Model Cationic Dye Research Articles

Synthesis and characterization of mesoporous geopolymer based on Moroccan kaolinite rich clay

The aim of this work was the synthesis of a mesoporous geopolymer material based on Moroccan clay rich in kaolinite. For developing the porosity of the geopolymer material, we have followed three different ways to create mesoporosity in the studied material which are; use of Cetyl trimethylammonium bromide (CTAB) organic surfactant, hydrogen peroxide (H2O2) addition to CTAB solution during synthesis and finally no use of CTAB surfactant and H2O2 blowing agent; only optimizing the geopolymerization temperature at 70 °C as well as the formulation ratios: H2O/Na2O = 15, Si/Al = 2 and Na/Al = 1.5. Our started and prepared materials were characterized by X-ray Diffraction (XRD), Fourier Transform Infrared (FTIR), Thermal Gravimetric Analysis (TGA), nitrogen adsorption-desorption isotherm analysis (BET and BJH methods) and Scanning Electron Microscopy (SEM). The prepared materials present a very interesting specific surface area witch reached 128 m2/g and homogeneous mesoporosity equal about 0.14 cm3/g. It has been tested in the retention of methylene blue as cationic dye model. The maximum amount retained was drastically improved from 60 to 183 mg/g.

A significant improvement in adsorption behavior of mesoporous TUD-1 silica through neodymium incorporation

Neodymium was incorporated into the three-dimensional mesoporous siliceous material TUD-1. In order to understand the chemical and morphological structure of the prepared material, several characterization techniques were performed. The characterization results show the formation of highly distributed isolated Nd3+ ions incorporated in the silica matrix in tetrahedrally coordinated structure, moreover no aggregation of separate phase(s) was/were observed. The prepared material was investigated as an adsorbent for methyl green (MG) dye in aqueous solution as a model cationic dye. The results show higher adsorption capacity for Nd-TUD-1 by almost 24 times higher than the neat parent TUD-1 material and more than 100 times higher than bulky Nd2O3 under neutral pH. The adsorption results were fitted perfectly with pseudo-second-order model. Moreover, the adsorption isotherms were perfectly fitted with Freundlich isotherm model which indicates the formation of a multilayer of the dye molecules onto the Nd-TUD-1 surface as a physisorption with endothermic nature.

Application of cellulose nanocrystals prepared from agricultural wastes for synthesis of starch-based hydrogel nanocomposites: Efficient and selective nanoadsorbent for removal of cationic dyes from water

A novel and bio-based hydrogel nanocomposite were developed using reinforcement of starch grafted copolymers of 2-acrylamido-2methyl propane sulfonate and acrylic acid (starch-g-(AMPS-co-AA)) hydrogel with magnetite-functionalized cellulose nanocrystals (MCNCs). The MCNCs-hydrogel was utilized as a proficient and environmentally benign nanoadsorbent for removal of cationic dyes with great capacity and selectivity. Sugar-beet pulp (SBP) was exploited for CNCs production through acid hydrolysis of enzymatic-mediated SBP. Fe3O4 nanoparticles were anchored on CNCs to synthesize MCNCs as the nanofiller of MCNCs/starch-g-(AMPS-co-AA) hydrogel. The synthesis of CNCs, MCNCs and hydrogel nanocomposite were confirmed using FESEM, FTIR, VSM and TGA analyses. Hydrogel nanocomposite showed excellent and reusable capacity for specific adsorption of cationic dyes. The effects of nanoadsorbent dosage, time, pH, dye initial concentration, and temperature on the adsorption were scrutinized for two model cationic dyes (crystal violet (CV) and methylene blue (MB). Adsorption capacities for CV and MB were 2500.0 mg/g and 1428.6 mg/g, respectively.

