Bath pH Research Articles

Sustainable Dyeing of Microwave Treated Polyester Fabric using Disperse Yellow 211 Dye

The aim of current work is to evaluate the dyeing performance of newly introduced disperse dye to improve its dyeing behavior onto polyester fabric using microwave radiation. Microwave heating has promisingly improved the disperse dyeing of polyester fabrics. Disperse Yellow 211 (DY 211) has been used to dye the polyester fabric under the influence of microwave treatment. Both the fabric and dye solution, were treated with the microwaves for 1- 6 min. Different dyeing parameters such as temperature, time, dispersant and dye bath volume were also optimized and ISO standard methods for colorfastness were employed to rate the influence of microwave and ultraviolet treatment on disperse dyeing. It is found that microwave treated polyester (RP, 6 min), has given good color strength and darker shades upon dyeing at 90°C for 40 min. in the presence of 2 g/100ml of dispersant using 70 mL of irradiated dye solution (RS, 6 min) of pH 8. Similarly using dye bath of pH 11, microwave treated polyester (RP, 6 min.) has given good color strength and darker shades upon dyeing at 70°C for 35 min.in the presence of 1 g/100ml of dispersant. using 50 mL of irradiated dye solution (RS). ISO standards for fastness to light, washing and rubbing revealed that good to excellent ratings have been obtained from different shades dyed at optimal condition. It is inferred that Microwave treatment has not only reduced the dyeing conditions but also improved the color characteristics of dyed polyester fabric.

Formulation development and evaluation of gastroretentive floating beads with Brucea javanica oil using ionotropic gelation technology

In the present study, a gastric retention floating system for Brucea javanica oil, composed of alginate and carrageenan, was prepared using ionotropic gelation. Parameters for floatability, drug load, encapsulation efficiency, bead morphology, in vitro release, and in vivo gastric retention were evaluated. The optimized formulation via Box–Behnken design consisted of 1.7% alginate (W/V), 1.02% carrageenan (W/V), 1.4% CaCO3 (W/V), and a gelling bath of pH 0.8. The alginate–carrageenan–Brucea javanica oil beads had a porous structure and exhibited up to 24 h of in vitro floatability with a load capacity of 45%–55% and an encapsulation efficiency of 70%–80%. A 6-h sustained release was observed in vitro. The beads had a prolonged gastric retention (> 60% at 6 h) in fasted rats, compared to non-floating beads (15% at 6 h), as measured by gamma scintigraphy with single-photon emission tomography/computed tomography (SPET/CT). In conclusion, the alginate–carrageenan–Brucea javanica oil system showed enhanced oil encapsulation efficiency, excellent floating and gastric retention abilities, and a favorable release behavior.

Microwave-assisted sustainable dyeing of wool fabric using cochineal-based carminic acid as natural colorant

ABSTRACTThe revival of natural dyes in textiles is gaining popularity due to their sustainable nature. The current study has been undertaken to improve the dyeing behaviors of cochineal-based natural dye (carminic acid) for wool dyeing under the influence of microwave treatment. For the purpose, wool fabric and extract obtained from cochineal insects (Dactylopius coccus costa) were irradiated for 1–6 min. The nature of dye bath (pH) and dyeing temperature were optimized using optimal irradiation conditions. To make dyeing process more sustainable and eco-friendly, bio-mordants and chemical mordants have been employed at optimal conditions. It is found that microwave treatment of extraction for 5 min is suitable to get darker shades with acceptable color characteristics using unirradiated wool fabric. K/S was found using acidic dye bath of cochineal insect of pH 1 for dyeing unirradiated fabric at 70°C using acidic extract of Cochineal bugs. Suggested ISO standards for color fastness revealed that 5% of henna and 3% pomegranate as bio-mordant have not only given high color depth but also rated excellent fastness properties as compared to chemical mordants used. It is found that MW treatment has not only improved the dyeing behavior of carminic acid but also enhanced the color characteristics.

Effect of Ethanolamines on the Electroless Deposition of Copper on Functionalized Organic Surfaces.

