Basic Dyes Research Articles

Steric and Energetic Studies on the Synergetic Enhancement Effect of Integrated Polyaniline on the Adsorption Properties of Toxic Basic and Acidic Dyes by Polyaniline/Zeolite-A Composite.

The synergetic enhancement effect of the polyaniline (PANI) integration process on the adsorption properties of the PANI/zeolite-A composite (PANI/ZA) as an adsorbent for malachite green and Congo red synthetic dyes was evaluated based on classic equilibrium modelling in addition to the steric and energetic parameters of advanced isotherm studies. The PANI/ZA composite displays enhanced adsorption capacities for both methylene blue (270.9 mg/g) and Congo red (235.5 mg/g) as compared to ZA particles (methylene blue (179.6 mg/g) and Congo red (140.3 mg/g)). The reported enhancement was illustrated based on the steric parameters of active site density (Nm) and the number of adsorbed dyes per active site (n). The integration of PANI strongly induced the quantities of the existing active sites that have enhanced affinities towards both methylene blue (109.2 mg/g) and Congo red (92.9 mg/g) as compared to the present sites on the surface of ZA. Every site on the surface of PANI/ZA can adsorb about four methylene blue molecules and five Congo red molecules, signifying the vertical orientation of their adsorbed ions and their uptake by multi-molecular mechanisms. The energetic investigation of the methylene blue (-10.26 to -16.8 kJ/mol) and Congo red (-9.38 to -16.49 kJ/mol) adsorption reactions by PANI/ZA suggested the operation of physical mechanisms during their uptake by PANI/ZA. These mechanisms might involve van der Waals forces, dipole bonding forces, and hydrogen bonding (<30 kJ/mol). The evaluated thermodynamic functions, including enthalpy, internal energy, and entropy, validate the exothermic and spontaneous behaviours of the methylene blue and Congo red uptake processes by PANI/ZA.

Effect of Prolonged Water Aging on the Bond Strength and Marginal Seal of Three Novel Restorative Materials.

To assess and contrast the shear bond strength (SBS) and microbial leakage of Cention-N, Fuji IX, and nanohybrid composite restorative materials after being exposed to prolonged water aging. A total of 30 self-curing acrylic blocks were prepared for SBS analysis. Extracted teeth were affixed on the acrylic resin to incorporate the root section. To expose the occlusal dentin, 3 mm of the midcoronal portion was sectioned. The sectioned samples were allocated into the following three groups: Group I: Fuji IX; group II: Filtek Z350; and group III: Cention-N. Cylindrical plastic tubing was used to place each material as directed by the manufacturer and water aging for 7, 14, and 28 days at 37°C. Also, a universal testing machine (UTM) was utilized for testing followed by a scanning electron microscope (SEM). For microleakage analysis, a total of 30 class-V cavities were prepared. The prepared samples were allotted to respective groups; Later, 200 thermocycles at 5°C and 55°C were applied for 30 seconds to mimic the oral environment. The root apices sealed with sticky wax and the exception of a 1-mm around the edges of the restorations were then painted twice with clear nail varnish and submerged in 0.5% basic fuchsin dye at 37°C. Samples were washed, dried, and sectioned longitudinally followed by stereomicroscopic evaluation. Groups I (0.083), group II (0.083), and group III (0.102) did not show significant variation in the SBS after water degradation. At the end of 28 days of water aging, group III showed 33.3% adhesive failure and 66.7% mixed failure mode. For marginal leakage in group III, the mean and standard deviation (SD) were 334.90 ± 418.454 with the p = 0.001 showing a significant difference compared to groups I and II. Compared to nanohybrid composite and Fuji IX, Cention-N showed a superior SBS after being exposed to water aging and exhibited lesser marginal leakage. Cention-N outperformed in its marginal adaptation with superior shear resistance and can be considered as an alternative bulk filling material.

