Garlic Cellulosic Powders with Immobilized AgO and CuO Nanoparticles: Preparation, Characterization of the Nanocomposites, and Application to the Catalytic Degradation of Azo Dyes

Nanomaterials have attracted specific consideration due to their specific characteristics and uses in several promising fields. In the present study, Chondrilla juncea was employed as a biological extract to facilitate the reduction of copper and silver ions within garlic peel powders. The resulting garlic-CuO and garlic-AgO nanocomposites were characterized using several analytical methods including FTIR, TGA/DTG, SEM, TEM, and XRD analyses. The garlic peel exhibited a rough surface. The nanoparticles were evenly dispersed across its surface. The incorporation of CuO and AgO nanoparticles affected the crystal structure of garlic peel. The establishment of CuO and AgO nanoparticles was evidenced by the highest residual mass values observed for the prepared nanocomposites. The thermogravimetric analysis showed that the prepared nanocomposites had lower thermal stability compared with garlic peel powders. The prepared nanocomposites were used for catalytic degradation of naphthol blue black B and calmagite. The decolorization process depended on the quantity of H2O2, initial concentration of azo dyes, duration of contact, and temperature of the bath. The calculated activation energy (Ea) values for the garlic-CuO nanocomposites were found to be 18.44 kJ mol−1 and 23.28 kJ mol−1 for calmagite and naphthol solutions, respectively. However, those calculated for garlic-AgO nanocomposites were found to be 50.01 kJ mol−1 and 12.44 kJ mol−1 for calmagite and naphthol, respectively.

The application of nanomaterials encompasses various fields such as sensors [15,16], medicine [17][18][19], water treatment [20][21][22], etc.In addition, significant attention has been directed toward the elimination of harmful contaminants from water through the implementation of nanostructured materials.The elimination of azo dyes, a type of pollutant found in water, has attracted high interest among researchers due to their harmful effects Garlic was bought from a local market (Zulfi, KSA).All chemicals and reagents were supplied by Sigma Aldrich and were of analytical grade.Naphthol blue black B (chemical formula: C 22 H 14 N 6 Na 2 O 9 S 2 , M.W = 616.5 g/mol, λ max = 610 nm) and calmagite (chemical formula: C 17 H 14 N 2 O 5 S, M.W = 358.3g/mol, λ max = 538 nm) dyes were purchased to study catalytic degradation.The chemical structures of both dyes are displayed in Figure 1.H 2 SO 4 and NaOH were used to adjust pH at constant values.Distilled water was used to prepare all aqueous solutions.

Preparation of Chondrilla juncea Aqueous Extract
Chondrilla juncea was collected from the region of Zulfi, Riyadh, KSA.The extraction protocol was the same as mentioned in our previous investigation [30].The leaves were extracted manually and subsequently cleansed with distilled water to eliminate any impurities that adhered to their surface.Following this, they were dried in darkness for a period of 7 to 10 days.Once completely dried, the leaves were ground into a fine powder using an electric mixer.Next, a mixture containing 450 mL of water and 30 g of grinded leaves was prepared and heated for 120 min at 70 • C. Subsequently, the solution was allowed to cool down to ambient temperature and then filtered; the resulting extract (Figure 2) was utilized for the synthesis of garlic-CuO and garlic-AgO nanocomposites.

Preparation of Chondrilla juncea Aqueous Extract
Chondrilla juncea was collected from the region of Zulfi, Riyadh, KSA.The extraction protocol was the same as mentioned in our previous investigation [30].The leaves were extracted manually and subsequently cleansed with distilled water to eliminate any impurities that adhered to their surface.Following this, they were dried in darkness for a period of 7 to 10 days.Once completely dried, the leaves were ground into a fine powder using an electric mixer.Next, a mixture containing 450 mL of water and 30 g of grinded leaves was prepared and heated for 120 min at 70 °C.Subsequently, the solution was allowed to cool down to ambient temperature and then filtered; the resulting extract (Figure 2) was utilized for the synthesis of garlic-CuO and garlic-AgO nanocomposites.

