Competitive gallium and indium adsorption from wastewaters on low cost chabazite

doi:10.21203/rs.3.rs-2283868/v1

Download PDF

Research Article

Competitive gallium and indium adsorption from wastewaters on low cost chabazite

https://doi.org/10.21203/rs.3.rs-2283868/v1

This work is licensed under a CC BY 4.0 License

Version 1

posted

You are reading this latest preprint version

The paper describes the gallium and indium adsorption from aqueous solutions employing chabazite as adsorbent. Kinetic and isotherm adsorption experiments in monometallic solutions were carried out to ascertain the adsorption mechanisms. The obtained results showed that the adsorption of Ga (III) onto chabazite was properly described by Sips model while indium adsorption is well described by Freundlich model. Competitive adsorption experiments showed that chabazite had more affinity towards gallium than towards indium due to, according to the speciation diagrams, in the case of gallium the predominant specie in solution is GaOH2+, while in the case of indium, the main ionic specie is In3+. However, the most outstanding conclusion is that it is possible to remove both metals from the aqueous media, employing a relatively high chabazite dosage while with a low chabazite dosage (1 g/L) it is possible to selectively retain gallium in solid, remaining indium ions in the solution.

gallium

indium

strategic metal

competitive adsorption

chabazite

Nowadays, a group of metals known as “strategic metals” are gaining a high market value due to their scarcity in the earth’s crust and their economic importance (European Comission 2020). Among these metals, gallium and indium has shown an increasing interest due to their wide range of applications.

In relation to gallium, it is a high valuable metal whose main applications are focused on the semiconductor industry (Foley et al. 2017). Concerning indium, is a soft silvery white metal, which is mainly employed in the electronic industry for the manufacture of photoconductors or thermistors, and in the manufacturing of liquid crystal screens (Alfantazi and Moskalyk 2003). However, because there do not exist primary ores whose main constituents are gallium or indium, they are usually recovered as secondary products from other metallurgical processes, such as Bayer process or zinc extraction process (Bautista 2003; Lu et al. 2017). The main drawback of obtaining these materials from metallurgical processes is that it involves many steps which cause a negative impact to the environment. Consequently, simpler, and more efficient alternatives are required.

In the last years, among the alternatives to obtain indium and gallium, their recovery from residual wastewater is gaining attention mainly because it implies a double target: purifying water on one hand, and recovery important raw materials on the other hand, within the framework of a circular economy and keeping in mind the Objectives for Sustainable Development. Amidst the different sources of wastewaters, those coming from electronic industry are especially suitable for gallium and indium recovery, as they usually contain both metals simultaneously. Therefore, the efforts must be focused on developing a suitable technique for selectively separating these two ions from the same aqueous matrix.

In literature, several alternatives have been studied when wastewaters contaminated with metals are concerned. Some of them are filtration (Lahti et al. 2020), chemical precipitation (Janin et al. 2009), membrane processes (Lahti et al. 2020), solvent extraction (Drzazga et al. 2021; Liu et al. 2006; Song et al. 2020) or electrochemical methods (Grevtsov et al. 2021). However, these processes have important drawbacks, such as sludge production, large operation costs or incapability of reaching a complete removal. For this reason, to overcome these drawbacks, adsorption has emerged as a promising technology, especially suitable when a high selectivity for a specific metal (as is the case of this study) or the pre-concentration of trace metal amounts are necessary.

The main inconvenient of an adsorption process is that the overall profitability of the process is mainly dependent on the adsorbent’s cost (Saravanan et al. 2021; Shrestha et al. 2021). So, in the last year, the efforts have been concentrated in finding relatively cheap and available adsorbents. One of the most promising solids to be used as adsorbents are natural zeolites; these solids are relatively cheap because are highly and naturally accessible. Among natural zeolites, one especially adequate is chabazite.

Chabazite is a natural zeolite member of the chabazite group which can be found in the cavities of basaltic rocks all around the world. Its generic chemical formula is (Ca_0,5,Na,K)₄[Al₄Si₈O₂₄]·12H₂O, with a silicon to aluminum ratio ranging from 2 to 5, what confers thermal stability to the zeolite. The crystal structure of chabazite consist of a three-dimensional pore structure with an opening of 3.8 Å, and occupied with water and exchangeable cations, such as Na⁺ or K⁺. These characteristics make chabazite a suitable adsorbent for metal ions removal from wastewater.

In previous studies chabazite has been employed as adsorbent of different compounds, what gives an idea of its potential applicability. Aysan et al. (Aysan et al. 2016), and Solisio and Aliakbarian (Solisio and Aliakbarian 2017) employed this natural zeolite to successfully remove methylene blue from aqueous solutions. It has also been employed to separate different compounds from gas streams, such as N₂, O₂ and Ar (Singh and Webley 2005) or N₂, CO₂ and CH₄ (Watson et al. 2012). Other applications of this solid as adsorbent have been CO₂ capture (Pham et al. 2014; Zhang et al. 2008), separation of CO₂/CH₄ mixtures (Shang et al. 2020) or alkane adsorption (Denayer et al. 2008; Göltl and Hafner 2011).