Determination of restricted dyes in textile raw material solid wastes by ultra-high performance liquid chromatography-tandem mass spectrometry

A rapid and highly sensitive method for the quantification of 34 restricted dyes (including acid, basic, disperse, direct, and azo dyes) in solid textile raw material wastes was developed by employing ultrasonic extraction coupled with ultra-high performance liquid chromatography-tandem mass spectrometry(UHPLC-MS/MS). More specifically, the proposed method employed methanol as the extraction solvent, while the mobile phases consisted of acetonitrile and 10 mmol/L ammonium acetate + 0.05% ammonia. A good linearity was achieved over the concentration range of 0.01–200 ng/mL with correlation coefficients (R) between 0.991–0.999, limits of detection (LODs) of 0.25–40.0 µg/kg (S/N = 3) and limits of quantification (LOQs) of 0.84–133.4 µg/kg (S/N = 10). 34 dyes were recovered at three levels ranging from 84.5 to 106.9% with relative standard deviation (RSDs) ranging from 0.59% to 10.61%. Further, the method was applied for the accurate analysis of 32 counts of cotton yarn, waste cotton, and printed fabrics within 15 min. The dyestuffs accurately quantified by this rapid chromatographic procedure covered a wide range of carcinogenic and allergenic dyestuffs listed in the Oeko-Tex Standard 100 (version 02.2023) colourants. The ultrasound technique combined with the ultra-high performance liquid chromatography-tandem mass spectrometry method proposed in this work is thus suitable for the rapid screening, confirmation, and quantitative detection of industrial synthetic dyes within solid waste originating from textile raw materials.

THE POSSIBILITY OF EFFECTIVE USE OF BASIC DYES OF THE "BAZAKRYL" TRADEMARK IN THE DETERMINATION OF ANIONIC SURFACTANTS

This study shows the prospects of using "Bazacryl" brand dyes in spectrophotometric analysis. On the basis of previous studies, their main spectrophotometric and protolytic characteristics have already been established, which made it possible to find out the optimal conditions for the formation of ionic associates of anionic surfactants with "Bazakrils". The studied dyes are characterized by a sufficiently high color intensity within a wide range of changes in the acidity of the medium, and in terms of these properties, they are not inferior to the majority of known basic dyes used in analytical practice. The kinetic factors of extraction were studied. As a result, the extraction equilibrium is established after 10-30 seconds of mixing the phases and practically does not depend on the used extractant, but 1-3 min. centrifugation is sufficient for complete phase separation. The optical density of the extracts of the formed IA does not change within 2 hours. It was established that such dyes show the ability to form IA from APAR and can serve as analytical reagents for their determination. The optimal conditions for the formation and extraction of IA APAR with new dyes have been established. A new, simple and rapid method for determining APAR in various samples of wastewater and natural waters, detergents, etc. is proposed.&#x0D; Keywords: dyes; spectrophotometry; ionic associate; protolytic properties; spectrophotometric properties.

Raw sawdust utilization for the removal of acid red57 and basic fuchsin dyes from aqueous solution: equilibrium, kinetics, and thermodynamic investigation

The aim of work is the use of a cheap adsorbent; sawdust (SD), for the adsorption of anionic dye, acid red57 (AR57), and cationic dye, basic fuchsin (BF). The adsorption of AR57 and BF on SD increased by increasing contact time and adsorbent dosage, while decreased with the increase of temperature and initial dye concentration. The increase in pH decreased the adsorption of AR57 and increased the adsorption of BF. The effective pH, adsorbent dose, and contact time on the AR57 removal efficiency were found to be 3, 0.1 g and 50 min, respectively. While for BF it was found to be 6, 0.2 g and 50 min, respectively. Fitting equilibrium data to Langmuir, Freundlich and Temkin isotherms showed that Freundlich model is the most suitable to describe the acid red57 and basic fuchsin. The kinetic studies indicate that the adsorption of AR57 and BF follows a pseudo-second-order model. The adsorption of both AR57 and BF is spontaneous (ΔG = −3.97, −3.27 kJ/mol) and exothermic (ΔH = −22.9, −8.3 kJ/mol) with negative values of ΔG and ΔH. The negative values of ΔS of both AR57 and BF (ΔS = −64.6, −16.7 J/mol. K) showed that the randomness decreases through the adsorption process.