Synthesis of Garlic-CuO and Garlic-AgO Nanocomposites
The initial step involved grinding the dried garlic peel into a fine powder using an electric pro grinder device.The garlic straw powders were rinsed repeatedly with water to remove impurities and were dried at 50 °C overnight.Afterward, 5 g of garlic powder underwent treatment with solutions of copper sulfate and silver nitrate (1 M, volume = 250 mL) for 6 h.Next, after the addition of 250 mL of a freshly prepared Chondrilla juncea solution into pretreated garlic powder, an additional time of 2 h was allotted for the temperature to be raised to 70 °C.The gradual change of color solution throughout the reaction might indicate the conversion of copper and silver ions into nanoparticles.The resulting materials were separated by filtration, washed many times with distilled water, and

Preparation of Chondrilla juncea Aqueous Extract
Chondrilla juncea was collected from the region of Zulfi, Riyadh, KSA.The extraction protocol was the same as mentioned in our previous investigation [30].The leaves were extracted manually and subsequently cleansed with distilled water to eliminate any impurities that adhered to their surface.Following this, they were dried in darkness for a period of 7 to 10 days.Once completely dried, the leaves were ground into a fine powder using an electric mixer.Next, a mixture containing 450 mL of water and 30 g of grinded leaves was prepared and heated for 120 min at 70 °C.Subsequently, the solution was allowed to cool down to ambient temperature and then filtered; the resulting extract (Figure 2) was utilized for the synthesis of garlic-CuO and garlic-AgO nanocomposites.

Synthesis of Garlic-CuO and Garlic-AgO Nanocomposites
The initial step involved grinding the dried garlic peel into a fine powder using an electric pro grinder device.The garlic straw powders were rinsed repeatedly with water to remove impurities and were dried at 50 °C overnight.Afterward, 5 g of garlic powder underwent treatment with solutions of copper sulfate and silver nitrate (1 M, volume = 250 mL) for 6 h.Next, after the addition of 250 mL of a freshly prepared Chondrilla juncea solution into pretreated garlic powder, an additional time of 2 h was allotted for the temperature to be raised to 70 °C.The gradual change of color solution throughout the reaction might indicate the conversion of copper and silver ions into nanoparticles.The resulting materials were separated by filtration, washed many times with distilled water, and

Synthesis of Garlic-CuO and Garlic-AgO Nanocomposites
The initial step involved grinding the dried garlic peel into a fine powder using an electric pro grinder device.The garlic straw powders were rinsed repeatedly with water to remove impurities and were dried at 50 • C overnight.Afterward, 5 g of garlic powder underwent treatment with solutions of copper sulfate and silver nitrate (1 M, volume = 250 mL) for 6 h.Next, after the addition of 250 mL of a freshly prepared Chondrilla juncea solution into pretreated garlic powder, an additional time of 2 h was allotted for the temperature to be raised to 70 • C. The gradual change of color solution throughout the reaction might indicate the conversion of copper and silver ions into nanoparticles.The resulting materials were separated by filtration, washed many times with distilled water, and dried at room temperature.Further, various analytical methods were employed to examine the structure of the resulting nanocomposites.These materials were subsequently utilized for the catalytic decomposition of naphthol blue black B and calmagite dyes.

Characterization Techniques
The studied materials were examined using a Perkin spectrum FTIR instrument (KSA).The spectra were displayed from a range of 400 to 4000 cm −1 , with a resolution equal to 4 cm −1 .A JEOL-5400 SEM (KSA) apparatus was used to evaluate the morphological characteristics.For this, compounds were covered with Au using a vacuum coater with the goal to enhance both image and conductivity qualities.The voltage of accelerating voltage was maintained at 20 kV.Thermal investigation was carried out in crucibles (Pt) in air and heated at a rate equal to 10 • /min.Using a copper radiation source, the XRD-7000 SHIMADZU (KSA) (Kyoto, Japan) was employed to investigate X-ray diffraction patterns of the samples.The diffraction angle (2θ) was between 10 • and 90 • , the scanning speed was 2 • /min, and the voltage and current were 40 kV and 40 mA, respectively.TEM images were obtained utilizing an 80 kV operated JEOL GEM-1010 transmission electron microscope (Tokyo, Japan).

