1 Introduction

Nuclear waste represents a great challenge and interesting material in a lot of research work because of the difficulty of finding suitable techniques for nuclear waste management and because the cost of the disposal process is so high to obtain a safe environment [1]. The main components of nuclear waste are the radioactive nuclides in their three forms: solid, liquid, and gaseous. All of these radioactive nuclides represent a great source of hazardous materials due to their continuous radiation particles like gamma, beta, and alpha [2]. From this point of view, a lot of researchers have been focused on removing these radioactive nuclides from nuclear waste to remediate those hazardous materials before discharging them into the environment to protect the environment from their risky effects [3, 4]. Removal of radioactive isotopes like cesium, strontium, zinc, thorium, cobalt, and erbium from nuclear wastewater is a very efficient process to decrease the effects of the different kinds of radiation, such as alpha, and beta, X-ray, neutrons, and gamma radiation, which penetrate the human body and cause biological cells damage [5, 6]. However, actinides and lanthanide ions have attracted attention because they are considered the most long-lived radioactive waste [7]. The removal of radioactive nuclides has been established by using a lot of techniques, like micro and nanomembranes, solvent extraction, ion exchange, precipitation, biosorption, and adsorption [8,9,10,11,12]. A comparative study was investigated by using graphene oxide and organic and inorganic ion exchange for the adsorption of diverse radioactive nuclides [8]. A layered metal–organic framework has been implemented for the adsorption of Cs radionuclides through an ion exchange mechanism [9]. Mexenes as a two-dimensional material have been implemented for the adsorption removal of radioactive pollutants [10]. A nanocomposite of chitosan, acrylic acid, and 1-vinyl-2-vinyl pyrrolidone mixed with a multi-walled of carbon nanotubes has been prepared using gamma radiation for the adsorption removal of 60Co, 152+154Eu, and 134Cs radioactive nuclides [11]. Acid-activated nano bentonite was reported for the adsorption of Co, and Zn as heavy elements in addition to their 60Co and 65Zn radioisotopes from aqueous media [12]. The targeted technique in this study was adsorption removal because it is a low-cost technique, simple, and can be implemented by using diverse materials like metal oxide nanoparticles, different polymers, clays, and metal–organic frameworks (MOFs) [12,13,14].

Herein, 60Co, and 152+154Eu are the two radioactive nuclides of our interest; these two radioactive nuclides are gamma emitters with a long half-life [14, 15]. The toxicity of Co and Eu have been categorized according to WHO as the permissible limit for cobalt in water is about 0.005 mg/L, on the other hand, the permissible limit for Eurobium in water is about 0.0001 mg/L. In previous literature, many researchers reported diverse publications for the adsorption of 60Co, and 152+154Eu by using various kinds of materials and techniques [7, 12,13,14,15,16,17,18,19,20,21]. Manganese oxide nanoparticles coated with oleyl amine as a ligand containing an amine group (–NH2) have been applied to adsorb 60Co, and it was reported that the adsorption capacity was 100.0 mg/g [14]. The geochemical adsorption of Eu(III) on rutile was investigated, and the obtained results indicated that the adsorption was controlled by the acidity of the rutile, where the adsorption occurred in the outer-sphere interaction and transformed to the inner-sphere interaction under neutral, and alkaline conditions [15]. Two-dimensional Ti3C2 as a kind of mxene material functionalized with carboxyl groups was used for Eu(III) adsorption; the maximum value of adsorption was 97.10 mg/g, the reaction was fitted kinetically with (pso), and the most fitted adsorption model was Langmuir model [16]. The γ-alumina and multi-walled kinds of carbon nanotubes, MWCNTs, were reported for the adsorption of Co presented on aqueous media, where the adsorption was investigated as a monolayer and the maximum adsorption of γ-alumina and MWCNTs were 75.78 and 78.94 mg/g, respectively [17], In addition, a lot of different nanocomposite materials with different conditions and mechanisms were investigated and established for the adsorption of radioactive nuclides 60Co, and 152+154Eu [7, 18,19,20,21]. Perovskite nano metal oxides are functional devices in a lot of technological applications, like wastewater treatment [22], solar cells [23], and a lot of other technological applications [24].