Synthesis and Characterization of Phosphorus-Containing Sorbent for Basic Dye Removal.

A new phosphorus-containing sorbent was prepared by copolymerizing ethylene glycol dimethacrylate (EGDMA) and trimethylvinyl silane (TMVS) with diphenylvinylphoshine oxide (DPVO). It was characterized and applied in the removal of cationic dyes such as C.I. Basic Yellow 2 (BY2), C.I. Basic Blue 3 (BB3) and C.I. Basic Red 46 (BR46) using the batch method. Spectroscopic analysis indicated that the phosphinoyl group was introduced into the sorbent structure. Equilibrium adsorption data were fitted to the Langmuir, Freundlich, Temkin and Dubinin-Radushkevich isotherm models. The Freundlich model is the most suitable to describe the adsorption of BB3 (the Freundlich constant kF = 32.3 mg1-1/nL1/n/g) and BY2 on the sorbent (13.8 mg1-1/nL1/n/g), while the Langmuir model is the most adequate to describe the adsorption of BR46 (the monolayer capacity Q0 = 2.7 mg/g). The kinetics of the dye adsorption follows the assumptions of the pseudo-second-order (the rate constants k2 = 0.087 ÷ 0.738 g/mg min) model rather than pseudo-first-order or intraparticle diffusion. The presence of Na2SO4 and cationic surfactant in the aqueous solutions inhibited dye retention by the DPVO-EGDMA-TMVS. Adsorbent regeneration efficiency does not exceed 60% using 1 M NaCl and 1 M HCl solutions in the presence of 50% v/v methanol.

Efficient Disposal of Basic Fuchsin Dye from Aqueous Media Using ZrO2/MgMn2O4/Mg(Mg0.333Mn1.333)O4 as a Novel and Facilely Synthesized Nanocomposite

In this work, amorphous and crystalline novel products based on Zr, Mg, and Mn were facilely fabricated through the Pechini sol–gel procedure using inexpensive chemicals and an uncomplicated apparatus. Also, these products showed high efficiency as novel adsorbents in getting rid of basic fuchsin dye from aqueous solutions. The adsorbent, which was fabricated before calcination, was abbreviated as KE. In addition, the adsorbents, which were created at 500 and 700 °C, were designated as KE500 and KE700, respectively. The created adsorbents were characterized using high-level transmission electron microscopy (HR-TEM), X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), N2 adsorption/desorption analyzer, and field emission scanning electron microscope (FE-SEM). The XRD showed that the KE adsorbent is amorphous, whereas the KE500 and KE700 adsorbents are mixtures of ZrO2, MgMn2O4, and Mg(Mg0.333Mn1.333)O4 nanostructures. The HR-TEM exhibited that the KE adsorbent consists of very fine irregular shapes, whereas the KE500 adsorbent contains quasi-spherical particles with a mean diameter of 45.16 nm. Furthermore, the HR-TEM exhibited that the KE700 adsorbent consists of polyhedral shapes with a mean diameter of 76.28 nm. Furthermore, the BET surface area of the KE, KE500, and KE700 adsorbents is 67.85, 20.15, and 13.60 m2/g, respectively. Additionally, the elimination of basic fuchsin dye by the KE, KE500, and KE700 adsorbents is exothermic, physical in nature, and follows the pseudo-first-order as well as Langmuir equations. Further, the maximum uptake capabilities of the KE, KE500, and KE700 adsorbents toward basic fuchsin dye are 239.81, 174.83, and 93.19 mg/g, respectively.

