Anionic Dyestuffs Research Articles

Preparation of Cationic Composite Hydrogel Improved by Activated Carbon and Its Use in Removal of Anionic Dye

Water-insoluble p(AETAC)/AC composite hydrogels containing quaternary ammonium were prepared by free-radical polymerisation method with [2-(Acryloyloxy)ethyl]trimethylammonium chloride (AETAC) and activated carbon (AC). The composite hydrogel was characterized by Fourier Transform Infrared Spectroscopy (FT-IR), Thermogravimetric analysis (TGA), X-Ray Diffraction (XRD), and Scanning Electron Microscopy (SEM) methods. In addition, the swelling behavior of p(AETAC)/AC composite hydrogels containing 50 mg, 75 mg, 100 mg, and 150 mg AC in deionized water was investigated. The swelling capacity of the p(AETAC)/AC75 composite hydrogel containing 75 mg AC in various waters was determined. Initial dye concentration, contact time, pH of dye solution, amount of adsorbent, and temperature parameters affecting MO adsorption of p(AETAC)/AC75 composite hydrogel were investigated. The obtained adsorption data agree with the Langmuir isotherm model and the PFO kinetic model. It was determined that the maximum adsorption ability of p(AETAC)/AC75 composite hydrogel according to Langmuir isotherm was 909.09 mg/g. ΔH° and ΔS° values for the adsorption of MO dye-stuff of p(AETAC)/AC75 composite hydrogel were calculated as 22.25 ± 1.43 and 85.40 ± 4.60, respectively. In addition, the value of ΔG° less than zero at four different temperatures indicates that the dye adsorption is spontaneous. According to all the data obtained, p(AETAC)/AC75 composite hydrogel can be considered a promising candidate for the removal of anionic dyestuffs from water.

Efficient removal of refractory dyestuffs from textile wastewater by composite hydrated alumina derived from waste aluminum polishing solution

The present investigation is aimed at fabricating a cheap and efficient adsorbent for the removal of refractory dyestuffs from wastewater. By using waste aluminium polishing solution as the raw material, a composite hydrated alumina (CHA) was successfully prepared and its properties were characterized by the methods of FTIR, SEM, EDS, BET, TGA, and XPS. It was shown that the resulting two-layer adsorbent exhibits a flower-like shape, in which, alumina acts as the core and the surface is modified by phosphate groups and hydrogen bonds in the outer layer. Various functional groups on the surface provide multiple interactions with anionic dyestuffs such as Congo red (CR) and Reactive blue (RB). However, due to the contained N- double bond in the molecular structure in CR, the adsorbent exhibits an especially excellent selectivity and adsorption capacity for the removal of CR, which is caused by the formation of the hydrogen bonds between the hydroxyl groups of CHA and the azo and aromatic rings in CR molecule. The obtained results provide a novel approach to remove refractory organic pollutants from wastewater by using a cheap adsorbent derived from industrial waste.

The use of pomegranate seed activated by mechanochemical process as a novel adsorbent for the removal of anionic dyestuffs: response surface method approach

This study aims to reveal the potential of using pomegranate seed (PS) as an alternative, new and cost-effective adsorbent for the removal of anionic dyestuffs such as Congo Red (CR) and Remazol Brillant Blue R (RBBR) from aqueous solutions. In addition, the PS was activated by a high-energy planetary ball milling. It was seen that the activated PS (APS) has a higher adsorption capacity and mechanical activation has a positive effect on the adsorption process. The effects of experimental factors were evaluated using both conventional univariate methods and multivariate methods such as response surface methodology (RSM) approach. The effects of experimental factors and possible interactions on both dyestuff removal and adsorption capacity were expressed in mathematical equations. The removal efficiencies over 90% were achieved for both dyestuffs at optimum conditions determined by central composite design (CCD). As a result of isothermic, kinetic, and thermodynamic evaluations, the nature of adsorption was best explained by the Temkin isotherm model and the adsorption mechanism was defined as a chemically controlled, exothermic, and spontaneous reaction. The functional groups and the morphological properties of the adsorbent were determined by Fourier transform infrared spectrophotometry (FTIR) and scanning electron microscopy (SEM) in order to explain the possible interactions between adsorbent and adsorbent molecules.

