Adsorption Of Ionic Dyes Research Articles

Designing pectin and hyperbranched polyethylene imine based hydrogel for the removal and adsorption of ionic dyes

In this study, we developed pectin based hydrogel modified with hyperbranched polyethylene imine integrated with graphene oxide as a filler for the removal of cationic and anionic dyes. Moreover, in this paper, we also studied dynamic adsorption capacity of hydrogel towards crystal violet dye. Graphene oxide was first prepared by the Hummers method. The result in this study illustrated that dynamic adsorption capacity of hydrogels enhanced with increase in GO concentration up to 192 mg g−1 this might be ascribed to the increase in active groups along with porosity created in hydrogel structure. Moreover, the change in parameters such as pH, salt concentration, flux rate and concentration of dye showed promising results. Hence the pectin based hydrogels have great potential for eradication of dyes.

Influence of flake size and electrolyte conditions on graphene oxide adsorption of ionic dyes

Influence of flake size and electrolyte conditions on graphene oxide adsorption of ionic dyes

Adsorption/desorption behavior of ionic dyes on sintered bone char

The aim of this study was to investigate the regularity and differences in the adsorption/desorption behavior of bovine rib char (BC) as an adsorbent material for the cationic Malachite Green (MG) and anionic Sunset Yellow (SY) dyes. The effects of pyrolysis temperature, adsorbent dosage, solution pH, initial concentration, contact time, and adsorption temperature were investigated. The pore characteristics of BC were determined by the Brunauer-Emmett-Teller (BET) method. The changes in functional groups before and after the adsorption of BC were analyzed by Fourier transform infrared spectroscopy. And the chemical composition and surface morphology of BC were characterized by X-ray diffraction and scanning electron microscopy. The experimental data were further analyzed using different isotherm models, kinetic models, and thermodynamic equations, and an understanding of the adsorption studies was carried out. The results show that BC is 90% mesoporous with a BET specific surface area of approximately 150 m2/g. BC is rich in active sites at 700 °C and performs best in the adsorption process. The adsorption of MG increases with increasing pH, while the opposite is true for SY, with optimum pH values of 7 and 3, respectively. Ionic dyes bind to BC easily (the fitted values for the Freundlich model 1/n are all less than 0.5, R2 > 0.748). The maximum adsorption capacity (Qmax) of MG was much higher than that of SY (the Langmuir model indicated Qmax of 1168.4 mg/g and 47.0 mg/g, respectively, R2 > 0.830). The adsorption of ionic dyes on BC was mainly non-homogeneous surface chemisorption, which was spontaneous (ΔG<0, ΔH>0). The desorption of BC after adsorption of MG and SY in HCl and NaOH solutions, respectively, was better. Analysis of the adsorption contribution of the BC fraction showed that the mineral fraction played an important role in the adsorption process (about 94%), while the organic fraction contributed about 6%. The experimental results indicate that the adsorption mechanism of MG and SY on BC can be attributed to the filling of mesopores, electrostatic interaction between the ionic polar sites of BC and the different charged dyes, the formation of chemical bonds between the oxygen-containing functional groups on the surface of BC and the dyes, and the ionic exchange between the polar sites of BC such as Ca2+, PO43−, CO32− and OH−.

Characteristics of 21 Types of Tea Waste for Adsorbance of Ionic Dyes from Aqueous Solutions.

In this study, 21 tea types (six black, four green, three Oolong, two herb, and five medicinal) were used to remove ionic dye from wastewater, as they could be potential adsorbents for several ionic dyes without purification or activated treatment. The majority of the 21 teas could adsorb cationic (MB) and anionic (ORII) dyes, with greater suitability for cationic dyes, as well as BB54 and BR46. Black dye (KBla), a mixture of several dyes, was adsorbed to a high degree. The tea waste treatment resulted in chromaticity reduction of the dye solution and turbidity changes. Dye adsorption was greater at higher temperatures than lower ones, although the effect of temperature was not strong. The adsorptions fit the pseudo-second-order-model; therefore, they involved chemical adsorption. The tea waste had great potential for the adsorption of several types of dyes without purification or activated treatment, although the mechanisms are yet to be determined. Therefore, the physical properties and structural components of each tea type should be analyzed by comparing common or different features of tea types. Taken together, many types of tea that are consumed worldwide can be used for efficient adsorption of ionic dyes by application of the tea waste.

