Introduction

The scientific community, regulatory institutions, and the general public have become more interested in emerging pollutants. One significant type of emerging pollutant is steroid sex hormones, which are considered as endocrine disrupting compounds (EDCS) (An et al. 2024; Kasonga et al. 2021). According to the WHO definition, an endocrine disruptor is an external substance or mixture that disrupts the functioning of the endocrine system, resulting in harmful health effects in a healthy organism, the next generation, or a population (WHO Endocrine disrupters 2024). The growing interest in these compounds can be attributed to the discovery of adverse environmental and health effects (Wang et al. 2024), their ability to accumulate in the food chain, advancements in detection methods, and the increased use of these compounds (Zhao 2024), leading to higher concentrations in water resources (Marumure et al. 2024; Mousavi et al. 2018).

The most potent estrogen among the known endocrine disrupting compounds is 17-beta-estradiol (E2) (Kim et al. 2015). This pollutant has been detected in various water environments and sewage samples (Georgin et al. 2024). The risks associated with E2 exposure include reproductive/hormonal disorders, neurobehavioral disorders and abnormal growth (Cosma et al. 2024). European Union has proposed a maximum limit of 50 ng/L for E2 in surface water to ensure human health and environmental protection (Moreira et al. 2022). Mammals, including humans, excrete this hormone and its derivatives on a daily basis through urine. Women can excrete approximately 2.4 µg/day; while, pregnant women have an average excretion rate of 259 µg/day; while, the reported concentration of E2 in water sources typically falls within the range of 1–10 ng/L (Grzegorzek et al. 2024). Hence, it is crucial to employ a sensitive, reliable, rapid, cost-effective, and efficient method for detecting and removing E2 at low levels (Georgin et al. 2024). So, biologically purifying endocrine disrupting compounds is challenging due to their toxicity to microorganisms (Guć and Schroeder 2020). Oxidizing these pollutants with ozone and UV is an option, but there is a risk of generating compounds that are even more toxic than the original substances. On the other hand, membrane processes are effective in removing pollutants without producing unwanted byproducts. However, these methods lack specificity, have high initial and operational costs, and require management of the produced sludge (Yang et al. 2024). Absorption is considered a viable and effective method for removing estrogens due to its high efficiency and accessibility. Various adsorbents, such as activated carbon, carbon resin, carbon nanotubes, silica zeolite, and molecular imprinting polymer (MIP), have been utilized in research to remove E2 (Cosma et al. 2024; Jatoi et al. 2024; Liu et al. 2024). MIPS, which are synthetic receptors, have gained significant popularity due to their selectivity, excellent physical and chemical stability, ease of preparation, reusability, and cost-effectiveness (Mayet et al. 2024; Sengar et al. 2024). This approach, pioneered by Vulff and Sarhan in 1972 (Wulff and Sarhan 1972), involves the formation of complexes between the analyte molecule, functional monomers, and cross-linkers. Upon removal of the template molecule, a porous polymer remains with binding sites that are complementary to the structure and chemical properties of the template molecule. An engraved polymer with high selectivity, sensitivity, and rapid detection capabilities can be synthesized by polymerizing polypyrrole (PPy) monomers in the presence of FeCl3 and K2S2O8 as oxidants to synthesis of MIP (Xia et al. 2013). PPy-MIP, a highly electrically conductive polymer, has garnered interest due to its simple synthesis, favorable environmental stability, and lack of requirement, making it a cost-effective choice compared to others. Despite numerous studies on the electropolymerization of PPy, there is currently limited information regarding its use in molecular engraving (Koudehi and Pourmortazavi 2018). Cáceres et.al studied the performance of PPy molecular template polymer for the selective extraction of bisphenol A and progesterone. The recovery rates for aqueous media were found to be 96.6% and 96%, respectively (Cáceres et al. 2018). In 2020, Huang et.al studied a combination of magnetic molecularly imprinted polymer and HPLC to determine the concentrations of hexsterol, nonylphenol, and bisphenol A in lake water and milk samples with low concentration levels. The method exhibited a detection range of 0.1–0.3 µg/L and a recovery range of 89.9–102.5% (Huang et al. 2020). The growing utilization of estradiol in diverse industries, particularly the pharmaceutical sector, and its presence in hospital and municipal wastewater systems have raised concerns about its potential impacts on human health, organisms, and the environment. Based on the best our knowledge, there is no information about the application of PPy molecular template polymer for the removal of E2. The objective of this research is to explore a cost-effective, rapid, and highly selective approach utilizing PPy-MIP to adsorb E2 from aqueous solutions in a safe manner.

