black 5 (RB5) decolorizations in solution, mainly in reactions initially containing Fe3+ as a catalyst (Fe3+-reactions), e.g., Fe3+/H2O2 decolorization of RB5 was increased from 54 % to 73 % after 60 min due to added AA. Decolorization increased from 0 up to 60–90 μmol L−1 of added reducer. At higher concentrations, AA did not improve decolorization. The dyes were decolorized below 10 % when incubated with 1 % tert-butanol, indicating that HO• radical is the main oxidant involved in the reactions. The kinetic analysis showed that the 1st- and 2nd-order kinetic models fitted well to both Fe2+- and Fe3+-reaction data. The BMG kinetic model also fitted well to the Fe2+-reactions (with and without AA), along with Fe3+/H2O2/AA. Based on these kinetic models, we verified that reaction rate constants were increased due to added AA. There was a decrease in activation energy (Ea) in decolorizing ST from added AA by varying the reaction temperatures. For example, Ea decreased from 111.6 to 81.8 kJ mol−1 for Fe3+-reactions and from 72.6 to only 69.3 kJ mol−1 for Fe2+-reactions. The AA/H2O2 system was least effective in decolorizing ST since Ea was 130 kJ mol−1. In summary, ascorbic acid decreases the energy barrier to improve Fenton-based ST oxidation.

A new type of calcium-rich biochars derived from spent mushroom substrates and their efficient adsorption properties for cationic dyes.

Adsorption is commonly accepted as a most promising strategy in dye wastewater treatment, and the widespread use of adsorption emphasizes the need to explore low-cost but excellent adsorbents. Herein, a low-cost adsorbent (calcium-rich biochar) was developed, which was directly pyrolyzed from spent mushroom substate without any modification. This study evaluated the potential application of two calcium-rich biochars (GSBC and LSBC) derived from spent substrates of Ganoderma lucidum and Lentinus edodes, respectively. The effects of pyrolysis temperature on the calcium-rich biochars characteristics and their adsorption mechanism for cationic dyes (Malachite Green oxalate (MG) and Safranine T (ST)) were studied systematically. The increase in pyrolysis temperature from 350 to 750 °C led to an increase in both biochar ash, Ca content, and specific surface area, which made high-temperature biochars (GS750 and LS750) the superior adsorbents for cationic dyes. Batch adsorption results showed LS750 was more efficient to adsorb dyes than GS750 attributed to its higher Ca content and larger specific surface area. According to the Langmuir model, LS750 had high adsorption capacities of 9,388.04 and 3,871.48 mg g−1 for Malachite green and ST, respectively. The adsorption mechanism of dye MG could be attributed to pore filling, hydrogen bonding, electrostatic interaction, ion exchange, and π-π stacking, while ST adsorption mainly involved pore filling, electrostatic interaction, ion exchange, and π-π stacking. Attributed to their excellent adsorption performance, cheap source, and good reusability, biochars obtained from SMSs were very promising in dyeing wastewater treatment.

Carboxylato-Pillar[6]arene-Based Fluorescent Indicator Displacement Assays for Caffeine Sensing.

In the present work, we have developed a new indicator displacement system based on pillararene for anionic water-soluble carboxylato pillar [6] arene (WP6) and aromatic fluorescent dye safranine T (ST). A large fluorescence enhancement and colour change of ST were observed after complexation with electron-rich cavity in WP6 because of host-guest twisted intramolecular charge-transfer interactions. The constructed pillararene-indicator displacement system can be applied for caffeine selective detection in water.

Magnetic graphene oxide-containing chitosan‑sodium alginate hydrogel beads for highly efficient and sustainable removal of cationic dyes

Developing recyclable and efficient adsorbents for cationic dyes removal from wastewater is crucial for ensuring green ecology and drinking water safety. Herein, we demonstrated a novel magnetic gel bead adsorbent that was synthesized by employing graphene oxide (GO) modified Fe3O4 as magnetic nanoparticles doped sodium alginate (SA)/chitosan (CS) gel (SA/GO@Fe3O4/CS). The GO@Fe3O4 sample was prepared based on GO by the chemical co-precipitation method, which not only reduced the aggregation of Fe3O4 but also increases the specific surface area of the composite gel beads. The prepared gel beads were used to adsorb methylene blue (MB), neutral red (NR), and safranine T (ST). The experimental results showed that the adsorption capacity of SA/GO@Fe3O4/CS gel beads for MB, NR, and ST reached 21.325 mg/g, 44.654 mg/g and 44.313 mg/g. After five recycles, the removal rates could still reach more than 90% of the original, exhibiting a high recovery rate. Therefore, this paper provides a strategy for the preparation of high efficiency and recyclable cationic dye adsorbents with a large specific surface area.