However, despite its, a priori, adequate characteristics, chabazite has not been deeply studied in literature as potential adsorbent for metal removal. Only few references can be found in literature. Gallant et al. (Gallant et al. 2009) compared chabazite and clinoptilolite as adsorbents to remove Cs, Co, Sr, Cu, Cd and Zn, which can be found in effluents of nuclear operations. They concluded that the better adsorption capacity of chabazite could be attributed to its larger pore volume as well as its higher silicon to aluminum ratio. Egashira et al. (Egashira et al. 2012) employed chabazite, mordenite and clinoptilolite, to adsorb Cu, Zn and Mn. They also concluded that the cation exchange capacity of natural zeolite increases with increasing its aluminum content. Yakout and Borai (Yakout and Borai 2014) employed chabazite to remove Cd from aqueous solutions, obtaining a maximum cadmium adsorption capacity of 120 mg/g, and concluding that the adsorption process is strongly pH dependent in the 2.5–8.5 range. Al Dwairi et al. (Dwairi et al. 2015) employed two Jordanian natural zeolites of type phillipsite-chabazite, for continuous removal of Pb and Li ions from industrial wastewater effluents with adsorption capacity values of 34.7 and 23.64 mg/g for Pb ions, and 18.65 and 21.43 mg/g for Li ions. Finally, Ibrahim et al. (Ibrahim et al. 2016) employed phillipsite–chabazite tuffs to adsorb Mo and Ni from aqueous solutions, reaching a Mo removal efficiency of 76% and a Ni removal efficiency larger than 90%.

The aim of this paper is to study the selective removal of gallium and indium from aqueous solutions by batch adsorption onto a low-cost zeolite. The main achievement of the work is that varying the solid dosage it is possible to selectively recover these two metals independently, to be further re-used, what has not been previously reported in literature.

2.1. Zeolite source, conditioning, and characterization

The natural zeolite employed in this study was obtained from St. Cloud Mining (New Mexico, EEUU) and its main constituent was chabazite with clinoptilolite, quartz, feldspars among other impurities, according to the supplier. Regarding to chemical composition of zeolite sample, the analysis carried out by the distributor revealed that the dominant cation was sodium. The chemical composition as well as other properties of the zeolite supplied are summarized in Table 1.

Table 1

Properties of chabazite based on supplier analysis.
Parameter	Value
Chemical composition (%)	SiO₂ 68.1; Al₂O₃ 18.59; Fe₂O₃ 2.84; CaO 0.27; MgO 0.75; Na₂O 8.32; K₂O 1.12.
Density (g/cm³)	1.73
Pore Size (Å)	4.1–3.7
Cavity Size (Å)	11.0-6.6
Surface Area (m²/g)	520
Total Pore Volume (cm²/g)	0.468
MOH’s Hardness	4–5
Stability	pH of 3 through 12
Ion Exchange Capacity (meq/g)	2.50

Before using it as adsorbent, the chabazite (CHA) was washed with deionized water, to remove its turbidity, dried at 373 K for 24 h and sieved to obtain a 1.00-1.18 mm size fraction. Additionally, to improve its adsorption capacity and to assure an acid medium to avoid Ga³⁺ and In³⁺ ions precipitation, the chabazite was further treated with HCl (H-CHA) to obtain the protonated form. The concentration of acid solution selected was 0.05 M to ensure a partial protonation without dealumination. The protonation was carried out by disposing the zeolite on a filter and adding the 0.05 M HCl solution, keeping a ratio of 20 g of zeolite per liter of acid. This technique has been successfully used in previously by the research group to protonate clinoptilolite (Sáez et al. 2021). The following steps were to wash the zeolite until no chlorides were present and to dry it at 373 K for 24 h. Finally, the treated zeolite was characterized and compared with raw chabazite to detect any possible structural alteration as well as to analyze the modification carried out. The characterization techniques employed were X-Ray Diffraction (XRD) to study for the crystal structure, Fourier Transform Infrared Spectroscopy (FTIR) for functional groups, X-Ray Fluorescence (XRF) for chemical composition, nitrogen adsorption-desorption isotherms at 77 K for textural properties and lastly Scanning Electron Microscopy (SEM) for morphology.

2.2. Adsorption experiments.

To evaluate the adsorption capacity of the zeolite, two kinds of experiments were made: (i) equilibrium sorption experiments with a single metal in solution, to obtain the maximum adsorption capacity for the corresponding metal at these conditions as well as the adsorption mechanism, and (ii) competitive kinetics experiments with both metals in solution (Ga³⁺ and In³⁺) in order to establish the affinity of the zeolite for each of them, to better understand the adsorption mechanism, and to analyse the possibility of separating both metals from the same aqueous matrix.

The sorption experiments were carried out at constant temperature of 298 K and agitation rate (approximately 250 r.p.m), free pH, ensuring that it was below 3.5 to avoid the precipitation of metal ions and a chabazite dosage of 1 g/L in 250 mL flasks. To obtain the isotherms, the concentration of Ga or In ions (prepared by dissolving Z(NO₃)₃·xH₂O, being Z Ga or In, in deionized water) was increased from 10 mg/L to 200 mg/L and the samples were under stirred until the equilibrium was reached (approximately 72 h), when samples were taken for analysis. Regarding the competitive kinetics experiments, different ratios of [Ga]/[In] were employed (from 0.5 to 2). In this case, the samples were initially taken every 15 min up to the first 90 min, after which they were taken every 60 min. When the equilibrium was close to be attained, samples were taken day by day until the concentration of the samples in consecutive days were same or very similar, with variations less than 5%. This value is the percentage of associated error, estimated as the ratio between the 95% confidence interval and the average value of the repeated sample measurements (5–6 times). For the kinetic experiments, the total volume extracted was less than 15% of the total sample volume. All the samples (corresponding on both kinetic and equilibrium experiments) were passed through a 0.2 µm filter prior to the analysis to separate the sorbent particles. The metal ion concentration remaining in solution was determined by atomic absorption spectroscopy (Shimadzu AA-7000). The amount of metal ions removed by chabazite was calculated using the equations 1 and 2.

