Adsorption Study of Rhodamine –B Dye on Plant (Citrus Leaves)

: The current research includes the adsorption of Rhodmine-B Dye on the surface of Citrus Leaves using the technique of UV. Vis spectrophotometer to determine data of quantitative adsorption at various contact time, ionic strength, PH and temperature conditions. As a function of temperatures 25,35,45,55 0 C, the dsorption phenomenon was examined, and the results showed that Rhodamine-B adsorption Citrus leaves rose with increasing temperatures on the surface (endothermic process). Using various NaCl solution concentrations, the effect of ionic strength on adsorption has also been studied. Increasing the importance of ionic strength has been shown to improve the amount of adsorption of Rhodamine-B on citrus leaves at constant temperatures.The quantity of Rh-B dye that was adsorbed on the citrus leaves was increased with increasing the PH of the solution in rang 3-7. Then the results were subjected to the practical results obtained with the use isotherms of the Langmuir, Frendelsh, and Temkin. The results can be shown that the isotherm suitable for adsorption applies to Ferndelsh and Temkin. The thermodynamic functions (the amount of change in enthalpy, the amount of change in entropy and the amount of change in the free energy of Gibbs) were also studied, and it was found that the thermodynamic results of the adsorption process of the Rhodamine-B dye on the powder of citrus leaves are endothermic and an automatic adsorption process.


Introduction:
Today, all societies suffer from water pollution problems due to the drainage of industrial effluents into surface water contaminated with toxic dyes from a wide range of industries, such as textiles, leather, sheet, printing, food, beauty products, paint, rubber, plastics, pesticides, wood preserving chemicals and pharmaceuticalindustries 1 . Water pollution is defined as water contamination and the alteration of water's physical, chemical and biological characteristics. It entails the dumping of any sewage or commercial waste or any other fluid. In water, gaseous or solid compounds are likely to produce a nuisance by means of their physical presence, odor or taste. Such discharge can damage and harm Water for the public as far as domestic hygiene is concerned. They are concerned with commercial, manufacturing and agricultural life.
The discharge of dye effluents also imparts color from the sources for miles downstream to the receiving stream. This color is aesthetically unacceptable and therefore decreases the penetration of light into the water, thus limiting the efficacy of photosynthesis in aquatic organisms and thereby making an adverse impact on their growth 2 .
Natural compounds like the toxins, surfactants, some synthetic dyes and their precursors have varying biochemical and morphological influences on plants and animals 3 .
A dye is a colored compound that binds chemically to the substrate to which it is added. This separates dyes from pigments that do not bind to the substance they color chemically. The dye is normally added in an aqueous solution and will need a mordant to enhance the dye's intensity on the fiber 4 Dyes can cause skin inflammation, accelerated heartbeat, vomiting, diarrhea, tissue necrosis, and shock 5 .
Dyes can be categorized in different ways: (e.g., according to the chemical constitution, application class, and end-use). The Principal categorizations of dyes are based on the natural fibers to which they will be applied and the chemical of each dye character. In order to form chemical bonds, reactive dyes react with fiber molecules 6 . Dyes may be categorized as anionic: direct, acid, and reactive dyes; cationic: simple dyes; and non-ionic: disperse dyes 7 . Rhodamine B (RH-B) is a synthesized organic colorant used as biological stain in paper, draw, food, leather, pharmacy, cosmetic, labs, etc. This colorant has a carcinogenic and toxic effect, hence the use in food and cosmetics is currently limited 8 .
For the removal of dyes, many methods involving biological, physical, chemical and related technology have been published. Adsorption is the treatment of choice among the many therapies and provides the best outcomes as it can be used to extract various forms of dyes simultaneously 9 .
In brief, by physical isolation, chemical methods or biological degradation, dye recovery from waste water can be accomplished. Adsorption, oxidation, biological therapy, electrochemical treatment, membrane filtration, and coagulation flocculation are several major techniques that are commonly used for the removal of dyes 10 .
This method of adsorption is used to remove chemical chemicals, hazardous substances, dyes, and other products that conventional techniques do not remove. Adsorption on certain textures, such as natural materials with porous properties such as activated charcoal, zeolite, silica gel, porous clays, some agricultural residues, and plant parts, may largely eliminate these components 11 .
In contrast to other processes, adsorption of farm waste has a low cost and high performance benefit [12][13][14][15] . In this work, the adsorption of RhB dye from aqueous solutions on Citurs leaves powder, which are considered environmentally friendly and of lowcost. The efficiency and behavior of adsorbents were studied at different concentration and temperatures.