In this study, different metal oxides were mixed in a one-pot reaction in the presence of formaldehyde mixed with water as a medium for this reaction and refluxed for about 12.0 h at 140 °C with vigorous stirring. The obtained product was mixed oxides of nickel, cobalt, molybdenum, copper, and zinc as well as two kinds of perovskites oxides; Co0.5Ni0.5O and Co2Mo3O8, according to the XRD patterns and FT-IR analysis. The new nanosorbent was characterized elementally by using PXRD analysis, FT-IR spectroscopy, and EDX. The morphological structure was established through SEM and HRTEM. Finally, the thermal stability of the synthesized nanosorbent was established by using thermal gravimetric analysis.

2 Experimental

2.1 Materials and Instrumentation

In this adsorption study, the used chemicals were applied without any purification process, all the specifications of these chemicals have been illustrated in Table 1, and the instrumentation specifications are given in Table 2.

Table 1 The chemical's purity and the specifications of the used materials
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Table 2 Instrumentation
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2.2 Synthesis of Co0.5Ni0.5O–Co2Mo3O8–CuO–ZnO Perovskite Metal Oxides Nanosorbent

2.2.1 Combustion Synthesis of Nano Perovskite Co–Ni Oxide

Nano perovskite Co–Ni oxide (Co0.5Ni0.5O) was synthesized through a combustion method. For this purpose, cobalt, and nickel hydroxides were prepared in one pot reaction as follows: firstly, 0.01 mol of nickel chloride hexahydrate (NiCl2·6H2O), and 0.01 mol of cobalt chloride hexahydrate (CoCl2·6H2O) were dissolved in 250.0 mL deionized water; after that, 0.04 mol of (NaOH) sodium hydroxide was dissolved using 50.0 mL deionized water, then the sodium hydroxide solution was added stepwise to the previous nickel–cobalt chloride solution. The mixture obtained from this reaction was stirred vigorously for 90.0 min at 80 °C until a greenish-brown nickel–cobalt double hydroxide precipitate was obtained, which was washed several times using deionized water, and dried at 70 °C for 4.0 h. Secondly, 3.0 g of nickel–cobalt hydroxides and 3.0 g of urea (NH2CONH2) were mixed, and the obtained mixture was put in a muffle for combustion at 700 °C for about 4.0 h to form cobalt–nickel perovskite nanoparticles (Nano-Co0.5Ni0.5O) as a black precipitate [23, 24].

2.2.2 Combustion Synthesis of Nano Copper Oxide N-CuO

This is a modified method from Mahmoud et al. (2019), the N-CuO was synthesized by using combustion synthesis from two precursor materials, copper(II) acetate, and sodium hydroxide. 20.0 mL containing dissolved 0.02 mol of NaOH was added gradually to a solution of 100.0 mL containing dissolved 0.01 mol of Cu(CH3COO)2 with vigorous stirring for 30.0 min at 90 °C, after a few minutes, a blue precipitate of copper hydroxide will appear. The precipitate was obtained through filtration, then washed three times, and dried in an oven at 70 °C for 6.0 h. N-CuO was synthesized by using the mass percent 2.0:2.0 g of Cu(OH)2 and glycine. This binary mixture was mixed very well, and after that, it was calcinated at 800 °C in a muffle for 6.0 h. Finally, the final product was a black precipitate of N-CuO, which had been ground, characterized, and identified previously [25].

2.2.3 Combustion Synthesis of Nano Molybdenum Oxide N-MoO3

This is a modified method of Allam et al. (2021). In this method, the N-MoO3 was synthesized through mixing of 1.0 g of molybdenum acetate (Mo2(CH3COO)4), with 1.0 g of glycine (NH2CH2COOH) together as solid materials. This mixture was then put in the muffle at 600 °C for 6.0 h, and at the end of this reaction, the N-MoO3 green crystals were obtained [26, 27].

2.2.4 Combustion Synthesis of Nano Zinc Oxide N-ZnO

This is a modified method from Allam et al. (2021). In this method, N-ZnO was synthesized by using a sodium hydroxide solution of about 10.0 mL deionized water containing dissolved 0.02 mol of NaOH that was added to the other solution that was about 50.0 mL deionized water containing dissolved 0.01 mol of zinc acetate dihydrate (Zn(CH3COO)2·2H2O) under vigorous stirring for 45.0 min at 90 °C. Finally, zinc hydroxide Zn(OH)2 as a white precipitate was formed, washed using deionized water several times, and then dried at 90.0 °C for 4.0 h. The second step was the mixing of zinc hydroxide (Zn(OH)2) with glycine (NH2–CH2–COOH) by using a suitable stoichiometry (1.0 g:1.0 g), followed by calcination of the mixture at 900 °C in a muffle for 6.5 h to obtain the nano zinc oxide [28].

