CharacterizationXRDThe phase composition and crystallinity of spinel ferrite AgxZn(0.5-x)Ni0.5Fe2O4, where x = (0.1, 0.3, 0.5) (SF) and Ag0.1Zn0.4Ni0.5Fe2O4@mSiO2 (SFS) were analyzed by XRD (Fig. 3). All prepared ferrite AgxZn(0.5-x)Ni0.5Fe2O4 exhibited characteristic peaks of the spinel structure of the face-centered cubic (fcc), according to the database of JCPDS (code 00-052-0279)49. These peaks appeared at 2θ = 29.8°, 35.1°, 38.07°, 42.65°, 53.09°, 56.56°, and 62.09°, which could be imputed to (220), (3 1 1), (2 2 2), (4 0 0), (4 2 2), (333), and (4 4 0), respectively. The spinel phase’s development is shown by the strong peak visible at the (311) plane50. The highest peaks slightly migrated towards lower angles as the Ag+ content rose (when x = 0.5), confirming the Ag+ substitution for Zn2+. Additionally, the peaks widened, indicating that the ferrite nanostructure had formed51. The broad peak in the range from 20° to 25° is attributed to the existence of amorphous SiO2 in the coated layer52.Figure 3XRD pattern of spinel ferrite AgxZn(0.5-x)Ni0.5Fe2O4 where x = (0.1, 0.3, 0.5) and Ag0.1Zn0.4 Ni0.5Fe2O4@mSiO2.Scherrer’s formula53, was used for calculating the size of the crystallite (d) from the strongest peak.$$d=\frac{0.9\lambda }{\beta \text{cos}\theta }$$
(4)
where β is the full width at half-maximum for the (311) peak in radians, λ is wavelength, and θ is diffraction angle. The size of the crystallites increased from 5.6 to 10 nm when the Ag+ content rose (Table 1). The difference in ionic radii between Ag+ (1.26 A°) and Zn2+ (0.74 A°) may be the cause of this. It was found that the average crystallite size of silica-coated ferrite increased from 5.6 nm for uncoated ferrite to 8.35 nm. This shows that the silica layer was successfully coated.Table 1 The crystallite size (d) of the prepared sample.FTIRFTIR spectra of prepared metal ferrites are shown in Fig. 4; they span 400–4000 cm−1. The distinctive band of all metal ferrite AgxZn(0.5-x)Ni0.5Fe2O4, where x = (0.1, 0.3, 0.5), are nearly similar, indicating the same structure of all prepared metal ferrite. There are two prominent absorption peaks observed at 585 cm−1 and 410 cm−1. These peaks correspond to the vibrational modes of tetrahedral metal–oxygen bonds and octahedral metal–oxygen bonds, respectively54. Moreover, when the silver doping ratio is increased, particularly at x = 0.5, both the bands related to octahedral and tetrahedral sites display a displacement towards higher wavenumbers. This shift happens due to the replacement of Ag+ ions with Zn2+ ions, which have a higher atomic weight55.Figure 4FT-IR spectra of spinel ferrite AgxZn(0.5-x)Ni0.5Fe2O4 where x = (0.1, 0.3, 0.5) and Ag0.1Zn0.4 Ni0.5Fe2O4@mSiO2.The strong band at approximately 3432 cm−1 and the small band at 1638 cm−1 refer to the stretching and bending vibrations of OH groups56. The spectrum of Ag0.1Zn0.4Ni0.5Fe2O4@mSiO2 (Fig. 4) confirms the presence of the same bands as in mixed ferrite as well as new bands at 1079.54 cm−1, 965.52 cm−1, 798.08 cm−1 and 455.8 cm−1. The stretching Si–O–Si, bending Si–O–Si, streching Si–O, and bending Si–O bands are presented here in the correct order57. All these bands indicate that SiO2 was successfully loaded onto Ag0.1Zn0.4Ni0.5Fe2O4.EDXEDX was used to analyse synthetic samples for elemental makeup (Fig. 5). The atomic percentages of Ag, Zn, and Ni in addition to Fe and O components in prepared samples indicate that spinel ferrite has been successfully prepared. The main elements of the all spinel ferrite AgxZn(0.5-x)Ni0.5Fe2O4, where x = (0.1, 0.3, 0.5), were Ag, Zn, Ni, Fe, and O (Fig. 5a and Table 2). In addition to the previously mentioned elements, Si appeared in the spectrum of Ag0.1Zn0.4Ni0.5Fe2O4@mSiO2 (Fig. 5b and Table 2), which is largely related to SiO2. This reflects the effective loading of silica on the ferrite surface of the composition Ag0.1Zn0.4Ni0.5Fe2O4.Figure 5The EDX spectra and atomic percentage of uncoated spinel ferrite Ag0.1Zn0.4Ni0.5Fe2O4 (a) and Ag0.1Zn0.4Ni0.5Fe2O4@mSiO2 (b).Table 2 The atomic percentage of various samples.VSMAt room temperature, VSM confirmed the samples’ magnetic characteristics. The magnetic permeability profiles are shown in Fig. 6. All the different compositions of mixed ferrite