Supporting Information

In-situ Growth of UiO-66-NH2 onto Polyacrylamide-Grafted

Nonwoven Fabric for Highly Efficient Pb(II) Removal

Feng Zhaoa, Caihong Sua, Weixia Yanga, Yong Hana, Xueli Luoa, Chunhua Lia, Wenzhi

Tanga, Tianli Yuea, Zhonghong Lia,b*

a College of Food Science and Engineering, Northwest A&F University, Yangling, Shaanxi

712100, PR China

b Laboratory of Quality & Safety Risk Assessment for Agro-products (Yangling), Ministry of

Agriculture, Yangling, Shaanxi 712100, PR China

Corresponding author. *E-mail: steveli@nwsuaf.edu.cn; lizhhsteve@163.com (Zhonghong Li)

SI Preparation of UiO-66-NH2-PAM-PET.

Activation and modification of PET nonwoven fabric. The PET nonwoven fabric was cut

into 5 cm × 8 cm pieces and was respectively washed with detergent, ethanol and deionized

water for three times, and then dried at 60°C to a constant weight before further use. PET was

surface activated by immersing into NaOH solution (4 mol L -1) at 80°C for 3 h under

continuous stirring, followed by washing in HCl solution (1 mol L -1) until the pH of the

solution was neutral, and was subsequently rinsed with deionized water and dried at 60°C to a

constant weight to obtain activated PET. The activated PAM-PET (hereinafter, PAM-PET) was

synthesized by immersing the activated PET in a 1% PAM solution for 12 h and was dried at

60°C till constant weight.

The weight loss of the PET after NaOH activation was calculated by (Eq. (1)):

p=m0-mm0

×100 % (1)

where p (%) is the hydrolysis degree of the PET after NaOH activation, m0 (g) and m

(g) are weights of original PET and activated PET, respectively.

The degree of grafting of PAM in the PAM-PET was calculated by (Eq. (2)):

p1=m1 -mm1

×100 % (2)

where p (%) is degree of grafting of PAM in the PAM-PET, m1 (g) and m (g) are weights

of the PAM-PET and activated PET, respectively.

Synthesis of UiO-66-NH2-PAM-PET. UiO-66-NH2 was in-situ grown onto PAM-PET via

the solvothermal method. ZrCl4 (0.2332 g, 1.0 mmol) was dissolved in DMF (41 mL) to

obtain solution A. NH2-BDC (0.1812 g, 1.0 mmol) was dissolved in the mixture of DMF (41

mL) and glacial acetic acid (4.6 mL) to obtain solution B. PAM-PET was immersed into

solution A for 1 h to obtain Zr4+-PAM-PET, then solution B was added and mixed thoroughly.

The mixture was transferred to a 100 mL Teflon-lined stainless steel autoclave together with

the fabric that was placed vertically. The UiO-66-NH2 growth was hydrothermally proceeded

at 120°C for 24 h. After being cooled naturally, the obtained UiO-66-NH2-PAM-PET

composite was washed with DMF and methanol for several times, followed by drying at 60°C

to a constant weight for further use. The activated UiO-66-NH2-PET and inactivated UiO-66-

NH2-PAM-PET were acquired by the same method as above, only the PAM-PET substrate was

changed to activated PET and inactivated PAM-PET.

The degree of grafting of UiO-66-NH2 on different substrates was calculated by (Eq.

(3)):

p2=m2 - m1

m2×100 % (3)

where p2 (%) is the degree of grafting of UiO-66-NH2, m2 (g) and m1 (g) are weights of

the UiO-66-NH2-PAM-PET and substrates (including activated PET, inactivated PAM-PET and

PAM-PET), respectively.