Where q is the amount of metal ion adsorbed per gram (mg/g); C₀ is the initial metal ion concentration (mg/L); C_t is the metal ion concentration after time t (mg/L); V is the solution volume (L); Mw is the molecular weight of the gallium and indium; and m is the mass of the adsorbent (g). The initial gallium and indium concentration values selected are like the usual concentration values of the two ions in wastewaters (Li et al. 2009).

3.1. Characterization

Figure 1 displays the FTIR spectra of natural chabazite (CHA) and the chabazite treated with HCl 0.05 M (H-CHA).

Typically, the FTIR spectrum of a natural zeolite is composed by two groups of vibrational frequencies: internal vibration of T-O (T = Si and Al) and vibration of external bonds between tetrahedrons, whose peaks appear at wavenumbers ranging from 1200 cm^− 1 to 400 cm^− 1, and the bands or peaks due to the presence of structural water (from 1600 cm^− 1 to 3700 cm^− 1). Regarding CHA spectrum, as it can be appreciated in Fig. 1, the zeolite showed strong bands between 521 cm^− 1 and 642 cm^− 1 which correspond to 6-membered rings structural units. The band observed at 722 cm^− 1 indicated 4-membered ring structure and the bands at 415 cm^− 1 and 468 cm^− 1 were formed as result of behaving as a ring band. Lastly the band at 1043 cm^− 1 indicate T-O stretching vibration. These structural peaks were also presented in H-CHA spectra, so it can be assumed that the acid treatment did not modify the structure of the zeolite. Concerning the other peaks identified in the spectra (3440 cm^− 1 and 1643 cm^− 1 ), they corresponded to isolated O-H stretching and H₂O bending respectively (Mozgawa et al. 2011).

Related to XRD analysis, Fig. 2 displays the results obtained from CHA and H-CHA. The XRD results revealed that the chabazite employed, shows the characteristic peaks of chabazite (*) but also contains clinoptilolite impurities (•), as indicated in the supplier’s data sheet (Aysan et al. 2016). Regarding the H-CHA peaks, the zeolite exhibited identical peaks than CHA, which confirm the FTIR observations that the acid treatment did not modify the structure of the zeolite, but with a very slightly lower intensity above all in clinoptilolite peaks. This statement was also observed by Kennedy and Tezel who attributed it to the substitution of cations such as Na⁺, K⁺ and Ca²⁺ by cations with higher charge to ionic radius ratio, such as H⁺ resulting in a less defined diffraction patterns due to the atomic density change and disorder increase (Kennedy and Tezel 2018).

Concerning XRF analysis, the initial chabazite showed an estimated Si/Al ratio of 3.2 with sodium as the majority cation (3.4%) and calcium and potassium as the other compensation cations (molar percentages around 0.5% and 0.7% respectively). After acid treatment, the Si/Al ratio increased to 3.4, so the dealumination process was completely dismissed. Regarding the protonation percentage, calculated as the difference between 1 and cations to aluminum ratio, this value was raised up from 27% for CHA to 44% from H-CHA after the washing with HCl 0.05M, being the majority cation exchanged Na⁺. So, the modification of the zeolite employing diluted acid was stronger enough to assure an increase in the quantity of protons, maintaining the crystallinity degree.

The nitrogen adsorption-desorption isotherms of CHA and H-CHA are shown in Fig. 3 and the textural properties obtained are summarized in Table 2.

Table 2

Textural properties for CHA and H-CHA.
Sample	Surface area BET (m²/g)	Micropore area t-plot (m²/g)	Micropore volume t-plot (cm³/g)	Total pore volume (cm³/g)
CHA	544	479	0.18	0.34
H-CHA	505	434	0.16	0.39

As seen in Fig. 3, the adsorption-desorption isotherms of CHA and H-CHA are IUPAC type IV (a) with hysteresis loop type H4, which are typical of materials with aggregates or mesoporous zeolites (Thommes et al. 2015). It shows the hysteresis loop at relative pressure of 0.45–0.99. This hysteresis loop usually reveals the constricted mesopores and/or macropores inside zeolite crystal. Regarding the textural properties, in Table 1 are compiled the surface area, calculated according Brunauer-Emmett-Teller (BET) method, the micropore volume, the area estimated with t-plot method and the total pore volume obtained by Density Functional Theory (DFT). As it can be observed, the acid treatment produced in the chabazite a slightly decrease in the BET surface area as well as in the amount of micropores. Nevertheless, considering the results observed in the other characterization techniques, it can be assumed that this decrease is neglectable, and it is not produced due to the acid treatment. Lastly, scanning electron microscopy (SEM) image of CHA and H-CHA samples are given in Fig. 4.