AgxZn(0.5-x)Ni0.5Fe2O4, where x = (0.1, 0.3, 0.5), are superparamagnetic, as evidenced by the presence of a slight hysteresis. In Table 3, the values for saturation magnetization, remanence, and coercivity are recorded.Figure 6Magnetization curves of spinel ferrite Agx Zn(0.5-x)Ni0.5Fe2O4 where x = (0.1, 0.3, 0.5) and Ag0.1Zn0.4 Ni0.5Fe2O4@mSiO2.Table 3 Saturation magnetization (Ms), remanence magnetization (Mr), and coercivity (HC) values.The saturation magnetization values of mixed ferrite AgxZn(0.5-x)Ni0.5Fe2O4, where x = (0.1, 0.3, 0.5), decrease as the ratio of Ag increases, mainly due to the presence of diamagnetic silver components in the Ag-based nanoferrite samples58,59. In the case of Ag0.1Zn0.4Ni0.5Fe2O4@mSiO2, the nonmagnetic silica shell is responsible for the drop in saturation magnetization, coercivity, and remanence of Ag0.1Zn0.4Ni0.5Fe2O4@mSiO260,61. However, the saturation magnetization of 14.1 emu/g was sufficient for facile separation of Ag0.1Zn0.4Ni0.5Fe2O4@mSiO2 from aqueous solutions with a magnet.SEM and TEMSEM and TEM techniques were employed to examine the morphological characteristics of the samples. In the SEM image of Ag0.1Zn0.4Ni0.5Fe2O4@mSiO2 (Fig. 7a), a smooth surface composed of spherical crystals was observed. TEM images of Ag0.1Zn0.4Ni0.5Fe2O4 and Ag0.1Zn0.4Ni0.5Fe2O4@mSiO2 illustrated the spherical morphology of the particles, with an average particle size of approximately 1 µm (Fig. 7b,c). Figure 7c exhibited the successful encapsulation of the ferrite within a thin core–shell structure of silica. Additionally, Fig. 7d displayed the presence of a thin mesoporous silica layer with silica aggregations at various locations on the surface of the ferrite, highlighting its porous nature in HRTEM.Figure 7SEM image of SFS (a) and TEM images of SF (b) and SFS (c,d).Textural characteristicsThe adsorbent surface area is a key factor in raising adsorption efficiency. According to BET and porosity measurements, the specific surface area and pore volume of spinel ferrite were determined to be 69.79 m2/g and 0.404 cm3/g, respectively. Coating the prepared spinel ferrite with a silica layer increased the specific surface area and pore volume to 180.81 m2/g and 0.771 cm3/g, respectively. The synthesized materials are porous, as shown by the average pore size (Table 4). According to N2-adsorption/desorption isotherm Fig. 8, both the SF and the SFS displayed a type IV with a hysteresis loop of the H2(b) type, indicating a mesoporous nature with a wide range of pore size distribution62. This takes place in porous materials characterized by a network of interconnected pores as well as in pores characterized by a broad body and a thin neck63,64.Table 4 The data of surface and pore properties.Figure 8Adsorption–desorption of N2 gas by SF (a) and SFS (b).Adsorption studiesThis research sets out to develop an efficient adsorbent for the elimination of harmful anionic and cationic dyes that pollute water and endanger human health. As a result, the adsorption abilities of different compositions of spinel ferrite AgxZn(0.5-x)Ni0.5Fe2O4, where x = 0.1, 0.3, and 0.5, to remove MG and IC from simulated wastewater were studied and compared. It was found that Ag0.1Zn0.4Ni0.5Fe2O4 (SF) is more efficient in dye removal, as shown in Fig. 9. Therefore, Ag0.1Zn0.4Ni0.5Fe2O4 was chosen for more adsorption studies, especially because it has the highest saturation magnetization for easy separation. Subsequently, the coating of the chosen spinel ferrite (x = 0.1) with a silica layer increased in surface area from 69.79 to 180.08 m2/g, as proven by BET. As shown in Fig. 10, the absorbance of MG and IC dyes diminishes over time after adsorption by SFS.Figure 9The comparison of the removal efficiency of MG (4 mg/L) and IC (19 mg/L) utilising 20 mg of various adsorbents AgxZn(0.5−x)Ni0.5Fe2O4 at pH = 7 and 25 °C.Figure 10The absorbance of MG (13 mg/L) (a) and IC (37 mg/L) (b) against time during adsorption onto SFS (20 mg), pH = 7, 25 °C.The influence of experimental conditionsSignificant effects of initial dye concentration, nanocomposite quantity, temperature, and solution pH on the adsorption of various dyes by spinel ferrite@mSiO2 (SFS) were observed. The results of varying each variable were examined