Response to editor and reviewers：
Manuscript ID: CJCE-12-0628
Title: "Molecularly imprinted β-cyclodextrin/kaoline particles for the selective recognition and
binding of bisphenol A"
Authors: Qingjie Xie, Linzi Li, Jianming Pan, Minjia Meng, Zhilong Song, Wenjing Zhu
Corresponding author: Dr Qingjie Xie.
Dear editor：
Thank you for your useful comments and suggestions on the language, structure and content of
our manuscript. We have revised the paper according to the comments of the Reviewers. The
amendments we have made were marked as those parts in red background in this revised
manuscript. Our responses to reviewers’ comments are listed as follows.
Sincerely
Qingjie Xie
Response to Reviewer 1
Question 1: In defining the pore diffusivity, can you correlate the significance of internal porosity
with Diffusivity coefficients?
Thanks for your suggestion. In our opinion, the pore diffusivity coefficients were not
related with the size of internal porosity. And it was just a indicator for the efficiency of pore
diffusivity. Thus, it was necessary to correlate the significance of internal porosity with Diffusivity
coefficients. Moreover, the binding pores were both ununiform in MIPs and NIPs, it was also
difficult to explain the relation between internal porosity and Diffusivity coefficients. We
apologize for our superficial response to this question. Hope that our reply serving you energy
satisfied.
Question 2: What is the 'zero point charge' of -Kaolin- adsorbent ? The zpc factor is
indispensable for studying the effect of pH with respect to a contaminant.
Thanks for your suggestion. Organic pollutants such as BPA were trapped by adsorbents
through the hydrophobic interaction and the hydrogen-bonding interaction simultaneously. Firstly,
the fact neutral molecules of phenolic compound (at the point of zero charge) are benefit for the
adsorption process has also been reported previously [1].
Moreover, in previous studies, the fact that neutral molecules of phenolic compound are
benefit for the adsorption process has also been reported [1, 2]. As mentioned in this article, the
neutral molecules of BPA (at the point of zero charge) are benefit for the adsorption and the
adsorption capacity of MIPs attained maxim value of 56.58 mg g-1 at pH 7.0 as expected. The
results may be bonded -CD and neutral BPA molecules could form complexes through the
hydrophobic interaction and the hydrogen-bonding interaction simultaneously. At a higher pH,
adsorption of BPA molecules released OH- from the adsorbent surface and this decreased the
adsorption effect. At a lower pH, the surface of MIPs and BPA molecules positively charged,
electrostatic repulsion was not benefit for the adsorption system.
Thus, we think that the surface charge could elucidate the general trend of the pH effect, and
it can be more useful to metal ions adsorption than organic molecules. And the specific effect of
surface charge for organic molecules could be discussed by the initial and equilibrium pH of the
testing solution simply.
Due to the absence of more advanced instrument such as electrophoretic light-scattering
spectrophotometer, the further study about the effect of zero point charge to organic pollutants
adsorption is difficult. We apologize for our superficial response to this question. Hope that our
reply serving you energy satisfied.
Related references:
[1] M. Sathishkumar, A.R. Binupriya, D. Kavitha, R. Selvakumar, R. Jayabalan, J.G. Choi, S.E.
Yun, Adsorption potential of maize cob carbon for 2,4-dichlorophenol removal from aqueous
solutions: equilibrium, kinetics and thermodynamics modeling, Chem. Eng. J. 147 (2009)
265-271.
[2] Jianming Pan, Wei Hu, Xiaohui Dai, Wei Guan, Xiaohua Zou, Xue Wang, Pengwei Huo and
Yongsheng Yan. Molecularly imprinted polymers based on magnetic fly-ash-cenosphere
composites for bisphenol A recognition. J. Mater. Chem., 2011, 21, 15741.
Question 3: Is the diffusion NON-FICKIAN (under different conditions)? In either or both cases,
(Fickian and non fickian) explain the phenomenon by experimental results and discussions.
Thanks for your suggestion. Fickian and non fickian equation have been widely used for
description the diffusion of member. But we think that either or both cases were not fit to use in
our work. This was because of the microstructure, degree of free radical solution polymerization
and polydispersity of the obtained MIPs particles were both uncontrollable. The imprinted
polymer layer was different from the uniform polymer member.
Question 4: What is the effect of Temperature on adsorption? Display the effect with
Arhenious Equation (if possible).
Thanks for your suggestion. “From Figure 5, with temperature increased from 288 K to 318
K, Qe of MIPs were elevated obviously than those of NIPs, it was probably because higher
temperature and imprinting effect provided more chances for BPA molecules to pass the external
boundary layer, and produced the increase of pore volume and surface area enabling BPA
molecules to penetrate into recognitive binding sites.23” Thus, we have discussed the effect of
Temperature on adsorption. In Arrhenius equation, activation energy Ea is regarded as a constant
which will not change with temperature. Considering the swelling of polymer layer (especially the
bonded β-cyclodextrin), the physicochemical properties of MIPs could be changed with the
increase of temperature. In our opinion, Arrhenius equation may not be fit to applied our materials.
Question 5: Does adsorption depends on the particle size of adsorbent? Explain it
mathematically with experimental validation.
Thanks for your suggestion. We have addressed this point in our work, and the related
results and discussion were shown in our revised manuscript. Adsorption capacity increases with
the decrease of particle size. When we control materials in relatively small size, thus can increase
the specific surface area which is benefit for adsorption. The size of synthesized materials in our
work is not very uniform. In order to reduce the error in batch mode experiments, we have made a
sieving to the materials before adsorption experiments. The distribution of particle size were
limited between 200 nm to 500 nm.