2.2.5 Synthesis of Nickel–Cobalt–Molybdenum–Copper–Zinc Oxide Nanosorbent

Nanosorbent was synthesized through a mixing step, which was implemented by mixing 2 g of the nano Ni–Co perovskite oxide (N-Co0.5Ni0.5O) and 1 g of each metal oxide (NMoO3, N-CuO, and N-ZnO) in a one-pot reaction by using the formaldehyde as a crosslinker for those metal oxides and refluxing for about 6.0 h at 140 °C with vigorous stirring. The obtained product was a mixed oxide of cobalt, nickel, molybdenum, copper, and zinc, as well as two kinds of perovskites (Co0.5Ni0.5O and Co2Mo3O8) [29,30,31,32]. Scheme 1 illustrates all the previous steps. The nanocomposite was characterized using FT-IR, EDX, and PXRD, and TGA was applied to study the thermal stability of the nanosorbent. Finally, the morphological structure was established through SEM and HRTEM.

Scheme 1
scheme 1

Synthesis of Co–Ni–Mo–Cu–Zn perovskite oxide nanosorbent

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2.3 Preparation of Radioactive Eu(III), and Co(II)

The radioactive nuclides 152+154Eu(III), and 60Co(II) were obtained through an irradiation process of 20.0 mg Eu2O3, and CoCl2·6H2O, respectively. The two materials were wrapped individually in thin aluminum foil after that they were put in an irradiation aluminum can for 48.0 h toward a thermal neutron flux of 1.8 × 1014 n/cm2/s. The two samples were put in the water-cooled ETRR-2 vertical channels (22.0 MW) at the Egyptian Second Research Reactor (ETRR-2), Inshas, Egypt. After the short-lived impurities were decayed through a suitable cooling time, both of the radioactive elements 60Co(II), and 152+154Eu(III) were dissolved using 10.0 mL of HCl (1.0 mol/L), after that this stock solution was stored to be used in the adsorption experiments. In this study, the determination 60Co(II), and 152+154Eu(III) γ-activity was investigated using (HPGe: GX2518 model, Canberra, USA) as a spectrometer for γ-ray that is calibrated in the presence of a coaxial detector connected with a multi-channel analyzer.

2.4 Adsorption Removal Study

The adsorption removal was established by using a 10.0 mL glass vial containing 0.01 g of the Co–Ni–Mo–Cu–Zn perovskite oxide nanosorbent that was equilibrated with 5.0 mL of different pH solutions from 1.0 to 6.0 those were spiked with radioactive 60Co(II), and 152+154Eu(III). All of the vials were shaken for about 24.0 h (140.0 rpm at 25 ± 1 °C) by using a thermostat shaker. After each equilibrium, about 1.0 mL of the resultant aliquot was taken from the aqueous solution of diverse vials, and then 60Co(II), and 152+154Eu(III) radioactivity was measured at their characteristic γ-energies by using a (Spetech ST 360-crystal-USA) with a single-channel analyzer. Both the adsorption capacities (qe in mg/g) and the removal percentages (%R) for 60Co(II), and 152+154Eu(III) were calculated through Eqs. (1) and (2) respectively [33,34,35].

$${\text{R}}_{\%} = \frac{{{\text{C}}_{{\text{o}}} - {\text{C}}_{{\text{e}}} }}{{{\text{C}}_{0} }} \times 100$$
(1)
$${\text{q}}_{{\text{e}}} = \frac{{{\text{C}}_{{\text{o}}} - {\text{C}}_{{\text{e}}} }}{{\text{m}}} \times {\text{ v}}$$
(2)

where, Co/starting concentration (mg/L) and Ce/concentration at the equilibrium of the radionuclides (mg/L), m/nanosorbent mass in grams; and V/solution volume in liters.

