Data on the fluoride adsorption from aqueous solutions by metal-organic frameworks (ZIF-8 and Uio-66).

The variables examined were initial fluoride concentration, ZIF-8 and Uio-66 dosage, pH, and contact time. The residual concentration of fluoride was measured by a spectrophotometer. According to BET, the specific surface area of the ZIF-8 and Uio-66 was 1050 m2/g and 800 m2/g, respectively. Total pore volume and average pore diameter of the ZIF-8 and Uio-66 were 0.57 cm3/g, 0.45 cm3/g and 4.5 nm, 3.2 nm, respectively. The best pH for fluoride adsorption was neutral conditions. By increasing the ZIF-8 and Uio-66 dose, the fluoride uptake increased at first, but then decreased. Also, the maximum adsorption for ZIF-8 and Uio-66 was observed in adsorbent dose 0.2 and 0.6 g/L, respectively. The best model for describing kinetic and isotherms of fluoride adsorption were the pseudo-second-order model and Langmuir isotherm model, respectively. Based on the Langmuir model, the adsorption capacity of fluoride by ZIF-8 and Uio-66 was reported to be 25 mg/g and 20 mg/g, respectively.

Specifications table

Value of the data

The dataset will be useful for the application of the metal-organic framework in the fluoride adsorption from aqueous solutions.

The data of this project can be used to improve drinking water quality by the authorities.

Information from this data, including, kinetic and isotherm constants, will be informative for predicting and modelling the adsorption capacity and mechanism of fluoride uptake by ZIF-8 and Uio-66.

The characterization data of the ZIF-8 and Uio-66 are useful for the scientific community to complete the studies for emerging absorbers.

Data

The XRD and SEM results of synthesized ZIF-8 and Uio-66 are shown in Fig. 1. All adsorption experiments were performed in triplicate. Results of BET present in Table 1. The effects of an adsorbent dose of ZIF-8 and Uio-66 on fluoride adsorption are presented in Fig. 2. The effects of solution pH of ZIF-8 and Uio-66 on fluoride adsorption are depicted in Fig. 3. The effects of the initial concentration of ZIF-8 and Uio-66 on fluoride adsorption are shown in Fig. 4. Calculated parameters of kinetic models for the fluoride adsorption onto ZIF-8 and Uio-66 are summarized in Table 2. As illustrated in Table 2, the pseudo-second-order model for ZIF-8 and Uio-66 has the highest R2 (coefficient of determination). As a result, the model was the most suitable model to express the kinetics of the fluoride adsorption onto ZIF-8 and Uio-66. Calculated parameters of isotherm models for the fluoride adsorption onto ZIF-8 and Uio-66 are given in Table 3. As illustrated in Table 3, the Langmuir isotherm model for ZIF-8 and Uio-66 has the highest R2. As a result, the model was the most suitable model to express the isotherm of the fluoride adsorption onto ZIF-8 and Uio-66.

Fig. 1

Results of XRD and SEM of synthesized ZIF-8 and Uio-66.

Table 1

Results of BET for synthesized ZIF-8 and Uio-66.

Adsorbent	SABET(m2g−1)	SALangmuir(m2 g−1)	Total pore volume (m3g−1)	Mean pore diameter (nm)
ZIF-8	1050	1150	0.57	4.5
Uio-66	800	970	0.45	3.2

Fig. 2

The effect of adsorbent dose of ZIF-8 and Uio-66 on fluoride adsorption.

Fig. 3

The effect of solution pH of ZIF-8 and Uio-66 on fluoride adsorption.

Fig. 4

The effect of initial concentration of ZIF-8 and Uio-66 on fluoride adsorption.

Table 2

Calculated parameters of kinetic models for the fluoride adsorption onto ZIF-8 and Uio-66.