Non-deteriorative eco-friendly water-saving tactic for removal of vegetable matters from wool fleece using xylanase and cellulase

The carbonization of wool fleece (WF) is conducted to remove the adhered vegetable matter (VM) from contaminated WF using sulfuric acid, followed by drying and backing. This process has a deteriorative effect on WF and requires a tremendous quantity of water for rinsing WF after carbonization to remove any H2SO4 residuals. Herein, we propose an alternative eco-friendly water-saving process for the removal of VM from WF using enzymes. Cellulase-containing xylanase from the fungus Aspergillus terreus, and cellulase-free xylanase from the fungus Aspergillus flavus AW1 were used to remove the VM from WF. The effect of some process parameters on the amount of the removed VM was assessed. Alkali solubility as well as sulfur and cystine content were used to follow the alteration in the chemistry of the bio-treated WF. The fiber morphology was examined using scanning electron microscopy. The dyeability of the treated WF towards acid, reactive, and basic dyes was monitored. The results revealed that the removal of the VM from WF by applying the examined enzymes was effective and could be an appropriate, non-destructive, eco-friendly water-saving substitute to the conventional carbonization procedures. By virtue of enzyme specificity, the proposed process removed the VM without deteriorating the fiber.

Thermally activated persulfate oxidation of Basic Fuchsin dye: Effect of different operating parameters, kinetic, and thermodynamic study

AbstractThe present paper aims to investigate the efficiency of thermal activation persulfate in eliminating the organic dye “Basic Fuchsin” (BF). In addition, the study attempts to elucidate the effect of different operating parameters, such as persulfate dosage (0.44–4.4 mM), the initial solution pH of (3–10), and temperature (25–50°C), on the process. The effects of various anions and water matrices on BF discoloration were investigated. Thus, the findings revealed that 94.15% of BF can be eliminated using persulfate at a concentration of 4.4 mM and a temperature equal to 50°C. It occurs under the following operating conditions: oxidation time of 60 min, initial pH equal to 6, the pollutant concentration of 10 ppm, and stirring speed equal to 300 rpm. Furthermore, the kinetic study indicated that the degradation of the BF dye using PS followed a first‐order pattern with rate constants varying within a range of 15.3 × 10−3–43.2 × 10−3 min−1. Based on the Arrhenius equation, the activation energy of the studied process was determined to be 29 kJ mol−1, suggesting that a moderate activation energy is required for BF discoloration. The results of the thermodynamic study confirm that the oxidation process is non‐spontaneous and endothermic. Coexisting inorganic anions delayed BF discoloration to varying degrees, and the inhibitory action followed the following order: carbonate &gt; chloride &gt; sulfate &gt; nitrate. Organic pollutants oxidation by the thermal activation of the persulfate is a simple and effective method for the depollution of waste textile water.

A study of basic and reactive dyes removal from synthetic and industrial wastewater by electrocoagulation process

Large-scale textile industries used large amounts of toxic chemicals which are very hazardous to human health and environmental sustainability. In this study, the removal of various dyes from effluents of textile industries using the electrocoagulation process was investigated. The studied dyes were Reactive Red 120 (RR-120), Basic Blue 3 (BB-3), and Basic Red 46 (BR-46), which were found in samples collected from effluents of three major textile factories in the Amhara region, Ethiopia. For maximum removal, the dye BB-3 required acidic pH 3, RR-120 basic pH 11, while BR-46 neutral pH 7 conditions. BB-3 required a longer treatment time of 80 min than BR-46 and RR-120, which required 30 and 40 min, respectively. The best removal efficiency of 99.5%, 93.5%, and 96.3% was achieved for BR-46, BB-3, and RR-120, respectively, from synthetic wastewater containing 10 mg l-1of each dye at an applied potential of 10 V. The method was applied to real textile wastewaters and 73.0 to 99.5% removal of the dyes was achieved, Indicating Electrocoagulation can be used as a simple, and reliable method for the treatment of real wastewater from textile industries. It is used as a potentially viable and inexpensive tool for the treatment of textile dyes Analysis of the electrochemically generated sludge by X-ray Diffraction, Scanning Electron Microscope, and Fourier Transform Infrared Spectroscopy revealed the expected crystalline aluminum oxides (bayerite (Al(OH)3 diaspore (AlO(OH)) found in the sludge. The amorphous phase was also found in the floc. Textile industry owners should be aware of the impact of the discharge of effluents on the Ecosystem and should use the investigated electrocoagulation method for effluent treatment before discharging into the environment.