carefully.Effect of adsorbent dosageThe effectiveness of SFS in eliminating MG and IC was studied by adjusting the dosage from 5 to 30 mg. As illustrated in Fig. 11, the removal percentage for dyes increases as the number of adsorbents increases. This is primarily due to the greater availability of adsorption sites on the adsorbent surface, which allows for more effective interaction between the dye molecules and the adsorption sites65,66,67.Figure 11Removal efficiencies of MG (13 mg/L) and IC (37 mg/L) using SFS as a function of adsorbent dosage.The pH effectThe pH level plays a crucial role in influencing the adsorption process. Both adsorbate dyes (MG or IC) and absorbent SFS possess various surface functional groups that gain or lose protons (H+) in response to the pH of the medium68. To optimize the adsorption process for pollutant removal, the adsorption process for MG and IC was examined across the pH range (2–12), as shown in Fig. 12.Figure 12The removal efficiency of MG (13 mg/L) and IC (37 mg/L) utilizing SFS as a function of medium pH molecules are now blocking the active sites of the remaining molecules in solution75.Pzc measurements show that the point of zero charge (pHpzc) of SFS is 6.45. At a pH > 6.45, SFS’s surface turns negatively charged due to the ionization of H+ from the active groups leaving negative charges; as a result, MG removal efficiencies increase with increasing pH above 6.45, where they reached 96.6% at a pH of 10 due to electrostatic interactions between cationic methyl green and negatively charged adsorbents69.However, IC is negatively charged at low pH and has a pKa of 12.670,71. So, the removal efficiencies of IC decrease at pH > 6.45 due to the increased electrostatic repulsion with negatively charged adsorbent surfaces. This result agrees with the work of Yazdi et al.72. As a result, the removal efficiency of IC increases with decreasing pH value until it reaches 93.8% at pH = 273 (Fig. 12), due to the electrostatic attraction between the cation surface of spinel ferrite and the negative IC, and furthermore, the formation of a hydrogen bond. As a result, the alkaline medium was the right choice for removing methyl green dye, and the acidic medium is efficient for removing IC.Effect of the initial concentration of dyeThe influence of dye concentration on the removal efficiency of pollutant dyes was investigated, as shown in Fig. 13. The removal percentages of MG and IC reached 91% within 90 min below the concentrations of 7 and 19 mg/L for MG and IC, respectively. As the dye concentration increases within 90 min, the percentage of MG and IC that is removed decreases. With an increase in dye concentration, the availability of adsorption sites became restricted, resulting in a decrease in dye removal prior to achieving equilibrium74. At higher concentrations, however, the removal effectiveness noticeably drops as a larger number of dye molecules compete for a smaller number of adsorption sites. This decrease is because the previously adsorbed dye molecules are now blocking the active sites of the remaining molecules in solution75.Figure 13The removal efficiency of MG (3.2–16.3 mg/L) and IC (18.6–56 mg/L) utilizing SFS as a function of initial dye concentration.Kinetics of adsorptionThe time-dependent behaviour of adsorption is depicted by the linear and non-linear adsorption kinetics of the pseudo-first and second-order models in, Eqs. (5)–(8)76. For the water treatment to be successful and economical, the adsorption process must be completed quickly. The contact time is the duration of time it takes for the maximum amount of dye adsorbed to reach equilibrium with the adsorbent surface in an adsorption experiment. Figure 14 shows how the quantity of MG and IC adsorbed (qt) varies with contact time in a nonlinear kinetic model. After 110 min of interaction, the qt had climbed to an equilibrium level. Also, the mechanism of adsorption of MG or IC dyes onto synthesized ferrite is determined by evaluating the adsorption kinetics in the intra-particle diffusion model, Eq. (9)77.$$ln\left({q}_{e}-{q}_{t}\right)=ln{q}_{e}-{k}_{1}t$$
(5)
$${q}_{t}={q}_{e}\left(1-{e}^{-{k}_{1}t}\right)$$
(6)
$$\frac{t}{{q}_{t}}=\frac{1}{{k}_{2}{q}_{e}^{2}}+\frac{1}{{q}_{e}}t$$
(7)