Catalytic Degradation Experiments
Catalytic experimentations were performed in Erlenmeyer flasks enclosing a mixture of 20 mL of naphthol blue black B or calmagite and 0.01 g of garlic-CuO or garlic-AgO nanocomposites and stirred at 150 rpm.A measured dose of H 2 O 2 was then added to the mixture.The pH of the solution was equal to 6, corresponding to the pH of the used water.When the experiment was supposed to reach equilibrium, the content was filtered with a filter paper.Then, absorbance of each colored solution was determined using a UV-Vis spectrophotometer at λ max of 610 nm and 538 nm for naphthol blue black B or calmagite, respectively.The experiments were also carried out at different H 2 O 2 doses (0-14 mL/L), contact times (0-10 min), temperatures (20-50 • C), and dye concentrations (10-50 mg/L).

FT-IR Exploration
The FT-IR spectra of garlic peel and prepared garlic-CuO and garlic-AgO nanocomposites are displayed in Figure 3.The extensive peaks observed in the region of 3310 to 3286 cm −1 are the stretching vibration peaks of -OH [37].The absorption peaks observed at 2919 and 2851 cm −1 are believed to be the stretching vibration peak of -CH in methyl and methylene [38].The peak at 1744-1736 cm −1 is attributed to the C=O group present in hemicelluloses.The absorption peaks recorded at 1584-1607 cm −1 are attributed to the stretching vibration of C=C aromatic groups of lignin.The absorption peaks at 1417 cm −1 and 1321 cm −1 correspond to the bending vibration of -CH 2 [39].The peak of 1122 cm −1 is assigned to the asymmetric stretching vibration of C-O-C in cellulose.The absorption peak of 1017 cm −1 is attributed to the stretching vibration of the C-O group.The β-D-glucoside bond in the cellulosic material is observed at 913 cm −1 .The comparison between the spectrum of the prepared garlic-CuO and garlic-AgO nanocomposites reveals that the main peaks of the studied materials remain similar, with a slight chemical shift during the chemical modification with silver nitrate and copper sulfate.For example, the position of the hydroxyl groups shifts from 3326 cm −1 to 3286 cm −1 .Such a shift suggests that copper and silver ions interact with the garlic surface through the -OH groups.It is also worth noting that the biomolecules naturally found in the biological extract of Chondrilla juncea are able to reduce copper and silver ions into CuO and AgO nanoparticles.

Morphological Investigation
Figure 4 shows the SEM photos of garlic peel powders observed at different magnifications (×500 and ×1000) and the prepared garlic-CuO and garlic-AgO nanocomposites.As observed, the SEM images of the starting cellulosic material show particles of varied sizes and irregular shapes.After saturation with silver nitrate and copper sulfate ions and synthesis of CuO and AgO nanoparticles, the surfaces of the materials become rougher, and the particles are much more agglomerated, with greater swelling.Garlic-AgO nanocomposites show very significant material surface changes compared with garlic-CuO composites.Higher magnification (×5000) (Figure 5) of garlic-AgO images shows spherical AgO nanoparticles that are clearly observed and fully distributed on the surface of the garlic peel.

Morphological Investigation
Figure 4 shows the SEM photos of garlic peel powders observed at different magnifications (×500 and ×1000) and the prepared garlic-CuO and garlic-AgO nanocomposites.As observed, the SEM images of the starting cellulosic material show particles of varied sizes and irregular shapes.After saturation with silver nitrate and copper sulfate ions and synthesis of CuO and AgO nanoparticles, the surfaces of the materials become rougher, and the particles are much more agglomerated, with greater swelling.Garlic-AgO nanocomposites show very significant material surface changes compared with garlic-CuO composites.Higher magnification (×5000) (Figure 5) of garlic-AgO images shows spherical AgO nanoparticles that are clearly observed and fully distributed on the surface of the garlic peel.

