Removal of Reactive Black-5 Dye by Adsorption Using Rhamnus pits as Agriculture Waste for Environmental Sustainability

The ability of reuse the agriculture waste to absorb Reactive Black 5 (RB5) dye from textile waste water is being investigated in this study. Rhamnus pits (RP) was used as an available waste material as an adsorbent by inciting and impregnating it with a strong base (KOH) and a strong acid (HCL) to produce a substance with high adsorption efficiency. The impregnation process was carried out in stages. First, the RP stones was incited at a temperature of 300 °C by the carbonization process, and then a part of the sample was impregnated with hydrochloric acid HCL (a strong acid) and a sample with sodium hydroxide KOH (a strong base), and then it was incited by the activation process by inciting it at a temperature of 600 °C. There were three types of adsorbents: one without impregnation, one impregnated with a strong acid, and one impregnated with a strong base. These samples were used for dye adsorption (RB5). Several factors and their impact on the adsorption procedure were investigated and utilized to calculate the adsorption capacity and the highest adsorption rate. It declared that the best removal percentage was achieved when impregnated with KOH (94.22%) and HCL (86.42%), while the free sample without impregnation had a 58% removal efficiency. The adsorption process was done at a temperature of 30 °C (86 °F), dose 0.05 g/10 ml of dye solution, time of 60 minutes, and 25 mg/l concentration of dye solution. Two standard adsorption isotherm models were used to determine the equilibrium adsorption curves. The Langmuir isotherm model provided a decent match to the data for RP pits activated with KOH. Adsorption kinetics were investigated using two different kinetic models: pseudo-second order and pseudo-first order. It was shown that the adsorption rate increases dramatically at first and then decreases to reach equilibrium. The data were showed good match by the model of the pseudo-second order with a confidence level of 0.9997.


Introduction
Due to the increased use of synthetic chemicals in industry, which causes the discharge of paints, dyes, and heavy metals and other inorganic and organic chemical compounds into the environment, water treatment has become a significant issue in the contemporary period.[1] Innumerable sectors employ the more than 70,000 metric tons of synthetic dyes produced each year.[2] Reactive dyes in particular are rising in popularity as a result of their numerous advantageous properties, such as their inexpensive price, outstanding color fastness, brilliant colures, and ability to generate a wide spectrum of colors, from dark to bright, vivid tones.[3][4][5] Chemically, the structures of reactive dyes are extremely complex.Reactive dyes have organic rings, vinyl sulfonic groups, and chlorine atoms in their chemical compositions.[6] [7]  The discharge of textile effluents into traditional systems need separation and improved treatment due to the presence of hazardous and carcinogenic dyes.[8] Because dyes are not easily broken down by bacteria, the typical biological wastewater treatment procedure is not effective when used to dye wastewater.Because of this, scientists have looked at physicochemical strategies for treating textile wastewater that effectively eliminates color.[9] Many products from the forestry and agricultural industries can be transformed into efficient bio sorbents.[10] Ziziphus seeds are biomaterial byproducts that have been used to remove "2-((10-octyl-9, 10-dihydroanthracene-2yl) methylene) malononitrile (PTZSCN)" aqueous solutions dyes from (GOZiziphus).In a batch study, the effec ts of PH, starting dye dose, temperature, and contact time were examined.In order to analyze the kinetic data, various nonlinear models and methods were used, including the elvoich model and intraparticiple diffusion as well as the general order model.Dye adsorption onto GO-ziziphus reveled good agreement of paints, dyes, and heavy metals kinetic model.According to the findings, GO-ziziphus powder might be utilized to successfully clean wastewater containing dyes.[11] The fibers from the banana stem is used to remove methylene blue dye (MBD), and their adsorbent effectiveness to examine their potential for use in cleaning up textile effluent waste.pH equal to 10, a temperature of 25 degrees Celsius, a concentration of 5 milligrams per milliliter, a stirring speed of 125 revolutions per minute, a dose of 2.5 milligrams per milliliter, and a mixing period of 150 minutes, banana stem fibers (BSF) killed 97% of MBD.[12] The porous nature of an eggshell makes it a promising material for adsorption studies.The eggshell has three distinctive layers: ceramic material, the cuticle, and a porous layer.The eggshell is made up of spongy layers for more than 90% of its total mass.Protein fibers coupled to calcite create a matrix inside these strata.[13] The equilibrium separation process of adsorption is well-known and has shown to be an efficient technique for the purification of water.Comparatively speaking to other water reuse techniques, adsorption excels in terms of its low cost of implementation, as well as its remarkable versatility and efficiency.Adsorption does not result in the development of hazardous compounds, and it is also simple to apply and is insensitive to toxic pollutants.[14] The purpose of this research is to use agriculture waste as adsorbent to be able to remove the harmful impact of RB5 dye from textile water by identify the optimal adsorption conditions (concentration, temperature, contact duration, and adsorbent dosage).Rhamnus pits (RP) a byproduct of the fruits, were shown to be promising adsorbent for RB5 removal after just a short period of agitation, indicating that RP is a viable material for future uses.The research included thermodynamic, kinetic, and isothermal models.