An Expanded IrO2/Ti Durable Electrode for Electrochemical Degradation of Basic Red 46 Textile Dye in Both Single and Binary Mixture Solutions

The use of dimensionally stable anode (DSA) for degrading organic pollutants is of concern recently. The electrocatalytic technique can efficiently treat biodegradable organic matter like dye-containing effluent discharge. This study focuses on applying modified DSA meshed IrO2/Ti electrode for the electrochemical degradation of wastewater effluents of Basic Red 46 (BR46) textile dye using different supporting electrolytes; sodium sulfate (Na2SO4) or/and sodium chloride (NaCl). The parameters affecting the proposed electrochemical degradation process were evaluated to select the optimal operating conditions. The results revealed that using a mixture of supporting electrolyte Na2SO4 and NaCl enhanced the removal of dye color %, chemical oxygen demand (COD) %, and total organic carbon (TOC) % by 94.9%, 65.7%, and 76.0%, respectively. The UV-Vis and FT-IR spectroscopic techniques followed the degradation efficiency. FT-IR data were in good agreement with the COD, TOC, and UV-Vis measurements, confirming the high refractory performance of the BR46 dye. The redox process was performed on the surface of the modified electrode and explained via cyclic voltammetry (CV), and it showed a diffusion mass transport mechanism followed by product adsorption. The identification of the degradation products was assessed by gas chromatography–mass spectrometry (GC-MS) analysis. The electrochemical degradation and mineralization of a binary mixture of Basic Yellow (BY28) and BR46 textile dyes were also studied. It gave similar degradation and mineralization behavior to the same extent as the single dye in solutions.

Preparation and application of irradiated polyvinyl alcohol/starch/pumice composites for adsorption of basic dye: Isotherm and kinetics study

Even at low concentrations, organic dye pollution entering water resources from the textile, paper, and pharmaceutical industry sectors poses a serious hazard to human and aquatic life. One of the most significant remediation methods is the adsorption method. In the present study, the uptake of basic violet 7 (BV7) synthetic dye was investigated utilizing Poly (vinyl alcohol)/starch/Pumice [poly (PVA/St/Pu)] composite films prepared by a simple casting of both PVA and St with Pu and then irradiated by electron beam (EB) source to prompt curing. Numerous characterization methods, such as SEM, FTIR, X-ray diffraction (XRD, and other measurements, were examined on the prepared sample. The tensile strength (TS) of all composites was increased by increasing the radiation dose up to 10 kGy. TS was increased by 3 php of Pu, and an overload of Pu led to a decrease in TS values. The elongation at break (Eb) of the prepared composite increased at 3 Pu, then decreased as the quantity of the pumice increased, while the Eb was decreased by irradiation. The effects of the produced polymeric films' composition and irradiation dose on the basic violet 7 (BV 7) dye adsorption were studied. It was found that the adsorption capacity of poly (PVA/St/9 php Pu-10 kGy) toward the BV 7 dye was 64.9 mg/g at the optimal conditions: pH = 11, contact time = 480 min., adsorbent dosage = 0.2 g., concentration = 150 mg/l, and temperature = 298 K. The adsorption process fitted with the pseudo-second-order model, Freundlich adsorption isotherms were found to be spontaneous and endothermic.

Development of a new CoS-Supported ZnAl2O4 catalyst for the visible photodegradation of a basic textile dye from water

The material is proven competitive for the solar treatment of wastewater from the textile industry -an essential source of water pollution worldwide. The system was prepared following a two-step hydrothermal method, showing photon absorption properties across the solar spectrum's UV and visible light regions. The main responsible species driving the photocatalytic process are proposed based on degradation experiments using appropriate scavengers. Further studies include consideration of operational parameters and cycling experiments to evaluate the stability of the catalyst. The results showed complete degradation (100%) based on dye bleaching and >90% mineralization of the dye based on total organic carbon analysis using dye concentrations of 20 ppm and catalyst loading of 1 g/l. Our findings point to sulfide-supported spinel materials as promising candidates for advanced solar oxidation technologies for wastewater treatment.

