Abstract
Bioadsorption using agricultural waste offers a promising approach for removing toxic metals from wastewater. This study explores the potential of chemically activated banana peels (BPs) as a green and cost-effective bioadsorbent for Cu(II) and Zn(II) removal. Fourier-transform infrared (FTIR) spectroscopy revealed the presence of functional groups like alcohols, phenols, and amino acids on activated BPs, potentially responsible for metal ion binding. Scanning electron microscopy (SEM) with energy-dispersive X-ray spectroscopy (EDS) confirmed the presence of cavities on the BPs surface and the existence of oxygen and potassium. The adsorption capacity of BPs was investigated under various conditions, including pH, contact time, sorbent dosage, metal concentration, and temperature. This study used Langmuir, Freundlich, Tempkin, and Dubinin–Radushkevich (D–R) isotherm models to describe the equilibrium results of Cu (II) and Zn (II) adsorption. The Langmuir isotherm model best described the adsorption process, suggesting monolayer coverage of metal ions on the BPs surface. Maximum adsorption capacities were 3.2 mg g−1 for Cu(II) and 2.8 mg g−1 for Zn(II), demonstrating the effectiveness of BPs in metal removal. Kinetic studies indicated pseudo-first-order (PFO) behavior for Cu(II) and pseudo-second-order (PSO) behavior for Zn(II) adsorption. Thermodynamic analysis revealed a spontaneous and exothermic process (negative Gibbes free energy (ΔG°) and enthalpy (ΔH°) with decreased randomness [negative entropy (ΔS°)] at the biosorption interface. Finally, the BPs sorbent was successfully applied to remove different metal ions from real wastewater samples collected from the El Wadi drain.
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1 Introduction
The potentially toxic trace metals are discharged into the natural environment by several industries such as steel production, mining, electroplating, transformation-coating, solder plates, etching, etc. [1, 2]. These metals can harm the flora and fauna of water bodies and all the aquatic systems. Cu (II) and Zn (II) are non-biodegradable metals, essential in biotic systems at low concentrations, and toxic at higher levels to animal and man health. Chemical treatments like ion exchange, precipitation, coagulation, reverse osmosis, membrane separation, and adsorption are the most common techniques with high affinity for removing metal ions from wastewater; [3, 4]. The most efficient one is the adsorption, especially using waste biomass materials (biosorption). Biosorption is an eco-friendly technique of low cost and readily biodegradable. There has been a great interest in employing agricultural wastes for HMs removal from industrial effluents [5]. Different biosorbents materials like Shea fruit shells, rice husk, oil palm waste potato peel, orange peel, banana peel, coconut husk, sugarcane bagasse, watermelon rind, coffee, tea, corn cob were employed for uptake the contaminants existing in wastewater [6,7,8]. Banana is consumed all over the world in massive amounts. Its peel is discarded as solid waste, representing 40% of the total banana weight. Due to its wide availability, banana peel is a promising biosorbent material for various pollutants, heavy metals, dyes, THMs, and phenolic compounds [9,10,11]. Banana peels have cellulose, hemicellulose, protein, and lignin. These substances contain carbonyl, carboxyl, hydroxyl, and amine groups which can adsorb various metal ions [12, 13] studied Cu (II) and Pb (II) uptake on BPs, and [14] analysed the equilibrium conditions using natural banana peel in the elimination of fluoride ions. Banana peels can be easily and inexpensively collected from local markets, chip manufacturing works, hotels, and homes. Banana peels are considered waste and emit greenhouse gases if disposed of under moist conditions [15, 16]. Thus, its use in treating toxic wastewater helps solve the waste disposal problem.
The objectives of this work include (1) improve the adsorption affinity of the banana peels (BPs) by chemical activation, (2) characterize the structure composition of activated biosorbent using FTIR and SEM–EDS, (3) enhance Cu(II) and Zn(II) adsorption under specific conditions such as pH of the solution, contact time, sorbent dose initial metal ion concentration and temperature, (4) assess the adsorption models of Cu (II) and Zn (II) via Langmuir, Freundlich, Tempkin and Dubinin–Radushkevich, (5) evaluate the adsorption kinetic model e.g., pseudo first order, pseudo second order in addition to intraparticle diffusion mechanism, (6) explore the thermodynamics variables, including Enthalpy (ΔH°), Gibbs free energy (ΔG°), and Entropy (ΔS°), (7) test the application of activated BPs onto wastewater samples to evaluate its selectivity and capacity in the removal of different metal ions.
2 Materials and methods
2.1 Chemicals
Potassium Hydroxide (KOH), Copper Chloride (CuCl2.2H2O), and Zinc Nitrate Zn (NO3)2 (analytical grade of purity 95%), All the chemicals were purchased from Sigma Aldrich. Deionized water was used for the preparation of adsorbate.