Materials and Methods
Nitrogen inert gas, purified to 95%, was used as the inert medium for the process.Hydrochloric acid (HCL) and Potassium hydroxide (KOH) with 97% of purity were used as impregnator.The RB5 stock solution prepared by dissolving 0.05 g of Reactive Black 5 (RB5) in 1L of deionized water.Table 1 shows the RB5 features.In this investigation, RB5 was chosen because it is often used in the textile industry under a variety of brand names.These include "Cavalite Black B, Celmazol Black B, and Diamira Black B". [15] Many different types of azo dyes have been employed in textile dying because of their inexpensive cost, ease of application, and low toxicity [16][17][18].Most azo dyes include just one azo group, but others have two (diazo), three (triazo), or more.The low degradation rates and potential for the development of harmful degradation by-products in synthetic dyes are a result of the one or more benzene rings present in their molecular structure.As a result, azo dyes must be removed from effluents before they may be released into the environment.

Preparing of the Rhamnus pit and two kinds of impregnation
Rhamnus pits (RP) was collected from the local markets in the city of Diwaniyah in Iraq, and the pits were extracted from them, and about one kilogram was collected for the purpose of preparing activated carbon, a picture and a diagram of the experimental installation of a system for the production of carbon from RP are shown in Figure 1.The pits were washed with de-ionized water, dried, ground and sifted with a sieve 88 mm. Figure 1) a) shows the form of the resulting powder ready for the incitation process.Several tools were used in order to complete the burning process correctly: 1-The reactor as shown Figure 1 (b) with a steel tube wrapped around the reactor that allows nitrogen to pass in controlled quantities to cool the sample and prevent it from burning due to high temperatures.1-The carbonization process by burning the RP powder at a temperature of 300 °C for 2 hours in the furnace.The resulting is activated carbon powder.
2-The impregnation process by soaking part of the sample with a HCL solution and part of the sample with a KOH solution for 24 hours.
3-The process of activation by burning again in the presence of nitrogen gas at temperature of 600 °C for 3 hours after that the powder washed many times by de-ionized water until the pH equal to7±0.15

Experimental work
In order to create the RB5 solution, 0.05 grams of RB5 powder were mixed with 1 liter of deionized water.Prepared solutions were diluted with de-ionized water to achieve a concentration of 25 ppm in accordance with the law of dilution through equation (1).We used five solutions with known concentrations to calculate kinetic and adsorption isotherm parameters.
Where V1, V2 stands for initial and final volume, C1, C2 stands for initial and final concentration (mg/g), and The equilibrium data, known also as the isotherm's adsorption, gives context for the kind of interaction between the adsorbent and the adsorbed species.Various models may be used to derive parameters that provide important details about the adsorbent's surface properties and its connection with the adsorbate.In this study, we analyze some of the equations from the Freundlich and Langmuir modules.A boiling flask was used to study the adsorption isotherms of RB5 onto natural (RP), RP pre-carbonization with base and then carbonation to activated carbon (RPKOH), and RP pre-carbonization with acid and then carbonation to activated carbon (RPHCL) at temperatures of 30, 40, 50, and 60 degrees Celsius.After that, we placed the flask on the magnetic stirrer's heated plate.
As a first step, the equilibrium time was determined to be 1 hour by periodically sampling liquid from a boiling flask; after this duration, there was no discernible change in concentration.
For the second part, adsorption equilibrium isotherms were obtained by combining 0.05 g of each kind of produced RP with solutions of RB5 at various concentrations (5, 10, 15, 20, and 25) ppm.For 1 hour, the mixture was stirred constantly while kept at the same temperature on a hot plate magnetic stirrer, achieving equilibrium.