Development of functional nanoporous membranes based on photocleavable columnar liquid crystals – Selective adsorption of ionic dyes

Self-standing polymer membranes with nanopores were prepared by polymerization of a liquid-crystalline (LC) columnar mixture of a taper-shaped molecule having a photocleavable moiety and a lithium salt. The photocleavable moiety, o-nitrobenzyl ester links the dendritic polymerizable hydrophobic part containing vinyl groups and a hydrophilic tri(oxyethylene) chain. The mixture of the taper-shaped molecule and lithium triflate forms a columnar LC phase at a temperature range wider than 50 °C. Self-standing polymer membranes with nanostructures were prepared by acyclic diene metathesis (ADMET) polymerization of the LC mixtures. Ordered anionic nanochannels were formed in the polymer membranes by photocleavage reaction of the linkers between the polymerized hydrophobic part and the non-polymerizable hydrophilic part. The nanoporous membranes showed selective adsorption of cationic organic dyes from their aqueous solutions depending on charges and sizes of the molecules.

Amphoteric Soy Protein-Rich Fibers for Rapid and Selective Adsorption and Desorption of Ionic Dyes.

Uniquely amphoteric soy protein (SP)-rich ultra-fine fibers (231 nm average diameter) have been facilely electrospun from aq. colloids and rendered water-insoluble by heating (150 °C, 12 h) to be highly stable over 14 d (pH 7) as well as under extremely acidic to basic (pH 0–10, 2 d) or at boil (2 h) conditions. The SP-rich fibrous membranes are easily tuned to be charged either negatively by deprotonation above or positively by protonation below the 4.5 PI of SPs. This pH-responsive amphoterism has been demonstrated for rapid adsorption of either cationic or anionic dyes, selective adsorption of either dye from their mixtures, and repetitive adsorption/desorption to recover and reuse both dyes and membranes. Chemisorption and heterogeneous adsorption of ionic dyes was confirmed by close fitting to the pseudo-second-order kinetic model (R2 = 0.9977–0.9999) and Freundlich adsorption isotherm (R2 = 0.9879). This is the first report of water-resilient and pH-robust ultrafine fibrous membranes fabricated from aqueous colloids of neat globular SPs, the major byproducts of under-utilized edible oil and biodiesel. The natural polyampholyte origin, amphoterism, and green processing make these fibrous materials unique and versatile for many potential applications involving both anionic and cationic species.

Electrospun polyacrylonitrile nanofibers functionalized with EDTA for adsorption of ionic dyes

The manipulation of nanofibers’ surface chemistry could enhance their potential application toward the removal of ionic dyes in wastewater. For this purpose, surface modification of electrospun polyacrylonitrile (PAN) nanofibers with ethylenediaminetetraacetic acid (EDTA) and ethylenediamine (EDA) crosslinker was experimented. The functionalized EDTA-EDA-PAN nanofibers were characterized using Fourier transform infrared (FT-IR) spectroscopy, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and Brunauer-Emmett-Teller (BET) technique. The impregnation of EDA and EDTA chelating agents on the surface of PAN changed the distribution of nanofibers as proximity is increased (accompanied by reduced softness), but the nanofibrous structure of the pristine PAN nanofibers was not substantially altered. Adsorption equilibrium studies were performed with Freundlich, Langmuir and Temkin isotherm models with the former providing better correlation to the experimental data. The modified PAN nanofibers showed efficient sorption of methyl orange (MO) and reactive red (RR) from aqueous synthetic samples, evinced by the maximum adsorption capacities (at 25 °C) of 99.15 and 110.0 mg g−1, respectively. The fabricated nanofibers showed appreciable removal efficiency of the target dye sorptives from wastewater. However, the presence of high metal ions content affected the overall extraction of dyes from wastewater due to the depletion of the adsorbent's active adsorptive sites.

Base-catalysed hydrolysis of PIM-1: amide versus carboxylate formation

Controlled hydrolysis of PIM-1 yields polymers tailored for the selective adsorption of ionic dyes.

Chemical Modification on Reactive Dye Adsorption Capacity of Castor Seeds

Abstract: The roles played by four major functional groups (amine, carboxyl, azo, hydroxyl groups) in the biomass of castor seeds in adsorption of seven dyes were investigated. These functional groups in castor seeds were chemically modified individually to determine their contribution to the adsorption of ionic dyes. The dyes used were remazol red B, procino yellow, fast green FCF, brilliant cresyl blue, methylene blue, neutral red, red‐141. It was found that hydroxyl group inhibited the adsorption of anionic dyes but it was major functional group in the adsorption of cationic dyes, hydroxyl group was important functional group in the adsorption of all seven dyes and the effect of methylation of amino group was not significant on the adsorption of seven dyes.

Effect of chemical modification on dye adsorption capacity of peanut hull

In this paper, the roles played by three major functional groups (amino, carboxyl and hydroxyl groups) in the biomass of peanut hull in adsorption of six dyes were investigated. These functional groups in peanut hull were chemically modified individually to determine their contribution to the adsorption of ionic dyes. The dyes used were methylene blue (MB), brilliant cresyl blue (BCB), neutral red (NR), amaranth (Am), sunset yellow (SY) and fast green FCF (FG). It was found that carboxyl group inhibited the adsorption of anionic dyes but it was major functional group in the adsorption of cationic dyes, hydroxyl group was important functional group in the adsorption of all six dyes and the effect of methylation of amino group was not significant on the adsorption of six dyes.