Materials and methods

Regents and material

The compounds such as 17-beta-estradiol (E2), PPy and iron chloride (FeCl3) were obtained from Sigma Aldrich (USA). Chemicals and solvents such as HCl, NaOH, and other necessary chemicals were purchased from Merck (Germany).

Preparation of PPy molecularly imprinted polymer (PPy-MIP) and non-imprinted polymer (NIP) toward Fe3O4-SDS MNPs

In this research, the non-covalent template method was utilized. In the case of creating PPy-MIP, a mixture containing 300 μl of pyrrole, 50ml of distilled water, and 0.3 g of estradiol was stirred using a magnetic stirrer for 30 min. Subsequently, the solution was placed under a nitrogen gas atmosphere for 10 min to eliminate any oxygen gas present. Finally, 3 g of ferric chloride, acting as an oxidant, was added to the solution and mixed using a magnetic stirrer for 2 h. The container was sealed, and the polymerization process took place in the presence of nitrogen gas. The resulting mixture was then stored at room temperature in a dark and undisturbed location for a period of 48–72 h. This duration allowed sufficient time for polymerization to occur and for the adsorbent to establish contact with the template. As a result, black polymers were formed and settled within the mixture. To remove the ferric chloride and separate it from the adsorbent, the adsorbent was washed using an Erlenmeyer flask connected to a vacuum setup, along with an ample amount of distilled water. Additionally, to separate the template from the adsorbent, the solvent extraction method was employed using the Soxhlet system. Specifically, n-hexane solvent was used to dissolve the estradiol. This process resulted in the formation of a porous adsorbent material, which retained cavities and molded sites that corresponded to the structure of the estradiol template.

The procedure for preparing the NIP was largely identical to that of the MIP, with one key distinction: The template molecule, E2, was not included in the NIP synthesis. Consequently, the polymerization process for the NIP occurred without the presence of a template, resulting in the absence of specific binding sites for E2 in the NIP. Moreover, since E2 was not used, there was no need for a solvent extraction step in the NIP preparation. Finally, both the MIP and NIP were subjected to smoothing and drying processes.

Quantification of E2 by GC

The efficacy of the adsorbent polymer in removing estradiol from aqueous environments was determined by analyzing the residual concentration of E2 in the solution using a GC device, specifically the Agilent 7890A model. The GC setup included a 30-m long HP-5 chromatography column (Diameter 0.32 mm/Thickness 0.25 μm). Nitrogen gas was utilized as the carrier gas, flowing at a constant rate of 1 ml/min, with a split ratio of 5:1. The injection, furnace, and detector temperatures were set at 315 °C, 291 °C, and 311 °C, respectively. Total running time was 21 min.

Optimization of E2 adsorption condition

The variables that affect the removal of E2 by the adsorbent include pH (3.0, 5.0, 7.0, 9.0, and 11.0), time (10, 20, 30, 45, 60, 90, and 120 min), temperature (20, 30, 40, and 50 °C), initial concentration of E2 (5, 10, 25, 50, 75, and 100 mg/L), and dosage (0.2, 0.4, 0.6, 0.8, and 1 g/L). For experiments, 0.04 g of finely ground absorbent was added to flask, and were sealed and placed on a shaker for 45 min. Once the time was completed, 10 cc of the filtered solution was transferred to closed tubes with a capacity of 20 cc. To extract E2 from the water and transfer it to a dichloromethane solvent, 1 cc of propanol was added as an intermediate solvent, followed by 2 cc of dichloromethane as the final solvent in each tube. The tubes were then centrifuged for 5 min. This process ensured the complete extraction of E2 from the water and its transfer to the dichloromethane solvent. Finally, each sample was injected into the gas chromatograph (GC) to determine the residual concentration of estradiol, using the standard curve. The obtained results, along with the initial concentration of E2 in the samples, were used to calculate the removal efficiency at different stages, utilizing Eq. (1).

$$E = \frac{{\left( {C_{i} - C_{f} } \right)}}{{C_{i} \times 100}}$$
(1)

where Ci and Cf represent the concentration of E2 before and after the removal process. All experiments were performed under the same conditions for both the MIP and NIP adsorbents.