B
The completed product was analyzed in September 2022 using an Ultra violet-visible photo spectrometer instrument (UV) at the laboratory at Al-Qadisiyah University/college of civil engineering.Using an equation, one may determine the amount of adsorption (2) [19] ( Finally, the kinetics were analyzed in the same way as in equilibrium, but samples were collected at varying periods up until the final sample was obtained at equilibrium.

Adsorption Models
Commonly, the equilibrium of adsorption of the adsorbate onto the surface of the adsorbent at a constant temperature is described by means of adsorption isotherms.Optimization of adsorbent utilization relies heavily on the information provided by adsorption isotherms, which characterize the interaction between adsorbates and adsorbents.[20] Due to this the interactions among the adsorbate and adsorbent molecules, adsorption isotherms may also provide light on the adsorption process.

Langmuir, Isotherm
It is a significant model that explains the adsorption of the pure substance on the surface of adsorbents and is considered to be one of the most important models.The following presumptions underlie this model: The adsorbate molecules had the same amount of energy in all of their localized places, a monolayer had formed on the catalyst's surface, and the result was predicted mathematically, and that the molecules adsorbed on the surface of the adsorbent did not interact with one another.Is given by eq. ( 3) [21]:

Freundlich Isotherm
The Freundlich adsorption isotherm model accounts for this fact that various locations on an adsorbent's surface will have varying enthalpies.The model of Freundlich adsorption isotherm is shown below.[22] 6 (4) KF = (mg/g (1/mg) 1/n) the affinity of the adsorbate for the adsorbent.

Kinetic-Models
The diffusion process and rate-controlling steps were investigated using kinetic modeling, which included [the pseudo-first order and pseudo-second order] [23]

Pseudo-First Order Model
Lagergren model, developed in 1898, assumes a first order adsorption kinetic and can be explain by the Equation ( 5): (5) For the first phases of an adsorption process, this formula is valid because the difference between the saturation concentration and the quantity of solid absorption over time is precisely proportional to the rate of change in solute uptake over time.The Lagergren the adsorption kinetics at an interface where diffusion regulates the adsorption rate is frequently explained using the pseudo-first-order equation. [24]

Pseudo Second Order Model
Pseudo-second-order kinetic rate of adsorption Expression of the equation (6) Predicts behavior over the whole adsorption range on the basis of the assumption that chemical sorption or chemisorption is the rate-limiting phase.Under these conditions, the adsorption rate depends on the adsorbent's capacity for absorption rather than the adsorbate's concentration.One advantage of this model over Lagergren first order is that it allows for equilibrium adsorption capacity forecasting, eliminating the need for experimental measurement of the adsorption equilibrium capacity.[24] 4. Result and discussion

Equilibrium of adsorption
The adsorption equilibrium isotherms showed the impact of temperature for various RB5 dye concentrations, as different temperatures and different concentrations were studied and the best removal was found at any temperature and at any concentration, and adsorbent is fit for a given models were studied to see their applicability to the entered values.
Figure 2 displays the proportion of RB5 dye that was removed by different types of activated carbon., where it was found that the best removal was when activate the RP with a KOH, where R% equal to 94.2% and qe 3.460 mg/g, as showed in Figure 3 (c) Adsorption equilibrium isotherms of RB5 onto RP, RPHCL, and RPKOH are shown in Figure 3.All three RB5 curves (RP, RPHCL, and RKOH) for the produced RP exhibit the same basic shape, a type (1) classic adsorption isotherm.The process generates heat, or "exothermic" the adsorption capacity (qe) of the RP diminishes as the temperature rises [25] Figure 2. Removal percentage of RB5 for varing concentrations(5,10,15,20& 25 mg/l) and temperatures(30, 40, 50& 60) C0 for RPKOH.
Table (2) and ( 3) shows the R 2 value for the two models use, it is shows applicability when using langrage isotherm since it reveals the largest value of R 2 .According to the parameters shows in figures 3 and 4 when using KOH as activating agent revels highest value of adoration.
Table ( 2) and ( 3) show that when using RPKOH as activating agent the parameter of the two-isotherm achieved best outcomes.This becomes more apparent when the experimental data is plotted linearly using the Frendlich and Langmuir isotherms, as illustrated by the related equations ( 3) and ( 4) [26] a b The data displayed in Figures 4 and 5 are supported by the outcomes of Equations 3 and 4.These graphs show that the Langmuir adsorption isotherm represents the experimental data more accurately than the Frendlich adsorption isotherm.When the adsorbate coverage is limited to a single molecular layer, the Langmuir adsorption isotherm can be used as an example.In other terms, the Langmuir model makes use of homogenous surfaces.As a result, it was determined that RB5 adsorption on all Rhamnus preparations is restricted to a monolayer and that the surfaces of all Rhamnus preparations are uniform.