3 Results and Discussion

3.1 Characterization of Co–Ni–Mo–Cu–Zn Perovskite Oxide Nanosorbent

3.1.1 FT-IR Spectroscopic Analysis

The synthesized nanosorbent Co–Ni–Mo–Cu–Zn perovskite oxides was characterized and investigated through FT-IR spectroscopy within the spectrum range (400–4000 cm−1). It was found that the FT-IR spectrum has diverse kinds of peaks, as illustrated in Fig. 1. The N-CuO appeared at two characteristic peaks at 438.30 and 496.36 cm−1 instead of the one peak in the case of N-CuO only at 482 cm−1 those peaks were attributed to the stretching vibration of the N-Cu–O bond. In addition, the peak at 1112.68 cm−1 was referred to copper oxygen bond in N-CuO [25]. Furthermore, the two strong peaks seen at 876.0 and 663.52 cm−1 were referred to as N-CuO [25]. N-MoO3 appeared in the FT-IR spectrum through different peaks; the first peak was at 568.59 cm−1 and referred to bending vibration modes of O–Mo–O with different bond lengths for Mo–O. The peak at 803.70 cm−1 refers to Mo6+ vibrations in Mo–O–Mo [26, 27]. The layered MoO3 orthorhombic phase, which has terminal Mo–O, was illustrated by the two splitting peaks at 921.54, and 948.89 cm−1 [27, 28].

Fig. 1
figure 1

FT-IR spectrum of Co–Ni–Mo–Cu–Zn perovskite oxides nanosorbent

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Also, the peak at 568.59 cm−1 was due to the vibrations in Ni–O, and the characteristic peak for Zn–O stretching vibration appeared at 438.30 cm−1 [28]. The peaks found at 717.31 were due to Co2Mo3O8 perovskite material [30, 31]. The peaks at 1619.66 and 2921.62 may be due to the Co–Ni perovskite metal oxide [23, 24, 32]. Finally, the peak at 3516.62 represents the OH groups stretching vibrations that were coordinated with the diverse metal oxides in the perovskite nanosorbent.

3.1.2 Thermal Gravimetric Analysis

The Co–Ni–Mo–Cu–Zn perovskite oxide nanosorbent was analyzed thermally using TGA instrumentation. The thermogram is shown in Fig. 2. The thermogram exhibited diverse small thermal degradation steps, about 3.14% of all the sample weight, from 0 to 800 °C, this is attributed to the loss of water molecules on the metal oxide's surface. The total nanosorbent residue weight was 96.86% of the initial weight due to the high thermal stability of all the metal oxides. This is evidence that the synthesized nanocomposite has extreme thermal stability.

Fig. 2
figure 2

TGA of Co–Ni–Mo–Cu–Zn perovskite oxides nanosorbent

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3.1.3 X-ray Diffraction Analysis

XRD was implemented for the characterization of Co–Ni–Mo–Cu–Zn perovskite oxide nanosorbent to investigate the nanosorbent’s formation. X-ray pattern of this nanosorbent has established the presence of the different metal oxides Co3O4, MoO3, ZnO, and NiO, two kinds of perovskite materials, cobalt–nickel oxide perovskite in the two stoichiometric Co0.1Ni0.9O, and Co0.5Ni0.5O, in addition to cobalt molybdenum oxide Co2Mo3O8 according to the reference codes in Table 3. The XRD characteristic peaks appeared in Fig. 3 as the following; 2θ = 17.96°, 21.38°, 24.40°, 25.21°, 25.82°, 27.93°, 33.37°, 36.37°, 37.20°, 38.67°, 43.23°, 59.36°, 62.79°, 65.24° and 75.36°. The exhibited peaks are due to the following metal oxides and perovskites: Co0.1Ni0.9O, Co0.4Ni0.6O, MoO3, Co3O4, Co2Mo3O8, CuO, ZnO and NiO [23,24,25,26,27,28,29,30,31].

Table 3 XRD pattern list of the Ni–Co–Mo–Cu–Zn perovskite oxides nanosorbent
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Fig. 3
figure 3

XRD pattern of Co–Ni–Mo–Cu–Zn perovskite oxides nanosorbent

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3.1.4 EDX for the Nano Perovskite Ni–Co Oxide

The EDX analysis was established for the newly synthesized perovskite nanosorbent to establish the successful combustion synthesis of this nano perovskite Ni–Co oxide, and the spectrum of the analysis was shown in Fig. 4b, the perovskite SEM was illustrated in Fig. 4a. The EDX spectrum found the characteristic peaks of Co, Ni, and oxygen within a percent intensity of about 29.94, 53.46, and 16.62, and this percent establishes the presence of nano perovskite in this percent of Co0.4Ni0.6O, as shown in Table 4.