As displayed in Fig. 4, chabazite zeolite type is composed of different aggregates as well as cube or rhombohedral crystals (CHA x5000) typical of sedimentary chabazite and plate-shaped crystals corresponding to clinoptilolite impurities (Mumpton and Ormsby 1976). Acid treatment, smooth the surface appearance. This effect was observed with clinoptilolite-type zeolite by other authors who related it to the exchange of cations for protons (Korkuna et al. 2006). In addition, the size of the chabazite crystals seems decreased as can be observed in Fig. 4 since at 5000x magnification for CHA the crystals are clearly visible whereas for H-CHA no (yellow circle in Fig. 4).

3.2. Batch sorption results.

3.2.1. Equilibrium adsorption.

The main purpose of the equilibrium study is to determine the adsorption mechanism of Ga and In- on chabazite separately, to further be able to conduct the competitive kinetics experiments. The equilibrium experiments were carried out increasing the initial concentration of the metal ion from 10 mg/L to 200 mg/L at constant temperature of 298 K, employing an adsorbent dosage of 1 g/L and free pH. The pH was kept stable at a value of around 2.8. The results are shown in Fig. 5.

It can be seen, in Fig. 5, that the adsorption mechanism of both metals on the chabazite surface is very similar. The greatest difference between the two isotherms is found in the plateau zone, with a difference between the values reached of 5%. The saturation adsorption capacity reached a value of 0.79 mmol/g (92 mg/g) for In (III) and 0.83 mmol/g (56 mg/g) for Ga (III). Regarding the type of adsorption isotherm, according to Giles classification (Giles et al. 1960), they can be classified as H2 for gallium adsorption isotherm and H4 for indium adsorption isotherm. The isotherm group H refers to a high affinity between adsorbate and adsorbent. As for the subgroup, type 2 indicates that the adsorbent surface is complete and therefore presents a plateau whereas type 4 indicates that chabazite when adsorbing indium can develop new active sites at high concentrations to adsorb more ions. To analyze the discrepancy between the isotherm types of the metal ions, Fig. 6 displays the speciation diagrams of both metals carried out with Medusa software. In relation to gallium’s, as it can be observed, at pH 3, the predominant specie is GaOH²⁺, while in the case of indium’s, the main ionic specie is In³⁺. Although both species have access to the active sites situated along the 3.8A channels, their different ionic radii causes a different cation realignment (Rivera-Ramos and Hernández-Maldonado 2007).

To describe the equilibrium sorption of Ga (III) and In (III) on H-CHA, several theoretical isotherms model have been selected taking in consideration the kind of isotherms (Hinz 2001). For Ga (III) isotherm the employed models were Langmuir, Freundlich and Sips whereas for In (III) isotherm were Double Langmuir and Freundlich. The isotherm model equations are summarized in Table 3.

Table 3

Isotherm models use to describe the equilibrium sorption of Ga (III) and In (III) onto H-chabazite.
Isotherm Model	Equation	Isotherm Type
Langmuir (Langmuir 1917)	\({q}_{e}=\frac{{q}_{sat}·{b}_{L}·{C}_{e}}{1+{b}_{L}·{C}_{e}}\)	H2;L2
Freundlich (Freundlich 1906)	\({q}_{e}={K}_{F}·{C}_{e}^{1/{n}_{F}}\)	H2;H4
Sips (Sips 1950)	\({q}_{e}=\frac{{q}_{sat}·{\left({b}_{S}·{C}_{e}\right)}^{1/{n}_{S}}}{1+{\left({b}_{S}·{C}_{e}\right)}^{1/{n}_{S}}}\)	H2; L2
Double Langmuir (Gómez et al. 2012)	\({q}_{e}=\frac{{q}_{s1}·{k}_{1}·{C}_{e}}{1+ {k}_{1}·{C}_{e}}+\frac{{q}_{s2}·{k}_{2}·{C}_{e}}{1+ {k}_{2}·{C}_{e}};\)\({ k}_{2}=\alpha ·{{C}_{e}}^{\beta }\)	H4;L4

where b_L is a constant describing the affinity between the adsorbent and adsorbate (L/mmol); q_sat is the maximum sorption capacity onto the monolayer (mmol/g); K_F is the Freundlich constant, (mmol/g/(mmol/L)^nF; n_F is the Freundlich intensity parameter; b_S (L/mmol) and n_S are empirical constants of Sips model; q_s1 and q_s2 are the saturation adsorption capacity for the first and second layer respectively (mmol/g); k₁ and k₂ are the adsorption equilibrium constants, for the first and the second plateaus respectively and α and β are empirical parameters of Double Langmuir model.

The experimental data were fitted to the models (Fig. 7) by means of non-linear regression. The isotherm parameters obtained are shown in Table 4. The analysis of the fitting goodness was carried out considering the values of correlation coefficient (R²) and root squared error (RMSE).

To describe the equilibrium sorption of Ga (III) onto H-CHA, the best model is Sips, because its high R² and low RMSE. Additionally, the value of q_sat obtained with this model is very close to the experimental one, suggesting that Sips equation can properly predict the adsorption system. As for the value of n, if the inverse is calculated, a value of 1.1 is obtained, which is close to 1, indicating that the adsorption isotherm exhibits a Langmuir-type behavior. In fact, if the Langmuir model results are observed, they are very similar to the estimated for Sips model, though the qs_at value is not as similar as the experimental one. Regarding Freundlich model, in view of the R² (< 0.9) and RMSE values, the poor applicability of the model to describe the adsorption is demonstrated.