2.2 Adsorbent preparation
Bananas were obtained from a local market in Egypt. The peels of banana were washed numerous times with hot deionized water to remove surface contaminants, and then the peels soaked in 50 ml KOH solution for 2 h. Then the filtered sample placed in an oven for 2 h. at 230 °C. Finally, the produced BPs was washed many times with deionized water to neutralize the pH value. The produced BPs was placed again in an oven at 80 °C overnight to dry and then ground into fine powders [15].
2.3 Characterization
FT-IR spectroscope is used to identify the molecular structure and chemical bonds present in the adsorbent material. This technique is carried out the measurement of the frequencies of infrared light that are absorbed by the sample, revealing information about the functional groups and molecular vibrations. SEM (Scanning electron microscope) was operated to analyze the morphological characteristics of the sorbent surface and its particle size. This technique involves bombarding the sample with a beam of electrons and detecting the resulting signals to generate a high-resolution image. SEM can provide data about the shape, size, and spreading of particles on the surface of the adsorbent material. By employing both FT-IR spectroscopy and SEM, a comprehensive description of the adsorbent material can be achieved, providing valuable insights into its chemical structure, surface properties, and potential applications. The FT-IR spectrum was recorded using a Bruker FT/IR Alpha-II instrument, which operates within the range of 400–4000 cm−1. The morphology and the fundamental structure of the adsorbent prepared were examined using a FESEM (Field Emission Scanning electron microscope -Zeiss SEM) with an Energy Dispersive X-ray (EDS).
2.4 Adsorbate preparation
A 2.683 g of Copper Chloride dihydrate [CuCl2.2H2O] was dissolved in a volumetric flask with 200 mL deionized water and subsequently top-up to a 1000-mL mark of the volumetric flask to obtained a stock solution of 1000 mg L−1 Cu (II). About 2.897 g of Zinc nitrate [Zn(NO3)2] was dissolved in 200 ml deionized water and subsequently top-up to a 1000-mL mark of the volumetric flask to obtained a stock solution of 1000 mg L−1 Cu (II). The bench solutions were prepared through serial dilution of the stock Cu (II) and Zn (II) solutions by the deionized water. A calibrated pH instrument, using buffers solution 4 and 7, was used to measure pH values. The pH of aqueous metal ion solutions was controlled by adding 1.0 M NaOH or 1.0 M HCl solutions. Cu (II) and Zn (II) concentrations were determined before and after adsorption using an inductively coupled plasma-optical emission spectrometer (ICP-OES; Optima 5300 DV, Perkin-Elmer, USA).
2.5 Equilibrium study
Batch adsorption experiments of copper and zinc were carried out to determine the adsorption capacity of Banana peels at different metal concentrations ranging from 2 to 50 mg L−1 and a fixed amount (0.50 g) of Banana peels to calculate the adsorption constant using different isotherms. 50 mL of different concentrations of copper (II) and zinc (II) solutions ranging from 2 to 50 mg L−1 was used. The Banana peels (0.5 g) were added to flasks and agitated at 25 °C and 400 rpm for 210 min for copper and zinc. The initial and final concentrations of the solutions were measured were determined by ICP-OES at the maximum adsorption wavelength and the adsorption capacities of the adsorbent were calculated. The effect of several factors: bioadsorbent dose (0.1–0.6 g), pH (3–7), Contact Time (30–210 min), Different concentrations of metal ions (2–50 mg/l), Temperatures (25–60 °C) were evaluated. After equilibrium was attained, the metal uptake capacity for each sample was calculated according to a mass balance on the metal ion using the Eq. 1 [17]:
where, C0 and Ce are the initial and final metal ion concentrations, respectively. The adsorption capacity (Qe) was calculated by Eq. 2.
V is the volume of the solution in (L), and m is the amount of the bioadsorbent in (g).
2.6 Adsorption isotherms
In this study, the Langmuir, Freundlich, Tempkin, and Dubinin-Radushkevich isotherms were used to describe the adsorption mechanism of Cu (II) and Zn (II) on activated BPs. The Langmuir model describes a homogeneinty of the adsorbent surface in which the adsorbent sites are energetically equivalent and thus can only hold one adsorbate species without any interactions between the adsorbate species [18].
Conversely, the isotherm that proposes non-ideal adsorption on heterogeneous surfaces is the Freundlich isotherm. Temkin isotherm considers the interactions of the surface of the bioadsorbent and the adsorbate molecules. Heat of adsorption released when molecules are adsorbed to the surface will decrease as more molecules are increased, due to the contact between the sorbent and adsorbate. Moreover, Dubinin–Radushkevich isotherm model (D-R) expresses the adsorbent surface heterogeneity and allows us to detect the process of adsorption, by calculating the surface energy [17]. Table 1 illustrates the equations used in calculating the adsorption isotherm models.
2.7 Adsorption kinetics
The kinetics models of the study were performed to recognize the equilibrium associations between adsorption and the contact time. The kinetic models like the pseudo-first-order (PFO), pseudo-second-order models (PSO), and the intraparticle diffusion model (IPD) were examined [18, 19]. Their equations are presented in Table 2.