Fig. 4
figure 4

EDX of Co–Ni-perovskite oxide; a SEM image, and b EDX spectrum

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Table 4 Element percent of nano perovskite Co–Ni-oxide from EDX analysis
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3.1.5 High-Resolution Transmission and Scanning Electron Microscopy (HR-TEM and SEM)

The surface morphology of Co–Ni–Mo–Cu–Zn perovskite oxide nanosorbent has been characterized by using SEM as well as HR-TEM, as shown in Figs. 5 and 6, respectively. The image of SEM indicates that there are two kinds of rods: the larger one may be the Co2Mo3O8 perovskite, the result of the refluxing process; the smaller one may be the Co0.5Ni0.5O perovskite, the result of the combustion synthesis; and the other kinds of spherical shapes are the other metal oxides like CuO and ZnO. The image of HR-TEM illustrates the average particle size and other aggregates like 65.71, 115.12, and 242.89 nm; however, the average value of particle size was 18.67–42.62 nm. The surface of Co–Ni–Mo–Cu–Zn perovskite oxide nanosorbent through HR-TEM looked like sticks that have rock points above them with a non-homogenous structure, as illustrated in Fig. 6.

Fig. 5
figure 5

SEM image of Co–Ni–Mo–Cu–Zn perovskite oxides nanosorbent

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Fig. 6
figure 6

HRTEM image of Co–Ni–Mo–Cu–Zn perovskite oxides nanosorbent

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3.2 Adsorption of 152+154Eu and 60Co onto Co–Ni–Mo–Cu–Zn Perovskite Oxide Nanosorbent

3.2.1 The pH Effect on the Adsorption Removal

The effect of the radioactive solution’s pH was investigated through diverse adsorption experiments at diverse pH values to observe the adsorption removal behaviors for 152+154Eu and 60Co ions as well as to determine the maximum pH for each of them. Figure 7 illustrates the results of the radionuclide's adsorption capacities (mg/g) that were presented versus different values of pH (1.0–6.0). The adsorption of this nanosorbent is mainly based on the hydroxide groups of the perovskite, and other metal oxides. The low pH region (pH 1–2) in Fig. 7 indicated that there were traces of removal for both radioactive nuclides. This was referred to as the protonation of hydroxide presented on the surface of perovskite and metal oxides of the nanosorbent, and this process increased by the increase in the hydrogen ions concentration, which leads to a high competition between the radioactive nuclides 152+154Eu and 60Co that possess positive charges and the high concentration of hydrogen ions. On the other hand, increasing the pH values gradually leads to less protonation of the surface of the perovskite nanosorbent, which leads to the freedom of the binding sites to interact with positively charged radioactive nuclides. In this case, the high adsorption removal of Co–Ni–Mo–Cu–Zn perovskite oxide nanosorbent towards the target radioactive nuclides is based on the surface function groups OH− reactivity according to Scheme 2. The lowest adsorption capacity for Eu was obtained at pH 3 as 29.51 mg/g, and for Co, it was obtained at pH 2 as 3.85 mg/g. On the other hand, the highest adsorption removal for both radionuclides was obtained at pH 6 for 152+154Eu and 60Co, respectively [20,21,22].

Fig. 7
figure 7

Adsorption values of 152+154Eu, and 60Co onto Co–Ni–Mo–Cu–Zn perovskite oxides nanosorbent at different pHs (Initial concentrations of 60Co(II) [200 mg/L] and 152+154Eu(III) [250 mg/L])

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Scheme 2
scheme 2

Adsorption mechanism of 152+154Eu and 60Co onto Co–Ni–Mo–Cu–Zn nanosorbent

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The pHpzc of the perovskite nanosorbent was determined and its zeta potential diagram was presented in Fig. 8. The Zeta potential is a parameter that indicates the electrochemical equilibrium in the case of the interface between solid particles, and liquid. From Fig. 8, it was indicated that the surface of the Co–Ni–Mo–Cu–Zn perovskite oxides nanosorbent has a negative charge between − 100.0 to 0.0 and this negative value is a good indication for the negative charge of the nanosorbent surface consequently the electrostatic interaction occurred between this nanosorbent as a negative charged and the two positively charged radioactive nuclides 152+154Eu and 60Co.

