Poly(dimethylsiloxane) and Poly[vinyltrimethoxysilane<i>-co-</i>2-(dimethylamino)ethyl methacrylate] Based Cross-Linked Organic-Inorganic Hybrid Adsorbent for Copper(II) Removal from Aqueous Solutions

Silva, Fábio A. B.; Chagas-Silva, Fátima A.; Florenzano, Fábio H.; Pissetti, Fábio L.

doi:10.5935/0103-5053.20160110

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Articles • J. Braz. Chem. Soc. 27 (12) • Dec 2016 • https://doi.org/10.5935/0103-5053.20160110 copy

Poly(dimethylsiloxane) and Poly[vinyltrimethoxysilane-co-2-(dimethylamino)ethyl methacrylate] Based Cross-Linked Organic-Inorganic Hybrid Adsorbent for Copper(II) Removal from Aqueous Solutions

Authorship SCIMAGO INSTITUTIONS RANKINGS

An organic-inorganic hybrid adsorbent was prepared and its application for the uptake of Cu^II ions from aqueous solutions was studied. The polymer network was composed of poly(dimethylsiloxane) (PDMS), vinyltrimethoxysilane (VTMS), and 2-(dimethylamino)ethyl methacrylate (DMAEMA), described as PDMS-net-P(VTMS-co-DMAEMA). The chemical groups, thermal stability and morphology of this hybrid adsorbent were characterized using techniques of attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). In adsorption studies, saturation of the active sites of the material was observed at pH 5, after 3 days, with each gram of material capable of adsorbing 0.48 mmol of copper(II). The fractionary-order and Sips models provided the best fits to the experimental data in kinetic and equilibrium studies of the adsorption process, respectively. Moreover, an acceptable reusability was found for this cross-linked organic-inorganic hybrid adsorbent after usage-regeneration cycles without significantly losing its original activity.

Keywords:
poly(dimethylsiloxane); 2-(dimethylamino)ethyl methacrylate; polymer network; heavy metal ions removal; adsorption-desorption cycles

Kinetic model	Equation	Parameter	Data
Pseudo-ﬁrst order	$q_{t} = q_{e} [1 - \exp (- k_{1} t)]$	q_e / (mmol g^-1) k₁ / h^-1 R² F_error F_exp F_crit	0.499 0.758 0.9819 0.0228 0.0181 2.54
Pseudo-second order	$q_{t} = \frac{k_{2} q_{e}^{2} t}{1 + k_{2} q_{e} t}$	q_e / (mmol g^-1) k₂ / (g mmol^-1 h^-1) R² F_error F_exp F_crit	0.667 0.979 0.9666 0.0307 0.0334 2.54
Chemisorption (Elovich)	$q_{t} = \frac{1}{β} L n (α β) + \frac{1}{β} L n (t)$	α / (mmol g^-1 h^-1) β / (g mmol^-1) R² F_error F_exp F_crit	0.816 6.13 0.9702 0.0290 0.0298 2.54
Fractionary order (Avrami)	$q_{t} = q_{e} {1 - \exp [- (k_{A V} t)]^{n_{A V}}}$	q_e / (mmol g^-1) k_AV / h^-1 n_AV R² F_error F_exp F_crit	0.465 0.872 1.40 0.9983 0.00614 0.00134 2.71
Intraparticle diffusion	$q_{t} = k_{i d} \sqrt{t} + C$	k_id / (mmol g^-1 h^-0.5)	0.403^a a Second stage. qt: Amount of metal ions adsorbed at time t; qe: amount of adsorbed metal at equilibrium per gram material; t: time of contact; k1: pseudoﬁrst order rate constant; k2: pseudo-second order rate constant; α: initial adsorption rate of Elovich equation; β: Elovich constant related to the extent of surface coverage and also to the activation energy involved in chemisorption; kAV: Avrami kinetic constant; nAV: fractionary reaction order (Avrami) related to adsorption mechanism; kid: intraparticle diffusion rate constant.

Isotherm model	Equation	Parameter	Data
Langmuir	$q_{e} = \frac{q_{s} K_{L} C_{e}}{1 + K_{L} C_{e}}$	q_s / (mmol g^-1) K_L / (mmol L^-1) R² F_error F_exp F_crit	1.38 0.165 0.9318 0.0565 0.111 2.93
Freundlich	$q_{e} = K_{F} C_{e}^{1 / n_{F}}$	K_F / (mmol g^-1) (mmol L^-1)n n_F R² F_error F_exp F_crit	0.190 1.25 0.9064 0.0648 0.146 2.93
Sips	$q_{e} = \frac{q_{s} K_{S} C_{e}^{1 / n_{s}}}{1 + K_{s} C_{e}^{1 / n_{s}}}$	q_s / (mmol g^-1) K_s / (mmol L^-1) n_S R² F_error F_exp F_crit	0.522 0.458 0.386 0.9982 0.0302 0.0318 3.23
Redlich-Peterson	$q_{e} = \frac{K_{R} C_{e}}{1 + a_{R} C_{e}^{g}}$	K_R / (g L^-1) a_R / (mmol L^-1) g R² F_error F_exp F_crit	0.228 0.164 1.00 0.9221 0.0605 0.127 3.23

Material	q_max / (mmol g^-1)	Reference
PDMAEMA grafted regenerated cellulose	5.25	¹1 Jiang, M.; Wang, J.; Li, L.; Pan, K.; Cao, B.; RSC Adv. 2013, 3, 20625.
PDMAEMA hydrogel	5.06	⁴4 Kavakh, P. A.; Yilmaz, Z.; Sen, M.; Sep. Sci. Technol. (Philadelphia, U. S.) 2007, 42, 1245.
PDMAEMA grafted starch	2.12	³²32 Zhang, L. M.; Chen, D. Q.; Colloids Surf., A 2002, 205, 231.
PDMAEMA functionalized activated carbon	0.49	³³33 Zhu, S.; Yang, N.; Zhang, D.; Mater. Chem. Phys. 2009, 113, 784.
PDMAEMA/SiO2 particles	0.35	³⁴34 Gao, B.; Chen, Y.; Zhang, Z.; Appl. Surf. Sci. 2010, 257, 254.
PDMAEMA-cotton copolymer	0.098	³⁵35 Waly, A.; Abdel-Mohdy, F. A.; Aly, A. S.; Hebeish, A.; J. Appl. Polym. Sci. 1998, 68, 2151.
PDMAEMA gel	0.0063	³⁶36 Tokuyama, H.; Ishihara, N.; React. Funct. Polym. 2010, 70, 610.
PVD	0.48	this work

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[1] *e-mail: fabio.pissetti@unifal-mg.edu.br, flpissetti@gmail.com