Converting waste polystyrene foam into new value‐added materials: A large‐capacity scavenger to remove cationic dyes and heavy metals

AbstractWaste white foam, toxic dyes, and metal ions are difficult to degrade in the ecological environment, posing a serious threat to human health and natural beauty, it is of great significance to design a functional material to jointly solve these problems. This study provided a facile approach to convert waste polystyrene foam into a new acid anhydride modified polystyrene adsorbent (PS‐MA) for the dyes and heavy metals removal from aqueous solution. The as‐obtained absorbent was characterized by Fourier transform infrared spectroscopy, thermogravimetry, scanning electron microscopy, energy dispersive spectroscopy, Brunauer Emmett Teller method, and X‐ray photoelectron spectroscopy. Influencing factors are including, pH, dye concentration, contact time and temperature on the adsorption of methylene blue (MB), safranine T (ST), and Cu(II) were systematically studied. Boehm titration showed that the content of surface carboxyl groups reached 4.53 mmol/g. The maximum adsorption capacity had reached 1405.37 mg/g for MB, 2269.33 mg/g for ST, 65.03 mg/g for Cu(II). Moreover, the kinetic data were in good agreement with the pseudo‐second‐order model and closed to adsorption equilibrium at 20 min. After five times of recycling experiments and the application of mixed dye wastewater with salinity, PS‐MA showed excellent stability and removal ability. Abundant efforts revealed a broad application prospect of PS‐MA materials in water remediation.

Synthesis, physicochemical properties and photocatalytic activity of Cu-containing activated carbons prepared from sulfo-resins under visible irradiation

Micro-mesoporous active carbons containing copper ions have been prepared by the pyrolysis of crosslinked styrene/divinylbenzene ion exchange resin with the sulphonic functional groups -SO3H and with the sorbed copper cations. The differentiation of the copper content was obtained by modification with nitric acid of different concentrations (1 M−7 M). The structure of ACs has been studied using nitrogen adsorption–desorption, TG/DTA, cryoporometry DSC, XRD as well as ED-XRF analyses, FTIR and XPS spectroscopy. The selected samples have been tested in the photocatalytic degradation of Safranin T (ST) under visible irradiation.It has been established that pyrolysis results in formation of micro-mesoporous structure which is accessible to molecules of different reagents that favors the processes of adsorption and photocatalysis. The DSC studies proved that the interactions between the molecules exhibiting hydrophilic-hydrophobic character with the surface of ACs are particularly effective, pointing out to the accessibility of pores to the organic molecules with different functionalities. It was found that the presence of the complex mixture of crystal copper-containing phases makes them an effective photocatalyst for water cleaning.

Study on removal of organic dyes by Fe3O4/amidation modified waste polystyrene composites

Design and fabrication of structurally optimized absorbents are important for wastewater treatment such as dyes removal. Herein, modifying the environmentally harmful waste polystyrene foam as an efficient recyclable adsorbent for organic dyes is important Magnetic amidated modified polystyrene (Fe 3 O 4 /PS-SD) was prepared by Friedel–Crafts reaction, N,N”-dicyclohexylcarbodiimide (DCC) dehydration condensation, and chemical co-precipitation reaction. Fe 3 O 4 /PS-SD had highly efficient removing performance for organic dyes in large volume of water sample solutions, and the equilibrium was achieved in 0.5 h. The maximum adsorption capacity for Methylene blue (MB), Safranine T (ST), and Congo red (CR) were 620.32 mg g −1 , 679.63 mg g −1 , and 1425.77 mg g −1 , respectively, at room temperature according to the Langmuir adsorption isotherm (R 2 > 0.91). The kinetic data of the three dyes followed pseudo-second-order kinetics. After ten regeneration cycles, the removal rate remained high (> 80%). Experimental results showed that Fe 3 O 4 /PS-SD was an excellent adsorbent for water treatment with high regeneration property and thermal stability. • Modification of waste materials. • High adsorption capacity. • Separable and thermally stable. • Recyclable.