Electroless deposition (ELD) is widely used in industry to deposit metals because it is inexpensive and compatible with organic materials. The deposition rate and deposited film properties critically depend on the reducing agent, complexing agent, and bath pH and temperature as well as bath additives. We have investigated the role of ethanolamine additives in the ELD of copper using the reducing agent dimethylamine borane on -CH3- and -OH-terminated self-assembled monolayers (SAMs) adsorbed on gold. Three additives were studied: ethanolamine (EOA), diethanolamine (DEOA), and triethanolamine (TEOA). Both the chemical identity and concentration of the ethanolamine significantly affect the deposition process. We show that the Cu deposition rate is faster on -CH3-terminated surfaces than on -OH-terminated SAMs because of the stronger interaction of the ethanolamines with the hydroxyl terminal group. In contrast to physical vapor deposition and other ELD processes, Cu deposits atop methyl-terminated SAMs using TEOA. However, using EOA and DEOA, copper penetrates through -CH3-terminated SAMs to the Au/S interface. For -OH-terminated SAMs, copper is observed to penetrate through the SAM for all ethanolamines investigated. The amount of copper penetration through the SAM to the Au/S interface increases with ethanolamine concentration. These effects are attributed to an adsorption-inhibition mechanism and differences in the chelation of Cu2+ in the deposition bath.

Encapsulation of purple corn and blueberry extracts in alginate-pectin hydrogel particles: Impact of processing and storage parameters on encapsulation efficiency

Purple corn (PC) and blueberry (BB) extracts were encapsulated in alginate-pectin hydrogel particles to protect anthocyanins (ACNs) from degradation. Combinations of alginate to pectin ratios at 82 to 18% and 43 to 57% and total gum concentrations (TGC) at 2.2% and 2.8% TGC were prepared to encapsulate both PC and BB ACN. The alginate-pectin hydrogel particles containing PC or BB extracts were produced by dripping solution into pH 1.2 buffer. Blueberry extract encapsulation efficiency was significantly higher than that of purple corn extract due to ACN chemical structure differences and the compatibility between the ACN structures and alginate-pectin hydrogel structure at the low pH environment. Effect of initial ACN concentration in droplets, particle shape, alginate to pectin ratio, TGC, ACN source, and curing bath conditions on encapsulation efficiency after curing (EEm) was investigated. The initial ACN concentration and particle shape didn't influence the EEm, while the alginate to pectin ratio, TGC, ACN source and the pH of the curing bath showed significant effect on the EEm. The EEm was improved from 26% to 65% for PC ACN and from 48% to 116% for BB ACN by augmenting curing bath with ACN at various concentrations. The ACN retention during storage (ARs) in hydrogel particles stored in pH 3.0 buffer was improved at low temperature and high particle weight to solution volume ratio. Higher amount of ACN was retained in the hydrogel particles when spherical particles were used. Encapsulation in hydrogel particles significantly reduced the anthocyanin photodegradation upon exposure to fluorescence light. The degradation of ACN was described with a first-order kinetics with half-life values of 630 h for encapsulated PC ACN and 58 h for PC ACN aqueous solution. Hydrogel production and subsequent storage conditions can be optimized to increase the anthocyanin delivered to human body using the low pH beverages such as fruit juices as a delivery vehicle.

Eco-friendly dyeing of modified cotton fabrics with grape pomace colorant: Optimization using full factorial design approach

ABSTRACTGrape pomace, which is a winery waste is studied and experimented to serve as a source of natural dyes that could be utilized in textile dyeing. In previous studies, it was found that grape pomace released from wine industry contains valuable resource of abundant natural coloring substances.The present work involves the optimization of dyeing process of cotton by natural colors extracted from grape pomace. The optimized dyeing conditions were; dyeing bath temperature 100°C, dyeing time 55 min, and dye bath pH 8. In addition, it was demonstrated that the dye bath of dyed cotton reduced the Chemical Oxygen Demand (COD) and the Biological Oxygen Demand (BOD)5 of the dye bath.