Isotherm, kinetic and thermodynamic modeling

Langmuir, Freundlich, Temkin, and Dubinin–Radushkevich (D-R) isotherms [Eqs. (2–5)] were applied to fit the experiment isotherms data (Leng et al. 2023a).

$${q}_{e}=\frac{{k}_{\text{l}}{C}_{e}}{1+{\propto }_{l}{C}_{e}}$$
(2)
$${q}_{e}={k}_{\text{f}}{C}_{e}^{nf}$$
(3)
$${q}_{e}={B}_{t}\text{ln}({C}_{e}{k}_{t})$$
(4)
$$q_{e} = q_{d} \exp \left( { - \beta_{d} \varepsilon^{2} } \right), \varepsilon = {\text{RTln}}\left( {1 + \frac{1}{{C_{e} }}} \right), E_{DR} = \frac{1}{{2\beta_{d}^{0.5} }}$$
(5)

The kl and kf (L/g) are the constants of Langmuir and Freundlich, respectively; αl is isotherm constant for Langmuir (L/mg); Bt, kt, and ε are the isothermal constants of the Temkin and Dubinin–Radushkevich model, respectively. qd (mg/g) is saturation capacity. EDR (kJ/mol), T (K) and R (8.314 J/mol K) show the free energy, temperature and gas constant, respectively. nf and βd are the exponents of the Freundlich and Dubinin–Radushkevich model.

Pseudo-first order, pseudo-second order, and intra-particle diffusion as kinetics models were applied [Eqs. (6–8)].

$${q}_{t}={q}_{e}(1-{e}^{-{k}_{1}t})$$
(6)
$${q}_{t}=\frac{{k}_{2}{q}_{e}^{2}t}{1+{k}_{2}{q}_{e}t}$$
(7)
$$q_{t} = k_{i} t^{\frac{1}{2}} + C$$
(8)

The qt (mg/g) is the rate of contaminant adsorbed by adsorbent; k1 (h−1), k2 (g/mg h), and ki (mg/g h1/2) related to the Pseudo-first-order, Pseudo-second-order, and Intra-particle diffusion constants. Parameter of t is the sorption time (min). C is a value associated with the boundary layer thickness.

The temperature effect on the sorption of E2 was studied via thermodynamic constraints like Gibb’s free energy (∆G°), enthalpy (∆H°) and entropy (∆S°). Thermodynamic parameters of the E2 adsorption are calculated via Eq. (9).

$${\Delta G}^{o}=-\text{RTln}K$$
(9)

where K represents thermodynamic equilibrium. The enthalpy changes of E2 adsorption as a temperature function on thermodynamic constant was obtained via Eq. (10).

$$d(\text{ln}K)=\frac{{\Delta H}^{o}}{{\text{RT}}^{2}}dT$$
(10)

Equation (11) then estimated the ∆S° value through the slope intercept of the linear plot.

$${\Delta G}^{o}=\Delta H-T\Delta {S}^{o}$$
(11)

Results and discussion

Characterization

SEM images showed that MIP has a more porous surface compared to NIP, which is attributed to the existence of etched holes in the presence of the target molecule, and this itself is a reason for the success of the imprinting process. It seems that NIP includes larger clusters and groups, and fewer apertures and small holes compared to MIP, which shows that the increase in MIP surface is due to its pattern ability and molding. [Fig. 1a and b]. XRD pattern of PPy-MIP are shown in [Fig. 1c]. Specific peaks at 2θ = 18.36, 30.22, 35.60, 43.26, 57.22, 62.84 distinguishes for PPy-MIP. The broad peak is characteristic of amorphous polypyrrole and is due to the dispersion of PPy chains in the interfacial space. According to the pattern analyzed by the Xpert software, the nanoparticles have a porous structure that verified by other (Caner et al. 2024).