$${q}_{t}=\frac{{k}_{2}{q}_{e}^{2}t}{1+{q}_{e}{k}_{2}t}$$
(8)
$$ q_{t} = k_{i} t^{1/2} + C $$
(9)
Figure 14Non-linear kinetic model for adsorption of MG (a) and IC (b) on SFS.Adsorbed dye amounts are given in terms of mg/g at equilibrium (qe) and contact time (qt) in minutes. Pseudo-first order diffusion has a rate constant of k1 (min−1), pseudo-second order diffusion has a rate constant of k2 (g/mg min), and intra-particle diffusion has a rate constant of ki (mg/g min1/2). The values of the correlation coefficient (R2) in Table 5, indicate that the linear and nonlinear equations forms of the pseudo-second-order approach, Eqs. (7, 8), respectively, are a better fit and more suited for the experimental data than the linear and nonlinear pseudo-first-order model Eqs. (5, 6), respectively. Also, for each dye under examination, the qe, exp, and the qe estimated from the pseudo-second-order model are all quite close to one another, within the experimental errors. Adsorption kinetics may be altered by a number of different processes. Most constrained are the processes of diffusion, which can only occur via (a) extracellular diffusion, (b) boundary layer diffusion, and (c) intra-particle diffusion77,78. Therefore, an intra-particle diffusion kinetic model is used to further evaluate the adsorption data and forecast the rate-limiting stage in the process. If the qt vs. t0.5 linear plot is through the origin, then intra-particle diffusion is supposed to be in charge of the adsorption process, as predicted by this theory. Figure 15 shows that qt is linearly related to t0.5. Here we see examples of both the outer and inner surface diffusions; the former refers to the surface’s exterior while the latter describes its interior. According to Table 6, there is a completely quick step of diffusion from the outside onto the adsorbent surface, followed by a completely sluggish step of diffusion into the inner surface75.Table 5 Kinetics data of the linear and non-linear forms of adsorption of methyl green and indigo carmine on SF and SFS.Figure 15Intra-particle diffusion kinetics model of the of MG and IC on SFS.Table 6 Adsorption of MG and IC dyes onto SF and SFS through intra-particle diffusion.Adsorption isotherm modelsThe surface properties, maximum capacity of the adsorbent, and adsorption mechanism were all stated by the values of certain parameters determined from adsorption isotherm models used to examine the produced ferrite’s potency and capacity as an adsorbent. Different adsorption isotherm models were employed to compare the results; these included the Langmuir, Freundlich, Temkin, and Dubinin–Radushkevich (D–R) models. Figure 16 shows nonlinear adsorption isotherm of MG and IC on SFS as a compared with SF adsorbent.Figure 16Nonlinear adsorption isotherm of MG (a,b) and IC (c,d) on SF and SFS, respectively.Adsorption of dye molecules onto an adsorbent surface has the same activation energy according to the Langmuir isotherm, as shown in Fig. 16, which assumes monolayer adsorption above a homogenous adsorbent surface with a set number of identical sites79. This led to the adsorption data of MG and IC being fitted into the nonlinear form of Langmuir’s equation80, the determination and quantification of the maximum adsorption capacity (qmax) were performed and tabulated in Table 7.$${q}_{e}=\frac{{q}_{max}.{C}_{e}.{K}_{L}}{1+{C}_{e}.{K}_{L}}$$
(10)
where Ce is the concentration of dye at equilibrium in mg/l, qe is the adsorption capacity of dye at equilibrium in mg/g, qmax is the maximum possible adsorption capacity in mg/g, and KL is the Langmuir constant in L/mg.Table 7 Adsorption isotherms parameters of methyl green and indigo carmine dye at 25°C.Table 7 shows the results. Adsorption results agreed with the Langmuir model, which postulated the existence of homogenous adsorption sites on SFS substrate, as indicated by high values of the correlation coefficient (R2) for the isotherm plots. The IC dye has sulfonated, amine, and hydroxyl groups in its structure that support electrostatic binding with mesoporous silicate Si–OH through hydrogen bonds, which may explain why the IC dye has a higher Langmuir monolayer coverage capacity value (qmax) than the MG dye and why the value of the same dye increases when