Morphological Investigation
Figure 4 shows the SEM photos of garlic peel powders observed at different magnifications (×500 and ×1000) and the prepared garlic-CuO and garlic-AgO nanocomposites.As observed, the SEM images of the starting cellulosic material show particles of varied sizes and irregular shapes.After saturation with silver nitrate and copper sulfate ions and synthesis of CuO and AgO nanoparticles, the surfaces of the materials become rougher, and the particles are much more agglomerated, with greater swelling.Garlic-AgO nanocomposites show very significant material surface changes compared with garlic-CuO composites.Higher magnification (×5000) (Figure 5) of garlic-AgO images shows spherical AgO nanoparticles that are clearly observed and fully distributed on the surface of the garlic peel.

TEM Images
TEM pictures of garlic-CuO and garlic-AgO nanocomposites reveal a spherical morphology (Figure 7).The prepared nanoparticles generally demonstrate a spherical bent structure.The overlap of the synthesized nanoparticles results in diverse patterns justified by the presence of garlic peel powders as support to CuO and AgO nanoparticles.The TEM results also agree with FT-IR, XRD, and SEM results.

Thermal Examination
TGA/DTG analysis is used to inspect the thermal strength of the studied compounds.Figure 8 depicts the TGA/DTG curves of garlic peel powders, garlic-CuO, and garlic-AgO nanocomposites.The thermal decomposition of garlic peel powders proceeds in different pyrolysis steps due to many reaction steps.As observed, at an initial stage, thermal curves show weight loss lower than 10% at 66 • C, 61.4 • C, and 63.1 • C for garlic powders, garlic-CuO, and garlic-AgO, respectively.This first weight loss is attributed to moisture evaporation and absorbed water in hydrophilic natural products [44].The residual mass, achieved at 799.6 • C, is equal to 13.52 • C for garlic powders.The DTG curve of garlic powders reveals a series of thermal events observed at 136.5 • C, 249.5 • C, 305.4 • C, 457.9 • C, and 643.1 • C, which could be related to the essential pyrolytic reaction of cellulose and also the oxidation of the burned residues.The thermal events of garlic-CuO nanocomposites reveal that the residual mass, reached at 799.

TEM Images
TEM pictures of garlic-CuO and garlic-AgO nanocomposites reveal a spherical morphology (Figure 7).The prepared nanoparticles generally demonstrate a spherical bent structure.The overlap of the synthesized nanoparticles results in diverse patterns justified by the presence of garlic peel powders as support to CuO and AgO nanoparticles.The TEM results also agree with FT-IR, XRD, and SEM results.

Thermal Examination
TGA/DTG analysis is used to inspect the thermal strength of the studied compounds.Figure 8 depicts the TGA/DTG curves of garlic peel powders, garlic-CuO, and garlic-AgO nanocomposites.The thermal decomposition of garlic peel powders proceeds in different pyrolysis steps due to many reaction steps.As observed, at an initial stage, thermal curves In this section, we discuss the influence of time of reaction, dye concentrations, and bath temperature on the degradation of naphthol blue black B and calmagite using the two binary garlic-CuO/H2O2 and garlic-AgO/H2O2 systems.Initially, we observe that naphthol and calmagite solutions are stable in the presence of H2O2 and no decolorization is shown.In addition, the adsorption of the two studied dyes onto nanocomposites alone

