Effect Of Initial Dye Concentration Research Articles

Insights into the role of metal cation substitution on the anionic dye removal performance of CoAl-LDH

The preparation of the adsorbent plays an important role in the adsorption technology, especially the selection of adsorbents with high specific surface area and special structure is particularly critical to the entire adsorption process. Herein, a series of ternary LDHs was designed via a facile hydrothermal method, and in another word, all derived from binary CoAl-LDH by substituting with another transition metals(Ni, Zn, Fe), used as adsorbents to remove MO and CR. The adsorption capacity of the obtained ternary LDHs are better than that of the pristine CoAl-LDH, and CoNiAl-LDH stands out with the higher adsorption capacity than other ternary LDHs samples whether the dye is MO or CR. Then the effect of initial dye concentration, pH and temperature on its MO adsorption performance was systematically studied. The maximum adsorption capacity reached more than 330 mg/g under the optimal conditions (25 °C, pH=3). This work may provide a method to design the advanced adsorbents design for further enhancing the adsorption activity in the field of water environmental protection.

Photocatalytic Oxidation of Acid Orange 10 dye Molecules using Cerium Oxide Nanosphere Particles under Ultraviolet and Visible Light Irradiations

Exploration of semiconductors in the field of photocatalysis plays a crucial role in energy and environmental remediation in particular oxidation/reduction of toxic organic contaminants from water and wastewater. The present research work aims on synthesis of pristine CeO2nanoparticles by precipitation method and was thoroughly characterized by Fourier Transform Infrared spectroscopy, X-ray Diffraction, UV-vis-Diffuse Reflectance Spectroscopy, High Resolution Scanning Electron Microscopy, EDAX and Electron Spin Resonance techniques. The band gap energy (Ebg) was found to be 3.19 eV. The synthesized nanomaterials showed spherical morphology and the particles size ranged from 50-93 nm. The insitu generation of ·OH radicals was confirmed from ESR studies. The synthesized CeO2nanospheres was evaluatedin photocatalytic oxidation of an azo dye Acid orange 10 under Ultraviolet and visible light irradiations. Experimental studies such as pH, catalyst amount and effect of initial dye concentration were also studied. Kinetic studies indicate the photo reaction follows pseudo-first order rate equation. The photocatalytic oxidation of dye molecules were monitored by UV-visible spectroscopy and COD analyses. The level of chemical oxygen demand (COD) of the photodegraded samples decreases in both the photocatalytic systems indicating that dye molecules readily degraded under present experimental conditions.Effect of electrolytes like MgSO4,KCl, Na2CO3 and NaHCO3 were also investigated to check interference of inorganic anions on photocatalytic oxidation of dye molecules using CeO2 nanospheres. Finally, the prepared catalyst was checked for its reusability and the photocatalyst exhibited better photocatalytic activity evenafter three cycles of regeneration.Copyright © VBRI Press.

Antibacterial Films of Alginate-CoNi-Coated Cellulose Paper Stabilized Co NPs for Dyes and Nitrophenol Degradation.

The development of a solid substrate for the support and stabilization of zero-valent metal nanoparticles (NPs) is the heart of the catalyst system. In the current embodiment, we have prepared solid support comprise of alginate-coated cellulose filter paper (Alg/FP) for the synthesis and stabilization of Co nanoparticles (NPs) named as Alg/FP@Co NPs. Furthermore, Alginate polymer was blended with 1 and 2 weight percent of CoNi NPs to make Alg-CoNi1/FP and Alg-CoNi2/FP, respectively. All these stabilizing matrixes were used as dip-catalyst for the degradation of azo dyes and reduction of 4-nitrophenol (4NP). The effect of initial dye concentration, amount of NaBH4, and catalyst dosage was assessed for the degradation of Congo red (CR) dye by using Alg-CoNi2/FP@Co NPs. Results indicated that the highest kapp value (3.63 × 10−1 min−1) was exhibited by Alg-CoNi2/FP@Co NPs and lowest by Alg/FP@Co NPs against the discoloration of CR dye. Furthermore, it was concluded that Alg-CoNi2/FP@Co NPs exhibited strong catalyst activity against CR, and methyl orange dye (MO) degradation as well as 4NP reduction. Antibacterial activity of the prepared composites was also investigated and the highest l activity was shown by Alg-CoNi2/FP@Co NPs, which inhibit 2.5 cm zone of bacteria compared to other catalysts.