Preparation of Cobalt tungstate nanomaterials and study on sonocatalytic degradation of Safranin t

Cobalt tungstate (CoWO4) nanoparticles were prepared by method of hydrothermal synthesis and regulated via adding different doses of surfactant sodium dodecyl sulfate (SDS). Then, degradation of dye Safranin T (ST) under the ultrasound irradiation utilizing CoWO4 nanoparticles as sonocatalysts was investigated. Through a series of experiments such as ultrasonic degradation methods, the following results were got: Firstly, CoWO4 nanoparticles with different dosage of SDS had good sonocatalytic performance in decomposition of ST. And the degradation rate of ST reached the optimum value of 85.9% under the conditions of CoWO4 with dosage of 0.5 g SDS (CoWO4-0.5), 1.0 g/L CoWO4-0.5, 15 mg/L initial dye concentration and 160 W ultrasonic power in 120 min, followed by the TOC removal rate of 74.57%. Secondly, there was a significant synergistic effect between COWO4-0.5 and ultrasonic (synergy index value was 3.75 for US + COWO4-0.5). Thirdly, the degradation of ST is mainly attributed to the generating of hydroxyl radicals and other reactive oxygen species. And the catalyst decomposes nitrogen atom in the ST molecule to produce NO3– ion. Lastly, CoWO4-0.5 exhibited good stability and reusability in the process of sonocatalytic decomposition after four cycles. With these results, a new research reference might be provided for degradation of organic pollutants.

β-cyclodextrin and magnetic graphene oxide modified porous composite hydrogel as a superabsorbent for adsorption cationic dyes: Adsorption performance, adsorption mechanism and hydrogel column process investigates

The β-cyclodextrin/magnetic graphene oxide (β-CD/MGO) functionalized polyacrylic acid-based porous superabsorbent composite hydrogel adsorbent (β-CD/MGO/PAA) was prepared via simple one-pot polymerization. Fourier transform infrared spectra (FT-IR), Raman spectra (Raman), scanning electron microscopy (SEM), The thermogravimetric analysis (TGA) and vibrating sample magnetometry (VSM) confirmed the successfully synthesized of β-CD/MGO/PAA hydrogel. This hydrogel as-prepared combined the advantages of β-cyclodextrin, magnetic graphene oxide and polyacrylic acid, owned exceedingly plentiful carboxyl and hydroxyl groups, and provide a large number of adsorption active sites. β-CD/MGO/PAA hydrogel adsorption performance test showed excellent removal efficiency for 50 mg/L of methylene blue (MB), safranine T (ST), rhodamine B (RhB) and malachite green (MG), which were 99.1%, 98.5%, 97.1% and 95.0%, respectively. Furthermore, batch and filtration adsorption experiments towards MB and ST were carried out to investigate the adsorption capacity and mechanisms in detail. Pseudo-first-order, Pseudo-second-order, Intra-particle diffusion and Liquid film diffusion models were used to evaluate the adsorption kinetic data while Langmuir isotherm, Freundlich isotherm and Temkin isotherm models were used to evaluate adsorption equilibrium data. The adsorption capacity of MB and ST at 298 K were as high as 2802.67 mg/g and 1470.33 mg/g, respectively. Meanwhile, β-CD/MGO/PAA hydrogel can effective selectively adsorbed cationic dyes in cationic/anionic mixture dyes solution, and can quickly separate from the aqueous solution under the action of an external magnetic field. Moreover, removal efficiency of MB and ST still were reached 95.0% and 85.0% after eight adsorption–desorption cycles. We found that electrostatic interactions, hydrogen bond interactions, π-π conjugate interactions and host–guest supramolecular interactions existed between β-CD/MGO/PAA hydrogel and cation dyes molecules in adsorption process. Finally, it was demonstrated that the β-CD/MGO/PAA hydrogel was suitable for used as adsorption column packing to rapidly purify wastewater by filtration.

Ethanol amine functionalized electrospun nanofibers membrane for the treatment of dyes polluted wastewater