Question 6: Do the researchers contemplate on conducting dynamic column studies for
determining breakthrough behaviour?MUST BE REPORTED IN CONCLUSIONS SECTION.
Thanks for your suggestion. In our further research, the MIPs were adopted to selective
solid-phase extraction of BPA, and the dynamic column studies have also been carried out. The
related work will be discussed in details in our further work as a full paper.
Question 7: Were the results triplicated? Give statistical correlation with respect to reproducibility
of the results. The deviation in the results is extremely significant with respect to the experimental
conditions.
Thanks for your suggestion. The batch mode experiments were carried out for two times,
and the mean data was used in our manuscript. For our further study, statistical correlation with
respect to reproducibility of the results will be carried out. Thanks again for your valuable
suggestion.
Response to Reviewer 2
Question 1: Molecularly imprinted technique belongs to special chemical adsorption. If the
adsorption capacity resulted from the molecularly imprinted cavities in the batch
experiment is above the molar amount of imprinted molecules in the solution, the imprinted
molecules will be adsorbed soon and the Ce (the equilibrium concentration) might be zero.
On the contrary, the spiked imprinted molecules minus the adsorption capacity will get Ce.
Therefore, it is hard to understand the type of “s” plot of Ce versus Qe of adsorption
isotherms for MIPs, which was similar to that for NIPs.
Thanks for your suggestion. In fact, the difference of adsorption behaviors between MIPs
and NIPs resulted from the presence of template molecules in imprinting polymerization. Thus,
both MIPs and NIPs have binding sites in the surface of materials, but the portion binding sites of
MIPs possessed of specific recognition (but it was poor for NIPs ). This difference between MIPs
and NIPs resulted in the distinctive adsorption capacity and rates. So, we think that the type of “s”
plot of Ce versus Qe of adsorption isotherms for MIPs, which was similar to that for NIPs is right.
Question 2: Line 230-231：KDR “Value of KDR <1.0 represents the rough surface with many
cavities.” Does the adsorption of imprinted molecules have relationship with rough surface?
Whether is it reasonable for the fitting to the Dubinin-Radushkevich isotherm model?
Thanks for your suggestion. The rough surface with many cavities will make template
molecule more easy to get into the binding sites. Dubinin-Radushkevich is one of the most
important polymolecular layer isotherm model which was proper to use in our work. Moreover, in
our work, we selected three common isotherm models to fit the experimental data, the key aim
was to find out which one was the best model for describing the adsorption equilibrium.
Question 3: Line 237：“indicating monolayer molecular adsorption…”. Can one imprinted
cavity adsorb two molecules?
Thanks for your suggestion. Imprinted cavity is complementary in shape, size and
functional groups to the template molecules. So one imprinted cavity could adsorb only one
molecules.
Question 4: Whether is it reasonable for the fitting to “Line 269: 3.5 Intraparticle diffusion
and Line 289：3.6 Film diffusion and pore diffusion” when the adsorption of imprinted
molecules to imprinted cavities ?
Thanks for your suggestion. Based on the comparison of diffusion parameters, including
intraparticle diffusion, film diffusion and pore diffusion, we can confirm the process of recognitive
binging sites in MIPs. As mentioned in our article: “But this kind of three steps in the
multi-linearity of the intraparticle diffusion plot were not observed in the adsorption of BPA onto
NIPs (Figure 7), indicating the effect of time for adsorption of BPA onto MIPs was more
obviously than NIPs.” “Furthermore, the values of Ki and D1 for MIPs were more than those of
NIPs, while the values of D2 were few than NIPs, suggesting that the checking and confirming
process of recognitive binging sites in MIPs.” These contents have been researched in our
previous and other researchers. The related references were listed bellow.
Related references:
[1] Jianming Pan, Hang Yao, Wei Guan, Hongxiang Ou, Pengwei Huo, Xue Wang, Xiaohua Zou,
Chunxiang Li. Chemical Engineering Journal. 172 (2011) 847-855.
[2] Yan Liu, Zhanchao Liu, Jie Gao, Jiangdong Dai, Juan Han, Yun Wang, Jimin Xie, Yongsheng
Yan. Journal of Hazardous Materials. 186 (2011) 197-205.
Question 5: Table 1 showed the difference on elemental composition of C, H and N(%) of
B-CD/Kaolin composites, MIPs and NIPs. Why didn’t compare the adsorption of
B-CD/Kaolin composites with NIPs? The adsorption of BPA onto NIPs might be mainly from
B-CD/Kaolin composites.
Thanks for your suggestion. In our work, we have compared B-CD/Kaolin composites with
NIPs, and the adsorption capacity followed the order NIPs＞B-CD/Kaolin composites. The reason
may be that more polymers were introduced onto the surface NIPs, which may increase the
roughness and porosity of the materials. Moreover, the most important purpose of our work is to
confirm the selectivity adsorption of MIPs by compare the difference between MIPs and NIPs.
Then, the result for the comparing B-CD/Kaolin composites with NIPs were not involved in our
manuscript.
Question 6: There are some minor error：for example: the superscript for units in the text; C
(%) and N (%) of Kaolin in table 1 (why?). Difference on abbreviation of MIPs in abstract
and introduction?
Thanks for your suggestion. The kaolin in our experiments were natural, it is inevitable that
there exist some impurity like C and N. We have revised the whole manuscript carefully and tried
to avoid any grammar, terminology or syntax error. The amendments have been made (marked as
those parts in red background) in our revised manuscript.
Thanks again for your suggestions and advice.
Best regards
Yours sincerely,
Qingjie Xie
School of environment Engineering,
Jiangsu University, Xuefu Road 301, Zhenjiang, 212013, China
E-mail:xieqingjiejsdx@126.com
Tel: 86-0511-88791683 Fax: 86-0511-88791683