Table 4

Isotherm parameters calculated by non-linear regression.
		Metal
Isotherm model	Parameter	Ga (III)	In (III)
	q_sat,exp (mmol/g)	0.83	0.79
Langmuir	q_sat (mmol/g)	0.86	-
	b (L/mg)	0.27	-
	R²	0.98	-
	RMSE (mmol/g)	2.10E-2	-
Freundlich	K_F (mmol/g)/(mmol/L)^nF	0.36	0.37
	n	5.09	6.51
	R²	0.88	0.98
	RMSE (mmol/g)	0.12	1.6E-2
Sips	q_sat (mmol/g)	0.84	-
	K_s (L/mg)	0.28	-
	n	0.91	-
	R²	0.98	-
	RMSE (mmol/g)	2.10E-2	-
Double Langmuir	q_sat1 (mmol/g)	-	0.58
	q_sat2 (mmol/g)	-	0.20
	K₁ (L/mg)	-	8.32
	α	-	3.18E-13
	β	-	5.94
	R²	-	0.95
	RMSE (mmol/g)	-	0.03

With regards to In (III) isotherm, Freundlich equation seems to be the model which best describe the adsorption of this metal on H-CHA by obtaining a high R² value and a low RMSE. The inverse of parameter n of this model is 0.15. This very close to 0 value indicates the heterogeneity of the adsorbent surface as well as a favorable adsorption process. As for the Double Langmuir model, although the goodness of the fit is slightly lower than Freundlich’s one, this model can define the multilayer of the adsorption isotherm as well as the saturation capacity for each of the plateaus. So, the model that best describes indium adsorption is Double Langmuir because it can predict the multilayer associated with the indium ion rearrangement.

3.2.2. Competitive kinetic.

After analysing the adsorption isotherms of each metal ion separately, a series of competitive studies were carried out. These experiments were conducted at different concentrations: 0.5 mM for both metals ([Ga³⁺] = [In³⁺]); 0.5 mM for Ga (III) and 0.25 mM for In (III) ([Ga³⁺] > [In³⁺]); and 0.25 mM for Ga (III) and 0.5 mM for In (III) ([Ga³⁺] <[In³⁺]). The results obtained are represented in Fig. 8.

As it can be seen in Fig. 8, regardless of the initial metal concentrations, chabazite showed a higher affinity for Ga (III) than for In (III). Similar behavior has been found in literature (Du et al. 2022). This can be due to what previously was commented in relation to the speciation diagrams: at pH 3, the majority specie in gallium´s diagram is GaOH²⁺, but in the case of indium’s, the main ionic specie is In³⁺, and the affinity is always higher towards covalent rather than trivalent species. When In (III) is present in the solution at higher concentration than Ga (III), the adsorption of gallium decreases to similar values as for In (III) due to the zeolite tendency to adsorb the ions that are in higher concentration (the driving force is greater). However, if Ga (III) concentration is similar or higher than In (III) concentration, then the zeolite is capable selectively to adsorb Ga (III). Summarizing, at low dosage values, the solid mainly will retain gallium, because the number of active centers is relatively small, so it will preferably absorb the cations towards it has more capacity. At high dosage values, the number of active centers increase, so the solid will be able to retain both cations.

The experimental adsorption capacity values for each metal have been compared with the theoretical values that would be reached if the metals were isolated in the solution. The theoretical capacity values were obtained from the adsorption isotherms (Fig. 5). Table 5 summarizes the comparison. In this table, theoretical values were expressed with “t” whereas the experimental ones with “exp”. The values, expressed in percentage, in parentheses in Table 5 have been calculated as the experimental/theoretical ratio to see the difference from having one metal in the medium to several. Additionally, it has been calculated the ratio Ga(III) adsorbed between In (III) adsorbed, as well as, the final concentration in the solution at the end of the kinetic for each metal expressed in mg/L.

Table 5

Comparison of theoretical (t) and experimental (exp) values of adsorption capacity and removal percentage.
	[Ga³⁺] = [In³⁺]		[Ga³⁺] > [In³⁺]		[Ga³⁺] < [In³⁺]
Parameter	Ga³⁺	In³⁺	Ga³⁺	In³⁺	Ga³⁺	In³⁺
q_t (mmol/g)	0.42	0.45	0.42	0.25	0.22	0.45
q_exp (mmol/g)*	0.23 (55%)	0.11 (24%)	0.25 (60%)	0.09 (36%)	0.17 (77%)	0.16 (36%)
(q_exp)_Ga³⁺ + (q_exp)_In³⁺ (mmol/g)**	0.34 (78.2%)		0.34 (80.9%)		0.33 (73.3%)
Ga^3 + _adsorbed/In^3 + _adsorbed (%/%)	2.1		2.8		1.1
Removal,t (%)	82	90	82	100	92	90
Removal, exp (%)	45	24	49	36	61	32
\({C}_{f},t(mg/L)\)	19.2	43.4	17.8	18.2	6.7	38.8
* The values in parentheses indicate the percentage of the theoretical value
** The value in parentheses indicate the percentage of the maximum theoretical value (gallium or indium, depending on the case)

The values collected in Table 5 show that the experimental adsorption capacity values achieved are lower than those which would be obtained if Ga (III) and In (III) were alone in solution. This is explained by the fact that the quantity of active sites is limited. When the two metals are in solution, there is a competition for these active sites, resulting in a decrease of both metal removal from the aqueous solution. As can be seen in the parameter (q_exp)_Ga³⁺ + (q_exp)_In³⁺, the adsorption capacity reached by the zeolite is 0.34 mmol/g, independently of the initial concentrations. From this situation, it can be assumed that when there are two metal ions in the medium, in addition to competition between the active sites, there may be a certain shield effect between them, preventing the theoretical capacity that would be reached if only they were in the medium.