Bio-inspired functionalization of microcrystalline cellulose aerogel with high adsorption performance toward dyes

As one of the materials from natural resources, the functionalization and application of cellulose attract increasing concerns. In this work, we reported a facile method to prepare the bio-inspired functionalization of microcrystalline cellulose (MCC) aerogel through polydopamine (PDA) coating, which was realized via the self-polymerization of dopamine in the MCC/LiBr solution followed by the freeze-drying technology. The morphological characterization showed that the pore morphologies of the compounded aerogel were influenced by the content of PDA. Adsorption measurements toward methylene blue (MB) showed that the compounded aerogel had high adsorption ability. Moreover, the compounded MCC/PDA aerogel exhibited excellent adsorption selectivity and it exhibited high efficiency to remove MB from different solutions, such as the mixed solution with anionic dyestuffs, the mixed solution with cationic dyestuffs and the mixed solution with common salt (NaCl). The high adsorption ability and excellent adsorption selectivity endows the compounded MCC/PDA aerogel with great potential applications in wastewater treatment.

Study on the Influence of Nitrogen Plasma on Dyeing Properties of Rex Rabbit Fibers

The surface of rex rabbit fibers is hydrophobic in nature because of the presence of the hard cuticle on its surface, and this hydrophobicity may give rise to many problems in the dyeing and finishing processes. In order to improve its dyeability and decrease dye pollution in sewage discharge, nitrogen plasma was used to modify rabbit fibers and after that the modified fibers were dyed with the anionic dyestuffs (C.I. number 16185). The effects of nitrogen plasma on the dyeing properties and the dyeing behavior for the rex rabbit fibers were studied, the related parameters including the treatment time and discharge power were optimized. Surface morphology and roughness of rex rabbit fibers were characterized by scanning electron microscope and atomic force microscopy. XPS and FTIR-ATR were further performed to determine the surface chemical compositions of rex rabbit fibers. The physical properties of rex rabbit fibers were characterized by tensile strength tests. The results show that nitrogen plasma treatment can remove surface scales on the rex rabbit fibers and introduce more active groups such as hydroxyl (–OH), carbonyl (–C=O), and amino (–NH2) on the surface of the fibers, which makes rex rabbit fibers have better dyeability, and effectively improves dyeing rate and dye fixation rate.

Prediction of recipes for cotton cationisation and reactive dyeing to shade match conventionally dyed cotton

Cationisation allows cotton to be dyed with anionic dyestuffs (including anionic pigment dispersions) without the need for salt, and with decreased usage of dye, water, and energy. Appropriate cationisation levels play a part in dyeing properties such as fabric levelness, in fastness properties such as lightfastness, and in the overall cost of the cationisation treatment. The objective of this work is to assess whether it is possible simultaneously to predict a dye recipe and cationisation treatment level for cotton to yield a colourless or nearly colourless dyebath at the completion of the dyeing to match the shade of conventional fibre reactive dyeing of cotton. It has been shown that it is possible to model a cold pad batch cationisation process, relate the colour yield data and cationisation level for individual dyes, and finally predict a dyeing recipe and the required corresponding cationisation treatment to match the shade of conventional fibre reactive dyeing of cotton. The predicted dye recipe and cationisation amount yield colourless or nearly colourless dyebaths at the conclusion of the dyeing process.

New elastomeric polymethylsiloxane membranes bearing cationic exchanging sites for anionic dyestuffs sensors

Novel anion exchanging materials based on functional polymethylsiloxane elastomers have been prepared and used as sensitive membranes of electrochemical sensors made of SiO2/Si heterostructures coated with thin films of functional polymer. Their synthesis and their use in electrolyte/insulator/semiconductor (EIS) electrochemical devices are reported. The anion exchanging materials are cationic cross-linked polymers based on either poly(methylhydrosiloxane) (PMHS) or poly(methylhydrosiloxane-co-dimethylsiloxane) copolymer (PMHS-co-PDMS 50/50). Their synthesis has been carried out in two stages. A brominated derivative was firstly prepared by hydrosilylation reaction of undecenyl bromide with SiH bonds of various polymethylsiloxane in the presence of Karstedt’s catalyst. The kinetics of the hydrosilylation reaction was investigated. The second stage is based on the formation of quaternary ammonium (+N(CH2CH3)3), pyridinium (+NC5H5) and phosphonium (+P(C6H5)3) groups by quaternarization reactions to brominated polymers. Full characterizations of the materials by IR, liquid 1H and 13C NMR and solid 29Si NMR spectroscopy are given. The sensitivity of EIS devices to different anionic dyestuffs species have been assessed for Acid Blue 25 (AB25), Acid Blue 74 (AB74) and Acid Yellow 99 (AY99) in aqueous solution. The shifts of flat band potential and the variations of capacitance in inversion mode were extracted from the impedance measurements as a function of the concentration of anionic dyestuffs species in solution. The electrical parameters of the EIS devices came from a non-specific adsorption of organic dyes and anion exchange phenomena that showed specificity with respect to the type of anion exchanging group. The membranes bearing pyridinium or phosphonium groups gave a Nernstian response towards anionic dyestuffs AB25 and AY99.