Influence of dyeing conditions of natural dye extracted from Berberis integerrima fruit on color shade of woolen yarn

ABSTRACTA new source of natural dye was introduced to obtain different colors on woolen yarn by varying the dyeing condition and formulation recipe. The fruit extract of Berberis integerrima was used as a natural dye for coloration of wool fibers. Response surface methodology (RSM) has been applied to design experimental runs to evaluate the interactive effects of the operating variables. The concentration of natural dye, concentration of mordant, pH of dye bath, and dyeing time at boiling temperature was selected as independent parameters. The effect of these parameters was examined on color shade (Hue angle) of dyed yarn samples as a dependent factor. The results were indicated that the different hue angles and color shades were achieved at proposed dyeing condition of wool fibers with B. integerrima which was in the range of 25° up to 282°. Extracted natural dye from B. integerrima was presented an inhibition zone at all applied concentrations and it was dependent on its concentration.

Effect of Bath pH on Interfacial Properties of Electrodeposited n‐Cu2O Films

For developing semiconductor junction devices with low cost electrodeposited cuprous oxide (Cu2O), it will be very useful to investigate possibilities to improve the interface properties of Cu2O with suitable junction materials. We have investigated the effect of electrodeposition bath pH on the interfacial properties of n‐Cu2O/electrolyte, n‐Cu2O/Au, and n‐Cu2O/p‐Cu2O junctions by exploiting capacitance–voltage and photoresponse measurements. In addition, XRD and SEM measurements were also employed for thin film characterization. We have observed that for an increase in bath pH from 5.7 to 6.5 the resulted n‐Cu2O films produced a shift in the extrapolated flat band potential at the aqueous electrolyte interface by 300 mV. In addition, we have observed that extrapolated built‐in potentials at n‐Cu2O/Au and n‐Cu2O/p‐Cu2O interfaces are also affected by the bath pH. With the change in bath pH, the shift in the flat band potential at n‐Cu2O/electrolyte interface is completely opposite to the built‐in potential shift at n‐Cu2O/Au interface. We explained the observation as a result of the change in net charge at the interfacial surface layers of the interfaces, due to the change in bath pH of the films. Evidence in support of the explanation was further established by the observation that the built‐in potential at n‐Cu2O/Au interface is increased due to the surface modification of n‐Cu2O films with S2− ions. In addition, bath pH could be optimized in the fabrication process of Cu2O homojunctions to yield high photoactivity. In comparison with the best n‐Cu2O/Au Schottky junction, we could fabricate a Cu2O homojunction with a 590% increase in Voc and an 800% increase in Isc. All the experimental evidences directed toward the idea that the relative band edge position of n‐Cu2O at the interfaces is affected by the bath pH. The results reported in this investigation will be very useful in the applications of electrodeposited Cu2O films in photocataytic, solar cell, and other electronic devices.

Establishing Environment Friendly Surface Treatment for AZ91 Magnesium Alloy for Subsequent Electroless Nickel Plating

A systematic study was made to develop the non-chromate and non-fluoride surface treatment for the AZ91 alloy to enable an adherent and corrosion resistant electroless nickel (EN) coating. The performance of the surface treatments is substantiated by the EN coating, in a single and two (duplex) layers on the prior surface pretreated AZ91 alloy, in the subsequent bath. The surface treatment in a solution containing cerium nitrate and subsequent single layer EN coating exhibited good adhesion and an excellent corrosion resistance in 0.5% NaCl solution. The duplex EN layer improved both corrosion as well as adhesion resistance. A remarkable long term (100h exposure) corrosion resistance, assessed using electrochemical impedance spectroscopy (EIS), was shown by the duplex EN coating with an outer layer produced in a bath of pH ∼ 5. In contrast, the duplex coating with an outer EN layer obtained in a bath of pH ∼ 10.5 failed within 4h of exposure. The porosity index of the coating in the order of 10−6 appears critical for achieving an excellent corrosion resistance. The adhesion resistance, as indicated by the critical load for coating delamination, was successively increased from 5.2 to 10.39N using different pretreatment processes. The adhesion resistance was influenced by the agglomerate particle size and coating thickness.