SII-1 Characterization

The morphologies of the UiO-66-NH2-PAM-PET composite were observed using S-4800

scanning electron microscope (SEM, Hitachi, Tokyo, Japan). Energy dispersive X-ray

(EDAX) analysis and elemental mapping were examined by using an energy-dispersive X-ray

spectroscope attached to Hitachi S-4800. Powder X-ray diffraction (XRD) spectra were

collected on a D8 Advanced Diffractometer System (Bruker Corp, Germany) from 5 to 40°

with Cu Kα radiation. Fourier transform infrared (FT-IR) spectra were recorded on a Vetex70

FT-IR Spectroscope (Bruker Corp, Germany). X-ray photoelectron spectroscopy (XPS) data

were determined using an Axis Ultra DLD X-ray photoelectron spectrometer equipped with

an Al Ka X-ray source (1486.6 eV). N2 adsorption-desorption measurement were obtained by

Autosorb iQ (Quantachrome Instruments, USA) at 77 K, and all the samples were outgassed

under vacuum at 60°C overnight prior to measurements being taken. The specific surface area

and pore size distribution were calculated by Brunauer-Emmett-Teller (BET) and Density

Functional Theory (DFT). Zeta potentials of UiO-66-NH2 were carried out at different pH on

Malvern ZETASIZER Nano analyzer (Malvern, ZEN3600).

SII-2 Stability tests of PET and PAM-PET in polar solvent (DMF)

The PET and PAM-PET substrates were submerged in DMF (82mL) and then heated at

120°C for 0 h, 4 h, 8 h, 16 h, 24 h, 48 h and 72 h, followed by drying at 60°C to a constant

weight. The change of mass was observed by weighing products before and after soaking. The

products were then characterized using FT-IR and SEM.

SIII Adsorption experiments

SIII-1 Adsorption capacity measurement

The adsorption capacity is calculated as (Eq. (4)):

q t =(C0- Ct )Vmp

(4)

where qt (mg g-1) represents the adsorption capacity of Pb(II). C0 (mg L-1) and Ct (mg L-1)

are the concentration at initial and time t, respectively. V (L) is the volume of the solution, m

(g) is the mass of the UiO-66-NH2-PAM-PET composite, and p (%) is the degree of grafting

of MOF on the UiO-66-NH2-PAM-PET composite.

SIII-2 Adsorption kinetics

Adsorption kinetics, mainly including pseudo-first-order model, pseudo-second-order

model and intra-particle diffusion model, are used to assist understanding the adsorption rate

of Pb(II) by the UiO-66-NH2-PAM-PET composite.

The pseudo-first-order model is used to describe the physisorption behavior between the

adsorbent and adsorbate, which is defined as (Eq. (5)):

ln(qe- qt)=ln qe-k1t (5)

where qe (mg g-1) and qt (mg g-1) represent the adsorption capacity at equilibrium and

time t. t (min) represents the contact time and k1 (min-1) is the constant of the pseudo-first-

order equation.

The pseudo-second-order model is used to describe the chemisorption behavior, which is

defined as (Eq. (6)):

tq t

=1k2 qe

2 +tqe

(6)

where k2 (g mg-1 min-1) is the rate constant of pseudo-second-order model. qe (mg g-1), qt

(mg g-1) and t (min) have the same definition with the pseudo-first-order model.

The intra-particle diffusion model is used to analyze the rate limiting step of the

adsorption process, which is defined as (Eq. (7)):

qt = kit1/2 + Ci (7)

where ki (mg g-1 min-0.5) is the rate constant and Ci (mg g-1) is the intercept of stage i.

SIII-3 Adsorption isotherms

Adsorption isotherms, mainly including Langmuir model Freundlich model and D-R

model, are used to reflect the surface properties of the adsorbent and its affinity for the

adsorbate. The Langmuir model is used to describe that the adsorption sites on the surface of

the adsorbent are homogeneous and the adsorption process is monolayer adsorption. It is

defined as (Eq. (8)):

qe =qmax KLCe

1+ KLCe

(8)

where qe (mg g-1) and qmax (mg g-1) are the equalized and theoretical maximum adsorption

capacity. Ce (mg L-1) represents concentration of Pb(II) in aqueous solution at equilibrium, KL

(L mg-1) is a Langmuir constant concerning adsorption energy of the binding sites.