Fig. 1
figure 1

a SEM image of PPy-MIP and b SEM image of PPy-NIP and (c) XRD pattern of PPy-MIP

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As it is clear from Fig. 2a, which is the image related to the PPy-MIP, the two absorption bands 1542 and 1456 cm−1 demonstrated the stretching vibrations of the C=C bond of the pyrrole ring. The absorption band 1294 cm−1 is related to the stretching vibrations of the C–N bond of the ring and the band 1163 cm−1 is related to the deformation of the C–H = band in pyrrole. The broad band at 2675 cm−1 corresponds to the N–H bond in pyrrole. The observed peaks at 962 and 667 cm−1 are related to the C–H = planar vibration, which characterizes the polymerization of pyrrole (Gao et al. 2020). Figure 2(b) is the FTIR spectrum of MIP after E2 absorption. The wide peak in the 3194 CM−1 region represents the hydrogen bond of the phenolic O–H group, which is sharper than usual due to the presence of the aromatic group. Absorption peaks in the 1537–1632 CM−1 are related to the C–C ring vibrations, which indicate the aromatic structure of the benzene ring. Peak at 1289 cm−1 (C–O stretching) correlated with E2 adsorption. These findings indicate the effective surface imprinting of MIP using a combination of monomers.

Fig. 2
figure 2

FTIR spectrum of (a) PPy-MIP and (b) after E2 adsorption

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Effect of pH

The pH influences on the adsorption of E2 were studied at varying pH (3.0–11.0). The rate of E2 adsorption at different pH are shown in Fig. 3. The pH exhibited a substantial influence on the process. The effectiveness percentage was higher within the neutral pH range, indicating the effect of the surface charges of the PPy-MIP. At pH 7.0, the maximum E2 percentage reached 98.85%. At pH 9.0 and 11.0, higher surface PPy-MIP charge decreases adsorption through electrostatic repulsion (Elias et al. 2021; Yang et al. 2018). Rising hydroxyl ions at higher pH values cause aqua-complexes and lead to competition of ions for carbonyl sites, consequently decreasing the adsorption capabilities of MIP (Baziar et al. 2018). Adsorption of pharmaceutical products onto PPy-MIP might occur through an electrostatic interactions and exchange of diffusion between the ions and MIP (Wee and Grinang 2024). The interactions involve hydrogen bonds, electron donor–acceptor compounds, and π-π dispersion exchanges between aromatic rings of E2 (17β-estradiol) and delocalized electrons (Yang et al. 2018; Wee and Grinang 2024).

Fig. 3
figure 3

Influence of pH to adsorb E2 by PPy-MIP. (Dosage 0.4 g, temp. 30°C, contact time 60 min)

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Effect of adsorbent dosage

Different amounts of PPy-MIP (0.2, 0.4, 0.6, 0.8, and 1 g/L) were analyzed to E2 adsorb. In Fig. 4, the rate of adsorption in the initial stage increased rapidly as the dose of adsorbent utilized was raised. However, the rate of E2 adsorption improved slowly until it reached equilibrium with the addition of MIP. When utilizing 0.6 g of the MIP, the adsorption process removed around 99.11% of E2. Therefore, 0.6 g/L of MIP were used for experiments as the optimum dose. The addition of the adsorbent could be attributed to a strong driving force, which leads to a proportional rise in adsorption (Phele et al. 2019). Higher removal of E2 associated with the increase in both the surface area and the available adsorption active sites to remove E2 from the aqueous solution (Aljeboree et al. 2017; Altintig et al. 2018). However, the progress in the adsorption was not affected by the adsorbent dose from 0.6 to 1.0 g/L. This may be due to the aggregation of adsorbent sites at a higher dose (Niavarani et al. 2023).