Kinetic of adsorption
In order to look into adsorption rates, both first-, as well as second-order kinetics were used.The rates of RB5 adsorption onto the three different types of Rhamnus pits at (30, 40, 50, or 60) Co are shown in Figure 5 for various types of prepared activated carbons (RP, RPHCL, and RPKOH).The figures show that, as anticipated by equations ( 5) and ( 6), the application of which was studied, the capacity for the RB5 dye grows fast in the first 15 minutes and subsequently increases very little until equilibrium is attained.The high initial rate of adsorption may be explained by the high concentration of absorbable solute molecules and the availability of the unoccupied active sites on the adsorbent.The experimental, the pseudo 2nd-order adsorption kinetic model provides a good explanation for the results.As a result, this model equation gave the best explanation of the data.For example, Figure 6 shows a linear representation of the data acquired by fitting the data to the equations of the pseudo-1st order kinetics model, and Figure 7 shows a similar representation of the data obtained by fitting the data to the equations of the (4,5).As the figures also illustrate, the data and the 2nd order kinetic model exhibit some moderate consistency.The adsorption process seems to go through a number of distinct phases as shown by this evidence.These findings further reveal the multi-step mechanism involved in the adsorption of RB5 onto the Rhamnus forms.

Temperature effect on the removal percentage
It states how temperature affects various types of activated carbon by demonstrating that higher temperatures result in less activated carbon being removed.Figure 8 demonstrates that at 30 C0, the R% of RPKOH is equivalent to 94.12%, and by 60 C0, it has dropped to 86%.This must be correct since comparable behavior was discovered by [28].They concluded that this was due to the fact that "adsorption forces among the dye molecules and the active location get smaller with increasing temperature," which explains why RB5 removal was diminished at higher temperatures.

Conclusion
The use of low-price agricultural waste in order to make a manufactured material that has an impact on creating a clean environment was investigated in this paper.Rhamnus Pits are considered an expensive because they are the waste of the fruit of the Rhamnus and treating them in a way that makes them useful for treating textile water.The results showed good results to remove RB5 dye by Rhamnus activated carbon , in order to raise the adoration efficiency chemical activating is been used, where the highest removal rates were found for the activated carbon activated with KOH, which reached (94.22%) and using HCL reached (86.42%) and activated carbon without activation reached 58%.The results showed excellent agreement with Langmuir isotherm model at temperature of 30 Co, nonetheless, adsorption effectiveness drops down significantly with increasing temperature.due to the fact that at higher temperatures the adsorbed molecules have a better chance of dissociating from the adsorbent surface and re-entering the solution.Because of the heterogeneous character of the surfaces, the adsorption of RB5 onto any kind of RP is best represented by the Langmuir model for the adsorption isotherms and the psuedo-2nd order kinetic model for the kinetics data.Overall, RPKOH had a greater adsorption capacity for RB5 than RP and RPHCL on most RP preparations.The findings from this study will make RP a more effective method for cleaning wastewater of dye.

2 -Figure 1 .
Figure 1.(a) Rhamnus pits preparation (b) picture of vessel (reactor) (c) graphite RP powder is prepared by placing 70 grams of powder in a graphite crucible, covering it with a piece of mineral wool, and placing it in the reactor.The sample was burned in steps as fallow: Where Ce = equilibrium solute concentration [mg/l].qe = equilibrium adsorption capacity at, [mg/g].KL = free energy of adsorption constant [l/mg].qm = monolayer maximum adsorption capacity [mg/g].

Table 2 .Figure 6 .
Parameters of the Frendlich isotherm for RB5 on RP, RPHCL, and RPKOH b c Adsorption of RB5 dye by powder of (a) RP, (b) RPHCL, (c) RPKOH as function with time