of Kufa for Chemical Sciences

In this research, we discuss the removal of malachite green dye by strontium hydroxyapatite supported BiOCl. A modified hydrolysis model, one can synthesise BiOCl/SrHA. BiOCl/SrHA was characterized using Fourier transform-infrared spectroscopy (FTIR), UV-visible (UV-vis) analysis, X-ray diffraction (XRD), energy diffraction X-ray (EDX), and scanning electron microscopy (SEM). SEM outcome confirmed the dispersion of BiOCl onto strontium hydroxyapatite. The shape of the BiOCl catalytic samples overlapped with each other to form 3D hierarchical flower-like structures. The UV-visible was used as a radiation source during photocatalysis. BiOCl/SrHA had an effect on malachite green dye degradation. The oxidative removal occurred through hydroxyl radical formation. UV-visible (UV-vis) /BiOCl/SrHA showed perfect photocatalytic property for the decay of malachite green (MG) from an aqueous solution. According to kinetics analysis, the dye degradation rates could be in a pseudo-first-order model.


INTRODUCTION
Pollutants can be elements, molecules, or particles that have a great impact on living organisms and cause damage to the environment (1) .Plants and trees cannot grow in the absence of clean water.That is, there is no source of food, and this, in turn, can affect the economic conditions of humans, and here we must admit that 521 bismuth oxychloride (BiOCl) as the first BiOX compound (8) .In recent years, there have been many medical, domestic, and industrial pollution problems.So As a result, efforts have been made to address this serious issue through practical research (9) .In this field, nanoparticles have been used extensively to reduce this dangerous phenomenon (10) Many nanomaterials have been used, including bismuth oxyhalide BiOX, and these compounds are distinguished by the fact that they have unusual properties that make them distinguished compounds in this field.The formed Bi nanoparticles on the BiOCl surface accelerate the transfer of photo-induced electrons from BiOCl to Bi, and the surface oxygen vacancies on the BiOCl photocatalyst result in its bandgap narrowing to the visible light range (11) .Many experiments have been carried out in the process of replacing the element strontium (Sr+2) to replace the element calcium (Ca+2) in the compound hydroxyapatite, particularly in biological experiments, specifically in bones, where experiments have proven that the element strontium (Sr+2) is non-toxic and stable when bound to hydroxyapatite (12)(13)(14)(15)(16) .
The use of more than one in pH of the liquid mixture(solution) has a significant influence on the process of adsorption of the solution, because of its action on both the solvent and solvent surfaces.In the situation of surfaces that include polarized or charged positions, the amount of adsorption increases if the surface obtains a charge that skips the charged minute charge through the action of the acidic function.On the contrary, the amount of adsorption is low if the surface and the absorbed minutes obtain a similar charge (17) .One of the parameters that are considered an important factor and play a major role in the absorption process is the temperature.The reaction takes one of two paths either it is an exothermic or endothermic process.

522
The Synthesis of SrHA in the following method: (18)(19) .A solution of H3PO4 0.3 mol.L-1 was vigorously mixed with a solution of Sr(NO3)2 0.5 mol.L-1 (Merck, 99.67%) (molar ratio Sr/P =1.67.By adding NH4OH (Merck, 30%), the pH of the solution was adjusted to 9.0.A white precipitate was formed, and the suspension was stirred for 2 h.Thereafter, the precipitate was washed with distilled water and vacuum filtered.
The preparation reaction occurs according to equation (1).