Removal of methylene blue from aqueous solution using sodium bis (2-ethylhexyl) sulfosuccinate-hexanol reverse micellar system

Textile manufacturing is one of the core industries which discharges a heavy load of chemicals during the dying process. As a result, the release of large contents of dyes through aqueous effluents leads to both environmental and economic concerns. The present study investigates the removal of a model cationic dye, i.e., methylene blue using a reverse micelles system of 1-hexanol as an organic solvent and sodium bis(2-ethylhexyl)sulfosuccinate (AOT) as an anionic surfactant. The influence of different parameters including surfactant concentration, reaction time and dye concentration on extraction performance, was studied. Extraction efficiency was increased with increasing time and surfactant concentration, while it was decreased with the increase in dye concentration. For this system, the optimum extraction condition correspond to surfactant concentration around 0.05M, equilibrium time 20min and dye concentration around 500 ppm, resulting in extraction efficiencies around 99%. The microdomains of water within the reverse micelle system are the driving force for the clarification of methylene blue dye from aqueous solution.

The efficient removal of anionic and cationic dyes from aqueous media using hydroxyethyl starch-based hydrogels

In this study, hydroxyethyl starch (HES)-based hydrogels, hydroxyethyl starch/p(sodium acrylate) (HES/p(NaAAc)), hydroxyethyl starch/p(3-(acrylamidopropyl) trimethyl ammonium chloride) (HES/p(APTMACl)) and hydroxyethyl starch/p(acrylamide) (HES/p(AAm)) were synthesized with redox polymerization. The structural, morphological, and water absorption characterization of the synthesized hydrogels was investigated. HES-based hydrogels, containing anionic, cationic and neutral functional groups, were used for adsorption of methyl violet (MV) as a model cationic dye and methyl orange (MO) as a model anionic dye from aqueous media. HES/p(APTMACl) and HES/p(NaAAc) hydrogels had maximum adsorption values for MO and MV dyes of 238.1 mg/g and 185.2 mg/g. The isotherm and kinetic parameters for both dye adsorptions were determined. The adsorption isotherm and kinetic data were compatible with the Langmuir isotherm and pseudo-first-order kinetic models.

Mesoporous Crosslinked Chitosan-Activated Charcoal Composite for the Removal of Thionine Cationic Dye: Comprehensive Adsorption and Mechanism Study

Chitosan (CS) was coalesced with activated charcoal (AC), followed by crosslinking reaction with epichlorohydrin (ECH) to form a mesoporous crosslinked chitosan–epichlorohydrin/activated charcoal composite (CS-ECH/AC). The structural and physicochemical properties of CS-ECH/AC were characterized by Brunauer–Emmett–Teller, X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, and point-of-zero charge (pHPZC) analyses. CS-ECH/AC was used to remove thionine (TH), a model cationic dye, from aqueous solution. Batch mode adsorption studies were performed by varying operational adsorption parameters, such as adsorbent dosage (0.04–0.30 g), solution pH (3–11), initial TH dye concentrations (10–100 mg/L), and contact time (0–270 min). The equilibrium data was described well by the Freundlich isotherm, and the maximum adsorption capacity of CS-ECH/AC for TH dye adsorption was 60.9 mg/g at 303 K. The kinetic uptake profiles were well described by the pseudo-second-order model. Thermodynamics results indicated a spontaneous and exothermic adsorption process. The proposed adsorption mechanism included mostly electrostatic attractions, H-bonding interactions, and π–π interactions. All these results showed that CS-ECH/AC can be considered as a feasible biocomposite material for the removal of cationic dyes from wastewater.

Visible light-assisted photodegradation by silver tungstate-modified magnetite nanocomposite material for enhanced mineralization of organic water contaminants

The modification of silica-coated magnetite nanoparticles with silver tungstate has been reported to form an effective heterogeneous photo-Fenton catalyst (Fe@AgW) for wastewater treatment. The prepared nanocomposite was analyzed and characterized with the help of SEM, TEM, Powder XRD, BET, UV-DRS, and FT-IR spectroscopy. The nanocatalyst was successfully investigated for mineralization of model cationic and anionic dyes representing industrial effluents pollution and colorless pollutant bisphenol A. The degradation of methylene blue (MB) and methyl orange (MO) was up to 92% and 82%, respectively, using Fe@AgW nanocomposite as a photo-Fenton catalyst. The nanocatalyst was also tested against pathogenic bacterial strains to explore its broad-spectrum use for water treatment. The material owns its desired properties such as economic, high efficiency, simple reaction conditions, and effortless magnetic separation for its potential broad scope applicability in water treatment.