Material and Methods: Chemicals and Apparatus
Rhodamine B molecular dye formula (C 28 H 31 ClN 2 O 3 ) and chemical composition Fig.1 is supplied by the HIMEDIA Company while citrus leaves were collected from the University of Baghdad gardens. The leaves of Citrus aurantium contain organic chemicals, including alkanes, alcohols, carboxylic acids, esters, soaps, etc. 16 Sodium hydroxide was supplied from BDH with purity 99%, Hydrochloric acid was provided from BDH with purity 37%, and Sodium chloride with purity 99.5%. Thermostated Shaker water bath model JEIOTECH (BS-11)-Germany was used to shake the aqueous solutions of dye with adsorbents, while Remi Centrifuge Model R&C. Bombay-India was utilized to separate the adsorbents from the aqueous solution of dye. UV-Vis spectrophotometer model PC1650 Doube beam -Shimadzu was used to record absorbance of Rhodamine B before and after adsorption experiments. pH-mater model Hanna-HI-8417-England was used to adjust the pH of the solutions

Absorbed Substance
By dissolving specifically weighted colour in refined water to the centralization of 8 ppm, the rohdamine B dye stock structure was set up, was used without aiding cleaning at λ max 542 nm, Fig.2 indicates the dye absorption spectrum. The arrangements were accomplished by weakening the structure of the color stock to different starting focuses in precise ranges from Fig.3 shows the calibration curve, which was used to convert the absorbance value of dye to concentration according to Beer-Lambert law.

Preparation of Citrus Leaves Powder
After they were picked, citrus leaves were washed and the leaves were cleaned with plain water from the soil clinging to them, then washed with purified water, dried in an oven (Hot Air Oven LTD, LDHAM, England at 90 Co for 30 min, and ground with an electric grinder after drying, sifted with a sieve 75μm and stored away from moisture

Batch Adsorption Experiment
To prepare 100ppm from the dye, 0.1 gm of RhB was dissolved in 1L of distilled water. Different dye concentrations were prepared for RhB at concentrations of 2-14 ppm. 0.1M of HCl and 0.1M of NaOH solutions were used to adjust the pH according to the media in which the adsorption process was conducted takes place and to reduce the error resulting from changing the acidity of the media on the sample size and prepare NaCl solution 0.1, 0.01, 0.001 M. The adsorption was observed by evaluating the convergence of Rhodamine B in a double bar Visible spectrophotometer configuration, at λmax 542 nm. The percentage of dye expulsion and volume of rhodamine B adsorbed on adsorbent was determined using the following equation to determine the-qyantity of dye adsorbed 17 Eq.1.
Where the main and equanimity (mg/l) amounts of dye, respectively, are C 0 and C e . At the moment of equanimity (mg/g), Q e is the sum of dye adsorbed on the adsorbent, V is the volume (l) of solution and W is the mass of the adsorbent (g).  The surface mass that provided the lowest absorbency (highest adsorption value) was picked and was 0.4 gm from the surface of the Citrus aurantium leaf powder.
Although the rise in the weight of the powdery orange leaf powder surface contributes to an increase in the amount of active sites primed for dye adsorption on the adsorbent surface, this means an increase in dye adsorption.removal percentage to increase the surface effectiveness.

Determine the equilibrium time of adsorption systems (Contact Time)
To evaluate the time necessary for the adsorption of Rohdamine B on the surface of the powdered Citrus leaves to achieve the equilibrium state at temperature 298 k and concentration C 0 = 8 ppm for coloring and with a steady adsorbent weight 0.4 g . Fig.5 indicates that the dye (RB) is quickly absorbed when the dye is adsorbed into the powdered citrus leaf in the first 30 minutes. This arises because the active centers on the adsorbent surface are empty, but the adsorption slows down as these active centers are filled with dye particles.