The Freundlich model is applied to depict that the adsorption sites on the surface of the

adsorbent are inhomogeneous and the adsorption process is multilayer adsorption. It is

defined as (Eq. (9)):

qe=KFCe1/n (9)

where n and KF represent Freundlich constants associated with adsorption intensity and

adsorption capacity. Ce (mg L-1) and qe (mg g-1) have the same definition with the Langmuir

model.

The D-R model is an empirical model, which is generally used to describe the adsorption

mechanism of a Gaussian energy distribution on heterogeneous surface. It is defined as (Eq.

(10)):

qe=qmaxexp(-kε2)

ε=RTln(1+1Ce

) (10)

where R (8.3145 J mol-1 K-1) represents the ideal gas constant and T (K) represents

absolute temperature. qe (mg g-1), qmax (mg g-1) and Ce (mg L-1) have the same meaning with

the Langmuir model.

SIII-3 Adsorption thermodynamics

To investigate the influence of the adsorption temperature on the adsorption progress of

Pb(II) by the UiO-66-NH2-PAM-PET composite, the adsorption performances at 298 K, 308

K and 318 K are studied. The thermodynamic parameters including standard Gibbs free

energy change (ΔG0), standard enthalpy change (ΔH0), and standard entropy change (ΔS0) can

be calculated as (Eq. (10-12)):

KC =qe

Ce

(11)

ln KC = ∆S0

R- ∆H0

RT (12)

∆ G0 =∆H0-T ∆S0 (13)

where qe and Ce have the same definition with adsorption isotherms. T (K) is the temperature

during adsorption. R (8.3145 J mol-1 K-1) and Kc are the ideal gas constant and

thermodynamic equilibrium constant.

Fig. S1 The degree of grafting of UiO-66-NH2 on activated PET, inactivated PAM-PET and PAM-

PET.

Fig. S2 The optical photographs of (a) PET, (b) activated PET, (c) PAM-PET, (d) UiO-66-NH2-PAM-PET, (e) activated UiO-66-NH2-PET and (f) inactivated UiO-66-NH2-PAM-PET.

Fig. S3 (a) The EDAX element composition analysis of UiO-66-NH2-PAM-PET, (b) EDAX elemental images of UiO-66-NH2-PAM-PET with corresponding elemental mapping images of C,

O, N and Zr, respectively.

Fig. S4 XPS spectra of PAM-PET, Zr4+-PAM-PET and UiO-66-NH2-PAM-PET.

Fig. S5 Pore size distribution of UiO-66-NH2 (a) and UiO-66-NH2-PAM-PET (b).

Table S1 The Porous properties of UiO-66-NH2 and UiO-66-NH2-PAM-PET

Adsorbents BET (m2 g-1) Pore volume (cm3 g-1) Average pore diameter (nm)UiO-66-NH2 313.433 0.6978 8.90518

UiO-66-NH2-PAM-PET 13.026 0.0052 8.03159

Fig. S6 FT-IR spectra (a) and mass change (b) of PET and PAM-PET after submerging in DMF.

Fig. S7 SEM images of PET (a) and PAM-PET (b) after submerging in DMF at 120°C for 24 h.

Fig. S8 Comparison of removal capacity of Pb(II) about different prepared materials.

Table S2 Kinetic parameters for the adsorption of Pb(II)

Pseudo-first order Pseudo-second order Intra-particle diffusionqe

(mg·g-1)k1

(min-1)R2 qe

(mg·g-1)k2*10-4

( g·mg-1·min-1)R2 Ci

(mg·g-1)ki R2

524.641±13.719

0.016±0.001

0.980648.890±

21.8050.242±0.030 0.985

31.021±3.021

35.831±32.385

0.897

Table S3 Adsorption isotherm model fitting parameters for Pb(II) adsorption

T(K)Langmuir Freundlich D-R

qm(mg·g-1) KL(L·mg-1) R2 KF(mg·g-1) n R2 qm(mg·g-1) k*10-4 R2

Pb(II)

298635.79±36.