. Effect of Experimental Conditions
In this section, we discuss the influence of time of reaction, dye concentrations, and bath temperature on the degradation of naphthol blue black B and calmagite using the two binary garlic-CuO/H 2 O 2 and garlic-AgO/H 2 O 2 systems.Initially, we observe that naphthol and calmagite solutions are stable in the presence of H 2 O 2 and no decolorization is shown.In addition, the adsorption of the two studied dyes onto nanocomposites alone is too small.However, after the addition of H 2 O 2 into the dye solutions, the decolorization occurs in just a few minutes.Figure 9 gives the impact of the reaction time on the decolorization of naphthol and calmagite solutions.As observed, the decolorization yield of calmagite is equal to 98% in the garlic-CuO/H 2 O 2 system after 10 min of reaction.However, the decolorization yield of naphthol is equal to 82% in the garlic-CuO/H 2 O 2 system.This variation in the decolorization process between the two studied dyes is justified by the number of azo groups present in each dye structure and the difference in the molecular weight.Indeed, the highest yield of dye degradation is reached using the garlic-CuO nanocomposite.This might be related to the power of metal oxide itself.Overall, the highest degradation yields obtained within the prepared nanocomposites are explained by the combination of the radical OH• and garlic-CuO or garlic-AgO to break the azo groups, chromophoric groups of calmagite, and naphthol molecules.The maximum yield of decolorization is achieved using an amount of H 2 O 2 equal to 10 mL/L.A high amount of H 2 O 2 (14 mL/L) decreases the yield of decolorization.In fact, the accumulation of high amounts of oxidant into the solution undergoes self-quenching (scavenger) of OH• to yield HO 2 • radicals [45][46][47].The efficiency of garlic-CuO and garlic-AgO nanocomposites/H2O2 to decolorize calmagite and naphthol solutions is also studied by varying the initial dye concentrations from 10 mg/L to 50 mg/L (Figure 10), while maintaining constant the amount of H2O2 at 8 mL/L.Results indicate that the decolorization yield decreases with the increase in initial dye concentrations.This indicates that there is only one optimum dose of H2O2 for every single initial dye concentration.As shown in Figure 11, the decolorization yield of the two studied solutions increases with the increase in bath temperature from 20 °C to 50 °C.This from 10 mg/L to 50 mg/L (Figure 10), while maintaining constant the amount of H 2 O 2 at 8 mL/L.Results indicate that the decolorization yield decreases with the increase in initial dye concentrations.This indicates that there is only one optimum dose of H 2 O 2 for every single initial dye concentration.As shown in Figure 11, the decolorization yield of the two studied solutions increases with the increase in bath temperature from 20 • C to 50 • C.This result proves that the degradation process is favored at high energies.The efficiency of garlic-CuO and garlic-AgO nanocomposites/H2O2 to decolorize calmagite and naphthol solutions is also studied by varying the initial dye concentrations from 10 mg/L to 50 mg/L (Figure 10), while maintaining constant the amount of H2O2 at 8 mL/L.Results indicate that the decolorization yield decreases with the increase in initial dye concentrations.This indicates that there is only one optimum dose of H2O2 for every single initial dye concentration.As shown in Figure 11, the decolorization yield of the two studied solutions increases with the increase in bath temperature from 20 °C to 50 °C.This result proves that the degradation process is favored at high energies.

Kinetic and Thermodynamic Investigations
In this study, 0th-order, 1st-order, and 2nd-order kinetic equations are used to better apprehend the decolorization process of calmagite and naphthol using garlic-CuO and garlic-AgO nanocomposites as catalysts.The expressions of the used kinetic equations are given in the following equations [48]: where C 0 is the initial dye concentration, C t is the concentration at time t, k 0-2 are the apparent kinetic rate constants of 0th-, 1st-and 2nd-order kinetic equations, respectively.

