Carbon Aerogels Prepared Based on Sol-Gel Reaction of Cellulose Colloid with AEP and Its Adsorption of Copper Ions in Aqueous Solution

doi:10.15541/jim20170053

Abstract

Abstract:

A novel cellulose-based carbon aerogel with well-developed porous structure and surface group of hydroxyl was synthesized from cellulose aerogel by means of Sol-Gel reaction, freeze-drying and carbonization. In this preparation, cellulose was taken as carbon precursor and phosphate of polyoxyethylene isooctyl ether (AEP) was chosen as structure inducer of micelle in cellulose colloid. Thermal decomposition of the prepared cellulose aerogel was studied by TG technique; the properties of the prepared carbon aerogel, such as porous structure and function groups were characterized with SEM, N₂ adsorption-desorption isotherms and Fourier-transform infrared spectroscopy (FT-IR). Adsorption of copper ion onto the test samples in aqueous solution was investigated through a static adsorption method. Results show that AEP can obviously regulate the porous structure and improve the adsorption performance of the prepared samples. The optimal sample of the prepared carbon aerogel possesses predominant pore structure of three-dimensional network, with a surface area of 655.4 m²/g and total pore volume of 0.73 cm³/g. The maximum copper ion adsorption capacity reached 86.27 mg/g in aqueous solution. In adsorption process, it is also found that the kinetics nicely follows pseudo-second-order rate expression, while the isotherm fits Langmuir model, displaying good adsorption properties. Therefore, the prepared carbon aerogel may have potential application in treatment of metal ion pollution in water. Meanwhile, the preparation strategies in this study provides a novel pathway for preparing carbon adsorbent with specific pore structure and functional groups on the surface.

Key words: cellulose, Sol-Gel, carbon aerogel, surfactant, copper ion

CLC Number:

TQ174

ZHENG Lei, LI Jin, LIU Hong-Bo. Carbon Aerogels Prepared Based on Sol-Gel Reaction of Cellulose Colloid with AEP and Its Adsorption of Copper Ions in Aqueous Solution[J]. Journal of Inorganic Materials, 2017, 32(11): 1159-1164.

Figures/Tables 9

Fig. 1 TGA curves of CAx (a) and FTIR spectrum of CCAx (b)

Fig. 2 SEM images of CCAx prepared from different ratios (w/v) of AEP in Sol-Gel reaction (a) 0; (b) 2%; (c) 4%; (d) 6%

Fig. 3 Nitrogen adsorption isotherms (a) and the pore size distribution curve (b) of samples

Table 1 Analysis of the physical properties of samples after carbonization

Sample	S_BET/(m²·g^-1)	V_tot/(cm³·g^-1)	V_mic/(cm³·g^-1)	V_mes/(cm³·g^-1)	D_a*/nm
CCA₀	476.9	0.2580	0.1777	0.0803	2.16
CCA₂	655.4	0.7324	0.3137	0.4187	4.87
CCA₄	523.5	0.5106	0.1740	0.3366	3.94
CCA₆	401.2	0.4875	0.1654	0.3221	3.21
AC	2729.8	1.8130	1.7672	0.0458	2.65

Fig. 4 Adsorption isotherm of Cu2+ on CCAx and AC

Fig. 5 Langmuir and Freundlich isotherms for adsorption of Cu2+ onto the CCA2

Fig. 6 Effect of contact time on adsorption of Cu2+ onto CCA2 at different temperatures

Fig. 7 Pseudo-first-order model (a) and pseudo-second- order model (b) for the adsorption of Cu2+ onto the CCA2

Table 2 Constants of pseudo-first-order and pseudo-second-order models

Temp./K	Q_e,exp/(mg•g)^-1	Pseudo-first order			Pseudo-second order
Temp./K	Q_e,exp/(mg•g)^-1	k₁/min^-1	Q_e,cal/(mg•g)^-1	R²	k₂/(g•mg^-1•min^-1)	Q_e,cal/(mg•g)^-1	R²
298	86.27	0.0552	69.57	0.8758	0.00333	90.91	0.9998
308	61.34	0.0675	42.57	0.7534	0.00302	65.24	0.9998
318	30.02	0.0984	40.12	0.7018	0.00319	32.25	0.9996

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