Fig. 4
figure 4

Effect of MIP dosage on E2 adsorption by PPy-MIP MNPs. (pH 7.0, temp. 30°C, contact time 90 min and E2 Con. 25 mg/L)

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Effect of contact time

The quantity of E2 adsorbed onto the PPy-MIP was studied at various contact times (10–120 min) at 30 °C and pH 7.0. Figure 5 shows that the adsorption of E2 onto PPy-MIP increased with rising contact time until 90 min. Moreover, the adsorption process was rapid in the first 20 min; hence, the percentage removal reached 96.82%. The adsorption of E2 enhanced increasingly during the following 45 min up to equilibrium time (60 min). The results illustrated that the uptake of E2 molecules onto the MIP is achievable on contact time. The quick adsorption of E2 during the initial phases (20 min) might be related to the attainability of the uncovered holes and active sites on the MIP surface (Elias et al. 2021; Adegoke et al. 2022). The saturation point was obtained at 45 min. Adsorbed E2 rate in equilibrium period indicates MIPs MAC capacity, even between 60 and 120 min. This phenomenon attributed to the time needed for E2 to encounter the boundary layer effect, diffuse to the surface of MIPs, and then penetrate the porous structure of the adsorbent (Dehghani et al. 2020; Lopes et al. 2021).

Fig. 5
figure 5

Adsorption of E2 using PPy-MIP by time. (pH 7.0, temp. 30°C, dosage 0.4 g/L, and E2 Con. 25 mg/L)

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Effect of concentration

The influence of initial E2 concentration was evaluated in varying levels of E2 in the range of 5.0 to 100 mg/L. The adsorption of the E2 uptake against various initial concentrations is exhibited in Fig. 6, showing an increased value from 5.0 up to 50 mg/L. The adsorption of E2 correlates with an increase in initial concentration. Results showed that 99.77% of E2 reduction was achieved at 50 mg/L. By increasing in the concentration from 50 to 100 mg/L, the adsorption of E2 reduced to about 98.58%; while, the adsorption capacity improved. The increase in initial concentration leads to higher E2 adsorption due to the enhanced mass transfer driving force. The rate of pollutant reduction becomes independent of initial concentration at low concentrations due to available active sites. However, at higher concentrations, active sites available for E2 are limited (Wee and Grinang 2024; Bhuyan and Ahmaruzzaman 2023; Subrahmanian et al. 2024). The reduced sorption of E2 can be related to the saturation of active sites at high concentrations, which leads to an unabsorbed E2 in the aqueous solution (Wee and Grinang 2024). Increasing initial concentration enhances E2 uptake by PPy-MIP. This could be associated with the raised electrostatic interactions, which enhance physical adsorption comparable to covalent interactions (Bhattu and Singh 2023; López et al. 2023).

Fig. 6
figure 6

Adsorption of E2 using PPy-MIP at various concentration. (Contact time 90 min, pH 7.0, dosage 0.4 g)

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Effect of temperature

The temperature influence on the E2 adsorption by MIPs was assessed within the temperatures (20, 30, 40, and 50 °C). Figure 7 indicates that E2 adsorption by the MIPs at different temperatures with optimal adsorption of 99.94% takes place at temperature (40 °C). Figure 7 clearly shows that temperature increase leads to decrease in adsorption. With increasing solution temperature, E2 molecules migrating from the solid phase to the bulk phase occur (Khan et al. 2023; Tatarchuk et al. 2023). Furthermore, the temperature-induced increase in solubility of E2 molecules leads to a more effective contact force between E2 molecules and the solvent than its effect between E2 molecules and PPy-MIP. These findings in accordance with others (Leng et al. 2023b). At high temperatures, adsorbate kinetic energy enhances binding to MIP active sites, weakening contact forces with E2 molecules (Wee and Grinang 2024; Leng et al. 2023b).

Fig. 7
figure 7

Effect of temperature on E2 adsorption by PPy-MIP. (Contact time 90 min, pH 7.0, dosage 0.4 g, and E2 Con. 50 mg/L)

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Adsorption isotherms

The correlation parameters related to isotherm models are shown in Table 1. The R2 value was greater than 0.98, which proved that the Langmuir model best explained the sorption mechanism. The Langmuir isotherm pointed to the surface adsorption process as a monolayer (Qiu et al. 2023). The Langmuir model refers to adsorption occurring on the monolayer adsorbents surface, where adsorption sites are evenly distributed to contaminants (Leng et al. 2023b). The Langmuir max capacity (Qm) of PPy-MIP for E2 was obtained 161.2 mg/g. Freundlich isotherm supposes multilayer adsorption occurs on active sites with various binding energies. The Freundlich model displayed an n value below 1, meaning chemical interaction-based conducive adsorption (Niu et al. 2021).