This study investigated adsorption kinetics, adsorption equilibrium, and adsorption isotherm of three dyes [i.e., methylene blue (MB), rhodamine-B (RB), and safranin T (ST)] onto polyacrylonitrile (PAN) and ethanolamine (EA) grafted PAN nanofibers (NFs) membranes (EA-g-PAN). The membranes were characterized by field emission scanning electron microscopy (FE-SEM), Fourier-transform infrared spectroscopy (FT-IR) spectroscopy, and Brunauer–Emmet–Teller (BET). FE-SEM showed a smooth morphology for the NFs before and after grafting, while FT-IR confirmed EA grafting into the nitrile group of PAN. The grafting percentage with no change in the physical nature of the membrane was 12.18%. The nitrogen adsorption–desorption isotherms for PAN and EA-g-PAN NFs membranes were similar and classified as a Type IV according to the International Union of Pure and Applied Chemistry. The surface area, pore-volume, and pore size of the EA-g-PAN increased to 21.36 m2 g−1, 0.16 cm3 g−1, and 304.93 A, respectively. The pores were cylindrical mesopores with bimodal openings, which means that pores were open at both ends. The adsorption of the MB, RB, and ST dyes onto the PAN and EA-g-PAN NFs membranes leveled off at ~ 60 min. The adsorption kinetics showed good fitting to pseudo-second-order kinetic model and multi-step diffusion process. The order of the dye adsorption was PAN < EA-g-PAN. The data were fitted to Langmuir and Freundlich models. The correlation coefficient (r2) for Langmuir ranged from 0.940 to 0.995, whereas that for Freundlich ranged from 0.941 to 0.998. After adsorption, FTIR only showed hydrogen bonding between the dyes and the membrane. The reusability experiments showed max desorption for MB (94%), RB (92%), and ST (85%). The EA-g-PAN NFs membrane showed potential for the removal of organic pollutants from the environment.

Multifunctional Carbon Dots with Solid–Liquid State Orange Light Emission for Vitamin B12 Sensing, Cellular Imaging, and Red/White Light-Emitting Diodes

In the current research work, safranine T (ST) was chosen to be the guest, and the preparation of carbon dots (CDs) was done by a one-step hydrothermal methodology with citric acid (CA) to be the p...

Electrochemical degradation of safranine T in aqueous solution by Ti/PbO2 electrodes

The electrochemical degradation of safranine T (ST) in aqueous solution was studied. The effects of current density, initial concentration of ST, initial pH values, and Na2SO4 concentration on electrocatalytic degradation of ST in the aqueous solution by Ti/PbO2 electrode were analyzed. The experimental results showed that the electrochemical oxidization reaction of ST fitted a pseudo first order kinetics model. By using the Ti/ PbO2 electrode as the anode, 99.96% of ST can be eliminated at 120 min. It means that the electrochemical degradation of ST in aqueous solution by the Ti/PbO2 electrode was very effective. The optimal reaction conditions were as follows: current density, 40 mA cm−2; initial ST concentration, 100 mg L−1; Na2SO4 concentration, 0.20 mol L−1; initial pH, 6. It can be known from the test of UV–vis and HPLC in the reaction process that the intermediates will be generated, and the possible intermediate structure was studied by HPLC–MS test. However, with the progress of degradation reaction, the intermediates will eventually be oxidized into CO2 and H2O. Cyclic voltammetry and fluorescence experiments proved that ST was indirectly oxidized through the generation of hydroxyl radicals. Under the optimal reaction conditions, the energy required to completely remove ST was 17.92 kWh/m3.

Electrospun lignin-based composite nanofiber membrane as high-performance absorbent for water purification

An alkali lignin/poly (vinyl alcohol) (lignin/PVA) composite nanofiber membrane was fabricated by electrospinning and tested as an adsorbent for efficient Safranine T (ST) adsorption. Effect of lignin/PVA ratios on the morphology and chemical properties of the prepared composite membranes were studied. The influence of initial dye pH, time and temperature on the adsorption performance of composite membranes were investigated, and further evaluated the desorption and recycling behavior. The results showed that strong intermolecular hydrogen bonds were formed between the hydroxyl groups of PVA and lignin. The diameter of fiber displayed decreasing tendency to the increase in lignin content and the carbonization process. The excellent bead-free membranes were produced with the lignin content as high as 50 wt%. Further study found that the adsorption capacity increased with increasing the initial dye pH and temperature. The results of adsorption indicated that the absorption behavior of composite membranes was better consistent with the Langmuir isotherm and pseudo-second-order kinetic models. The adsorbent exhibited the excellent desorption behavior with an optimal desorption time of 4 h and constant recycling performance. Overall, these results indicate that lignin/PVA composite nanofiber membrane can be applied as a cost-efficient absorbent for removal of dyes from wastewater.