A supramolecular gel made from an azobenzene-based phenylalanine derivative: synthesis, self-assembly, and dye adsorption

In the present work, a new supramolecular gel of azobenzene-based phenylalanine derivative (AZO-Phe) and its application in methylene blue (MB) adsorption have been developed. The gelator has shown great ability to form stable gels with a critical gelation concentration as low as 1.0 mg/mL in EtOH/H 2 O. The studies also showed that the gel has a good adsorptive performance to MB in aqueous solution. The adsorption process and mechanism of MB on AZO-Phe gel was systematic investigated. Batch experiments were performed to study the effects of initial dye concentration, contact time and pH on the adsorption performance of AZO-Phe gel. The adsorption process and data was fitted well with Langmuir isotherm model and pseudo-second-order kinetic model. Moreover, AZO-Phe gelator could be recovered after MB adsorption, and rate of recovery was achieved 95%. These results provide a mixed solvent gel method for the purification of dye-polluted water systems, while also paving the way for future design of functionalized supramolecular self-assemble systems.

Experimental and computational studies on the removal of crystal violet dye from aqueous solution using juglans regia leaves treated with acetic acid and L-arginine

ABSTRACT In this study, the leaves of juglans regia chemically treated with acetic acid and L-arginine were used as adsorbents for removal of crystal violet dye from aqueous solution. The adsorbents were characterised using powder x-ray diffraction, Fourier transform infrared spectroscopy and Brunauer–Emmett–Teller techniques. The adsorption isotherm, kinetics and thermodynamic parameters were examined for adsorption of dye on various adsorbents. The effect of initial dye concentration on adsorption capacity was studied and maximum adsorption capacity of adsorbents as per Langmuir linear fit was found for (JRACD: 263.85 mg g−1, JRACCHR: 273.97 mg g−1 and JRLRG: 290.70 mg g−1) at an initial dye concentration of 300 ppm, pH of dye solution 8, dosage of adsorbent 0.3 g, contact time of 70 minutes and at temperature of 303.15 K. It was observed that Freundlich isotherm fitted well for adsorption of dye on all the adsorbents compared to Langmuir isotherm. The kinetics of adsorption was found to follow the linear pseudo-second-order rate equation (R2 ≥ 0.9967). The Gibbs free energy was spontaneous in nature for the three adsorbents. The response surface methodology was also applied for all the adsorbents and optimisation of initial dye concentration (100, 200, 300) ppm, dosage of adsorbent (0.1, 0.3, 0.5) g and pH of dye solution (2, 5, 8) led to the development of quadratic models. The maximum adsorption capacity as per response surface model was found as 260.12 mg g−1 for JRLRG under optimum conditions. The significance of these models was also characterised by analysis of variance test. Additionally, density functional theory was used to support the experimental analysis and using Fukui function analysis the site for adsorption has been proposed.

Factors Affecting Synthetic Dye Adsorption; Desorption Studies: A Review of Results from the Last Five Years (2017-2021).

The primary, most obvious parameter indicating water quality is the color of the water. Not only can it be aesthetically disturbing, but it can also be an indicator of contamination. Clean, high-quality water is a valuable, essential asset. Of the available technologies for removing dyes, adsorption is the most used method due to its ease of use, cost-effectiveness, and high efficiency. The adsorption process is influenced by several parameters, which are the basis of all laboratories researching the optimum conditions. The main objective of this review is to provide up-to-date information on the most studied influencing factors. The effects of initial dye concentration, pH, adsorbent dosage, particle size and temperature are illustrated through examples from the last five years (2017–2021) of research. Moreover, general trends are drawn based on these findings. The removal time ranged from 5 min to 36 h (E = 100% was achieved within 5–60 min). In addition, nearly 80% efficiency can be achieved with just 0.05 g of adsorbent. It is important to reduce adsorbent particle size (with Φ decrease E = 8–99%). Among the dyes analyzed in this paper, Methylene Blue, Congo Red, Malachite Green, Crystal Violet were the most frequently studied. Our conclusions are based on previously published literature.