Cost-effective adsorbent from arabinogalactan and pectin of cactus pear peels: Kinetics and thermodynamics studies

Cactus pear peel as agricultural waste containing arabinogalactan and pectin was thermally treated at 300 °C for 4 h and the resultant carbonized material was applied as adsorbent for the removal of methylene blue dye as a model cationic dye. The prepared adsorbent was characterized by means FTIR for structural characterization, N2 physisoprtion measurements for texture properties, SEM and EDAX for morphological and elemental analysis. The characterization results clearly show that the prepared material is porous with several –OH and CO terminals. The point of zero charge was found to be 7 as detected by batch equilibrium method. The adsorption process was optimized in terms of pH values, contact time, initial dye concentration and temperature. The kinetic study indicated that the pseudo-second-order model can perfectly describe the investigated adsorption process; moreover, the equilibrium results were best fitted by Freundlich model. Furthermore, at pH 8.0, the adsorption capacity was achieved to the maximum value of methylene blue as 102 mg/g. Thermodynamic investigation showed that the adsorption process is spontaneous, endothermic in nature with higher entropy, while the activation energy calculations indicated a physisorption process. The obtained results showed the high potential of the bio-based adsorbent for removal of methylene blue from wastewater.

Adsorption of selected dyes on Ti3C2Tx MXene and Al-based metal-organic framework

MXene and metal organic framework (MOF) were used as the main adsorbents to remove synthetic dyes from model wastewater. Methylene blue (MB) and acid blue 80 (AB) were used as the model cationic and anionic synthetic dyes, respectively. To investigate the physicochemical properties of the adsorbents used, we carried out several characterizations using microscopy, powder X-ray diffraction, a porosimetry, and a zeta potential analyzer. The surface area of MXene and MOF was 9 and 630 m2 g−1, respectively, and their respective isoelectric points were approximately pH 3 and 9. Thus, MXene and MOF exhibited high capacity for MB (~140 mg g−1) and AB (~200 mg g−1) adsorption, respectively due to their electrostatic attractions when the concentrations of the adsorbents and adsorbates were 25 and 10 mg L−1. Furthermore, the MOF was able to capture the MB due mainly to hydrophobic interactions. In terms of the advantages of each adsorbent according to our experimental results, MXene exhibited fast kinetics and high selectivity. Meanwhile, the MOF had a high adsorption capacity for both MB and AB. The adsorption mechanisms of both adsorbents for the removal of MB and AB were clearly explained by the results of our analyses of solution pH, ionic strength, and the presence of divalent cation, anion, or humic acids, as well as other characterizations (i.e., Fourier-transform infrared spectroscopy and X-ray photoelectron spectroscopy). According to our results, MOF and MXene can be used as economical treatments for wastewater containing organic pollutants regardless of charge (e.g., MB and AB), and positively charged one (e.g., MB), respectively.

Surface Modified of Cellulose Acetate Electrospun Nanofibers by Polyaniline/β-cyclodextrin Composite for Removal of Cationic Dye from Aqueous Medium

This paper concerns with the enhancement of a safe and clean procedure for remediation of water pollution. Cellulose acetate (CA) nanofibers were prepared via electrospinning technique prior to surface modification with polyaniline/β-cyclodextrin (PANI/β-CD) nanocomposite. Morphology and structure of the modified CA nanofibers were characterized by different analysis like X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and Thermogravimetric analyses (TGA). We studied the influence of modification of CA with PANI/β-CD nanocomposite for removal of cationic dyes from colored aqueous solution in dynamic batch mode. Methylene blue (MB) dye was selected as a cationic dye model for the study. The effects of various parameters like pH, nanosorbent dose, dye concentration and reaction time on the adsorption capacity were studied. Some mathematical isotherm and kinetic models have been utilized to investigate the adsorption mechanism of MB into the CA-PANI/β-CD nanofibers. The reusability of the CA-PANI/β-CD nanofibers was also verified in sequent cycles and rapid process was detected. Different real water samples like tap water, industrial wastewater, municipal wastewater and sea water were applied to test the MB removal efficiency.