2.8 Thermodynamic study
Adsorption experiments were conducted under various states of temperatures (25–50 °C), initial concentration (5 mg L−1) of prepared metal ions (Cu (II) and Zn (II)) and fixed amount of BPs (0.5 g) adsorbent to analyze the spontaneity of the adsorption process. Thermodynamically parameters such as a variation in the entropy (ΔS˚), the enthalpy (ΔH˚), and the free energy (ΔG˚) were computed according to the next equations:
where Kd is the constant of the distribution equilibrium, the temperature T is in (K), and the ideal gas constant R is (8.314 Jmol−1 K −1) [20, 21].
2.9 Application
The effectiveness of the BPs biosorbent in removing metals ions was evaluated using actual wastewater obtained from the Elwadi drain, Fayoum, Egypt,” under the optimal conditions (210 min shaking time, 0.5 g of sorbent, 500 rpm at 25 °C) without changing the actual pH value of drain. Then, the filtered sample was digested using conc. HNO3 on a hot plate at 180 °C. A 50 ml effluent without treatment was digested in the same method. The metals ions concentrations in filtered samples were measured before and after treatment by ICP-Plasma to assess the effectiveness of the BPs biosorbent.
3 Results and discussion
3.1 Adsorbent characterization
3.1.1 FTIR characterization
The FTIR analysis was conducted to explore the available functional groups on the surface of BPs (Fig. 1). The analysis revealed a broad peak at 3250.42 cm−1 indicating the presence of O–H hydroxyl group stretching of phenols and alcohols. The peak at 1585 cm−1 refers to the group of N–H scissoring of amino acids. Peaks at 1401.83 and 1304.81 cm−1 correspond to C-H group stretching of alkanes and O–H bending, respectively. The bands at 702.98–829.08 cm−1 are attributed to the group of N–H deformation of amines [18]. The spectra predicted the coexistence of –NH2, –OH, groups on BPs surface from cellulose and hemicellulose. The cation exchange may be the proposed mechanism of the adsorption [22].
3.1.2 SEM–EDS
Scanning Electron Microscopy (SEM) analysis was performed to examine the morphological construction of the sorbent surface. The SEM images revealed the presence of cavities with varying shapes and sizes on the surface of the activated BPs. Energy-Dispersive X-ray Spectroscopy (EDS) was then employed to determine the elemental composition of the activated BPs. The EDS analysis confirmed the presence of potassium and oxygen on the BPs surface, supporting the FTIR results that suggest a cation exchange mechanism for metal ion adsorption (Fig. 2). Additionally, the absence of other significant elements in the EDS data indicates the high purity of the activated BPs [11].
3.2 Equilibrium adsorption
3.2.1 Effect of adsorbent dose
When the adsorbent dose of BPs increased gradually from 0.1 to 0.5 g, the removal efficiency of Cu (II) increased from 33 to 60%. However, there was minimal improvement in the removal efficiency of Cu (II) between a dose of 0.5 and 0.6 g of the adsorbent (Fig. 3a), which is due to agglomeration of BPs particles at higher doses; thus, the available adsorption sites decreased. While, in the case of Zn (II) adsorption, the maximum removal percent was for an adsorbent dose of at least 0.4 g. The initial growth in the metal ions removal may be because of increasing the adsorbent surface area and, the available functional sets for the adsorption [23, 24].
3.2.2 Effect of pH
The dependence of Cu (II) and Zn (II) biosorption on the pH value of the aqueous medium is assessed and presented in Fig. 3a, b. The pH has an influence on the surface charge of the adsorbent and the chemical form of the metal ions. When the pH increased from 3 to 6, the removal efficiency increased from 30 to 40% for Cu (II) and increased from 42 to 58% for Zn (II). The lower removal percent at low pH is likely due to the competition of positive charge of hydrogen ions against positive charge of metal ions and the interaction with the active sites on the surface of PBs [25]. Figure 3b inferred that at pH 6 the BPs had the highest removal efficiency of Cu (II) and Zn (II) with 40 and 58% percentages, respectively. Our finding agreed with pervious research [22], which evaluated the impact of pH value from 2 to 8 on the biosorption of Cu (II) on the BPs surface and reported the highest removal % at pH value from 4 to 6 [10]. Stated the highest removal % of Zn (II) on BPs surface at pH 6.50, which agreed with our obtained results. Similarly [5], reported a pH of 5 as the optimum pH for Cd (II) adsorption on Shea fruit shell biomass.
3.2.3 Effect of contact time
Figure 4a illustrates the dependence of metal ions % removal on contact time. The removal efficiency increased gradually with rising time by the reason of many active sites on the BPs surface of adsorbent until it became constant at equilibrium. The equilibrium state likely occurs due to the saturation of active sites on the BPs surface and the repulsion forces between the adsorbed ions on the surface and those remaining in the aqueous solution [26]. The maximum removal percent of Cu (II) was 72% at 150 min, while Zn (II) achieved a higher removal of 80% at 180 min [27]. Reported 120 min as the equilibrium time in case of Cu (II) adsorption on the BPs surface.