Table 1 Different adsorption isotherm models of E2
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Adsorption kinetics

The kinetic model parameters of E2 using PPy-MIP are shown in Table 2. The regression coefficient of the pseudo-second-order model (R2 0.99) was larger than those of the pseudo-first-order (R2 0.64) and intra-particle diffusion (R2 0.97). Thus, the pseudo-second-order model describes the E2 adsorption. Moreover, the qe value computed by the pseudo-second-order kinetic was in accordance with the experimental measurement. The adsorption behavior was also calculated by the intra-particle diffusion kinetic to show the diffusion mechanism. The parameters of the multi-linear step process are exhibited in Table 3. The study found a strong linear relationship in the early stage (R2 0.98–0.92) indicating rapid E2 molecule adsorption at this stage through non-bonded interactions (Guo et al. 2019). The interaction weakened in the second stage over time, and the diffusion rate reduced, controlled via the intra-particle diffusion (kip1 3.21 > kip2 0.48). The third stage depicted the adsorption reached dynamic equilibrium. As a result, the adsorption process was involved by either intra-particle diffusion or external mass transfer. The results were approved with the intra-particle diffusion kinetic by others (Leng et al. 2023b). In conclusion, the adsorption of E2 onto MNPs followed a heterogeneous multilayer process. Notably, intra-particle diffusion has an important role (Ma et al. 2019).

Table 2 Kinetics modeling of E2 on the PPy-MIP
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Table 3 Parameters of the multi-linear step of intra-particle diffusion
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Thermodynamic studies (∆G°, ∆H° and ∆S.°)

Table 4 displays the thermodynamic parameters for the adsorption of E2 at 20, 30, 40, and 50°C). Spontaneity is proposed based on the ∆G°. Based on the results, ∆G° values of − 4.608 to − 13.31 kJ/mol proposed that the E2 adsorption on the PPy-MIP was spontaneous. The decrease in ∆G° values with increasing temperature indicates that the adsorption became thermodynamically unfavorable at higher temperatures (Wee and Grinang 2024). ∆G° < −20 kJ/mol suggests electrostatic force between E2 and MIPs proving the physisorption mechanism. On the other hand, a ∆G° value between − 80 to – 400 kJ/mol is necessary for charge transfer in chemisorption mechanism. Range of ∆G° − 4.608 to − 13.31 kJ/mol supports electrostatic interactions between E2 and PPy-MIP, thereby supporting physisorption mechanisms. The enthalpy (∆H°) and the entropy (∆S°) values calculated as 24.2 kJ/mol and 0.028 J/mol at 293.15–323.15 °K, respectively (Table 4). The positive ∆H° proposes that the adsorption process mechanism was endothermic. A positive ∆S° means that the degree of freedom of E2 adsorbed on PPy-MIP was not restricted. The thermodynamic properties of E2 adsorbed on MIPs show that the adsorption is spontaneous and endothermic, indicating that the physisorption mechanism is dominant (Sriharan et al. 2023).

Table 4 Thermodynamic properties of E2 adsorbed onto PPy-MIP (∆G°, ∆H° and ∆S°)
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Adsorption mechanism of E2 onto PPy-MIP

An E2 adsorption mechanism using PPy-MIP is presented in Fig. 8. This mechanism applies the integrated action of surface complexation, H-bonds, n-π EDA interactions, and hydrophobic interactions. PPy-MIP have -OH and hydrophobic internal holes that prevent agglomeration and facilitate E2 adsorption. PPy-MIP crosslinking create a complex 3D network structure. The shape of MIP during the synthesis makes the material porous, exposing more active sites for E2 adsorption. –OH and –NH species as the main functional groups form surface complexes and H-bonds with the functional groups of PPy-MIP. Due to the presence of hydrophobic holes, the hydrophobic group E2 can penetrate its hydrophobic hole. Hence, the synthesized PPy-MIP harbor remarkable steroid reduction capacity and applicable for adsorbing contaminants.