So, if the main purpose of metal adsorption is wastewater treatment, a possible solution to achieve maximum elimination would be to add more zeolite to the solution to increase the number of actives sites. However, this could imply a drawback: due to the zeolite is relatively friable, the number fine particles in the suspension could increase. Otherwise, if the main objective of adsorption is to separate both metals for their further selective recovery, it would be sufficient to continue using low dosages of chabazite (1g /L) and enhancing the selectivity of chabazite towards gallium, especially with mixtures where gallium is in major concentration. For example, in semiconductor wastewaters this situation is very common, since gallium is usually more concentrated than indium (Li et al. 2009). As mentioned above, chabazite seems to have a higher affinity for gallium than for indium, regardless of the starting concentration. However, and considering the adsorbed Ga/In ratio, the higher affinity becomes less pronounced the more indium there is in the medium due to a higher driving force. So, for semiconductor industry wastewater, this higher affinity would have a greater advantage. However, although there is still no regulation on emission of these metals, it would be advisable to increase the amount of chabazite to further reduce the concentrations, thus avoiding damage to environment. It is important to point out that adding more adsorbent to the medium is not a problem from the economic point of view, since we are working with a cheap and abundant material.

In this paper, chabazite has been employed as a low-cost adsorbent to remove gallium and indium ions from aqueous solutions, with a double purpose: water purification and metal separation.

The adsorption experiments carried out in monometallic solutions, showed that chabazite is able of removing both metals, being the adsorption of Ga (III) properly described by Sips model and In adsorption by Freundlich model.

From the competitive adsorption experiments it can be concluded that chabazite has more affinity towards gallium due to its higher electronegativity and smaller ionic radius (although both ionic radii are quite similar). Nevertheless, the main conclusion is that varying the employed adsorbent it is possible to fulfil the two objectives initially posed: with a relatively high chabazite dosage it is possible to remove both metals from the aqueous media, while with a low chabazite dosage (1 g/L) it is possible to selectively adsorb gallium, while indium ions remain in the solution.

Ethical approval

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Fundings

The authors gratefully acknowledge the financial support from Ministerio de Economía y Competitividad CTQ2014-59011-R (REMEWATER). PSG was supported by a FPU contract-fellowship (Formación de Profesorado Universitario) from Ministerio de Educación Cultura y Deporte (FPU 14/00500).

Special acknowledgement to St. Cloud mining for supplying the chabazite used in this research.

AUTHOR CONTRIBUTION

Patricia Sáez: Conceptualization, investigation, data curation, original draft

Eduardo Díez: Supervision, data curation, review & editing

José María Gómez: Conceptualization, data curation, supervision

Carmen López: investigation, data curation

Araceli Rodríguez: Conceptualization, funding acquisition, project administration, resources, supervision, review & editing