Effect of Temperature
The effect of the adsorption temperature of the simple rhodamine B dye on the surface of the powder of Citrus aurantium leaves in the thermal range 25, 35, 45, and 55 o C was analyzed by fixing the adsorbent mass 0,4 g from the surface of the powder of Citrus aurantium leaves and at the concentrations 2,4,6,8,10,12 ppm of the dye Fig.6 .  bearing in mind the overarching objective of how the additional set of sodium chloride courses of action triggers increased rivalry at first glance between rhodamine B particles and electrolyte particles over the expulsion aims 19 .

Adsorption Isotherm
The adsorption on the surface of Citrus aurantium leaf powder of rhodamine B dye from its aqueous solution was tested at varying amounts and at different temperatures 298, 308, 318, 328K . The findings demonstrate that Ferndelsh and Temkin are protected by an isotherm appropriate for adsorption.
-Langmuir Adsorption Isotherm The Langmuir isotherm was calculated by the following Eq.2 C e /Q e = 1/q max K L + (1/q max ) C e ………………. 2 If C e is the adsorbate equilibrium concentration (mg/L),Q e is the sum of adsorbed per gram of equilibrium adsorbent (mg/g),q max is the overall adsorption power (mg/g) and K L is Langmuir is the adsorption energy constant Fig.11 .

Freunddlich Isotherm
The isothermal equation was determined as follows log Q e = log K f + 1/n log C e ……… 3 Where Q e is adsorbed dye (mg/g) is the indicator of Rh B, C e is the equilibrium grouping of in the structure, color (mg/l), K f and 1/n are constants that integrate the elements influencing the adsorption cap and the force of adsorption, individually, separately Fig.12.,

Temkin Isotherm
Temkin discovered the impacts of certain circuitous sorbate/adsorbate relationships on adsorption isotherms and proposed that the warmth of adsorption of a large number of particles with scope decreases directly in the sheet in view of these relations. The Temkin isotherm was used after the Eq.4 Fig.13. Q e = B T ln K T + B T ln C e ……………… 4 Where . B T , K T = the equilibrium binding constant (1/g)

Figure 13. Temkin Isotherm relationship between Qe and lnCe for Rhodamine B dye on Citrus aurantium leaf powder at a temperature range: a) 298 b) 308, c) 318 and d) 328 K
As can be seen from the calculated results in the Tab.1 the R coefficient figures were akin to 1, and for all isotherms, which means that a reasonable one is available in the relationship between Qe and lnn, the corresponding Ce at various temperatures that suggest the useful calculations of the constants. Adsorption of the Freundlich and Temkinin have better explained isothermal for isotherm shows.

Thermodynamic of Adsorption Process
The effect of thermodynamic factors on the adsorption of rhodamine B on the surface of Citrus aurantium leaf powder at the temperature range 298-318K was studied. Where the study of the effect of temperature on the adsorption process enables us to specify the values of the thermodynamic functions (enthalpy, entropy, free energy) for all adsorption forms, as shown by the Van't Hoff equation, the adsorption equilibrium constant (K eq ) was calculated as (ln Q e /C e ) against the temperature as (1/T) by means of plotting) 20 . The outcomes are recorded in Tab.2 and Fig.14 for the importance of these functions in understanding the adsorption phase system. ΔG = -RTlnK eq …………………. 5 Ln K eq = -∆H/RT + ∆S/R………………6 ΔG = ΔH -TΔS …………………….7 where K eq is adsorption equilibrium constant and R is the gas constant

Conclusion:
The adsorption of Rhodamine B dye by citrus leaves powder has been determined. The adsorption was measurement that the dose of adsorbents was 0.4g. The amount adsorption of Rhodamine B dye increasing in PH = 3,7 but decreased with increasing PH. The best contact time within of 30 min for citrus leaves powder. The ionic strength was increasing with an increasing concentration of Sodium chloride. The adsorption process supplied Freundlich and Temkin isotherm models. The thermodynamic factors: ΔG spontaneous, ΔH was endothermic in nature, in addition, the values of ΔS were positive (higher).