Synthesis of a novel gellan-pullulan nanogel and its application in adsorption of cationic dye from aqueous medium

The current study focused on synthesizing a novel gellan-pullulan composite nanogel via chemical crosslinking with DPPH. The physical and rheological properties of the synthesised nanogel was assessed by determining its particle size, zeta potential and effect of temperature and stress on viscosity of nanogels. Furthermore, the novel nanogel was assessed for its ability to ameliorate water resources by efficiently adsorbing cationic dyes. Methylene blue (MB) was used as a model cationic dye compound in the study. The adsorption capacity of nanogels for MB was evaluated by fitting different isotherm models and understanding thermodynamics and kinetics of the process. It was revealed from the overall analysis that nanogels had the property to adsorb MB in multilayer alignment. The gellan-pullulan composite nanogel was found to have better adsorption capability as compared to native gellan nanogel. This is the first report of gellan-pullulan nanogel and its application for cationic dye adsorption.

Study of the interaction between methylene blue dye and quenched polyelectrolyte with tunable hydrophobicity in aqueous media

Polyelectrolytes are used in many industrial applications. In perspective of dye removal from textile effluents, they have been used in coagulation–flocculation and to a lesser extent in polyelectrolyte enhanced ultrafiltration. To optimize the above mentioned process, we need to study in detail the interaction in conditions near to the industry reality of a model cationic dye, methylene blue with new synthesized anionic tricopolyelectrolytes called poly(acrylamide-co-styrene-co-2-acrylamido-2-methylpropane-sodium sulfonate), abbreviated as (AMxSTyAMPSz) and for which the hydrophobicity and the chemical/electrostatic charge fraction can be varied independently. In this context, we investigate by spectrophotometry the effect of several physical-chemical parameters and it was found that (AMxSTyAMPSz) induced metachromasy in the dye, following the appearance of a new blue shifted band with respect to monomer absorption, confirming thus the formation of dye-polyelectrolyte complexes. Their formation results essentially from attractive electrostatic interactions between the two species of opposite sign. More original, the existence of additional hydrophobic interactions between the dye and the tricopolyelectrolyte enhance the stability of the complexes, which is advantageous point of view application.

Filter paper supported nZVI for continuous treatment of simulated dyeing wastewater

In this study, polyacrylic acid modified filter paper (FP/PAA) was synthesized by in-situ polymerization of acrylic acid, which was used as a matrix to chelate nano-scale zero valent iron (nZVI). The loading content of nZVI in the filter paper reached 24.8%. The fabricated composite FP/PAA/nZVI was characterized by SEM, FT-IR and TGA respectively. Moreover, it was used for the removal of methyl blue and methylene blue as model anionic and cationic dyes. The effect of initial dye concentration on decolorization efficiency was investigated. The results showed that FP/PAA/nZVI enhanced the removal of dye from the simulated dye wastewater and the decolorization efficiency exceeded 95% for the dye solutions lower than 20 mg/L. More importantly, the filter paper supported nZVI realized the continuous treatment of simulated dye wastewater by a simple filtration process. This study hopes to serve as a basis for the application of nZVI in textile wastewater treatment.

Cucurbit[7]uril encapsulated dye-sensitized enhanced solar photocatalysis using positively charged sheet-like anatase TiO2 mesocrystals