using SFS as an absorbent. The results show that ultimate capacity qmax and KL values increased as the temperature of adsorption increased, thus, the affinity of the adsorbent to the investigated dyes increased with increasing temperature.The maximum monolayer adsorption capacity (qmax) for methyl green and indigo carmine adsorption is compared across a variety of adsorbent surfaces in Table 8. We found that our SFS as an adsorbent is effective in removing methyl green and indigo carmine from aqueous solutions, when compared to data from the relevant literature.Table 8 Maximum adsorption capacity (qmax) comparison of MG and IC on various adsorbents.An experimental expression that accounts for surface heterogeneity and an exponential distribution of site and energy energies is the Freundlich isotherm81. The Freundlich adsorption Eq. (11) describes this equilibrium.$${q}_{e}={K}_{f}.{{C}_{e}}^{1/n}$$
(11)
The Freundlich isotherm constant is denoted by kF ((mg/g) (mg/L)−1/nF)82, where n is the dimensionless exponent of the Freundlich. KF and n are the determined values. Estimates of nF in this work ranged from 4 to 7, indicating that the adsorption processes are close to irreversible83. When the KF value is large, the adsorption is driven with greater efficiency. This means that the adsorption driving force for IC dye is greater than that for MG dye, and the driving force grows when SFS is employed as the adsorbent. The favourable nature of the adsorption process is confirmed at higher temperatures by an increase in KF value84.Adsorption data for MG and IC were analyzed using the Temkin isotherm model. This model supports limited interactions between the adsorbent and adsorbate and demonstrates that all molecules in the surface layer have decreased adsorption energies at the cover surface. Additionally, it was believed that adsorbate-adsorbent interactions directly reduced the adsorption heat with coverage85. Equation (12) represents the Temkin isotherm model.$${q}_{e}=\frac{RT}{b}.ln{K}_{T}+\frac{RT}{b}.ln{C}_{e}$$
(12)
where KT (L/mol) represents the equilibrium binding constant, R is the perfect gas constant, T is the absolute temperature, and b (kJ/mol) represents the heat of adsorption. Table 7’s b values match up with an adsorption mechanism involving electrostatic interactions and hydrogen bond formation. Temperature has a beneficial influence on the binding energy of dyes with ferrite surfaces, as evidenced by the rise in KT as the temperature rises.To identify the adsorption mechanism (physical or chemical), we can use Dubinin–Radushkevich isotherm Eqs. (13–15) to determine the activation energy E (KJ/mol). Adsorption has been explained by ion exchange adsorption if E ranges from 8 to 16 kJ/mol; if E is 8, the process has been validated physically. Adsorption in this study may occur by chemisorption or ion exchange, where E ranges from 8 to 16 kJ/mol.$$ln{q}_{e}=ln{q}_{s}-\beta {\varepsilon }^{2}$$
(13)
where qs (mol/kg) is the theoretical capacity of adsorption calculated from Eq. (13) of the D-R model, ε (kJ/mol) is the Polanyi potential, and β (mol2/kJ2) is the mean free energy of adsorption for each molecule adsorbed as given by Eq. (14).$$E=\frac{1}{\sqrt{2\beta }}$$
(14)
$$\varepsilon =RTln\left(1+\frac{1}{{C}_{e}}\right)$$
(15)
Thermodynamics studiesThe Langmuir model is the best-fitted model at the different temperatures according to the R2 values in Table 7. The effect of temperature on the adsorption process according to the Langmuir isotherm is studied as shown in Fig. 17, where qmax and KL (L/mg) at different temperatures are shown in Table 9. To determine the thermodynamic parameters, the obtained equilibrium constant must become dimensionless before being applied to the Vant´Hoff equation using Eq. 1695.$${k}_{e}^{0}= (1000.{K}_{L}.mol.wt\, of\, dye).\frac{\left[Dye\right]^\circ }{{\varvec{\gamma}}}$$
(16)