Eco-friendly titanium tanning for the manufacture of bovine upper leathers: pilot-scale studies

Conventional chrome-tanning process is constantly under pressure from increasingly stringent environmental regulations on discharges of chromium-containing effluents and wastes. For this reason, in the past years alternative chrome-free tanning processes have been developed. Among these, titanium tanning is one of the most promising substitutes for chromium tanning in today’s leather industry. In this study the use of titanyl sulfate masked with citrate was investigated as tanning agent for the production of high-quality bovine upper leather on pilot scale. Preliminary experimental activities were performed to individuate the minimum citrate/titanium mole ratio to ensure a good titanium sulfate solution stability and minimum quantity of salt (sodium chloride) in pickling solution sufficient to depress acidic swelling of the skins. Ti-tanned leathers produced by the developed Ti-tanning process showed comparable physical–mechanical properties to those of traditionally Cr-tanned leathers, used as control, but a lower hydrothermal stability although acceptable. The Ti-tanned leathers complied with the standards for high-quality upper leather exhibiting better dyeability, due to their higher affinity to anionic dyestuffs, and similar softness, fullness, roundness, and hand compared to the control leathers.

Synthesis, characterisation and utilisation of hyperbranched poly (ester‐amide) for the removal of some anionic dyestuffs from their aqueous solutions

PurposeThe purpose of this paper is to show how to remove some dyestuffs, as pollutants, from their aqueous solutions.Design/methodology/approachTo achieve the goal, a water soluble hyperbranched poly (ester‐amide) (HBP) was synthesised using the melt polycondensation method by the reaction of maleic anhydride (MA) and diisopropanol amine (DIPA) at 140°C at a molar ratio of 1:1.3 MA: DIPA, respectively. This HBP was incorporated in the preparation of an effective microcrystalline cellulose (MCC)/dimethyloldihydroxyethylene urea (DMDHEU)/HBP adduct by crosslinking HBP with DMDHEU in presence of MCC. Furthermore, the prepared adduct was characterised by investigation its infra red and then utilised in the removal of three anionic dyestuffs from aqueous solutions, namely Irgalan Blau 3GL (an acid dye), SIRIUS Blau S‐BRR (a direct dye) and Levafix Brill Orange P‐GR (a hydrolysed reactive dye).FindingsThe results obtained revealed that the optimum conditions for preparing MCC/DMDHEU/HBP adduct are [HBP], 90 g/l; [DMDHEU], 200 g/l; LR, 1/3.3; [NC4LH], 20 g/l; a time of 30 min and a temperature of 160°C. Moreover, the results also showed that the extent of removal of such dyestuffs from their aqueous solutions by the prepared adduct follows the order: reactive dye>acid dye>direct dye, it is more pronounced at lower than at higher pH values and the removal of each dye by that adduct follows a first‐order reaction.Research limitations/implicationsOther substrates such as chitosan can be used to prepare more effective adducts.Practical implicationsHyperbranched polymers can be used effectively to prepare ion exchangers capable of removing the pollutants of dyestuffs from their aqueous solutions.Originality/valueThe aforementioned prepared HBP is a novel hyperbranched polymer and could be applied in the removal of many other pollutants.