Removal of methyl red in wastewater by activated carbon derived from rice husk

The textile industry is the largest industry contributing to the wastewater pollution and is a concern for the environment today. This pollution occurs when wastewater from the textile industry discharges the water into the river and it will affect both aquatic and human life. There are several ways to overcome this pollution problem but the current method is very expensive and its effectiveness depends on the colour of the dye. In this research, activated carbon of rice husk was used as an adsorbent to remove the methyl red dye from the wastewater. To detect the effectiveness of rice husk, two materials were used which were raw rice husk and also activated carbon to remove methyl red dyes from wastewater. There are four parameters used to investigate the optimum level which are the effect of initial dye concentrations ranges from (2 mg/L-10 mg/L), contact time (20-100 minutes), pH (2-10) and adsorbent dosage (0.5-2.5 g). The percentage of dye is calculated and recorded to see the comparison between raw rice husk and also activated carbon of rice husk. The results show that the rice husk can be used as a potential adsorbent to remove methyl red from the waste water.

Green photocatalyst Cu/NiO doped zirconia for the removal of environmental pollutants

Three distinct copper/nickel oxide doped zirconia (Cu-NiO-ZrO2) photocatalysts were synthesized using one pot hydrothermal method. In these synthesized photocatalysts Cu-NiO ratio were 1:1, 1:2, 2:1 while CuNiO to ZrO2 ratio was kept constant (1:4). It was observed that these prepared materials displayed strong photocatalytic properties for the reduction of 4-nitrophenol (NP) and degradation of methylene blue (MB) and methyl orange (MO) respectively. XRD pattern, BET surface area, SEM and EDX have determined the physical properties of these synthesized photocatalysts. The effect of initial dye concentration, photocatalyst dose, pH, and time on the efficiency of degradation were evaluated by selecting efficient catalyst for 4-nitrophenol (4-NP) reduction, methylene blue (MB) and methyl orange (MO) degradation respectively. It was found that the degradation efficiency of these pollutants decreased with increase in the solution’s pH and the initial concentration of dye while it enhanced by increasing the catalyst dose and irradiation reaction time during photocatalysis. Almost complete reduction of 4-NP was accomplished while using 20 mg/L of 4-NP and 0.02 g of catalyst within 5 min using 25 Mm NaBH4 solution. The reduction of 4-NP to 4-AP using Cu/NiO-ZrO2 photocatalyst follows pseudo-first order kinetics having a rate constant 0.882 min−1 with R2 value of 0.9957. In reactions of MB (50 mg/L) and MO (50 mg/L), approximately 99% degradation efficiency was achieved by using 0.03 g of catalyst dose with reaction time of 10 and 35 min, respectively.

Fe/S Co-Doped Titanium Dioxide Nanotubes: Optimization of the Photoelectrocatalytic Degradation Kinetics of Phenol Red

Photoelectrocatalysis has emerged as a promising technology to degrade recalcitrant pollutants such as textile dyes in wastewater completely. Titanium dioxide is typically used as a photocatalyst, but its wide bandgap constrains its use to the use of ultraviolet light. To extend its use to the visible-light region, we doped titanium dioxide nanotubes with iron and sulfur. We used them as a photoelectrode for the photoelectrocatalytic degradation of a model pollutant – phenol red. Response surface methodology using a Box-Behnken design of experiments was used to investigate the effects of initial dye concentration, applied potential, and dopant loading on phenol red degradation kinetics. Statistical analysis showed that our reduced cubic model adequately correlates these parameters. The fastest dye degradation rate was achieved at the optimized conditions: initial phenol red concentration = 5.0326 mg L-1, applied voltage = 29.9686 V, and dopant loading = 1.2244 wt.%. Complete degradation of phenol red may be achieved after 11.77 hours of treatment under the optimized conditions in a batch reactor. Our model's robustness enables it to be used for process modeling and a basis for designing scaled-up photoelectrocatalytic reactors.

Fe3O4-NPs/orange peel composite as magnetic heterogeneous Fenton-like catalyst towards high-efficiency degradation of methyl orange.