where γ is the activity coefficient (dimensionless) and [Dye]° is the standard concentration of dye (1 mol/L).Figure 17Nonlinear Langmuir adsorption isotherm of MG (a,b) and IC (c,d) on SF and SFS, respectively at different temperatures.The entropy ΔS° and enthalpy ΔH° of adsorption are determined according to the Eqs. (17, 18) from the intercept and slope of the relationship between \(ln{K}_{e}^{0}\) vs. 1000/T, respectively, where R is the perfect gas constant (8.314 J/mol K), and T is the absolute temperature96. The adsorption of MG or IC dye onto the synthesized ferrite is endothermic due to the positive values of ΔH° as shown in Table 9. Also, the measured ΔH° values varied from 25 to 48 kJ/mol, suggesting that both physisorption and chemisorption may be involved in the adsorption of the dyes of interest97. Adsorption is characterized by an increase in the degree of disorder at the solid-solution interface, as measured by an increase in the entropy parameter, ΔS°98. This is the normal outcome of electrostatic force interactions that lead to the phenomenon known as physical adsorption. The spontaneous process for MG and IC sorption is revealed by negative values of ΔG°, and as the temperature is raised, the value of ΔG° decreases even further, showing that the adsorption process is more favoured at a higher temperature99.Table 9 Adsorption process thermodynamic characteristics for both MG and IC at various temperatures.$$ln{K^\circ }_{e}=\frac{{\Delta S}^{^\circ }}{R}-\frac{{\Delta H}^{^\circ }}{RT}$$
(17)
$$\Delta {G}^{^\circ }= {\Delta H}^{^\circ }-T{\Delta S}^{^\circ }$$
(18)
Characterization Silica coated spinel ferrite after Adsorption.FTIR analysisA Comparison of the FTIR spectra of the used SFS before and after adsorption of IC as a model of the investigated dye showed the appearance of additional peaks after their contact with the IC dye (Fig. 18). Peaks appearing at 2930 cm were due to CH stretching, at 1374 cm−1, it corresponds to the C–H bending vibration or C–N stretching vibration of amines100. A comparison between newly appeared peaks and those of IC showed that the new peaks were probably the characteristic of this textile pollutant. The band broadening about 3400 cm−1 is assigned to the vibration formed by hydrogen-bonded –O–H groups in the absorbent and adsorbate molecules. The band broadening at 3390, 3433 cm−1 indicate to the hydrogen bonding in comparison to the FTIR analysis before the adsorption process as well as existence of (-NH) stretching bond of dye101.Figure 18FTIR of SFS before (a) and after adsorption (b) of IC.The N–H bond between the dye’s N atom and the H–O–H bond resulted in a noticeable shift of the H–O–H peak from 1638 to 1627 and an increase in its width. This effect resulted from the establishment of oxygen-hydrogen bonds between the dye and the adsorbent102. The adsorption of molecules onto the SFS nanoparticles in this study is consistent with physical adsorption mechanisms, involving hydrogen bonding and electrostatic forces. The low adsorption heat indicated by the Temkin isotherm model, the formation of a monomolecular layer according to the Langmuir isotherm, and FTIR analysis collectively support the physical adsorption process on the SFS nanoparticle surface.SEM/EDX analysisScanning electron microscopy revealed a substantial change in surface shape following adsorption (Fig. 19). SEM–EDX analysis was used to analyse the morphological aspects of SFS. The dye molecules appear on the surface of spinel ferrite. The principal components of ferrite/IC are Fe, Ni, Zn, O, Si, and C, N from dyes, according to the EDX analysis, confirming the efficient adsorption of IC.Figure 19SEM/EDX of SFS after adsorption of IC.Reusability and recovery studyThe regeneration and reusability of adsorbent surfaces are critical aspects of determining their true value. The use of adsorbents with high adsorption capacity and high desorption assets reduces additional environmental pollution and overall costs. As a result, desorption studies on SFS are carried out to determine its recyclable accessibility. The adsorbent was recovered by treating the used sample with 0.1 M HCl for 2 h, washing it three times with distilled water, and finally testing the filtrate with a silver nitrate solution to make sure the HCl was gone before drying it at 45 °C for 18 h. For four cycles, 20 mg of adsorbent was used. The elimination percentage changed with each cycle, as seen in Fig. 20103.Figure 20The reuse of dyed SFS samples.
Design of silver-zinc-nickel spinel-ferrite mesoporous silica as a powerful and simply separable adsorbent for some textile dye removal