Green synthesis of zinc oxide nanoparticles from Rhododendron arboreum extract and their potential applications in photocatalytic degradation of cationic dyes malachite green and Fuchsin basic dye

Green synthesis of zinc oxide nanoparticles from Rhododendron arboreum extract and their potential applications in photocatalytic degradation of cationic dyes malachite green and Fuchsin basic dye

Using nano clay and graphite as low-cost, sustainable adsorbents to remove dye toxins from waste water

Purpose This study aims to observe the coloring efficacy of graphite (G) and nano bentonite clay (BCNPs) on the adsorption of Basic Blue 5 dye from residual dye bath solution. Design/methodology/approach Some factors that affected the adsorption processes were examined and found to have significant impacts on the adsorption capacity such as the initial concentration of G and/or BCNPs (Co: 40–2,320 mg/L), adsorbent bath pH (4–9), shaking time (30–150 min.) and initial dye concentration (40–200 mg/L). The adsorption mechanism of dye by using G and/or BCNPs was studied using two different models (first-pseudo order and second-pseudo order diffusion models). The equilibrium adsorption data for the dye understudy was analyzed by using four different models (Langmuir, Freundlich, Temkin modle and Dubinin–Radushkevich) models. Findings It has been found that the adsorption kinetics follow rather a pseudo-first-order kinetic model with a determination coefficient (R2) of 0.99117 for G and 0.98665 for BCNPs. The results indicate that the Freundlich model provides the best correlation for G with capacities q_max = 2.33116535 mg/g and R2 = 0.99588, while the Langmuir model provides the best correlation for BCNPs with R2 = 0.99074. The adsorbent elaborated from BCNPs was found to be efficient and suitable for removing basic dyes rather than G from aqueous solutions due to its availability, good adsorption capability, as well as low-cost preparation. Research limitations/implications There is no research limitation for this work. Basic Blue 5 dye graphite (G) and nano bentonite clay (BCNPs) were used. Practical implications This work has practical applications for the textile industry. It is concluded that using graphite and nano bentonite clay can be a possible alternative to adsorb residual dye from dye bath solution and can make the process greener. Social implications Socially, it has a good impact on the ecosystem and global community because the residual dye does not contain any carcinogenic materials. Originality/value The work is original and contains value-added products for the textile industry and other confederate fields.

Comprehensive evaluation of HKUST-1 as an efficient adsorbent for textile dyes.

This study aimed to comprehensively assess the performance of HKUST-1, a metal-organic framework (MOF), as an adsorbent for various classes of textile dyes, including direct, acid, basic, and vinyl sulfonic reactive dyes. Real-world dyeing scenarios were simulated using carefully selected combinations of dyes to evaluate HKUST-1's effectiveness in treating dyeing process effluents. The results demonstrated that HKUST-1 exhibited highly efficient adsorption capabilities across all dye classes. Isolated direct dyes showed the best adsorption outcomes, with adsorption percentages exceeding 75% and reaching 100% for direct blue dye (Sirius Blue K-CFN). Basic dyes exhibited adsorption levels of nearly 85% for blue dye (Astrazon Blue FG), while the adsorption performance for the yellow dye (Yellow GL-E) was the poorest. The adsorption of dyes in combined systems followed a similar trend to that of isolated dyes, with the trichromy of direct dyes yielding the best results. Kinetic studies indicated that the adsorption of dyes followed a pseudo-second-order model, with nearly instantaneous adsorption observed in all cases. Furthermore, most dyes adhered to the Langmuir isotherm, further confirming the effectiveness of the adsorption process. The exothermic nature of the adsorption process was evident. Importantly, the study demonstrated the feasibility of reusing the HKUST-1, highlighting its potential as an exceptional adsorbent for removing hazardous textile dyes from effluents.