Abstract Recent progress in the field of advanced oxidation process (AOP) has triggered the use of surface engineered visible light active TiO2 as a competent photocatalyst material in solar photocatalysis. Herein, we adopted host-guest inclusion complexation for the site-directed immobilization of a model cationic dye, Rhodamine B (RhB) on to the surface of oxygen-rich positively charged TiO2, resulting in rapid mineralization of the dye pollutant under solar irradiation. Relatively recent macrocyclic host, cucurbit[7]uril (CB7) is used as the host for the formation of inclusion complex with RhB. In this study, solar photocatalysis of dye encapsulated system results in 97% mineralization of dye molecules within 10 min with an excellent kinetic rate of 351 × 10−3 min−1. Here, the formation of CB7-RhB inclusion complex enables direct anchoring of encapsulated dye molecules through carboxylic (-COOH) groups of RhB, which in turn facilitate heterogeneous electron transfer resulting in instantaneous and direct cleavage of the chromophore. The binding of CB7 encapsulated RhB to microwave-assisted sonochemically synthesized TiO2 (MST) surface via monodentate ester-like linkage was established by XPS and FT-IR analysis. Gas chromatography (GC) and high-resolution mass spectrometry (HR-MS) substantiate the complete mineralization of RhB and the intactness of CB7 molecular structure after photodegradation, confirming the reusability of CB7/MST as an efficient and economically viable photocatalytic system. Encapsulation of pollutant dye to CB7 host proves to be an excellent approach to facilitate the photoelectron transfer to the photocatalyst and faster mineralization of dye molecules under solar irradiation. Thus, our approach would be a feasible solution for environment-friendly remediation of dye pollutants.

As Catalytic as Silver Nanoparticles Anchored to Reduced Graphene Oxide: Fascinating Activity of Imidazolium Based Surface Active Ionic Liquid for Chemical Degradation of Rhodamine B

A kinetic study, first of its kind, regarding the catalytic activity of imidazolium-based surface-active ionic liquid (SAIL) viz. 1-dodecyl-3-methyl imidazolium chloride ([DDMIM][Cl]) toward the reductive degradation of a model cationic dye viz. rhodamine B (RhB) is presented. The catalytic activity of the pre and post micellar concentrations of SAIL [DDMIM][Cl], its conventional analogue surfactant dodecyltrimethylammonium bromide ([DTAB]) and silver (Ag) nano-particles anchored to the reduced graphene oxide (Ag-rGO) toward reductive degradation of RhB was explored. The catalytic activity observed for the [DDMIM][Cl] is much better than that of DTAB and is almost comparable to the activity exhibited by Ag-rGO. The catalytic rate constants (kcat) estimated in presence of pre-micellar concentrations of [DDMIM][Cl] (10 mM), DTAB (12 mM) and in presence of Ag-rGO as catalyst were found to be 11.48 × 10−2 min−1, 3.4 × 10−2 min−1 and 14.35 × 10−2 min−1 respectively. The results clearly establish the fascinating catalytic activity (almost comparable to that exhibited by Ag-rGO) of [DDMIM][Cl] for the reductive degradation of a widely used carcinogenic, mutagenic and toxic organic dye of great environmental concern. The presented results are expected to stimulate intense research activities that may uncover new opportunities toward exploitation of the catalytic activity of aqueous SAIL solutions. Surface active ionic liquid [DDMIM][Cl] is significantly more active than its conventional analogue DTAB and almost as active as Ag-rGO in facilitating the NaBH4 assisted chemical degradation of rhodamine B (RhB)-one of the most carcinogenic, mutagenic and toxic organic dyes.

Grafting of Poly(propylene imine) Dendrimer on Polypropylene Nonwoven: Preparation Optimization, Characterization, and Application

The aim of this study is to prepare a polypropylene nonwoven with the ability to adsorb both anionic and cationic compounds from aqueous media. Polypropylene nonwoven was activated with oxygen plasma and acrylic acid was grafted on it. Then, poly(propylene imine) dendrimer was grafted on it by a pad-dry-cure process. The effect of three parameters on the dendrimer grafting yield was studied and the process was optimized using response surface methodology. The prepared samples were analyzed using ATR-FTIR, FESEM, EDS, AFM, and XPS. The results of different analyses confirmed the grafting of acrylic acid and dendrimer on the surface of the polypropylene nonwoven. The XPS results showed that the sample prepared under the optimal conditions contains both amine and carboxylic acid groups which enables it to interact with various compounds. The ability of acrylic acid grafted and dendrimer grafted samples for removal of model anionic and cationic dyes was studied. The dendrimer grafted sample removed more than 70% and 99% of cationic and anionic dyes from water, respectively.