Magnetic hollow poly(cyclotriphosphazene-co-4,4′-sulfonyldiphenol)-Fe3O4 hybrid nanocapsules for adsorbing Safranine T and catalytic oxidation of 3,3′,5,5′-tetramethylbenzidine

The development of novel adsorbents with high adsorption capacity and easy recovery property is imperative in the field of wastewater treatment. In this study, a hard template-induced assembly strategy was developed to fabricate the magnetic hollow poly(cyclotriphosphazene-co-4,4′-sulfonyldiphenol)-Fe3O4 (PZS-Fe3O4) hybrid nanocapsules, in which Fe3O4 nanoparticles were well embedded in the cross-linked PZS shell. The resulting samples were well characterized using SEM, TEM, EDS, FT-IR, VSM, XPS, XRD and N2 sorption. Then, using Safranine T (ST) as model dye, the adsorption behavior of as-prepared hollow PZS-Fe3O4 nanocapsules including adsorption kinetics, adsorption isotherms, adsorption mechanism, and recyclability were systematically evaluated and discussed. The results revealed that the magnetic hollow PZS-Fe3O4 nanocapsules own high adsorption capacity towards ST dye and outstanding magnetic separation functionality. The pseudo-second-order kinetic model and the Langmuir model can well describe the experimental data, and the adsorption process is controlled by more than one diffusion step. The interaction between ST dye and hollow PZS-Fe3O4 nanocapsules is ascribed to π-π interaction and electrostatic interaction. The thermodynamic parameters demonstrated that the adsorption processes were physical, endothermic, and spontaneous. Additionally, the magnetic hollow PZS-Fe3O4 nanocapsules also shows excellent peroxidase-like catalytic activity in the oxidation of 3,3′,5,5′-tetramethylbenzidine with H2O2, indirectly confirming the adsorption kinetic results.

Preparation of a Stable Nanoscale Manganese Residue-Derived FeS@Starch-Derived Carbon Composite for the Adsorption of Safranine T.

To develop a novel, low-cost adsorbent with natural material and industrial waste as raw materials, nanoscale manganese residue-derived FeS@starch-derived carbon (MR–FeS@SC) composite was prepared by the carbonization of starch–manganese residue gel. Manganese residue-derived FeS (MR–FeS) and starch-derived carbon (SC) were also prepared as contrasts for comparative studies. The MR–FeS@SC nanocomposite exhibited relatively large specific surface area and micropore volume, appropriate pore size, abundant functional groups, strong interaction between the functional groups of SC and MR–FeS, and the immobilization and uniform distribution of MR–FeS nanoparticles onto SC support material, which contributed to better adsorption properties for the removal of Safranine T (ST) from the aqueous solution compared with those of MR–FeS and SC. The adsorption could be conducted at a wide range of pH and temperature to achieve a satisfy removal efficiency of ST with MR–FeS@SC nanocomposite as adsorbent. The adsorption kinetics well followed the pseudo-second-order model, and the dominant mechanism was chemisorption. The adsorption behavior was well described by the Langmuir isotherm model. Due to the strong interaction between MR–FeS nanoparticles and SC support, MR–FeS@SC nanocomposite exhibited better reusability and stability even after fifteen cycles. This study provides a facile method of preparing effective and stable adsorbents for the treatment of dye wastewater.

Trimellitated sugarcane bagasse: A versatile adsorbent for removal of cationic dyes from aqueous solution. Part II: Batch and continuous adsorption in a bicomponent system

In the second part of this series of studies, the bicomponent adsorption of safranin-T (ST) and auramine-O (AO) on trimellitated sugarcane bagasse (STA) was evaluated using equimolar dye aqueous solutions at two pH values. Bicomponent batch adsorption was investigated as a function of contact time, solution pH and initial concentration of dyes. Bicomponent kinetic data were fitted by the pseudo-first-order and pseudo-second-order models and the competitive model of Corsel. Bicomponent equilibrium data were fitted by the real adsorbed solution theory model. The antagonistic interactions between ST and AO in the adsorption systems studied contributed to obtain values of maximum adsorption capacity in mono- (Qmax,mono) and bicomponent (Qmax,multi) lower than unity (Qmax,multi/Qmax,mono at pH 4.5 for ST of 0.75 and AO of 0.37 and at pH 7 for ST of 0.94 and AO of 0.43). Mono- and bicomponent adsorption of dyes in a fixed-bed column was evaluated at pH 4.5. The breakthrough curves were fitted by the Thomas and Bohart-Adams original models. Desorption of ST in a fixed-bed column was studied. The results obtained from the bicomponent batch and continuous adsorption showed that the presence of ST most affected the AO adsorption than the presence of AO affected the ST adsorption.