3.2.4 Effect of initial concentration
Figure 4b infers the removal percent of Cu (II) ion and Zn (II) ion on BPs at different initial concentrations. The removal percent of Cu (II) and Zn (II) decreased from (84 and 85%) to (60% and 64%); respectively, when the metal ion initial concentration raised from 2 to 50 mg L−1; this possibly due to the BPs surface overload at higher metal ion concentrations [28]. However, BPs adsorption capacity was 3.2 mg g-1 for Cu (II) metal ion and 2.8 mg g−1 for Zn (II) metal ion at the high initial concentration 50 mg L−1 (Fig. 5); this may predict a particle diffusion mechanism of metal ions on the BPs pores. This study reports a higher adsorption capacity for Cu(II) compared to previous research, which found a capacity of 2.433 mg g-1 for BPs [27] However, the observed adsorption capacity for BPs aligns with findings for Cr(VI) adsorption using another agricultural waste material [23] They reported an adsorption capacity of 2.355 mg g−1 for Cr(VI) under specific optimized conditions.
3.3 Adsorption isotherms
Adsorption isotherm models offer valuable insights into the interaction mechanism between the molecules of adsorbate in the aqueous phase and the active sites that on the surface of the adsorbent under equilibrium states [18]. These models explain the surface properties and adsorption mechanism in sorption systems design. The isotherm models of Langmuir, Freundlich, Tempkin, and Dubinin–Radushkevich (D–R) were used to analyze the equilibrium results of Cu (II) and Zn (II) adsorption.
A plot of 1/Ce vs 1/Qe is presented in the Fig. 6. The Langmuir maximum sorption capacity (Table 3) was 4.51 for Cu (II) mg/g and 6.99 mg g−1 for Zn (II) respectively. R2 in Fig. 6 showed a good fit for Langmuir isotherm of Cu and Zn (0.96 and 0.95), respectively. The Langmuir separation factor (RL) describes the nature of adsorption; RL is 0.133 for Cu (II) and 0.216 for Zn (II). Thus, their adsorption process is favorable.
The maximum adsorption capacity calculated from Freundlich isotherm for Cu (II) and Zn (II) was 1.377 and 0.771 (mg g−1) (L g −1)1/n, respectively (Fig. 7). 1/n value refers to the heterogeneity of the adsorbent surface [10]. 1/n values were estimated to be 0.624 and 0.665 for Cu (II) and Zn (II), respectively, suggesting a favorable adsorption process. As the n value (in Table 1) is more significant than 1 for Cu (II) and Zn (II) adsorption,
It suggests a physical adsorption process (weak intermolecular forces). Otherwise, n values are lower than one, inferred to chemical adsorption (more vital valence forces) [29]. High n values in the range of 2–10 indicate high adsorption intensity. On the other hand, n values less than 0.5 indicate low adsorption intensity. The Freundlich adsorption intensity in this study is moderate (n value is 1.5 of Cu (II), 1.6 of Zn (II)). Although Freundlich isotherm showed an excellent fitting for Cu adsorption, the Langmuir model fitted better with Cu equilibrium adsorption data, with a higher correlation coefficient (R2) and higher adsorption capacity calculated.
By comparing the applied adsorption models isotherms (Table 3 and Figs. 6, 7), the study gives a better fitness of the regression line of Langmuir isotherm than Freundlich. However, the Langmuir isotherm had a lower R2 but got a higher Zn (II) sorption capacity (Table 3). Thus, Cu (II) and Zn (II) metal ions adsorption on BPs followed the Langmuir model.
From the Tempkin adsorption isotherm, the heat adsorption of Cu (II) and Zn (II) metal ions were 3.047 and 3.229 J mol−1, respectively, suggesting the exothermic adsorption (Table 3). Tempkin constant (αT) describes the bioadsorbent affinity for the metal ions.
Cu (II) and Zn (II) had αT values of 0.625 and 0.723 (L g−1), respectively. The Tempkin isotherms illustrated an excellent fit of R2 estimated to be 0.93 for Cu (II) and 0.96 for Zn (II), respectively. High R2 values detected a superb interaction between the active sites on the adsorbent surface and the metal ions (Fig. 8).
The Dubinin–Radushkevich isotherm model was applied to calculate Qm and β in Fig. 9 from the intercept and slope value. E values of PBs bioadsorption for Cu (II) ion and Zn (II) ion was estimated to be 2.24 kJ mol−1. The E values less than 8 kJ mol−1 present a physisorption mechanism [30]. Therefore, the results suggest that the adsorption of Cu(II) and Zn(II) onto BPs likely occurs via physisorption.