Electrodeposition of Tin-Bismuth Alloys: Additives, Morphologies and Compositions

Electrodeposition of tin-bismuth alloys on polycrystalline copper electrodes has been studied from an acidic bath comprising SnCl4, Bi(NO3)3, citric acid, poly(vinyl alcohol) and betaine. Using linear sweep voltammetry (LSV) and chronoamperometry (CA), co-deposition of tin and bismuth from the above bath has been examined. Bismuth (III) ions get reduced in a single-step, three-electron-transfer reaction while tin (IV) ions undergo a two-step reduction through the formation of tin (II) ions. Nitric acid in the bath not only enhances solubility of the precursors but also decreases the peak potential separation between bismuth (III) and tin (II) ions. Through the introduction of various additives and variation in bath pH, co-deposition is preserved while the composition of tin in the obtained alloy is modified. The morphologies, composition and crystallinity of the deposits have been determined using scanning electron microscopy, inductively coupled plasma atomic emission spectroscopy and X-ray diffraction, respectively. A wide range of alloy compositions (from 14% to 75% tin), including the eutectic Sn-Bi alloy have been deposited. Novel morphologies such as yarns-of-spool have been obtained.

Electrochemical Nucleation and Growth of Cobalt from Methanesulfonic Acid Electrolyte

Electrochemical nucleation and growth of cobalt onto glassy carbon electrode (GCE) from methanesulfonic acid (MSA) electrolyte was investigated, the influence of pH and cobalt concentration on the electrocrystallization mechanism was also examined. Cyclic voltammetry experiments indicate a pH and cobalt concentration dependence of the onset potential and a deposit phase change with decreasing pH was also noted. From analysis of current transients, the diffusion coefficient of cobalt ion was estimated as 1.89 × 10−5 cm2s−1. The electrocrystallization mechanism for 0.6 mol/L Co2+ follows the instantaneous nucleation with kinetic controlled growth and is independent of the bath pH while the mechanism for 0.2 mol/L Co2+ follows the progressive nucleation with diffusion controlled growth at pH = 2.0 and then goes to instantaneous nucleation with kinetic controlled growth at pH = 1.5 and exhibits a process of progressive nucleation with kinetic controlled growth with lower pH of 1.0.

Electrodeposition of Copper/Carbonous Nanomaterial Composite Coatings for Heat-Dissipation Materials

Carbonous nanomaterials are promising additives for composite coatings for heat-dissipation materials because of their excellent thermal conductivity. Here, copper/carbonous nanomaterial composite coatings were prepared using nanodiamond (ND) as the carbonous nanomaterial. The copper/ND composite coatings were electrically deposited onto copper substrates from a continuously stirred copper sulfate coating bath containing NDs. NDs were dispersed by ultrasonic treatment, and the initial bath pH was adjusted by adding sodium hydroxide solution or sulfuric acid solution before electrodeposition. The effects of various coating conditions—the initial ND concentration, initial bath pH, stirring speed, electrical current density, and the amount of electricity—on the ND content of the coatings were investigated. Furthermore, the surface of the NDs was modified by hydrothermal treatment to improve ND incorporation. A higher initial ND concentration and a higher stirring speed increased the ND content of the coatings, whereas a higher initial bath pH and a greater amount of electricity decreased it. The electrical current density showed a minimum ND content at approximately 5 A/dm2. Hydrothermal treatment, which introduced carboxyl groups onto the ND surface, improved the ND content of the coatings. A copper/ND composite coating with a maximum of 3.85 wt % ND was obtained.

Synthesis of heterostructure Cu2O/TiO2 nanotube arrays by AC electrochemical deposition

ABSTRACTCu2O/TiO2 nanotube arrays are synthesized by ac electrodepositing Cu2O directly into TiO2 nanotube arrays. The asymmetry of the I-V characteristics show the heterostructure has clear rectification, indicating good electrical contacts between the TiO2 and the embedded Cu2O. FESEM and HRTEM analysis identified the formation of one-dimensional Cu2O/TiO2 nanotube arrays. A bath pH in the range of 9.0 to 11.5 is preferred to form the high crystallinity of cubic Cu2O loaded into TiO2 nanotube arrays.

