Preparation of polyvinyl alcohol-graphene aerogel by emulsion method and its adsorption on pure organics

doi:10.11949/j.issn.0438-1157.20180995

Abstract

Abstract:

A polyvinyl alcohol-graphene aerogel was prepared by using a graphene oxide (GO)-stabilized Pickering emulsion as a soft template. The effects of GO concentration, homogenization speed, oil/water ratio, the amount of ethylenediamine (EDA) and polyvinyl alcohol (PVA) on the stability, particle size distribution of the emulsion and the formation of aerogel were investigated. It was found that the drop size of the emulsion could be controlled by changing the emulsion composition ratio. Then, the density and porosity of the aerogel also could be controlled. The polyvinyl alcohol-graphene aerogel (PGA) prepared under optimal preparation conditions was characterized by SEM, FT-IR, Raman and XRD. It was found that GO had been reduced and assembled to form a three-dimensional network structure (PGA) after the hydrothermal reaction and the pore size of the PGA was substantially the same as the particle size of the emulsion. The extrusion test of PGA was carried out and it was observed that PGA had both longitudinal and lateral bidirectional extrusion resilience. And the PGA still had good elasticity after more than 200 times repeated extrusion. The adsorption amount of pure organics by PGA was up to 280 g·g^?1, and the volume of organics adsorbed per gram of PGA was constant value.

Key words: polyvinyl alcohol, graphene, aerogel, emulsions, elasticity, composites

摘要：

采用氧化石墨烯(GO)稳定的Pickering乳液为软模板，制备聚乙烯醇-石墨烯气凝胶。探究GO浓度、均质转速、油水比、乙二胺(EDA)和聚乙烯醇(PVA)用量等因素对乳液稳定性、粒径分布及气凝胶成型的影响，发现改变乳液配比可控制乳液粒径的大小，进而对气凝胶的密度和孔隙率进行调控。通过SEM、FT-IR、Raman、XRD对最优制备条件下制得的聚乙烯醇-石墨烯气凝胶(PGA)进行表征，可知GO经水热反应后被还原组装形成三维网络气凝胶结构(PGA)且其孔道直径与乳液粒径基本一致。对PGA进行挤压实验发现其具有轴、径双向挤压回弹性，且重复挤压200次以上PGA仍然具良好的弹性。PGA对纯有机物的吸附量最高可达280 g·g^?1，且每克PGA吸附的有机物的体积为恒定值。

关键词: 聚乙烯醇, 石墨烯, 气凝胶, 乳液, 弹性, 复合材料

CLC Number:

TQ 013.2

Zhenyou WANG, Hui’e LIU, Jiameng ZHU, Shuang CHEN, Anran YU. Preparation of polyvinyl alcohol-graphene aerogel by emulsion method and its adsorption on pure organics[J]. CIESC Journal, 2019, 70(3): 1152-1162.

王振有, 刘会娥, 朱佳梦, 陈爽, 于安然. 乳液法制备聚乙烯醇-石墨烯气凝胶及其对纯有机物的吸附[J]. 化工学报, 2019, 70(3): 1152-1162.

Figures/Tables 22

Table 1 Aerogel preparation conditions

Sample	C_GO/ (mg·ml^?1)	R/ (r·min^?1)	Oil/water ratio	V_EDA∶V_GO/%	V_PVA∶V_GO/%
1	10	16000	5∶3	2	25
2	8	16000	5∶3	2	25
3	6	16000	5∶3	2	25
4	4	16000	5∶3	2	25
5	10	12000	5∶3	2	25
6	10	10000	5∶3	2	25
7	10	16000	1∶3	2	25
8	10	16000	2∶3	2	25
9	10	16000	3∶3	2	25
10	10	16000	4∶3	2	25
11	10	16000	6∶3	2	25
12	10	16000	7∶3	2	25
13	10	16000	8∶3	2	25
14	10	16000	9∶3	2	25
15	10	16000	5∶3	1	25
16	10	16000	5∶3	3	25
17	10	16000	5∶3	4	25
18	10	16000	5∶3	2	15
19	10	16000	5∶3	2	35

Fig.1 Optical micrographs of Pickering emulsion with varied GO concentrations

Fig.2 Droplet size distribution of Pickering emulsions with varied GO concentrations

Fig.3 Photographs of Pickering emulsion with varied GO concentrations after 24 h

Fig.4 Relationship between average droplet size of emulsions and aerogel density with varied GO concentrations

Fig.5 Photographs of aerogels prepared with varied GO concentrations

Fig.6 Relationship between average droplet size of emulsions and aerogel density with varied stirring speeds

Fig.7 Photographs of aerogels prepared with varied stirring speeds

Fig.8 Relationship between average droplet size of emulsions and aerogel density with varied oil/water ratio

Table 2 Average droplet size of emulsions, density and porosity of aerogel with different oil/water ratios

Oil/water ratio	d/μm	ρ/(mg·cm^?3)	η/%
1∶3	20.81	9.609	99.56
2∶3	24.66	7.279	99.67
3∶3	26.81	5.94	99.73
4∶3	27.45	5.243	99.76
5∶3	28.64	4.565	99.79
6∶3	30.72	4.195	99.81
7∶3	37.21	5.421	99.75
8∶3	38.94	5.313	99.76
9∶3	41.83	5.358	99.76

Fig.9 Relationship between average droplet size of emulsions and aerogel density with varied EDA dosage

Fig.10 Photographs of aerogels prepared with varied EDA dosages

Fig.11 Relationship between average droplet size of emulsions and aerogel density with varied PVA dosages

Fig.12 Photographs of aerogels prepared with varied PVA dosages

Fig.13 Raman (a) and FT-IR spectra (b) of GO and PGA

Fig.14 SEM images of PGA

Fig.15 XRD patterns of GO and PGA

Fig.16 Extrusion-resilience test of PGA

Fig.17 Strain-stress curves of PGA

Table 3 Adsorption data of PGA on different organic solvents

Organic solvent	ρ_o^①/(g·ml^?1)	q/(g·g^?1)
n-heptane	0.683	126.778
diesel	0.838	137.018.
DMF	0.945	148.259
methyl benzoate	1.09	150.096
dichloromethane	1.33	230.062
carbon tetrachloride	1.592	268.667

Fig.18 Relationship between organic matter density and adsorption amount

Table 4 Results of q-ρo linear fitting

Slope	Intercept	R²/%
167.96	0	99.81

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