550.010±0.00

10.970

39.85±7.24

2.347±0.205

0.937488.83±28.

304.212±0.4

330.926

308645.91±57.

490.014±0.00

30.936

43.22±12.93

2.301±0.304

0.912504.00±64.

421.658±0.6

410.676

318711.99±14.

170.020±0.00

30.993

57.87±10.35

2.425±0.187

0.989611.03±11.

950.756±0.2

640.909

Table S4 The maximum adsorption capacities of Pb(II) on different adsorbents.

Table S5 The thermodynamic parameters for the adsorption of Pb(II)

Adsorbent T(K) △G0(kJ·mol-1) △H0(kJ·mol-1) △S0(kJ·mol-1·K-1)

UiO-66-NH2-PAM-PET298 -1512.95

394.74 6.40308 -1576.96318 -1640.98

Fig. S9 Pb 4f XPS spectra of UiO-66-NH2-PAM-PET after Pb(II) adsorption.

Adsorbents Adsorption capacity (mg g-1) referencesFe3O4/MIL-96(Al) 301.5 [1]COF-TE 185.7 [2]MOF-545 73 [3]M-NMOFs 293.52 [4]MOF 808 NMOM 170.74 [5]MoS2-N-H 303.04 [6]ZnO-ZnFe2O4-C 344.83 [7]UiO-66-NH2-PAM-PET 711.99 This work

Fig. S10 The degree of grafting of UiO-66-NH2 on PAM-PET during recycling.

Fig. S11 FT-IR spectra of UiO-66-NH2-PAM-PET after sixth cycle.

Fig. S12 SEM image of UiO-66-NH2-PAM-PET after the sixth cycle.

References

[1] A. Mehdinia, D. Jahedi Vaighan, A. Jabbari, Cation Exchange Superparamagnetic Al-

Based Metal Organic Framework (Fe3O4/MIL-96(Al)) for High Efficient Removal of

Pb(II) from Aqueous Solutions, ACS Sustain. Chem. Eng., 6 (2018) 3176-3186.

[2] G. Li, J. Ye, Q. Fang, F. Liu, Amide-based covalent organic frameworks materials for

efficient and recyclable removal of heavy metal lead (II), Chem. Eng. J., 370 (2019) 822-

830.

[3] S. Tokalioglu, E. Yavuz, S. Demir, S. Patat, Zirconium-based highly porous metal-organic

framework (MOF-545) as an efficient adsorbent for vortex assisted-solid phase

extraction of lead from cereal, beverage and water samples, Food Chem., 237 (2017)

707-715.

[4] M. Chen, N. Gan, Y. Zhou, T. Li, Q. Xu, Y. Cao, Y. Chen, A novel aptamer-metal ions-

nanoscale MOF based electrochemical biocodes for multiple antibiotics detection and

signal amplification, Sensor. Actuat. B-Chem., 242 (2017) 1201-1209.

[5] J.E. Efome, D. Rana, T. Matsuura, C.Q. Lan, Metal-organic frameworks supported on

nanofibers to remove heavy metals, J. Mater. Chem. A., 6 (2018) 4550-4555.

[6] N. Kumar, E. Fosso-Kankeu, S.S. Ray, Achieving Controllable MoS2 Nanostructures with

Increased Interlayer Spacing for Efficient Removal of Pb(II) from Aquatic Systems, ACS

Appl. Mater. Inter., 11 (2019) 19141-19155.

[7] D. Chen, W. Shen, S. Wu, C. Chen, X. Luo, L. Guo, Ion exchange induced removal of

Pb(II) by MOF-derived magnetic inorganic sorbents, Nanoscale, 8 (2016) 7172-7179.