Alfantazi, A.M., Moskalyk, R.R.: Processing of indium: A review. Miner. Eng. 16, 687–694 (2003). https://doi.org/10.1016/S0892-6875(03)00168-7
Aysan, H., Edebali, S., Ozdemir, C., Celi̇k Karakaya, M., Karakaya, N.: Use of chabazite, a naturally abundant zeolite, for the investigation of the adsorption kinetics and mechanism of methylene blue dye. Microporous Mesoporous Mater. 235, 78–86 (2016). https://doi.org/10.1016/j.micromeso.2016.08.007
Bautista, R.G.: Processing to obtain high-purity gallium. Jom. 55, 23–26 (2003). https://doi.org/10.1007/s11837-003-0155-2
Denayer, J.F.M., Devriese, L.I., Couck, S., Martens, J., Singh, R., Webley, P.A., Baron, G. V.: Cage and window effects in the adsorption of n-alkanes on chabazite and SAPO-34. J. Phys. Chem. C. 112, 16593–16599 (2008). https://doi.org/10.1021/jp804349v
Drzazga, M., Palmowski, A., Benke, G., Ciszewski, M., Leszczyńska-Sejda, K.: Recovery of germanium and indium from leaching solution of germanium dross using solvent extraction with TOA, TBP and D2EHPA. Hydrometallurgy. 202, (2021). https://doi.org/10.1016/j.hydromet.2021.105605
Du, J., Zhang, M., Dong, Z., Yang, X., Zhao, L.: Facile fabrication of tannic acid functionalized microcrystalline cellulose for selective recovery of Ga(III) and In(III) from potential leaching solution. Sep. Purif. Technol. 286, 120442 (2022). https://doi.org/10.1016/j.seppur.2022.120442
Dwairi, R. Al, Omar, W., Al-Harahsheh, S.: Kinetic modelling for heavy metal adsorption using jordanian low cost natural zeolite (Fixed bed column study). J. Water Reuse Desalin. 5, 231–238 (2015). https://doi.org/10.2166/wrd.2014.063
Egashira, R., Tanabe, S., Habaki, H.: Adsorption of heavy metals in mine wastewater by Mongolian natural zeolite. Procedia Eng. 42, 49–57 (2012). https://doi.org/10.1016/j.proeng.2012.07.394
European Comission: Critical Raw Materials Resilience: Charting a Path towards greater Security and Sustainability. , Brussels (2020)
Foley, N.K., Jaskula, B.W., Kimball, B.E., Schulte, R.F.: Gallium. Prof. Pap. 48 (2017). https://doi.org/10.3133/pp1802H
Freundlich, H.M.F.: Over the adsorption in solution. J. Phys. Chem. 57, 385–471 (1906)
Gallant, J., Prakash, A., Hogg, L.V.E.W.: Removal of selected radionuclides and metal contaminants by natural zeolites from liquid effluents. In: Curran Associates, I. (ed.) 30th Annual Canadian Nuclear Society Conference and 33rd CNS/CNA Student Conference 2009. pp. 599–610. Canadian Nuclear Society, Calgary (Canada) (2009)
Giles, C.H., MacEwan, T.H., Nakhwa, S.N., Smith, D.: Studies in adsorption. Part XI. A system of classification of solution adsorption isotherms, and its use in diagnosis of adsorption mechanisms and in measurement of specific surface areas of solids. J. Chem. Soc. 846, 3973–3993 (1960). https://doi.org/10.1039/jr9600003973
Göltl, F., Hafner, J.: Alkane adsorption in Na-exchanged chabazite: The influence of dispersion forces. J. Chem. Phys. 134, (2011). https://doi.org/10.1063/1.3549815
Gómez, J.M., Romero, M.D., Fernández, T.M., Díez, E.: Immobilization of β-glucosidase in fixed bed reactor and evaluation of the enzymatic activity. Bioprocess Biosyst. Eng. 35, 1399–1405 (2012). https://doi.org/10.1007/s00449-012-0728-y
Grevtsov, N., Chubenko, E., Bondarenko, V., Gavrilin, I., Dronov, A., Gavrilov, S.: Electrochemical deposition of indium into oxidized and unoxidized porous silicon. Thin Solid Films. 734, 138860 (2021). https://doi.org/10.1016/j.tsf.2021.138860
Hinz, C.: Description of sorption data with isotherm equations. Geoderma. 99, 225–243 (2001). https://doi.org/10.1016/S0016-7061(00)00071-9
Ibrahim, K.M., Khoury, H.N., Tuffaha, R.: Mo and Ni removal from drinking water using zeolitic tuff from Jordan. Minerals. 6, 116 (2016). https://doi.org/10.3390/min6040116
Janin, A., Zaviska, F., Drogui, P., Blais, J.F., Mercier, G.: Selective recovery of metals in leachate from chromated copper arsenate treated wastes using electrochemical technology and chemical precipitation. Hydrometallurgy. 96, 318–326 (2009). https://doi.org/10.1016/j.hydromet.2008.12.002
Kennedy, D.A., Tezel, F.H.: Cation exchange modification of clinoptilolite – Screening analysis for potential equilibrium and kinetic adsorption separations involving methane, nitrogen, and carbon dioxide. Microporous Mesoporous Mater. 262, 235–250 (2018). https://doi.org/10.1016/j.micromeso.2017.11.054
Korkuna, O., Leboda, R., Skubiszewska-Ziȩba, J., Vrublevs’ka, T., Gun’ko, V.M., Ryczkowski, J.: Structural and physicochemical properties of natural zeolites: clinoptilolite and mordenite. Microporous Mesoporous Mater. 87, 243–254 (2006). https://doi.org/10.1016/j.micromeso.2005.08.002
Lahti, J., Vazquez, S., Virolainen, S., Mänttäri, M., Kallioinen, M.: Membrane Filtration Enhanced Hydrometallurgical Recovery Process of Indium from Waste LCD Panels. J. Sustain. Metall. 6, 576–588 (2020). https://doi.org/10.1007/s40831-020-00293-4