The maximum theoretical bioadsorption capacity estimated from D-R Isotherm was 1.86 and 2.1 mg g−1 for Cu (II) ion and Zn (II) ion, respectively. By comparing the investigated isotherm models, the results of Cu (II) and Zn (II) adsorption fitted better with Langmuir Isotherm (Table 3) with higher sorption capacity. The Langmuir model's suitability aligns with previous research demonstrating its effectiveness in describing the adsorption of various metal ions (Cd(II), Cr(VI), Co(II), and Cu(II)) onto BPs [4, 30, 31].
3.4 Adsorption kinetic studies
The kinetic models express the speed upon which adsorption occurs. It plays a major role in designing the batch adsorption experiments [17]. In this study, two kinetic models, Pseudo-First-Order (PFO) and Pseudo-Second-Order (PSO), were applied to analyze the Cu(II) and Zn(II) adsorption data (Figs. 10 and 11), the corresponding models parameters are presented in Table 6. R2 Values of Cu (II) obtained from PFO and PSO models were 0.86 and 0.84, respectively, for 5 mg L−1 initial metal concentration. The experimental adsorption capacity (qexp.) for Cu (II) showed a closer fit to the adsorption capacity (qcal.) calculated from the PSO than the PFO. However, values from the sums of squares error (% SSE) computed in the case of the PFO were less than that of the PSO model—a more excellent R2 value is in the PFO model. Thus, the PFO kinetic model explained well the Cu (II) adsorption confirmed by the superior fitness of the regression line in Fig. 10. On the other hand, the results of Zn (II) adsorption kinetics followed the PSO model as it evaluated higher R2 and lower % SSE in addition to the better closeness among the experimental adsorption capacity (Qe) and the calculated adsorption capacity (Qcal) (Table 4 and Fig. 11). It's important to note that neither the PFO nor the PSO model offers insights into the diffusion mechanisms or the rate-determining step of the adsorption process [20].
Chen et al. [32] stated that metal ions may penetrate the porous sites of BPs through the intraparticle diffusion mechanism. By plotting Qt against t0.5 (Fig. 12), the result of R2 is (0.94) for Cu (II) and (0.96) for Zn (II), respectively. High R2 values indicate that the diffusion process is a rate a limiting step. Also, because the trend line does not cross the origin, other mechanisms may include, e.g. boundary layer diffusion and liquid film diffusion mechanisms. Thus, The interaparticle diffusion (IPD) is not shown as the only variable that determines the rate [24].
3.5 Thermodynamics
Table 5 summarizes the results of thermodynamic parameters for adsorbed Cu (II) and Zn (II) metal ions on the activated BPs. Kd values decreased from 7.33 to 1.22 for Cu (II) and from 11.5 to 1.94) for Zn (II) with rising temperature from 298 to 333 K, thus inferring the exothermic adsorption; This might be happening because of raised kinetic energy of some adsorbed metal ions that make them disassociate from the surface of adsorbent then back into the solution [4]. A plot of Ln Kd versus the reciprocal of temperature (1/T) of adsorbed Cu (II) and Zn (II) which allows us to calculate the thermodynamic constants (ΔHo and ΔSo). ΔGo values of Cu (II) and Zn (II) adsorption reduced as the temperature increased; however, ∆G° showed negative values at all temperatures that referred to a feasible, spontaneous process in addition to a good affinity of BPs adsorbent for Cu (II) ion and Zn (II) ion. The calculated ΔHo = −43.03 and −40.21 kJ/mol for Cu (II) and Zn (II) adsorption, respectively, inferring exothermic adsorption processes [33]. Stated that physisorption has ∆H° values of 2.1–20.9 kJ/mol, while, values exceeding 40 kJ/ mol may indicate chemisorption. Thus, the present results inferred Cu (II) and Zn (II) chemisorption on activated BPs. That might be attributed to the –NH2 and -OH groups on the BPs interacting with the metal ions [13].
The calculated entropy change (ΔS°) was −0.13 and −0.12 kJ mol−1 K−1 for Cu (II) and Zn (II) adsorption, respectively. These negative values suggest a decrease in randomness or increased order at the BPs surface during the adsorption process [34]. The BPs adsorption capacity was compared with other sorbents in previous studies are presented in Table 6 [5, 34,35,36,37,38].