Kinetic and Thermodynamic Investigations
In this study, 0th-order, 1st-order, and 2nd-order kinetic equations are used to better apprehend the decolorization process of calmagite and naphthol using garlic-CuO and garlic-AgO nanocomposites as catalysts.The expressions of the used kinetic equations are given in the following equations [48]: When the values of C t , Ln C t /C 0 , and 1/C t are plotted vs. the time of reaction under the conducted conditions (H 2 O 2 dose, temperature, and initial dye concentrations) (Figures 12 and 13), the kinetic rate constants and regression coefficients are deduced.The values of the regression coefficients (R 2 ) (Tables 1 and 2) vary from 0.90 to 0.99 for the 2nd-order reaction kinetic, which are much higher than those determined for both 0th-order (0.47 < R 2 < 0.78) and 1st-order (0.25 < R 2 < 0.87) kinetic equations.Based on the obtained results, we can conclude that the decolorization of calmagite solution using garlic-CuO and garlic-AgO nanocomposites/H 2 O 2 fits well to the 2nd-order reaction model.The apparent rate constants, calculated at different temperatures, allow us to calculate entropy, activation energy, enthalpy, and free energy.
The values of the activation energies of the reaction, Ea (kJ mol −1 ), are calculated according to the Arrhenius law [49]: where A is the Arrhenius factor, T is the temperature, R is the gas constant (J K −1 mol −1 ), and K is the calculated constant kinetic rate.
The values of ΔS* (J mol −1 K −1 ) and ΔH* (kJ mol −1 ) are determined using the Eyring formula: [50]: where Kb is the Boltzmann constant and h is the Plank constant.Ln K2 values are plotted vs. 1/T values.Then, gradients of the plots are used to define activation energy (Figures 12a and 13a).However, activation enthalpy and entropy values are calculated using Ln (K2/T) plots vs. 1/T (Figures 12b and 13b).Finally, activation energy (kJ mol −1 ) is calculated from Equation ( 6): Δ = Δ − T.Δ (6) The negative values of entropy of the system indicate the fall of the disorder during dye degradation, while the positive values of the enthalpy prove that the studied system is endothermic, which is consistent with the increase in decolorization when the temperature increases.Ea values calculated for garlic-CuO nanocomposite are equal to18.44 kJ mol −1 and 23.28 kJ mol −1 for calmagite and naphthol solutions, respectively (Figures 12 and 13).However, Ea values calculated for garlic-AgO nanocomposite are equal to 50.01 kJ mol −1 and 12.44 kJ mol −1 for calmagite and naphthol solutions, respectively.The calculated low Ea values suggest that the prepared nanocomposites are efficient for the degradation of calmagite and naphthol solutions.It is noteworthy to clarify that the calculated Ea values are comparable to results reached using some other prepared compound-based catalysts for the degradation of different organic molecules investigated in the literature [23,31,[51][52][53][54][55][56].