Fig. 8
figure 8

Proposed adsorption mechanism of E2 by PPy-MIP

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Regeneration of the PPy-MIP

Six adsorption–desorption cycles were performed to investigate the regeneration ability of MNPs. As Fig. 9 exhibits, after six regeneration cycles, the adsorption capacity of PPy-MIP to adsorb E2 was 96.91%; this could be illustrated by that fewer binding active sites in the PPy-MIP after regeneration cycles (Ma et al. 2023). The results revealed that the prepared adsorbent had a satisfactory regeneration efficiency and was practical and promising. As a result, PPy-MIP have customizable properties for easy recovery and reusability advantage.

Fig. 9
figure 9

Regeneration and reusability of PPy-MIP

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Selectivity study

A competitive adsorption study was conducted in the presence of steroid hormones (SHs), such as cholesterol and progesterone that are both comparable and different in structure to the template PPy-MIP to demonstrate the selective cavities in a polymer. Based on the result, the MIP should be more selective than the NIP to adsorb SHs. At optimum conditions, specific concentration of E2 and the interfering SHs were added to each Erlenmeyer flask, and was agitated in a shaker. At a certain time, the SHs adsorbed on the polymer was calculated by subtracting the final SHs concentration from the starting SHs concentration in the mixture. MIP has a 99.93% selectivity for E2, compared to other SHs with adsorption rates ranging from 24.13% to 11.65%. Thus, the selectivity findings prove that MIP holes are solely selective for the template (E2) molecule. The results are presented in Fig. 10.

Fig. 10
figure 10

Selectively of the PPy-MIP toward various SHs

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Comparison of the PPy-MIP with other adsorbents

The adsorption capacity (mg/g) of the synthesized PPy-MIP was comparable with other reported E2 adsorption, as summarized in Table 5.

Table 5 Comparison of adsorbents used in previous studies to remove E2
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Real sample analyses

In Table 6, the performance results of the synthesized MIP in the removal of estradiol from hospital wastewater samples, city water, urine, and serum of pregnant women were shown using the developed method in this study. As observed, the recovery percentage in real samples was excellent, and the synthesized adsorbent was easily capable of extracting and separating estradiol values present in various matrices. Also, comparing the recovery percentage of estradiol by MIP and NIP in the studied samples, the results show that MIP has shown a selective and specific performance toward estradiol and the synthesized adsorbent was well able to remove estradiol from real samples.

Table 6 Concentrations (ng/mL) and relative recoveries (%) of E2 in the environmental and biological samples
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Conclusion

This study successfully synthesized PPy-MIP through non-covalent method for efficient 17β-estradiol (E2) adsorption from aqueous solution. Characterization analysis verified a polypyrrole-based molecularly imprinted, providing good stability. PPy-MIP enabled 99.77% of E2 reduction at optimum conditions (50 mg/L concentration, 0.6 g/L dosage, and pH 7.0). The highest R2 value in isotherm modeling is associated with Langmuir isotherm (R2 0.98). The adsorption kinetic of E2 on PPy-MIP followed by the pseudo-second-order model (R2 0.99). PPy-MIP detected E2 with a recovery rate of 94.6%, 89.2%, 98.2%, and 86.25% in tap water, hospital wastewater, urine, and blood samples, respectively. The thermodynamic properties for ∆G° (− 4.608 to − 13.31 kJ/mol), ∆H° (24.2 kJ/mol), and ∆S° (0.028 J/mol) of E2 adsorbed on the adsorbent indicate that the adsorption is spontaneous and endothermic, revealing that the electrostatic forces and van der Waals interactions are dominant. Based on the competitive adsorption study, the MIP should be more selective than the NIP to adsorb Estradiol (99.93%), Cholesterol (24.13%), and Progesterone (11.65%). Integrated action of surface complexation, H-bonds, n-π EDA interactions, and hydrophobic interactions are proposed as the dominant mechanism to adsorb E2. In addition, after six regeneration processes, the capacity of PPy-MIP to adsorb E2 was 96.91%; this could illustrate acceptable recovery ability, practical and beneficial.