Glutaraldehyde crosslinked and alkaline denaturation induced self association of haemoglobin to design nanocarriers for In vitro release of insulin in simulated gastrointestinal fluids (SGFs)

Adopting a novel synthetic route the haemoglobin nanoparticles were prepared by its simultaneous microemulsion mediated crosslinking with glutaraldehyde and alkaline induced denaturation. The as prepared nanoparticles were characterized by techniques like Fourier transform infrared spectroscopy (FTIR), Transmission electron microscopy (TEM), Scanning electron microcopy (SEM), Zeta potential and Dynamic Light Scattering measurements. The particle size analysis revealed that size of the nanoparticles lays in the range 60–150 nm with surface charge of −27.1 mV. The TEM images suggested for aggregated structures which confirm denaturation of haemoglobin macromolecules under alkaline conditions. The nanoparticles were assessed for water intake capacity and the effect of various factors like chemical composition of nanoparticles, pH and temperature of the swelling bath, and simulated biological fluids on water sorption capacity was investigated. The insulin was loaded on to the prepared nanoparticles and investigated for swelling controlled release of insulin in simulated gastrointestinal fluid (SGIFs). The influence of chemical composition of nanoparticles, pH and temperature of the release media, and simulated physiological fluids was studied on the released amount of insulin and an optimized formulation was achieved. The prepared haemoglobin nanoparticles were also investigated for their in-vitro cytotoxicity.

Magnetic properties of crystalline nickel and low phosphorus amorphous Ni1-XPx nanoparticles

This paper explores how synthesis parameters can affect the size, composition and crystallinity degree of the Ni1-xPx nanoparticles and describes the process for preparing nanoparticles with tunable ferromagnetic, superparamagnetic and paramagnetic properties. Ni1-xPx nanoparticles of different sizes, compositions and crystallinities were synthesized through microemulsion method and by variation of micellar ratio, type of reducing agent and process pH. The results of particle size analysis (PSA), transmission electron microscopy (TEM), atomic absorption spectroscopy (AAS) and X-ray diffraction (XRD) confirmed successful synthesis of Ni1-xPx nanoparticles. While pure and crystalline nickel nanoparticles can be synthesized in the presence of hydrazine, phosphorus is doped on the structure of nanoparticles synthesized by sodium hypophosphite reducing agent. In this case, lower bath pH caused to synthesis of amorphous nanoparticles with higher phosphorous concentrations. It was shown that ferromagnetic nickel nanoparticles can be transferred to superparamagnetic ones if their particle size reduces to less than 14 nm. As well, crystalline to amorphous transition by phosphorus addition led to preparation of paramagnetic nanoparticles. Magnetic properties measurement using vibrating sample magnetometer (VSM) suggested interesting relationship between the magnetic properties and characteristics of nanoparticles. Moreover, the results indicated that synthesis method is flexible for preparation of nanoparticles with tunable magnetic properties from ferromagnetic to paramagnetic.

Preferential regions of growth of chemical bath deposited ZnO and Zn(OH)2 thin films at room conditions

Zinc oxide (ZnO) and zinc hydroxide (Zn(OH)2) films were deposited onto glass substrates at room conditions (25°C and atmospheric pressure) by the chemical bath deposition technique. ZnSO4, KOH, and NH4NO3 were used as chemical reagents for the chemical bath. The species distribution diagrams and the solubility curves were used to find the most adequate chemical conditions for the selective film deposition according to the concentrations and type of chemical reagents. The selective deposition of ZnO and/or Zn(OH)2 was achieved by adjusting the pH of the chemical bath in the range from 11.35 to 12.30, where three regions of growth were determined. The optical bandgap energy measured on the films ranged from 3.31eV for Zn(OH)2 to 3.41eV for ZnO. Lower values of Urbach energy were found when the ZnO formation was dominant. X-ray diffraction analysis showed that the pH of the chemical bath influences on the crystallinity of the films, where better crystallinity was observed for films with higher presence of ZnO. An aging experiment to evaluate the stability of the ZnO 15weeks after the deposition process was carried out.

Carboxylic polyethersulfone: A novel pH-responsive modifier in support layer of forward osmosis membrane