Effect of drying process and calcination on the structural and magnetic properties of cobalt ferrite

Synthesis of CoFe2O4 nanoparticles was carried out using a co-precipitation method. The resulting precipitate was dried by using conventional method (oven), and spray drying process. The products obtained from the two drying processes were calcined at 500 and 700 °C; and characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM) transmission electron microscopy (TEM), and N2 gas adsorption technique. Magnetic measurements were performed on a SQUID magnetometer. The magnetic saturation value (76 emu g−1) of the spray dried cobalt ferrite calcined at 700 °C (SD-700) was higher than its corresponding oven-dried sample. The as-received spray dried CoFe2O4 nanoplates (SD-100) has the highest BET specific surface area (138 m2 g−1), while the oven-dried sample calcined at 700 °C (OD-700) has the lowest area (47 m2 g−1). Cobalt ferrite samples obtained from the two drying processes were briefly applied to adsorb methylene blue solution as a cationic dye model to know the effect of drying process on the adsorption of dye. The studies showed that all the spray dried samples performed better in adsorbing methylene blue (MB) solution. Energy-filtered TEM (EFTEM) analysis that was carried out on SD-700 ascertained the adsorption of MB on its surface.

Gelatin/alginate composite nanofiber membranes for effective and even adsorption of cationic dyes

Nanofiber membranes from natural alginate are ideal adsorption materials for removing cationic dyes in solution, yet the regulations to their adsorption and desorption properties are of great challenges. In this research, gelatin/calcium alginate (GA) composite nanofiber membranes were successfully prepared via electrospinning to resolve these issues. The structural changes of composite membranes induced by the gelatin addition were confirmed by SEM, FT-IR and BET analysis. The enhanced mechanical strength of GA membranes disclosed the strong interactions between gelatin and alginate chains. Taking methylene blue (MB) as the model cationic dye, it was found the resultant composites could slow down the adsorption rate and obviously improve the adsorption evenness without apparent influences on its adsorption capacity. Moreover, the gelatin modification would generate better reusability for the composite membranes during a serial of adsorption and desorption cycles for strong electrostatic repulsions induced by protonated amino groups in gelatin chains. This effective composite strategy would pave the way for the development of natural alginate to the next generation high-performance adsorbent for cationic dyes.

Solar synthesis of carbon microparticles from polymer waste

Abstract This study reports the obtaining of carbon microspheres through the combined solar pyrolysis and solar physical vapor deposition process of a polypropylene-rich fraction from municipal wastes. A synthesis reactor heated by a 2kW solar furnace (CNRS PROMES solar research facility in Font Romeu, France) has been used for the carbonaceous materials obtaining. The material was characterized in terms of morphology (SEM), chemical composition (EDS) and sorption kinetic behavior towards two model anionic and cationic dyes (methylorange and methylene blue) from aqueous solutions.

Preparation of the Sodium Alginate-g-(Polyacrylic Acid-co-Allyltrimethylammonium Chloride) Polyampholytic Superabsorbent Polymer and Its Dye Adsorption Property.

A polyampholytic superabsorbent polymer (PASAP), sodium alginate-g-(polyacrylic acid-co-allyltrimethylammonium chloride) (SA-g-(PAA-co-PTM)), was prepared by free-radical graft copolymerization and characterized. The polymer exhibited pH-dependent swelling behaviors with extremely high swelling ratios, and was saline tolerant. The dye adsorption properties of SA-g-(PAA-co-PTM) were investigated using methylene blue (MB) as a cationic dye model. It was found that its dye adsorption capacity was significantly affected by the TM content in PASAP and pH of dye solution. The dye adsorption kinetics and isotherm obey the pseudo-second-order kinetic model and the Langmuir isotherm model, respectively, and the adsorption process is chemisorption in nature. In addition, SA-g-(PAA-co-PTM) exhibited high MB adsorption capacities in a wide pH range and reusability in at least five adsorption-desorption cycles, indicating its great application potentials as the adsorbent for dye removals from effluents.