Magnetite nanoparticles (Fe3O4-NPs)/orange peel (MOP) composite was prepared via one-step in-situ co-precipitation method as magnetic heterogeneous Fenton-like catalyst. The properties of MOP were characterized by scanning electron microscopy, transmission electron microscopes, Brunauer-Emmett-Teller, X-ray diffraction, Fourier-transform infrared, thermogravimetric analysis and X-ray photoelectron spectroscopy technologies. Its Fenton-like catalytic responses towards removal of methyl orange (MO) were investigated, in which the effects of initial dye concentration, pH, temperature and hydrogen peroxide dosage were studied. The MO degradation ratio up to 98.0% was obtained within 20 min in optimized conditions. The catalyst showed excellent catalytic stability exhibiting nearly 90% degradation ratio in the 10th cycle within 20 min, whereas pure Fe3O4-NPs showed only 62.5% in this stage. Due to the stabilization of complexing orange peel hydroxyl to iron oxide in the composite and its magnetic separation property, MOP composite exhibits excellent Fenton-like catalytic performance, which offers great prospects for low-cost and high-efficiency organic dye wastewater treatment.

Carbonized chilli stalk adsorbent to remove methylene blue dye from aqueous solution: Equilibrium and kinetics studies

The fast growth of textile industry has led to afflictive water pollution problems. The discharge of dyes into the environment poses health threats to the ecosystem due to their carcinogenicity and mutagenicity. Adsorption process is among the most utilized approach in treating textile wastewater. Chilli stalk which is abundantly available as agrowaste was transformed into adsorbent through carbonization process at various temperatures for the adsorption of methylene blue (MB). Dye batch adsorption studies were conducted to evaluate the effects of initial dye concentration (25 – 300 mg/L), contact time (0 – 24 hours) and carbonization temperature (350 - 400 °C). The surface characteristics, proximate and elemental analyses, surface morphology and chemistry were studied on both chilli stalk (CS) and carbonized chilli stalk adsorbent (CCSA). The maximum MB dye removal was 97.04% at 400 °C of carbonization temperature. The data fitted Freundlich isotherm model and pseudo-second-order kinetic model for adsorption equilibrium and kinetic studies, respectively.

Locally available agroresidues as potential sorbents: modelling, column studies and scale-up

Sawdust, cotton stalk and groundnut shell were used for removal of methylene blue from aqueous solution using batch sorption. Effect of initial dye concentration, temperature, and particle size of sorbents on methylene blue removal was investigated. Sorption capacity increases with rise in initial dye concentration and temperature. Impact of particle size on sorption of methylene blue was investigated and indicated that removal of dye increases with decrease in particle size of sorbents. Maximum sorption for sawdust, cotton stalks and groundnut shell were 9.22 mg g−1, 8.37 mg g−1 and 8.20 mg g−1 respectively; at 60 °C and 100 ppm initial dye concentration. Sorption isotherms were analyzed using fundamental Freundlich isotherm. Subsequently, sips isotherm model was employed for better fitting. Kinetic study shows that, biosorption process is pseudo-second-order in nature. During the course of this study, adsorption dynamics revealed that film diffusion was key step for biosorption. In addition, thermodynamics of sorption was studied; and it was found that Gibbs free energy (∆G°) decreases with increase in temperature. Sawdust was found to be best among all the sorbents. Therefore, column studies and breakthrough curve modelling were performed using sawdust. Furthermore, it was estimated that a scaled-up column using sawdust can treat 6672 L of wastewater in 24 h with 80% efficiency.

The Removal of Methylene Blue and Congo Red Dyes from Aqueous Solution by Using Sulfonated Carbon Derived Fishbone

In the world, the dyes pollutant from industrial activity is big issue that must be sought the solution. Among of dyes pollutants were methylene blue (MB) and congo red (CR). In this research have been conducted the removal of methylene blue and congo red onto sulfonated carbon derived fishbone (SCFB) as adsorbent from aqueous solution. The preparation steps of SCFB adsorbent involved the sulfonation (H2SO4; 1M) of fishbone powder for 6 h, by stirrer at room temperature, and followed by carbonization at 500 °C for 2 h. The physical properties of the adsorbents were characterized using Fourier Transform Infrared, X-Ray Diffraction (XRD), and nitrogen adsorption-desorption studies. The dye removal study using SCFB adsorbent was carried out by varying contact time and initial dye concentration. The kinetics models were determined by the effects of contact time. The adsorption isotherms were tested to isotherm Langmuir and Freundlich with a base on the effect of initial dye concentration. The result showed that The removal of MB and CR dyes using SCFB adsorbent fitted a pseudo-second-order kinetic models. The maximum dye removal capacity of SCFB was 128.2 mg g−1 for CR and 35.7 mg g− 1 for MB. Base on the maximum dye removal capacity, the SCFB can be considered as good adsorbent to remove dyes pollutant from environment.