Carboxylic polyethersulfone (CPES) was synthesized through a facile acetylation reaction followed by an oxidation treatment and used as a modifier in support layer composition of forward osmosis (FO) membrane. The hydrophilic CPES polymer could ameliorate thin film composite (TFC) membrane performance in water permeation. The inferior sponge-like structure of the pristine PES substrate was changed to appropriate long finger-like one, when the CPES modified polymer dope solution was casted in a basic coagulation bath. In such operational condition, attached carboxylic functional groups were almost deprotonated and the electrostatic repulsion forces among them resulted in the formation of a substrate with open pores and less dense morphology. To prove pH-responsive characteristics of the CPES blended membranes, pH of coagulation bath was switched from 3 to 12. By doing so, water flux drastically increased from 14.23 to 28.03 LMH and from 27.80 to 46.17 LMH in FO mode (active layer facing feed water) and PRO mode (active layer facing draw solution), respectively. Further studies showed that such pH treatments could also lower the unfavorable structure parameter (S) from 1423.54 to 653.94µm. The pH-reversibility of the obtained membranes were evaluated using different draw solution pH values. In an acidic draw solution (pH = 3), the protonated carboxylic functional groups started shrinking and thus could open the substrate’s pores, which facilitate rapid water transportation. This investigation may open up a new class of pH-responsive and pH-reversible material for promising FO process, in which permeability and selectivity of a FO membrane could be readily controlled through fluctuation in pH of coagulation bath or draw solution.

Preparation of Hollow Fiber Membranes by Nonsolvent Induced Phase Separation along with Hydrogen Gas Formation Using a Single Orifice Spinneret

AbstractTraditional nonsolvent induced phase separation (NIPS) process for fabrication of hollow fiber membranes (HFMs) faces challenges, like design and manufacture of spinneret with two concentric orifices to provide parallel and continuous feed of polymer solution and bore fluid at specific rates. These factors limit the use of traditional technique to produce HFMs. Here, a new direct spinning method for fabricating HFMs by feeding a polymer solution, containing a gas producing agent using single orifice spinneret is reported. Polysulfone‐dimethylacetamide solution containing NaBH4 is extruded through a stainless‐steel needle (single orifice spinneret) into HCl aqueous solution (coagulation bath) at specific rates. Effects of polysulfone concentration, temperature, and pH of coagulant bath on structure and performance of the HFMs are investigated. Synergy between hydrogen from NaBH4 hydrolysis and NIPS process benefits fabrication of HFMs with good hollow bore structure and high porous wall. The prepared HFMs show good dye separation.

Studies on Coloration and UV Protective Action of Anar Peel (Pomegranate Rind) as an Effective Natural Colorant for Cotton Khadi Fabric

Besides optimization of conditions of colour extraction from dried anar peel, effect of different single and double mordants, dyeing process variables and UV protective action of anar peels (pomegranate rind i.e. Punica granatum L.) as a natural colourant is studied in this work. Mordants used are potash alum, aluminium sulphate and stannous chloride (as metallic salt mordant) and harda (i.e., myrobolan as natural mordant) from natural source. Relevant results indicate that 50:50 ratio of harda plus potash aluminium sulphate at overall 15% application level offers maximum K/S value and overall good colour fastness than any other combination. After finalizing the mordants, dyeing process variables were studied for standardization of conditions for dyeing cotton khadi fabric with aqueous extract of pomegranate rind. The results indicate that standardized conditions for dyeing are (a) dyeing time : 60 min, (b) dyeing temperature: 80 °C, (c) dye bath MLR : 1:30, (d) dye bath pH : 9.0, (e) max dye concentration : 20% and (f) common salt : 3%. Studies of FTIR, UV scan, Atomic Absorption Spectrophotometry (AAS) and UV Protection Factor (UPF) characters show a medium to good level of ultraviolet protection. Corresponding reaction mechanism amongst mordant/fibre and dye forming giant complex is also reported.

Growth behavior of co-electrodeposited CZTS precursor thin films from acidic baths containing tartaric acid

We synthesized Cu2ZnSnS4 precursor thin films on Molybdenum-coated soda lime glass substrates using a single-step co-electrodeposition process. The as-deposited films, however, were severely Zn-poor, Sn-rich and S-poor, possessing rough, powdery surface morphologies. In this study, the effects of deposition potential, deposition time, and bath composition on the stoichiometries and morphologies of the as-deposited films are systematically investigated, with the aims to understand the growth behavior and to improve the film properties. The poor morphologies of the initial films are attributed to diffusion-limited growth modes and hydrogen co-evolution. Removal of the tartaric acid from the bath increases the bath pH, decreases the hydrogen evolution reaction, and significantly improves the film compositions and morphologies. Possible mechanisms to describe the observed deposition behavior, morphology trends, and composition trends are discussed.