Initial dye concentration
Figure 6 displays the impact of initial dye concentration on photocatalytic dye decay at various time intervals.The results show that dye degradation decreases as the initial dye concentration increase.The potential reason for the increase in the dye concentration, is the intervention of intermediates composed upon the decay of the parental dye molecules.Such repression would be more obvious in the presence of a high level of degradation intermediates composed upon an increased initial concentration (22) .To insert the application of the zero-order, first-order, and second-

Bi 2 O 3 ( 1 . 3 .
5g) was dissolved in excessive concentrated hydrochloric acid (10 mol/L, 10 mL) to obtain a transparent BiO 3 -HCl aqueous solution.To this solution, 1.2 g of SrHA was added with simultaneous stirring.The obtained mixture was sonicated for 15 min.The pH of the solution was adjusted between 2 and 3 using ammonia.The mixture was heated at 90 o C for half an hour to obtain white precipitates.The precipitates were washed several times with water and ethanol and then dried at 75 o C for 10 h.The acquired product is calcined in an electric furnace for 3 h at 550 o C. to obtain BiOCl/SrHA nanoparticles.Photocatalytic dyes degradation and reactor 523 Experiments were carried out in a mode photoreactor.The sample was irradiated with UV light using (λ=254nm, 30V).The photocatalytic dye's degeneration tests were operated by mixing different amounts of BiOl/SrHA nanoparticle in a photoreactor containing 1000 mL of each dye solution (20 mg/L) at room temperature (25 o c).The solution patterns were withdrawn from the reaction medium at systematic time intervals.We separate BiOCl/SrHA from the solution and note the change in the catalyst adsorption process for these dyes at the maximum wavelength (ʎ max ) 615 nm for Malachite green (MG) by UV-vis spectrophotometer (Perkin-Elmer Lambda 25).The effect of BiOCl/SrHA nanoparticles concentration on photocatalytic dyes degeneration was investigated by contacting 1000 mL of dyes solution 10 mg/L for Malachite green (MG) at room temperature (25 o C) for 5 h.Various amounts of BiOCl/SrHA nanoparticles were used.The effect of initial dye concentration on photocatalytic dye degeneration was calculated.The BiOCl/SrHA nanoparticles (0.05 g) Malachite green (MG) were added to 1000 mL of different dye concentrations (10, 20, 30 and 40 mg/l) of Malachite green (MG).

Figure 1
Figure 1 shows the FT-IR spectra of BiOCl/SrHA, the range of (3483-3448) cm−1 may refer to the stretching vibrations of −OH that existed in the adsorbed water molecule.Furthermore, the distinct peaks at range (1627) cm-1 refer to the O-H bending vibrations-for pure BiOCl, 509 cm−1 corresponds to valence symmetrical

Figure 2
Figure 2 was sample BiOCl/SrHA overlapped with each other.The morphology of BiOCl/SrHAp diagnosed by scanning electron microscopy (SEM) is fixed in SEM visual data which shows a quite different morphology.Notably, the surface structureof BiOCl/SrHA changes to marked rise with some holes that look like bunches of grapes that were not present before being installed when modified, This explains the presence of a large surface area, which increased the adsorption process of the dye Malachite green (MG).The widely used dyes, were chosen as the test pollutant to evaluate the photocatalytic activity of synthesized BiOCl/SrHA.The phase structures of the as-synthesis BiOCl/SrHA specimens were examined by XRD.

Fig. 3 :Fig. 4 :
Fig.3 : (A) X-rays diffraction patterns of BiOCl, (B) X-rays diffraction patterns of SrHA (C) X-rays diffraction patterns of BiOCl/SrHA 3) where C o and C are the initial dye absorbance and dye absorbance at time t, respectively.The k o , k 1 , and k 2 are the zero-order, first-order, and second-order rate constants, respectively.To insert the applicability of the zero-order, first-order, and second-order kinetics models for photocatalytic dye degradation by the nanoparticle of BiOCl/SrHA at different catalyst dosages, linear plots of C o -C against different t), ln (C o /C) against different irradiation time (t), and 1/A against different irradiation time (t) are plotted.The values of k o , k 1 , and k 2 , R 2 (correlation coefficient values) are displayed in Table

2 Fig. 6 :
Fig.6 :(a) Dye concentration effect on the degradation of dyes using UV/BiOCl/ SrHA , (b) The zero-order (c) The first-order (d) The second-order kinetic of photocatalytic dye degradation by BiOCl/SrHA at different dye concentrations