Enhanced adsorption of steroid estrogens by one-pot synthesized phenyl-modified mesoporous silica: Dependence on phenyl-organosilane precursors and pH condition

Pei Gao; Zhijie Liang; Zhiwei Zhao; Wenhao Wang; Chun Yang; Bibo Hu; Fuyi Cui

doi:10.1016/j.chemosphere.2019.06.089

Enhanced adsorption of steroid estrogens by one-pot synthesized phenyl-modified mesoporous silica: Dependence on phenyl-organosilane precursors and pH condition

Chemosphere. 2019 Nov:234:438-449. doi: 10.1016/j.chemosphere.2019.06.089. Epub 2019 Jun 14.

Authors

Pei Gao¹, Zhijie Liang¹, Zhiwei Zhao¹, Wenhao Wang¹, Chun Yang², Bibo Hu³, Fuyi Cui¹

Affiliations

¹ Key Laboratory of the Three Gorges Reservoir Region's Eco-Environment, Ministry of Education, Chongqing University, Chongqing, 400045, PR China.
² Key Laboratory of the Three Gorges Reservoir Region's Eco-Environment, Ministry of Education, Chongqing University, Chongqing, 400045, PR China. Electronic address: c.yang@cqu.edu.cn.
³ Key Laboratory of the Three Gorges Reservoir Region's Eco-Environment, Ministry of Education, Chongqing University, Chongqing, 400045, PR China. Electronic address: b.hu@cqu.edu.cn.

PMID: 31228846
DOI: 10.1016/j.chemosphere.2019.06.089

Abstract

In this study, the phenyl-modified mesoporous materials were successfully synthesized using phenyl-organosilanes (trimethoxyphenylsilane and triethoxyphenylsilanea) by one-pot co-condensation method for the removal of estrone (E1), 17β-estradiol (E2), and 17α-ethinyl estradiol (EE2). Both the triethoxyphenylsilane-modified material (20%EtPh-MCM-41) and trimethoxyphenylsilane-modified material (20%MePh-MCM-41) could rapidly achieve equilibrium in 30 min at low adsorbent dosage of 0.025 g L^-1. But the different hydrolysable groups of trimethoxyphenylsilane and triethoxyphenylsilane led to the discrepancies in physicochemical properties of the 20%EtPh-MCM-41 and 20%MePh-MCM-41, and thus affected adsorption performance. The 20%EtPh-MCM-41 exhibited the faster estrogen adsorption rates expressed in pseudo-second-order kinetic constant than the 20%MePh-MCM-41 due to the more hydrophobicity. Conversely, the 20%MePh-MCM-41 had much more estrogen adsorption capacities than the 20%EtPh-MCM-41 because of the more available adsorption sites. The addition of the phenyl-organosilane improved estrogen adsorption by π-π and hydrophobic interactions, and the Langmuir-model-based maximum adsorption amounts could reach 99.02, 83.47, and 53.60 mg g^-1 for EE2, E2, and E1, respectively. But excessive concentration of phenyl-organosilane decreased adsorption capacities due to poor pore structure. Alkaline solution, which induced estrogen deprotonation and negative surface charge of absorbents, inhibited estrogen adsorption by electrostatic repulsion and the decreased hydrophobic interaction, but acidic and neutral solutions, ionic strength, and humic acid did not significantly affect estrogen removal. This work not only showed the high potential of trimethoxyphenylsilane-modified MCM-41 used in water purification for steroid estrogens, but also demonstrated the suitable selection of organosilane precursors was key in producing favorable materials with designed functionality.

Keywords: Adsorption; Mesoporous silica; Organic functionalization; Phenyl-organosilane precursors; Solution chemistry; Steroid estrogens.

MeSH terms

Adsorption
Estradiol / analysis
Estradiol / isolation & purification
Estrogens / isolation & purification*
Estrone / analysis
Estrone / isolation & purification
Ethinyl Estradiol / analysis
Ethinyl Estradiol / isolation & purification
Hydrogen-Ion Concentration
Hydrophobic and Hydrophilic Interactions
Kinetics
Osmolar Concentration
Silicon Dioxide / chemistry*
Water Pollutants, Chemical / analysis
Water Pollutants, Chemical / isolation & purification*
Water Purification / methods*

Substances

Estrogens
MCM-41
Water Pollutants, Chemical
Estrone
Ethinyl Estradiol
Estradiol
Silicon Dioxide