3.6 Application
Several attempts were made to test the ability of BPs to remove metals ions from actual wastewater samples under optimal conditions. One sample from the Elwadi drain, discharged into the Rayan lakes in Fayoum, Cairo, was analyzed for the potentially toxic metals content by ICP-Plasma. El Wadi drain water contained Al, Ba, Cd, Cr, Cu, Fe, Pb, Mn, Mo, Ni, Se, and Sr in concentrations of 2.07, 0.08, 0.05, 0.05, 0.17, 0.98, 0.05, 0.20, 0.06, 0.09, 0.05, 0.61 mg/l; respectively. BPs was added to the wastewater sample at a rate of 0.5 g for each 50 ml, and shaking time was 200 min without changing the pH value of the drain water. Although the activated BPs removed only 8.33% Cu (II) where Zn (II) was absent into drainage water. BPs was also able to remove about 62% Cd (II), 6.52% Cr (II), 28.5% Fe (II), 95.83% Pb (II), 54.73% Mn (II), 14.29% Mo (II), 24.49% Se (II), 79.80% Sr (II) respectively, as shown in Table 7. Decreased removal percent of Cu (II) might be because of the influence of other interfering metals in the solution. Hence, BPs was efficacious adsorbent of harmfully metals: Cd, Pb, and Sr in addition to Mn. The choosiness of activated BPs towards the assorted metal ions followed the sequence: Pb > Sr > Cd > Mn > Fe > Se > Mo > Cu > Cr. This study revealed good sorbent BPs for treating wastewater from different metal ions.
4 Conclusions
The present investigation is carried out to study the suitability of Banana peels bioadsorbent for the removal of heavy metals such as copper and zinc from the wastewater. The influence of process parameters such as pH, adsorbent dosage, temperature, contact time, and initial metal ion concentration were at moderate levels such that they can affect the removal efficiencies of the heavy metals was concerned. The optimum pH of the solution for Cu and Zn removal was found to be 6. Within the scope of the experimental investigation, the optimum temperature was found to be 25 °C. The optimum time for adsorption of zinc and copper was found to be 180 and 210 min, respectively. Initial metal ion concentration showed a negative effect on adsorption efficiency i.e. at lower levels the adsorption was higher. Kinetic studies of adsorption revealed that the adsorption process followed a pseudo-second-order kinetic model for both metals. The adsorption data were fitted to different isotherm model equations and the Langmuir model was found to be the best model for both metals i.e. Cu and Zn with R2 values of 0.96, and 0.95 respectively. Thermodynamic parameters of adsorption studies revealed that the adsorption of heavy metals using Banana peels is exothermic in nature; hence it can be concluded to be a physical adsorption phenomenon. In addition, BPs sorbent succeeded in the elimination of different metal ions from effluent water. The selectivity order of BPs towards the other metal ions followed the sequence: Pb > Sr > Cd > Mn > Fe > Se > Mo > Cu > Cr.
Data availability
The dataset used and analyzed during the current study is presented in the manuscript.
References
Bayuo J, Rwiza MJ, Sillanpää M, Mtei KM. Removal of heavy metals from binary and multicomponent adsorption systems using various adsorbents—a systematic review. RSC Adv. 2023;13:13052–93. https://doi.org/10.1039/d3ra01660a.
Jahin HS, Kandil MI, Nassar MY. Facile auto-combustion synthesis of calcium aluminate nanoparticles for efficient removal of Ni(II) and As(III) ions from wastewater. Environ Technol. 2023;44:2581–96. https://doi.org/10.1080/09593330.2022.2036248.
Ezekoye OM, Akpomie KG, Eze SI, Chukwujindu CN, Ani JU, Ujam OT. Biosorptive interaction of alkaline modified Dialium guineense seed powders with ciprofloxacin in contaminated solution: central composite, kinetics, isotherm, thermodynamics, and desorption. Int J Phytoremediation. 2020. https://doi.org/10.1080/15226514.2020.1725869.
Chai WS, Cheun JY, Kumar PS, Mubashir M, Majeed Z, Banat F, Ho SH, Show PL. A review on conventional and novel materials towards heavy metal adsorption in wastewater treatment application. J Clean Prod. 2021. https://doi.org/10.1016/j.jclepro.2021.126589.
Sirilamduan C, Umpuch C, Kaewsarn P. Removal of copper from aqueous solutions by adsorption using modify Zalacca edulis peel modify. Songklanakarin J Sci Technol. 2011;33:725.
Singh S, Kumar V, Datta S, Dhanjal DS, Sharma K, Samuel J, Singh J. Current advancement and future prospect of biosorbents for bioremediation. Sci Total Environ. 2020. https://doi.org/10.1016/j.scitotenv.2019.135895.
Bayuo J. Decontamination of cadmium(II) from synthetic wastewater onto shea fruit shell biomass. Appl Water Sci. 2021;11:1–8. https://doi.org/10.1007/s13201-021-01416-2.
Escudero LB, Quintas PY, Wuilloud RG, Dotto GL. Recent advances on elemental biosorption. Environ Chem Lett. 2019. https://doi.org/10.1007/s10311-018-0816-6.
Bayuo J. An extensive review on chromium (vi) removal using natural and agricultural wastes materials as alternative biosorbents. J Environ Heal Sci Eng. 2021;19:1193–207. https://doi.org/10.1007/s40201-021-00641-w.
Akpomie KG, Conradie J. Banana peel as a biosorbent for the decontamination of water pollutants. A review. Environ Chem Lett. 2020. https://doi.org/10.1007/s10311-020-00995-x.