Cobalt–nickel mixed oxide surface: A promising adsorbent for the removal of PR dye from water

A mixed oxide of cobalt (Co) and nickel (Ni) with an approximate composition of Co 0.4Ni 0.4O 0.2 was prepared chemically by precipitating from the corresponding metal carbonates and heating the mixture of carbonates at 650 °C under ambient atmosphere. The mixed (Co–Ni) oxide thus prepared was characterized by IR, SEM and XRD methods. The composition of the mixed metal oxide was obtained by EDX analysis. The surface behavior of the Co–Ni mixed oxide matrix was tested by adsorption studies and pH pzc measurement. The Co–Ni mixed oxide matrix behaves as a charged adsorbent at the pH media higher and lower than its pH pzc value (9.50) and thus found to be capable of anchoring the oppositely charged species onto its surface. Removal of cationic and anionic dyestuffs, viz., methylene blue (MB) and procion red (PR), respectively, was attempted using the mixed oxide surface as adsorbent. Although both the dyes can be removed by the mixed oxide, the extent of PR removal (∼70%) seems to be much higher than that of MB (∼20%) demonstrating the superior performance of the Co–Ni mixed oxide for its use as adsorbent in removing the anionic PR dyestuff from water.

Synthesis, characterisation and utilisation of hyperbranched poly (ester-amide) for the removal of some anionic dyestuffs from their aqueous solutions

Synthesis, characterisation and utilisation of hyperbranched poly (ester-amide) for the removal of some anionic dyestuffs from their aqueous solutions

Characterization of membrane-bound nitrate reductase from denitrifying bacteriaOchrobactrum anthropi SY509

In this study, we have purified and characterized the membrane bound nitrate reductase obtained from the denitrifying bacteria,Ochrobactrum anthropi SY509, which was isolated from soil samples.O. anthropi SY509 can grow in minimal medium using nitrate as a nitrogen source. We achieved an overall purification rate of 15-fold from the protein extracted from the membrane fraction, with a recovery of approximately 12% of activity. The enzyme exhibited its highest level of activity at pH 5.5, and the activity was increased up to 70°C. Periplasmic and cytochromic proteins, including nitrite and nitrous oxide reductase, were excluded during centrifugation and were verified using enzyme essay. Reduced methyl viologen was determined to be the most efficient electron donor among a variety of anionic and cationic dyestuffs, which could be also used as an electron donor with dimethyl dithionite. The effects of purification and storage conditions on the stability of enzyme were also investigated. The activity of the membrane-bound nitrate reductase was stably maintained for over 2 weeks in solution. To maintain the stability of enzyme, the cell was disrupted using sonication at low temperatures, and enzyme was extracted by hot water without any surfactant. The purified enzyme was stored in solution with no salt to prevent any significant losses in activity levels.

Synthesis, Characterization, and Some Utilization of Cellulose/Melamine Formaldehyde/Methylamine Anion Exchange Resin

Cellulose, melamine formaldehyde precondensate (MF), and methylamine hydrochloride (MA.HCl) were reacted in aqueous medium at different conditions, including time, temperature, MF/MA.HCl molar ratio, and liquor-to-cellulose ratio (LR). Reaction conditions were selected to prepare a cellulose/MF/MA anion exchanger having a total nitrogen and an amino nitrogen of 23.1% and 131 mEq/100 g, respectively. Potentiometric titration showed that the strength, pKb , of this resin was 7.2. The resin lost about 3% and 9% of its total and amino nitrogen, respectively, during the first five cycles of the durability test, after which it suffered no losses up to 25 cycles. The resin was utilized in the removal of three anionic dyestuffs (direct, acid, and reactive) as well as permanganate and dichromate anions from aqueous solutions at different pH values ranging from 3 to 12. Maximum extents of removal were manifested at a pH value of 3, at which they followed the descending order: (permanganate ∼ acid dye) > (reactive dye ∼ dichromate) » direct dye.

Animation of Wood Sawdust for Removing Anionic Dyes from Aqueous Solutions

Inexpensive and efficient cellulose-based adsorbents were prepared by the reaction of cross-linked polyethylenimine (CPEI) with an agricultural waste (i.e., wood sawdust). Factors affecting the extent of amination, such a CPEI concentration, pH, time, and temperature of reaction as well as sawdust particle size range, were studied. The obtained adsorbents were found to be highly effective for removal of anionic dyestuffs (i.e., direct, reactive, and acid dyes) from aqueous solutions. The presence of CPEI on and/or within the purified sawdust provides cationic active sites (i.e., amino groups) and enhances the substantivity of wood cellulose for anionic dyes, thereby improving the percent color removal.