Fig. 8
figure 8

pHpzc of Co–Ni–Mo–Cu–Zn perovskite oxides nanosorbent

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3.2.2 Kinetics of Adsorption Removal at Different Contact Times

Adsorption removal of radioactive nuclides 152+154Eu and 60Co was established by using a batch technique at different intervals of time (1.0–20.0 min). The adsorption removal was very low at 0.5, 1.0, 2.0, 3.0, and 4.0 min. The adsorption was increased gradually for both radioactive nuclides by increasing the contact time. The removal capacity was 1.11 mg/g at 0.5 min and became 30.47 mg/g at 25.0 min for the 152+154Eu radionuclide. On the other hand, for 60Co was 3.95 mg/g at 0.5 min and became 13.41 mg/g at 25.0 min. The equilibrium of the adsorption removal for both radioactive nuclides was obtained at around 25.0 min for both radionuclides 152+154Eu and 60Co and the equilibrium adsorption values were 30.47 and 13.41 mg/g for Eu(III) and Co(II), respectively. Figure 9 illustrates the results of this parameter. This adsorption removal study was analyzed kinetically to establish the adsorption removal mechanism, which includes diffusion control through mass transfer. Four different models kinetic, in this study, were analyzed by using, pseudo-first and second-order models, the intraparticle model, and finally Elovich model [20,21,22].

Fig. 9
figure 9

Adsorption values of 152+154Eu, and 60Co onto Co–Ni–Mo–Cu–Zn perovskite oxides nanosorbent at different times (Initial concentrations of 60Co(II) [200 mg/L] and 152+154Eu(III) [250 mg/L])

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The kinetic models were established by using four models as illustrated in supplementary Fig. S1. The first one was pseudo-first order which represented the time (t) versus ln (qe − qt) according to Eq. (3) Where qt is the adsorbed radionuclide (mg/g) at time t and qe are the adsorbed radionuclide (mg/g) at equilibrium, respectively and in this case, the slope is k1 and the adsorption rate constant which was formulated by g/mg min

$${\text{ln }}\left( {{\text{q}}_{{\text{e}}} - {\text{q}}_{{\text{t}}} } \right) = {\text{lnq}}_{{\text{e}}} - {\text{K}}_{{1}} {\text{t}}$$
(3)

The second model was the pseudo-second-order which is represented \(q_{e}^{2}\) and t/qt according to Eq. (4) and after that k2 (mg/g min) which is the rate constant was calculated as the reciprocal of slope as shown in Eq. (4).

$${\text{t}}/{\text{q}}_{{\text{t}}} = { 1}/{\text{k}}_{{2}} {\text{q}}_{{\text{e}}}^{2} + {\text{ t/q}}_{{\text{e}}}$$
(4)

In third model the intraparticle diffusion which is considered the adsorption divided into two stages, firstly the diffusion of radionuclides as adsorbate ions towards the surface of the adsorbent externally secondly was the diffusion of radioactive nuclides towards the pores of nanosorbent internally. Therefore, this model is represented t1/2 versus qt as shown in Eq. (5), the Kid (mg/g/min1/2) intraparticle diffusion rate constant is estimated from the slope of this graph.

$${\text{q}}_{{\text{t}}} = {\text{ k}}_{{{\text{id}}}} {\text{t}}^{{{1}/{2}}} + {\text{ C}}$$
(5)

The final implemented model in this study was Elovich which considered adsorption as a chemisorption process occurring on a heterogeneous surface as shown in Eq. (6).

$${\text{q}}_{{\text{t}}} = { 1}/\beta {\text{ ln}}\alpha \beta \, + { 1}/\beta {\text{ lnt}}$$
(6)

where α/adsorption rate (mg/g min), and β/the coverage of surface in addition to the minimum required energy of activation to obtain the adsorption via a chemisorption process.

These four models have been established for 152+154Eu, and 60Co radioactive nuclides adsorption onto Co–Ni–Mo–Cu–Zn perovskite oxides nanosorbent. The parameters of the kinetics study were estimated and calculated in Table 5. It could be concluded that the adsorption of 152+154Eu was fitted with First, and intraparticle models more than the two other models on the other hand 60Co was fitted with First, Second, and intraparticle models those results were according to the values of different correlation coefficients.

Table 5 Kinetic parameters for the adsorption of 152+154Eu, and 60Co onto Co–Ni–Mo–Cu–Zn perovskite oxides nanosorbent
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From the kinetic study, it was concluded that; the adsorption of radioactive nuclides was established through a one-step only according to the p-second-ord model, and the mechanism of film diffusion was accepted more than the intraparticle diffusion consequently the Co–Ni–Mo–Cu–Zn perovskite oxides surface is non-homogenous according to the low correlation with Elovich and this increase the probability that the reaction occurs through an ion-pair reaction mechanism and a complex formation [20,21,22, 36,37,38,39,40,41].