Conclusions
In summary, Chondrilla juncea was used as a biological extract to prepare stable CuO and AgO nanoparticles into garlic peel powders.The evidence of the formation of garlic-CuO and garlic-AgO nanocomposites was confirmed using FTIR, XRD, SEM, TEM, and TGA/DTG analyses.CuO and AgO nanoparticles were well distributed on the surface of the garlic peel.The incorporation of CuO and AgO nanoparticles affected the crystal structure of garlic peel.The thermal events confirmed that the prepared nanocomposites were thermally less stable compared with garlic peel powders, confirming again the incorporation of nanoparticles.The catalytic degradation experiments were assessed for naphthol blue black B and calmagite dye solutions.The decolorization mechanism depended on several experimental parameters such as amount of H2O2, initial dye concentration, time of contact, and bath temperature.The activation energy (Ea) values calculated for garlic-CuO nanocomposite were equal to 18.44 kJ mol −1 and 23.28 kJ mol −1 for calmagite and naphthol solutions, respectively.However, those calculated for garlic-AgO nanocomposite were found to be 50.01kJ mol −1 and 12.44 kJ mol −1 for calmagite and naphthol, respectively.The calculated low Ea values suggested that the prepared nanocomposites could be used as efficient catalysts for the catalytic degradation of azo dye solutions.Further experiments will be extended for the preparation of new nanocomposite-based natural products for water remediation.Other toxic pollutants will be investigated including metals, phenolic compounds, pesticides, etc.
Author Contributions: Conceptualization, N.S.; software, N.S. and M.J.; validation, M.J.; investigation, F.S.; data curation, N.S. and F.S.; writing-original draft, N.S.; supervision, M.J. and F.S.; project administration, M.J.All authors have read and agreed to the published version of the manuscript.The apparent rate constants, calculated at different temperatures, allow us to calculate entropy, activation energy, enthalpy, and free energy.
The values of the activation energies of the reaction, E a (kJ mol −1 ), are calculated according to the Arrhenius law [49]: where A is the Arrhenius factor, T is the temperature, R is the gas constant (J K −1 mol −1 ), and K is the calculated constant kinetic rate.
The values of ∆S* (J mol −1 K −1 ) and ∆H* (kJ mol −1 ) are determined using the Eyring formula: [50]: where K b is the Boltzmann constant and h is the Plank constant.
Ln K 2 values are plotted vs. 1/T values.Then, gradients of the plots are used to define activation energy (Figures 12a and 13a).However, activation enthalpy and entropy values are calculated using Ln (K 2 /T) plots vs. 1/T (Figures 12b and 13b).Finally, activation energy (kJ mol −1 ) is calculated from Equation ( 6): The negative values of entropy of the system indicate the fall of the disorder during dye degradation, while the positive values of the enthalpy prove that the studied system is endothermic, which is consistent with the increase in decolorization when the temperature increases.
E a values calculated for garlic-CuO nanocomposite are equal to18.44 kJ mol −1 and 23.28 kJ mol −1 for calmagite and naphthol solutions, respectively (Figures 12 and 13).However, E a values calculated for garlic-AgO nanocomposite are equal to 50.01 kJ mol −1 and 12.44 kJ mol −1 for calmagite and naphthol solutions, respectively.The calculated low E a values suggest that the prepared nanocomposites are efficient for the degradation of calmagite and naphthol solutions.It is noteworthy to clarify that the calculated E a values

Figure 1 .
Figure 1.Chemical structures of (a) calmagite and (b) naphthol blue black B.

Figure 6
Figure 6 gives the XRD patterns of garlic peel powders, garlic-CuO, and garlic-AgO nanocomposites.As shown, the XRD data of the garlic peel powder display three diffraction peaks at 2θ = 16.2°,22°, and 32.4° which correspond to the (101), (002), and (040) crystal planes, respectively.It is assigned to cellulose type I [40].The strong diffraction

Figure 9 .
Figure 9.Effect of H 2 O 2 on the catalytic degradation of calmagite and naphthol (T = 20 • C, pH = 6, C 0 = 30 mg/L) solutions in the presence of garlic-CuO and garlic-AgO nanocomposites.The efficiency of garlic-CuO and garlic-AgO nanocomposites/H 2 O 2 to decolorize calmagite and naphthol solutions is also studied by varying the initial dye concentrations

Figure 10 .
Figure 10.Effect of initial concentrations of calmagite and naphthol solutions (T = 20 °C, pH = 6, H2O2 = 10 mL/L) on catalytic degradation in the presence of garlic-CuO and garlic-AgO nanocomposites.

Figure 10 .
Figure 10.Effect of initial concentrations of calmagite and naphthol solutions (T = 20 • C, pH = 6, H 2 O 2 = 10 mL/L) on catalytic degradation in the presence of garlic-CuO and garlic-AgO nanocomposites.

Figure 10 .
Figure 10.Effect of initial concentrations of calmagite and naphthol solutions (T = 20 °C, pH = 6, H2O2 = 10 mL/L) on catalytic degradation in the presence of garlic-CuO and garlic-AgO nanocomposites.

Figure 11 .
Figure 11.Effect of temperature on the catalytic degradation of calmagite and naphthol solutions (pH = 6, C 0 = 30 mg/L, H 2 O 2 = 10 mL/L) in the presence of garlic-CuO and garlic-AgO nanocomposites.

Table 1 .
Kinetic rates and thermodynamic parameters calculated during degradation of calmagite using garlic-CuO nanocomposite/H 2 O 2.

Table 2 .
Kinetic rates and thermodynamic parameters calculated during degradation of naphthol using garlic-CuO nanocomposite/H 2 O 2.