A comparative study of ozonation on aqueous reactive dyes and reactive‐dyed cotton

AbstractOzonation is increasingly being used and reported in recent years. This paper investigates ozonation on aqueous reactive dyes and their dyed cotton comparatively. The effects, including pH, temperature and initial dye concentration (for aqueous dyes)/water pick‐up (for dyed cotton), on Reactive Blue FL‐RN, Reactive Red FL‐2BL and Reactive Yellow FL‐2RN, were studied via Fourier Transform–infrared spectroscopy, ultraviolet‐visible absorption and k/s curves. The kinetic results indicated that all the aqueous dyes were of pseudo‐first order kinetics, while dyed cotton represented pseudo‐secondary or pseudo‐third order kinetics. Based on their different mechanisms, there was a dramatic gap between dyes and dyed cotton in ozonation performance. The curve of rate constant vs pH of dye ozonation exhibited a U‐shape with the minimum value at pH 7, but for dyed cotton ozonation, the curve showed a Λ‐shape optimised at pH 10. Also, high temperature resulted in hydrolysis of dyes in aqueous solution, whereas this was not applicable to dyed cotton. The effect of pick‐up (0%‐150% with an interval of 75%) on reactive‐dyed cotton was greater than the effect of initial dye concentration (which varied from 120 to 40 mg/L) on the colour yield of aqueous reactive dyes.

Adsorption using chitosan and nano zerovalent iron composite material for sustainable water treatment

The growing global population and rapid urbanization have led to a water crisis. Current environmental issues emphasize the exploration of advanced materials and economical methods for purification of wastewater. The present work focuses on using advanced composite material made up of chitosan, activated carbon, zerovalent iron nanoparticles for adsorption of Congo red dye. The adsorbent was characterized using SEM, XRD and FTIR. An investigation was conducted on the critical parameters such as pH, the effect of initial dye concentration, temperature and the adsorbent dosage. The optimum dye to adsorbent ratio was analyzed. The composite material proposed as adsorbent was found to be very effective in adsorption of the Congo red dye. 100% adsorption was noted in 70 min under room temperature for the dye concentration of 100 ppm using 1 g of the adsorbent at pH 7. The efficacy of adsorption increased with the increase in temperature and found to increase under acidic pH. The optimum dye to adsorbent dosage is found to be 1:10. 100% of degradation is achieved within 50 min at a temperature of 80 °C and pH 1. The optimization studies were incorporated to investigate the effects of the variables on the process of adsorption using Box-Behnken design of experiments. The inquest of the present study provides an economical and efficient method for water treatment which can be easily adapted for the wastewater purification.

Single-step fabrication and environmental applications of activated carbon-containing porous cellulose beads

Activated carbon (AC)-containing porous cellulose beads (ACPBs) with a three-dimensionally interconnected porous structure and high impact strength were prepared in a single step from cellulose acetate and AC via a non-solvent-induced phase separation process at room temperature. The adsorption behavior of the ACPBs was evaluated using toluidine blue (TB) dye as a model adsorbate. The effects of initial dye concentration and contact time on the adsorption kinetics and isotherms of ACPBs were studied. The adsorption of TB by the ACPBs followed pseudo-second-order kinetics and could be expressed by the Langmuir adsorption isotherm model. ACPB adsorbed 119.1 mg/g of TB at an initial TB concentration of 101.0 mg/L and the Langmuir equation predicted that the maximum adsorption capacity of ACPBs for TB was 123.5 mg/g. ACPBs could retain original shape and around 85% of their adsorption capacity after three times recycle. Furthermore, ACPBs efficiently removed malodorous gases from gas mixtures, indicating potential for environmental applications including toxic dye and gas elimination.

Tarımsal bir Atık Tarafından Malaşit Yeşilinin Adsorpsiyonu: Pirinç Kavuzu

The main objective of this research was to investigate the adsorption of malachite green as a cationic dye on rice husk as an agricultural waste. Effect of initial dye concentration, pH and time was evaluated. The adsorption data were calculated Langmuir, Freundlich isotherm model and kinetics. Langmuir isotherm (Qmax=8.688 mg/g) is more fitted than Freundlich isotherm. Scanning electron microscope (SEM) results described that characterization of rice husk. Pseudo second order kinetic model fitted well for removal of malachite green. Thus, rice husk was using no-cost and effective adsorbent for adsorption of cationic dyes.