Kinetics (ZIF-8)	Constants	F concentration (mg l−1)		kinetics (Uio-66)	Constants	F concentration (mg l−1)
		2	4			2	4
Pseudo-First-Order	k1	0.0156	0.0167	Pseudo-First-Order	k1	0.0187	0.0196
	R2	0.745	0.667		R2	0.765	0.798
	qcal	5.678	12.674		qcal	6.576	14.243
Pseudo-Second-Order	k2	0.0443	0.0465	Pseudo-Second-Order	k2	0.0456	0.0645
	R2	0.895	0.834		R2	0.886	0.978
	qe(cal)	12.6	17.5		qe(cal)	13	15.7

Table 3

Calculated parameters of isotherm models for the fluoride adsorption onto ZIF-8 and Uio-66.

Isotherm (ZIF-8)	Constants	F concentration (mg l−1)		Isotherm (Uio-66)	Constants	F concentration (mg l−1)
		2	4			2	4
Freundlich	n	3.5	5.3	Freundlich	n	2.7	3.6
	R2	0.775	0.845		R2	0.675	0.778
	KF	18.5	18.9		KF	19	19.8
Langmuir	KL	1.5	1.8	Langmuir	KL	0.576	0.657
	R2	0.897	0.898		R2	0.879	0.898
	qm	25	29		qm	20	28

Experimental design, materials, and methods

Materials

Chemicals used were zinc nitrate hexahydrate, methanol, N, N-dimethylformamide, zirconium chloride, 2-methylimidazole, and terephthalic acid. All the above-mentioned materials are prepared with high purity. The Materials were purchased from MERK and Sigma-Aldrich companies.

Synthesis of ZIF-8 and Uio-66

ZIF-8 was first synthesized. This adsorbent was synthesized based on the procedure presented by two previous works [1], [2]. In the second step, the absorbent of Uio-66 was synthesized. For the synthesis of this absorbent, previous studies were used [3], [4]. After synthesizing adsorbents, the general characterization of the adsorbent was determined based on XRD, SEM, and BET.

The adsorption experiments

Fluoride adsorption was investigated by the metal-organic frameworks of ZIF-8 and Uio-66. The experiments were performed in batch conditions. The main variables examined were initial concentration of fluoride, ZIF-8 and Uio-66 dosage, solution pH, and contact time. At first, a stock solution of fluoride (NaF, 1000 mg/l) was made and stored under standard conditions. An adsorbent of ZIF-8 and Uio-66 was added to 50 ml of fluoride solution. The solution pH was adjusted using NaOH [0.1 N] and H2SO4 [0.1 N]. At the end, the used adsorbents were separated using a centrifuge (3000 rpm, 5 min). After separation, the final concentration of fluoride was measured by a spectrophotometer DR-5000 (UV-UVIS, 570 nm) [5], [6], [7], [8]. Finally, fluoride adsorbed (q, mg/g) and the removal efficiency (%) on the ZIF-8 and Uio-66 was computed based on Eqs. (1), (2), respectively [9], [10]:where, C and C, and C are an initial, equilibrium, and final concentration, respectively. V and m are the volume of solution and the adsorbent weight, respectively [11], [12], [13], [14], [15], [16], [17], [18], [19], [20], [21], [22], [23].

Subject area	Water treatment
More specific subject area	Adsorption
Type of data	Figures and tables
How data was acquired	Spectrophotometer (UV-UVIS, 570 nm)
Data format	Analyzed
Experimental factors	The main variables examined were initial concentration of fluoride, ZIF-8 and Uio-66 dosage, pH, and contact time. At first, a stock solution of fluoride (NaF, 1000 mg/l) was made and stored under standard conditions. At the end of the experiments, the remaining adsorbents were separated using a centrifuge (3000 rpm, 5 min). After separation, the residual fluoride was measured by a spectrophotometer DR-5000.
Experimental features	ZIF-8 was first synthesized. In the second step, the absorbent of Uio-66 was synthesized. After synthesizing adsorbents, the general characterization of the adsorbent was determined based on XRD, SEM, and BET.
Data source location	Khorramabad, Lorestan University of Medical Sciences, Iran
Data accessibility	Data are included in this article
Related research article	A.A. Mohammadi, A. Alinejad, B. Kamarehie, S. Javan, A. Ghaderpoury, M. Ahmadpour, M. Ghaderpoori. Metal organic framework Uio-66 for adsorption of methylene blue dye from aqueous solutions. Int J Environ Sci Te. 14 (2017) 1959–1968.