3.2.3 Metal Concentration Effect on the Adsorption

The effect of radioactive nuclide’s initial concentration on the 152+154Eu, and 60Co adsorption was investigated. It was found that the adsorption increased with increasing the concentration of radioactive nuclides and versus case was observed at low concentrations of radioactive nuclides. This behavior was attributed to the barrier of mass transfer which increases between 152+154Eu, and 60Co radionuclides in the radioactive solution and nano perovskite metal oxides functional groups. The lowest adsorption was obtained by using 25.0 ppm from 60Co and 50.0 ppm from 152+154Eu, the adsorption was 8.19 mg/g, and 0.28 mg/g for 152+154Eu and 60Co, respectively. On the other hand, the highest remediation was obtained by using 300.0 ppm of 152+154Eu, and 600.0 ppm of 60Co the adsorption was 45.17 mg/g for 152+154Eu, and 14.32 mg/g for 60Co. This study is shown in Fig. 10. The adsorption models were studied to establish the suitable mechanism in the adsorption in addition to the maximum adsorption onto the nano perovskite metal oxides. In this paper, 4-linear models for the adsorption process were reported as follows, Langmuir; Freundlich in addition to Dubinin–Radushkevich (D–R), and Temkin were applied, and investigated after that the adsorption parameters were calculated as illustrated in supplementary Fig. S2.

Fig. 10
figure 10

Adsorption values of 152+154Eu, and 60Co onto Co–Ni–Mo–Cu–Zn perovskite oxides nanosorbent at different concentrations (Initial concentrations of 60Co(II) [200 mg/L] and 152+154Eu(III) [250 mg/L])

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The first adsorption model was Langmuir; in this model, the adsorption mechanism is considered an unimolecular chemical reaction that can make a reversible reaction. In this model, the adsorption occurs in a monolayer of the nanosorbent surface and is homogenous at the same time the following Eq. (7) illustrates this model.

$${1}/{\text{q}}_{{\text{e}}} = { 1}/{\text{q}}_{{{\text{max}}}} + {1}/{\text{q}}_{{{\text{max}}}} {\text{K}}_{{\text{L}}} {\text{C}}_{{\text{e}}}$$
(7)

qe/equilibrium concentration of the adsorbates EuIII, and CoII onto the adsorbent Co–Ni–Mo–Cu–Zn perovskite oxides (mg/g). qmax/maximum adsorption of the radioactive nuclides onto the nanosorbent surface (mg/g), Ce/equilibrium concentration of 152+154Eu and 60Co (mg/L), and KL/saturation constant (L/mg).

The second adsorption model was Freundlich in this model, the remediation is supposed to occur through an interaction of the adsorbate with the nanosorbent active binding sites onto a heterogeneous surface according to Eq. (8).

$${\text{q}}_{{\text{e}}} = {\text{ K}}_{{\text{F}}} {\text{Ce}}_{{1}} /{\text{n}}$$
(8)

Equation (9) has another linear form as the following;

$${\text{lnq}}_{{\text{e}}} = {\text{ ln K}}_{{\text{F}}} + { 1}/{\text{n lnC}}_{{\text{e}}}$$
(9)

qe/adsorbed 152+154Eu and 60Co(mg/g), Ce/equilibrium of 152+154Eu and 60Co in the liquid phase, KF/Freundlich constant according to the energy of bonding.

The third model is Temkin model, in this model the remediation is supposed to depend on the heat of the reaction according to Eq. (10).

$${\text{q}}_{{\text{e}}} = \, \left( {{\text{R}}_{{\text{T}}} /{\text{b}}_{{\text{t}}} } \right){\text{ ln a}}_{{\text{t}}} + \, \left( {{\text{R}}_{{\text{T}}} /{\text{b}}_{{\text{t}}} } \right){\text{lnC}}_{{{\text{e}} }}$$
(10)

qe/adsorbed 152+154Eu, and 60Co(mg/g), bt (mg/L)/Temkin constant, at (L/g)/binding constant at equilibrium, and (RT/bt) heat constant of the adsorption (J/mol).