Light-induced degradation of rhodamine B by tellurium quantum dots.

Tellurium quantum dots (Te QDs) were prepared using bulk tellurium as the precursor. Te QDs can be a highly active photocatalyst for boosting the photocatalytic degradation of rhodamine B (RhB) under visible light irradiation. The morphology and composition of Te QDs were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The results showed that in the presence of H2O2, the photocatalytic efficiency of Te QDs on RhB could achieve a good degradation effect within a very short time (30 min). The effects of initial dye concentration, pH value, light intensity, catalyst dosage and H2O2 concentration on dye degradation were successively studied. The effects of inorganic ions (NO3-, Cl-, SO42-, Ca2+, Mg2+ and Fe3+) on photocatalytic degradation were also discussed. Experimental results of free radical capture showed that OH• and O2•- played important roles in photocatalytic degradation. More importantly, Te QDs efficiency still remained above 85% after four cycles of use, indicating good stability, recyclability and utility. This work may inspire further design of other semiconductor QDs for highly efficient dye degradation.

Kinetic Studies of Methylene Blue Degradation using CaTiO3 Photocatalyst from Chicken Eggshells

This study details the kinetic of photodegradation of methylene blue in aqueous medium using CaTiO3 photocatalyst. The CaTiO3 catalyst was prepared by sol-gel reaction using CaCO3 derived from chicken eggshell and anatase TiO2 powder. The CaTiO3 particles were prepared using a mixture of starting materials in of (1:1); (1:3); (2:5) and (2:7) CaCO3/TiO2 molar ratio at T = 900°C. The physical and microstructural properties of CaTiO3 microstructural were characterized by X-ray diffractometer (XRD), scanning electron microscope (SEM), Fourier Transform Infrared (FTIR) and UV/vis spectrometer. As prepared CaTiO3 particles with various composition of CaCO3/TiO2 were then applied for removal of dye molecules under simulated UV irradiation. The effect of initial dye concentration, catalyst composition, and degradation time on the adsorption property of CaTiO3 was systematically investigated. The results reveal that methylene blue (MB) molecules are efficiently adsorbed and degraded within 120 min using CaTiO3 catalysts. Considering the low-cost preparation process and considerably high photocatalytic performance obtained in this work, CaTiO3 can further be used as an efficient photocatalyst for organic pollutant removal from industrial wastewater.

Characterization of Ethyl Violet Adsorption on Used Black Tea Leaves from Aquatic Environment: Kinetic, Isotherm and Thermodynamic Studies

Ethyl violet (EV) is one of the common pollutants in industrial wastewaters. This study presents the kinetic, isotherm and thermodynamic characterization of the adsorptive removal of EV from aqueous solution by used black tea leaves (UBTL) as a low cost adsorbent. Batch adsorption experiments were performed to investigate the effects of initial dye concentration, solution pH and temperature on the adsorption kinetics. Experimental data were evaluated by inspecting the liner fitness of different kinetic model equations such as pseudo-first order, pseudo-second order, Elovich and Intra-particle diffusion models. The equilibrium amounts adsorbed at different equilibrium concentrations were determined from well fitted pseudo-second order kinetic plot to construct the adsorption isotherm. The maximum adsorption capacity, <i>q</i>_m=91.82 mg/g was determined from the well fitted Langmuir plot compared with Freundlich and Temkin plots. Thermodynamic parameters such as free energy change (∆<i>G</i>_ads), enthalpy change (∆<i>H</i>_ads) and entropy change (∆<i>S</i>_ads) of adsorption were determined from adsorption equilibrium constants at different temperatures. The values of thermodynamic parameters revealed that the adsorption of EV on UBTL was feasible, spontaneous and endothermic in nature leading to chemisorption. Again, the equilibrium amount adsorbed, calculated from pseudo-second order kinetic plots for different initial pH of solution was found to be minimum at neutral medium compared with acidic and basic media due to the amphoteric nature of Ethyl violet in aqueous solution and zero point charge of pH of UBTL.