Cationic surface modification by polyelectrolytes: Polyelectrolyte complex formation at inorganic particle surfaces

AbstractThe surface charge of inorganic finely dispersed materials like diatom earth, perlite, glass or clay may be changed from negative to positive by the adsorption of cationic polyelectrolytes. Different materials exhibit equivalent electrokinetic surface properties with high amounts of the polycation adsorbed. Interfaces modified this way are able to adsorb anionic dye stuffs. Their adsorption capability for the dye stuff may be enhanced by addition of polyanions due to the formation of a nonstoichiometric polyelectrolyte complex (PEC) and therefore an increased number of cationic centres in the interface. Experimental results indicate that the zeta potential is correlated to the outer PEC layer whereby dye stuff adsorption measurements are sensitive for the more inner surface regions, too. Immediately after modification, materials modified with poly(diallyldimethylammonium chloride) and poly(maleic acid‐co‐α‐methylstyrene) have negative zeta potentials at high excess of added polyanion and a positive one after separation of the solid. This behaviour is attributed to the formation of a nonstoichiometric PEC with polycation in excess and reversible interaction with polyanion in the surrounding solution. Experimental results indicate that the surface may act as “solid‐like” polyelectrolyte in competition to the polyanion.

Formation of ternary ion associates using diprotic acid dyes and its application to determination of cationic surfactants

A sensitive and selective method is described for the determination of cationic surfactants, such as benzethonium, benzalkonium, cetylpyridinium and trimethylstearylammonium, based on the formation and extraction of ternary ion associates with an acid dye (bromophenol blue or bromochlorophenol blue) and quinidine. Quinidine reacts with divalent anionic dyestuffs to form a bulky 1∶1 complex anion, which is extractable into 1,2-dichloroethane as ternary ion associates with cationic surfactants in nearly neutral media. The ternary ion associate gives a blue product. Linearity of the calibration curve is improved and the extractability of the cationic surfactants is enhanced in the presence of quinidine. In addition, many other amines do not interfere with the determination. The blue ion associates can be used for the selective and sensitive spectrophotometric determination of cationic surfactants.

A study of dyestuff aggregation: Part III—The effect of levelling agents on the aggregation of some anionic dyes

The disaggregating properties of four commonly used dyestuff levelling agents and of urea, in combination with a range of five anionic dyestuffs, were determined at 55° C and 95° C. Urea is the only compound investigated which very effectively disaggregated all of the dyestuffs studied. The disaggregating properties of the four levelling agents appear to depend on specific dyestujf-levelling agent interactions. No general explanation can be given in the absence of detailed published information about the chemical composition of two of the levelling agents.

A study of dyestuff aggregation. II. The influence of temperature on the aggregation of some anionic dyestuffs

The aggregation of eight anionic dyes has been studied by a diffusion method at 55°C and by light scattering at 55, 75, and 95°C. Some of the dyes are highly aggregated in 0.03 M aqueous NaCl even at 95°C and these dyes are difficult to apply uniformly to wool. Aggregation, however, need not be the cause of poor leveling, since the copper phthalocyanine tetrasulfonate dye studied is not highly aggregated but is difficult to level. The aggregation behavior of the eight dyes studied has been related to dye structure.

Practical Methods for Purification of Anionic Dyes as Their Sodium, Potassium and Lithium Salts

Anionic dyestuffs having high purity can be obtained employing standard recrystsllization techniques. The dye may be obtained as the sodium, potassium or lithium salt. The free acid form of the dye is dissolved in butanol. Impurities are removed during partition with water. The metal salt of the dye is obtained by adding the appropriate alkali. Alter natively, dimethyl formamide (DMF) is employed to extract the dye from the ionic impurities. The sodium salt of the dye is recovered. The free acid may be obtained using DMF-acid extraction followed by conversion to the desired metal salt with alkali. The purification and characterization of four direct dyes (C. I. Direct Red 2, C. I. Direct Yellow 12, C. I. Direct Blue 78, C. I. Direct Green 26) and two acid dyes (C. I. Acid Red 85, C. I. Acid Blue 78) is described.

MEASUREMENT OF DYEING PROPERTIES AND CORRELATION WITH ORIENTATION IN NYLON YARN

ABSTRACT Dyeing rate, equilibrium dye uptake and penetration rate studies have been carried out with anionic and dispersed acetate dyestuffs on a range of “66” nylon samples of various degrees of orientation. Differences in the appearance of dyed nylon fabrics produced by irregularities in orientation are shown to be primarily dependent on differences in dyeing rate. A routine method of assessing the magnitude of within package variations in orientation is described.