Jahin HS, Hesham A, Awad YM, El-Korashy S, Khairy G. THMs removal from aqueous solution using hydrochar enhanced by chitosan nanoparticles: preparation, characterization, kinetics, equilibrium studies. Int J Environ Sci Technol. 2023. https://doi.org/10.1007/s13762-023-05150-x.
Castro RSD, Caetano L, Ferreira G, Padilha PM, Saeki MJ, Zara LF, Martines MAU, Castro GR. Banana peel applied to the solid phase extraction of copper and lead from river water: Preconcentration of metal ions with a fruit waste. Ind Eng Chem Res. 2011. https://doi.org/10.1021/ie101499e.
Afolabi FO, Musonge P, Bakare BF. Bio-sorption of a bi-solute system of copper and lead ions onto banana peels: characterization and optimization. J Environ Heal Sci Eng. 2021. https://doi.org/10.1007/s40201-021-00632-x.
Mondal NK. Natural banana (Musa acuminate) peel: an unconventional adsorbent for removal of fluoride from aqueous solution through batch study. Water Conserv Sci Eng. 2017. https://doi.org/10.1007/s41101-016-0015-x.
Mohamed RM, Hashim N, Abdullah S, Abdullah N, Mohamed A, Asshaary Daud MA, Aidil Muzakkar KF. Adsorption of heavy metals on banana peel bioadsorbent. J Phys Conf Ser. 2020. https://doi.org/10.1088/1742-6596/1532/1/012014.
Rao M, Parwate AV, Bhole AG. Removal of Cr6+ and Ni2+ from aqueous solution using bagasse and fly ash. Waste Manag. 2002. https://doi.org/10.1016/S0956-053X(02)00011-9.
Bayuo J, Abukari MA, Pelig-Ba KB. Desorption of chromium (VI) and lead (II) ions and regeneration of the exhausted adsorbent. Appl Water Sci. 2020;10:1–6. https://doi.org/10.1007/s13201-020-01250-y.
Khairy GM, Hesham AM, Jahin HES, El-Korashy SA, Mahmoud Awad Y. Green synthesis of a novel eco-friendly hydrochar from Pomegranate peels loaded with iron nanoparticles for the removal of copper ions and methylene blue from aqueous solutions. J Mol Liq. 2022;368:120722. https://doi.org/10.1016/j.molliq.2022.120722.
Zheng H, Liu D, Zheng Y, Liang S, Liu Z. Sorption isotherm and kinetic modeling of aniline on Cr-bentonite. J Hazard Mater. 2009. https://doi.org/10.1016/j.jhazmat.2008.12.093.
Nassar AE, El-Aswar EI, Rizk SA, Gaber SES, Jahin HS. Microwave-assisted hydrothermal preparation of magnetic hydrochar for the removal of organophosphorus insecticides from aqueous solutions. Sep Purif Technol. 2023. https://doi.org/10.1016/j.seppur.2022.122569.
Li ZC, Fan HT, Zhang Y, Chen MX, Yu ZY, Cao XQ, Sun T. Cd(II)-imprinted polymer sorbents prepared by combination of surface imprinting technique with hydrothermal assisted sol-gel process for selective removal of cadmium(II) from aqueous solution. Chem Eng J. 2011. https://doi.org/10.1016/j.cej.2011.05.023.
Thirumavalavan M, Lai YL, Lee JF. Fourier transform infrared spectroscopic analysis of fruit peels before and after the adsorption of heavy metal ions from aqueous solution. J Chem Eng Data. 2011. https://doi.org/10.1021/je101262w.
Bayuo J, Pelig-Ba KB, Abukari MA. Adsorptive removal of chromium(VI) from aqueous solution unto groundnut shell. Appl Water Sci. 2019;9:1–11. https://doi.org/10.1007/s13201-019-0987-8.
Qasem NAA, Mohammed RH, Lawal DU. Removal of heavy metal ions from wastewater: a comprehensive and critical review. Npj Clean Water. 2021. https://doi.org/10.1038/s41545-021-00127-0.
Kandil MI, Jahin HS, Dessouki HA, Nassar MY. Synthesis and characterization of γ-Al2O3 and α-Al2O3 nanoparticles using a facile, inexpensive auto-combustion approach, Egypt. J Chem. 2021;64:2509–15. https://doi.org/10.21608/EJCHEM.2021.61793.3330.
De Sousa PAR, Furtado LT, Neto JLL, De Oliveira FM, Siqueira JGM, Silva LF, Coelho LM. Evaluation of the adsorption capacity of banana peel in the removal of emerging contaminants present in aqueous media—study based on factorial design. Br J Anal Chem. 2019. https://doi.org/10.30744/brjac.2179-3425.AR.119-2018.
Šabanović E, Memić M, Sulejmanović J, Huremović J. Pulverized banana peel as an economical sorbent for the preconcentration of metals. Anal Lett. 2015. https://doi.org/10.1080/00032719.2014.947534.