Preparation of Nanostructured β-PbO2 Films for the Electrochemical Oxidation of Acid Blue and Basic Brown Dyes

Preparation of Nanostructured β-PbO2 Films for the Electrochemical Oxidation of Acid Blue and Basic Brown Dyes

Removal of dyes from water using Citrullus lanatus seed powder in continuous and discontinuous systems

The objective of this study is to develop a low-cost biosorbent using residual seeds of the Citrullus lanatus fruit for the removal of cationic dyes. Physicochemical parameters such as pH, adsorbent mass, contact time, and temperature were evaluated for their effects on dye removal. The biosorbent is composed of lignin and cellulose, exhibiting a highly heterogeneous surface with randomly distributed cavities and bulges. The adsorption of both dyes was most effective at natural pH with a dosage of 0.8 g L−1. Equilibrium was reached within 120 min, regardless of concentration, indicating rapid kinetics. The Elovich model and pseudo-second-order kinetics were observed for crystal violet and basic fuchsin dye, respectively. The Langmuir model fitted well with the equilibrium data of both dyes. However, the increased temperature had a negative impact on dye adsorption. The biosorbent also demonstrated satisfactory performance (R = 43%) against a synthetic mixture of dyes and inorganic salts, with a small mass transfer zone. The adsorption capacities for crystal violet and basic fuchsin dye were 48.13 mg g−1 and 44.26 mg g−1, respectively. Thermodynamic studies confirmed an exothermic nature of adsorption. Overall, this low-cost biosorbent showed potential for the removal of dyes from aqueous solutions.

Malachite green dye adsorption by jackfruit based activated carbon: Optimization, mass transfer simulation and surface area prediction

The exposure of basic dye towards human and environment can caused severe adverse effects. Hence, this study aimed (i) to optimize the adsorption of malachite green (MG) dye onto jackfruit peel based activated carbon (JPAC) by using response surface methodology (RSM) and (ii) to simulate the mass transfer process using Polymath mass transfer (PMT) model. The RSM revealed that the optimum activation temperature, activation time and potassium hydroxide (KOH) impregnation ratio, IR to be 782 °C, 1 h and 2.96 g/g which translated into 66.80 mg/g of MG adsorption and 34.52 % of JPAC's yield. The Freundlich isotherm model described the adsorption process the best while the Langmuir monolayer adsorption capacity was computed to be 376.33 mg/g. The kinetic data obeyed the PMT model the best where the rate constant, KPMT decreased from 1.20 to 0.41 h−1 as the MG concentration increased from 25 to 300 mg/L. Also, the PMT model was succeeded in predicting the surface area, aPMT of JPAC to be 807.77 m2/g and this value is comparable with the actual JPAC's mesopores surface area of 714.25 m2/g (error 11.58 %). The adsorption of MG onto JPAC was aided by several functional groups such as primary or secondary alcohol, non-bonded hydroxy group and methoxy through ion-dipole force and dipole-dipole force. Based on thermodynamic parameters, MG-JPAC adsorption system was endothermic in nature (∆H° = 37.12 kJ/mol), had an increment of randomness at solid-liquid interface (∆S° = 0.19 kJ/mol·K), spontaneous in nature (−20.11 kJ/mol) and physisorptionally governed (Ea = 9.46 kJ/mol).

Effect of air bubbles on the membrane filtration of rhodamine B.

Effect of air bubbles on the membrane filtration of a basic dye, rhodamine B (RB), using a hydrophilic PTFE membrane filter (pore size: 0.20μm) was studied. The air bubbles were generated by vigorously mixing the aqueous solution containing 0.05% (v/v) of 1-butanol with a shaft generator of a homogenizer. RB being far smaller than the pore size of the membrane filter could not be rejected without air bubbles, but it was rejected by the membrane filter in the presence of air bubbles. The rejection ratio increased with increasing the rotation speed of the shaft generator because of the increase in the amount of air bubbles and therefore the increase in the surface area of air bubbles for the adsorption of RB. On the other hand, another basic dye, methylene blue (MB), was negligibly rejected in the same condition. Dynamic surface tension measurement of aqueous solutions containing different amounts of dye indicated that RB strongly adsorbed to the air-water interface, while MB hardly adsorbed. The results obtained in the present study strongly suggest the potential usefulness of air bubbles for the selective microfiltration of dissolved organic molecules or ions.