Parabens paraben’s safety have been proven by

Parabens are esters of
parahydroxybenzoic acid which mainly include methylparaben (MP), ethylparaben
(EP), propylparaben (PP), butyl paraben (BuP) and benzylparaben (BP). It is
nearly a century, parabens, alone or in combination with other compounds, have
been routinely utilized as preservatives in formulation of approximately all
types of cosmetics, pharmaceuticals and food products because of having
antibacterial and antifungal effects1-2 . Furthermore, the widespread use of parpens as the most common
preserving agents is attributed to their extraordinary physical and chemical
properties such as having imperceptible odor or taste, chemical stability at
high temperature or wide pH range, low toxicity and low production cost 3. Researches have shown a direct correlation exists between
increasing the anti-microbial activity of parabens and the chain length of
their aster group, the shorter esters including methyl paraben(MP) and propyl
paraben (PP)  are frequently used because
these kinds of parabens have higher solubility in water4567.

Over the past few years, the vast
use of  paraben compounds  has raised  worldwide concerns about their unpredictable
influence over human life and environment systems .Although paraben’s safety
have been proven by various studies, currently, some vitro studies have
identified parabens as Endocrine-Active Chemicals (EACs) which might make an
adverse impact on human health8. Since,
parabens are able to be absorbed by skin, their estrogenic activity may
increase the risk of breast cancer or the male reproductive tract910

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In order to remove these compounds,
a number of technics have been applied. For example, extraction of parabens
from cosmetic products and environmental samples using Solid Phase Extraction
(SPE) 11, detection of parabens by Gas Chromatography–Mass Spectrometry
(GC–MS) 12 and  adsorption13. Among them, the adsorption technics has been considered as a
cost-effective and practical way to remove and detection of specific compounds14.

Silica nanotubes (SiO2NT),
discovered by Nakamura and coworkers 15 in1995, have drawn a great deal of attention because of their
exceptional properties such as hydrophilic nature, easy colloidal suspension
formation, and distinctive inner and outer surface. In addition, their
widespread applications in many fields including separation, adsorption,
catalysis, optics, electronics, drug delivery and chemical sensing lead to
remarkable advances in the use of silica nanotubes in medicine and industry161718. Since the discovery of SiO2NT s, a wide range of
research on  their preparation and the
applications have been carried out. Utilizing the SiO2NT s as the
catalyst carriers by Zhang et al.19 is example of finding research. Additionally, For the first time, SiO2NT
s were introduced as adsorbents for heavy metals due to their intriguing
characterizations by Wang et al.20.

Recently, in an experimental
investigation the adsorption MP, EP and PP on PS/Fe3O4
was studied by Chen et al13. Afterward, we decided to investigate the interaction of SiO2NT
 with paraben molecules, such as the
geometrical structures, energetic and electronic properties based on the
density functional theory and explore the feasibility of applying SiO2NT
s as a novel detection for the removing methyl and propyl paraben molecules.