The fourth model was (D–R), in this model the adsorption mechanism occurs on the nanosorbent porous and it estimates the energy in the adsorption according to the Eq. (11).

$${\text{lnq}}_{{\text{e}}} = {\text{ lnq}}_{{\text{s}}} - \, \left( {{\text{K}}_{{{\text{ad}}}} \varepsilon^{{2}} } \right)$$
(11)

where qs/nanocomposite theoretical saturation capacity (mg/g), Ɛ/Polanyi potential related to equilibrium that is calculated in Eq. (12), and Kad/D–R constant related to the mean amount of free energy in the process per mole of the nanosorbent (J/mol).

$$\varepsilon \, = {\text{ RTln }}\left( {{1} + { 1}/{\text{ C}}_{{\text{e}}} } \right)$$
(12)

where R/universal gas constant (8.314 J/mol/K), T/temperature measured in Kelvin and qe/amount of 152+154Eu and 60Co(mg/g).

This study established that both radioactive nuclides 152+154Eu, and 60Co have fitted with the Langmuir as well as the Freundlich models and this is a good indication that the adsorption occurs chemically as unimolecular adsorption in addition to the non-homogeneity of this nanosorbent in the adsorption process which make it fitted with Frendlich model. The parameters of the adsorption process were calculated and illustrated in Table 6. [20,21,22, 42,43,44,45].

Table 6 Adsorption isotherm parameters for the adsorption of 152+154Eu, and 60Co onto Co–Ni–Mo–Cu–Zn perovskite oxides nanosorbent
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3.2.4 Effect of Adsorbent Dose on 152+154Eu, and 60Co Adsorption

In adsorption experiments, the adsorbent dose is also a crucial factor as it establishes the material's capacity to adsorb radionuclides at a certain starting solution concentration. Figure 11 illustrates how the amount of Co–Ni–Mo–Cu–Zn perovskite oxides nanosorbent affects the adsorption of 152+154Eu, and 60Co. The study examined the elimination of Europium and cobalt using Co–Ni–Mo–Cu–Zn perovskite oxides nanosorbent at varying V/m ratios of 152+154Eu and 60Co. As predicted, since increasing the adsorbent dose gives a higher surface area or adsorption sites for a certain radioactive ion concentration, the experimental findings showed that the increase in adsorbent dosage enhanced the percent removal capability of radionuclides.

Fig. 11
figure 11

Effect of V/m ratio on the adsorption of 152+154Eu, and 60Co onto Co–Ni–Mo–Cu–Zn perovskite oxides nanosorbent at initial concentrations of 60Co(II) [200 mg/L] and 152+154Eu(III) [250 mg/L]

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3.2.5 Recyclability of Co–Ni–Mo–Cu–Zn Perovskite Oxides Nanosorbent for Adsorption of 152+154Eu, and 60Co Radionuclides

To test the capability of the Co–Ni–Mo–Cu–Zn perovskite oxides nanosorbent for reusability, a small chromatographic column was packed with 0.5 g of the nanosorbent, then a radioactive solution contains 152+154Eu, and 60Co radionuclides was loaded on the column. Since low adsorption for 152+154Eu, and 60Co was obtained at lower pH values, HCl solution was used for complete elution of the radionuclides. The previous steps were repeated many times and the adsorption % was calculated in each time and the results are shown in Table 7. The obtained findings indicate that the nanosorbent may be used efficiently many times.

Table 7 Adsorption % of 152+154Eu, and 60Co radionuclides from 0.5 g (Co–Ni–Mo–Cu–Zn perovskite oxides nanosorbent based column (0.6 cm i.d.) at a flow rate of 0.5 mL/min
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4 Conclusion

A new nanosorbent consisting of cobalt–nickel–molybdenum–copper–zinc oxides and containing two kinds of perovskite metal oxides was successfully synthesized. The nano sorbent was characterized and investigated through its chemical description and morphological appearance using using FT-IR, EDX, XRD, TGA, SEM, and HRTEM. The synthesized Co–Ni–Mo–Cu–Zn perovskite oxides nanosorbent was examined for the adsorption process of 152+154Eu, and 60Co. The highest adsorption for both radionuclides was obtained at pH 6.0. The adsorption of 152+154Eu was fitted with First, and intraparticle models more than the two other models on the other hand 60Co was fitted with First, Second, and intraparticle models. The adsorption for 152+154Eu and 60Co was fitted with Langmuir and Freundlich models, however, 60Co was also fitted with D–R. The obtained results established the capability of this nanosorbent for the adsorption of nuclear wastewater from those radioactive nuclides152+154Eu, and 60Co to remove their risk before discharging the wastewater into the sea which leads to environmental contamination.