Ali I, Al-Othman ZA, Al-Warthan A. Removal of secbumeton herbicide from water on composite nanoadsorbent. Desalin Water Treat. 2016. https://doi.org/10.1080/19443994.2015.1041164.
Sahmoune MN. Evaluation of thermodynamic parameters for adsorption of heavy metals by green adsorbents. Environ Chem Lett. 2019. https://doi.org/10.1007/s10311-018-00819-z.
Zhu F, Zheng YM, Zhang BG, Dai YR. A critical review on the electrospun nanofibrous membranes for the adsorption of heavy metals in water treatment. J Hazard Mater. 2021. https://doi.org/10.1016/j.jhazmat.2020.123608.
Chen Z, Ma W, Han M. Biosorption of nickel and copper onto treated alga (Undaria pinnatifida): application of isotherm and kinetic models. J Hazard Mater. 2008. https://doi.org/10.1016/j.jhazmat.2007.11.064.
Chen Y, Wang H, Zhao W, Huang S. Four different kinds of peels as adsorbents for the removal of Cd (II) from aqueous solution: kinetics, isotherm and mechanism. J Taiwan Inst Chem Eng. 2018. https://doi.org/10.1016/j.jtice.2018.03.046.
Borousan F, Yousefi F, Ghaedi M. Removal of malachite green dye using IRMOF-3-MWCNT-OH-Pd-NPs as a novel adsorbent: kinetic, isotherm, and thermodynamic studies. J Chem Eng Data. 2019. https://doi.org/10.1021/acs.jced.9b00298.
Dawodu FA, Akpan BM, Akpomie KG. Sequestered capture and desorption of hexavalent chromium from solution and textile wastewater onto low cost Heinsia crinita seed coat biomass. Appl Water Sci. 2020. https://doi.org/10.1007/s13201-019-1114-6.
Mohd Salim R, Khan Chowdhury AJ, Rayathulhan R, Yunus K, Sarkar MZI. Biosorption of Pb and Cu from aqueous solution using banana peel powder. Desalin Water Treat. 2016. https://doi.org/10.1080/19443994.2015.1091613.
Annadurai G, Juang RS, Lee DJ. Adsorption of heavy metals from water using banana and orange peels. Water Sci Technol. 2003;47:185–90. https://doi.org/10.2166/wst.2003.0049.
Lakshmi KB, Sudha PN. Adsorption of Copper (II) ion onto chitosan/sisal/banana fiber hybrid. Int J Environ Sci. 2012;3:453.
Choi JW, Chung SG, Hong SW, Kim DJ, Lee SH. Development of an environmentally friendly adsorbent for the removal of toxic heavy metals from aqueous solution. Water Air Soil Pollut. 2012. https://doi.org/10.1007/s11270-011-0988-1.
Kadouchea S, Zemmourib H, Benaoumeura K, Drouichea N, Sharrockd P, Lounici H. Metal ion binding on hydroxyapatite (Hap) and study of the velocity of sedimentation. Proc Eng. 2012;33:377–84.
Onundi YB, Mamun AA, Al Khatib MF, Amed YM. Adsorption of copper, nickel and lead ions from synthetic semiconductor industrial wastewater by palm shell activated carbon. Int J Environ Sci Tech. 2010;7(4):751–8.
Abdulrasaq OO, Basiru OG. Removal of copper (II), iron (III) and lead (II) ions from Mono-component simulated waste effluent by adsorption on coconut husk. Afric J Environ Sci Technol. 2010;4(6):382–7.
Anirudhan TS, Radhakrishnan PG (2008) Thermodynamics and kinetics of adsorption of Cu(II) from aqueous solutions onto a new cation exchanger derived from tamarind fruit shell. J Chem Thermodyn 2008;40:702–9.
Larous S, Meniai A. H, Bencheikh Lehocine M. Experimental study of the removal of copper from aqueous solutions by adsorption using sawdust. Desalination 2005;185:483–90.
Kadouche S, Lounici H, Drouiche N, Hadioui M, Sharrock P. Enhancement of sedimentation velocity of heavy metals loaded hydroxyapatite using chitosan extracted from shrimp waste. J Polym Environ. 2012; 20:848–857
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All authors contributed to the study conception and design. Material preparation, data collection and analysis were performed by [Hossam S. Jahin], [Alaa I. Khedr] and [Hala E. Ghannam]. The first draft of the manuscript was written by [Alaa I. Khedr and Hala E. Ghannam] and all authors commented on previous versions of the manuscript. All authors read and approved the final manuscript.
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Jahin, H.S., Khedr, A.I. & Ghannam, H.E. Banana peels as a green bioadsorbent for removing metals ions from wastewater. Discov Water 4, 36 (2024). https://doi.org/10.1007/s43832-024-00080-2
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DOI: https://doi.org/10.1007/s43832-024-00080-2