Langmuir, I.: THE CONSTITUTION AND FUNDAMENTAL PROPERTIES OF SOLIDS AND LIQUIDS. II. LIQUIDS. 1. J. Am. Chem. Soc. 39, 1848–1906 (1917). https://doi.org/10.1021/ja02254a006
Li, Y., Xi, M., Kong, F., Yu, C.: Experimental study on the removal of arsenic in waste water from semiconductor manufacturing. J. Water Resour. Prot. 1, 48–51 (2009). https://doi.org/10.1109/ICBBE.2008.1025
Liu, J.S., Chen, H., Chen, X.Y., Guo, Z.L., Hu, Y.C., Liu, C.P., Sun, Y.Z.: Extraction and separation of In(III), Ga(III) and Zn(II) from sulfate solution using extraction resin. Hydrometallurgy. 82, 137–143 (2006). https://doi.org/10.1016/j.hydromet.2006.03.008
Lu, F., Xiao, T., Lin, J., Ning, Z., Long, Q., Xiao, L., Huang, F., Wang, W., Xiao, Q., Lan, X., Chen, H.: Resources and extraction of gallium: A review. Hydrometallurgy. 174, 105–115 (2017). https://doi.org/10.1016/j.hydromet.2017.10.010
Mozgawa, W., Król, M., Barczyk, K.: FT-IR studies of zeolites from different structural groups. Chemik. 65, 667–674 (2011)
Mumpton, F.A., Ormsby, W.C.: Morphology of zeolites in sedimentary rocks by scanning electron microscopy. Clays Clay Miner. 24, 1–23 (1976)
Pham, T.D., Hudson, M.R., Brown, C.M., Lobo, R.F.: Molecular basis for the high CO2 adsorption capacity of chabazite zeolites. ChemSusChem. 7, 3031–3038 (2014). https://doi.org/10.1002/cssc.201402555
Rivera-Ramos, M.E., Hernández-Maldonado, A.J.: Adsorption of N2 and CH4 by ion-exchanged silicoaluminophosphate nanoporous sorbents: interaction with monovalent, divalent, and trivalent cations. Ind. Eng. Chem. Res. 46, 4991–5002 (2007). https://doi.org/10.1021/ie061016m
Sáez, P., Rodríguez, A., Gómez, J.M., Paramio, C., Fraile, C., Díez, E.: H-Clinoptilolite as an Efficient and Low-Cost Adsorbent for Batch and Continuous Gallium Removal from Aqueous Solutions. J. Sustain. Metall. (2021). https://doi.org/10.1007/s40831-021-00437-0
Saravanan, A., Senthil Kumar, P., Jeevanantham, S., Karishma, S., Tajsabreen, B., Yaashikaa, P.R., Reshma, B.: Effective water/wastewater treatment methodologies for toxic pollutants removal: Processes and applications towards sustainable development. Chemosphere. 280, 130595 (2021). https://doi.org/10.1016/j.chemosphere.2021.130595
Shang, J., Hanif, A., Li, G., Xiao, G., Liu, J.Z., Xiao, P., Webley, P.A.: Separation of CO2 and CH4 by Pressure Swing Adsorption Using a Molecular Trapdoor Chabazite Adsorbent for Natural Gas Purification. Ind. Eng. Chem. Res. 59, 7857–7865 (2020). https://doi.org/10.1021/acs.iecr.0c00317
Shrestha, R., Ban, S., Devkota, S., Sharma, S., Joshi, R., Tiwari, A.P., Kim, H.Y., Joshi, M.K.: Technological trends in heavy metals removal from industrial wastewater: A review. J. Environ. Chem. Eng. 9, 105688 (2021). https://doi.org/10.1016/j.jece.2021.105688
Singh, R.K., Webley, P.: Adsorption of N2, O2, and Ar in potassium chabazite. Adsorption. 11, 173–177 (2005). https://doi.org/10.1007/s10450-005-5918-3
Sips, R.: On the Structure of a Catalyst Surface. II. J. Chem. Phys. 18, 1024–1026 (1950). https://doi.org/10.1063/1.1747848
Solisio, C., Aliakbarian, B.: Methylene blue adsorption using chabazite: Kinetics and equilibrium modelling. Can. J. Chem. Eng. 95, 1760–1767 (2017). https://doi.org/10.1002/cjce.22838
Song, S.J., Le, M.N., Lee, M.S.: Separation of Gallium(III) and Indium(III) by Solvent Extraction with Ionic Liquids from Hydrochloric Acid Solution. Processes. 8, 1347 (2020). https://doi.org/10.3390/pr8111347
Thommes, M., Kaneko, K., Neimark, A. V., Olivier, J.P., Rodriguez-Reinoso, F., Rouquerol, J., Sing, K.S.W.: Physisorption of gases, with special reference to the evaluation of surface area and pore size distribution (IUPAC Technical Report). Pure Appl. Chem. 87, 1051–1069 (2015). https://doi.org/10.1515/pac-2014-1117
Watson, G.C., Jensen, N.K., Ru, T.E., Chan, K.I., May, E.F.: Volumetric Adsorption Measurements of N2 , CO2 , CH4 , and a CO2 + CH4 Mixture on a Natural Chabazite from (5 to 3000 kPa). 93–101 (2012)
Yakout, S.M., Borai, E.H.: Adsorption behavior of cadmium onto natural chabazite: Batch and column investigations. Desalin. Water Treat. 52, 4212–4222 (2014). https://doi.org/10.1080/19443994.2013.803938
Zhang, J., Singh, R., Webley, P.A.: Alkali and alkaline-earth cation exchanged chabazite zeolites for adsorption based CO2 capture. Microporous Mesoporous Mater. 111, 478–487 (2008). https://doi.org/10.1016/j.micromeso.2007.08.022

No competing interests reported.

Download PDF

Version 1

posted

You are reading this latest preprint version

Competitive gallium and indium adsorption from wastewaters on low cost chabazite

Status:

Version 1

Abstract

Figures

1. Introduction

2. Materials And Methods

2.1. Zeolite source, conditioning, and characterization

2.2. Adsorption experiments.

3. Result And Discussion

3.1. Characterization

3.2. Batch sorption results.

3.2.1. Equilibrium adsorption.

3.2.2. Competitive kinetic.

4. Conclusions

Declarations

References

Additional Declarations

Status:

Version 1