Adsorption de colorants ioniques sur le dechet lainier de carbonisage

Wool carbonizing waste is not used although large amounts are available in the countries where wool is processed. Wool carbonizing waste is made up of two components: the plant particles can be considered as sulfo lignins; the short-size wool fibres have undergone chemical modifications. Owing to its physical structure and to the polar as well as apolar properties of its macromolecules, this waste is liable to adsorb ionic organic solutes. The adsorption of ionic dyes on wool carbonizing waste was therefore investigated so as to evaluate its possible use for the decolourization of dyeing effluents. The effect of the solution-substrate reaction time on the adsorption at various temperatures was studied first. Temperature had a marked effect on the adsorption of the acid dye (AB 80) (Fig. 1) whereas the basic dye (BR 22) (Fig. 2) was characterized by its faster diffusion within the wool carbonizing waste particles. These differences can be ascribed to the higher steric hindrance of the AB 80 molecules and to their possible aggregation. The L-type adsorption isotherms corroborated the temperature effect already mentioned as well as the high affinity of the wool carbonizing waste with acid (Fig. 3) and basic (Fig. 4) dyes. The shape of the adsorption isotherms suggests that the adsorption proceeds through ionic bonding; as the dye molecules are oriented flatwise on the surface of the waste, the dye-substrate hydrophobic interactions can be maximum. The amounts adsorbed were 0.744 mmol g −1 (i.e. 52.5%) for AB 80 at pH 2 and 0.193 mmol g −1 (i.e. 5.5%) for BR 22 at pH 4. Higher amounts of basic dyes might however be expected to be adsorbed since the adsorption maximum is reached at pH 9 in the case of BR 22 (Fig. 5), as a result of the increasingly electronegative charge of the substrate. The Langmuir and Freundlich equations (Table 1) were used to have a mathematical model for the operation of a waste water processing unit. As shown by the L-type adsorption isotherms, the wool carbonizing waste used is suitable for the processing of low concentration effluents, such as dyeing waste waters: the decolourization of synthetic solutions was therefore considred. The column processing of an AB 80 solution showed the effect of the reaction time on the efficiency of the material used (Table 2). Investigation of the processing of a BR 22 solution in a stirred reactor led to the determination of the optimum carbonizing waste concentration (Fig. 6). as well as of the optimum effluent-substrate reaction time and the number of reactors to be used (Fig. 7). Eventually, the adsorptive power of the wool carbonizing waste used was compared with that of various materials (Table 3): the uptake capacity of wool carbonizing waste is lower than or equal to that of other substrates in the case of basic dyes but it is 6–10-fold higher in the case of acid dyes.

Adsorption of ionic dyes on charred plant material

AbstractThe adsorption of ionic dyes on charred plant material was investigated to assess the possible use of this adsorbent for the processing of dyeworks waste waters. The diffusion of the acid dye (AB 80) within the carbon particles was much slower than that of the basic dye (BR 22), as a result of the greater size of the former molecule. The rate of diffusion of the dyes increased with temperature as a result of the disaggregation of the dye molecules. This effect was more pronounced in the case of the acid dye. The L‐shaped adsorption isotherms suggest that the adsorption proceeds through ionic bonding and that the dye molecules are adsorbed flatwise on the surface of the charred plant particles; the substrate‐solute hydrophobic interactions can thus be maximum. The charred plant material used is suitable for the processing of low‐concentration effluents, as corroborated by the treatment of a BR 22 solution in a series of stirred reactors and by the decolourisation of dyebaths containing acid and basic dyes.

The behaviour of dyes at oil/water interfaces

The adsorption of ionic dyes, the builder effect, and the interaction between ionic dyes and surface active agents were investigated by using the electrocapillarity at oil/water interfaces. The oil phase was the solution of tetra-butylammonium chloride, sodium cetylsulphate, cetylpyridinium chloride or stearylamine in methylisobutylketone, and the water phase contained various dyes in addition to the inorganic electrolyte. The interfacial tension decreased over the anodic (or cathodic) polarization range, when anionic (or cationic) dyes were added to the water phase, thus indicating the dye adsorption at the interface. The interfacial excess of dye ions was found to increase linearly with the cubic roots of dye concentration and of ionic strength of the water phase. The counterion binding took place at the oil/water interface between anionic (or cationic) dyes and positive (or negative) head groups of surface active agent ions adsorbed at the interface. It was found that the equilibrium constants of binding between anionic dyes and cationic surface active agents at the oil/water interface were of the same order of magnitude as, and a little larger than, those obtained at the water bulk phase.