Removal of Berberine from Wastewater by MIL-101(Fe)Performance and MechanismJuan Li Liangjie Wang Yongqiang Liu Ping Zeng Yan Wang and Yizhang Zhang

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ABSTRACT The water contamination from pharmaceuticals and personal careproducts (PPCPs) has attracted worldwide attention in recent years because of itsthreat to public health Berberine is a typical anti-inflammatory medicine andberberine wastewater is difficult to be treated due to its high toxicity poorbiodegradability and high acidity Metalminusorganic frameworks would be a goodchoice to remove berberine from wastewater due to its advantages of high specificsurface area ultrahigh porosity and structural and functional tunability In thisstudy MIL-101(Fe) was synthesized and used for the removal of berberine fromwater Experimental results indicated that MIL-101(Fe) showed promisingcharacteristics when berberine was adsorbed in acidic wastewater The highconcentration of chloride in berberine wastewater could promote the adsorptionof berberine by MIL-101(Fe) Fitting of batch equilibrium data showed that MIL-101(Fe) had a maximum adsorption capacity of 16393 mgg for berberineremoval at pH 7 and the berberine sorption on MIL-101(Fe) followed the pseudo-second-order model Furthermore the associatemechanism for berberine removal was proposed by characterizing the material and theoretical calculation The X-ray powerdiffraction (XRD) Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) analysis showedthat no chemical reaction occurred during the adsorption of berberine by MIL-101(Fe) Also the theoretical calculation resultsindicated that πminusπ interactions may play the main role in the adsorption of berberine onto MIL-101(Fe) The findings of this studysuggest that MIL-101(Fe) is a promising sorbent for berberine removal from wastewater

1 INTRODUCTIONThe contamination of water by pharmaceuticals and personalcare products (PPCPs) has attracted worldwide attention inrecent years because of its threat to public health1 Berberine isan anti-inflammatory medicine with broad-spectrum antibioticactivity and pharmacological effects2 Berberine can be used totreat cancer diabetes and liver disease3 and the demand forberberine is increasing in recent years4 Berberine is originallyisolated from a variety of Chinese herbs but nowadays it ismainly produced by chemical synthesis5 During the chemicalsynthesis of berberine a large amount of wastewater would beproduced which usually contains a high concentration ofresidual berberine At present the berberine wastewater ismainly discharged into the traditional sewage treatment plantsdirectly for treatment6 However the conventional biologicaltreatment system was usually inefficient for the treatment ofberberine wastewater because it is usually highly acidiccontaining a high concentration of berberine and organicswith antibacterial characteristics35 Because of the adverseeffects of berberine78 efficient treatment methods are urgentlyneeded to treat this berberine wastewaterMany methods have been used for the removal of berberine

including Fenton oxidation9 electrochemistry method10

electrocoagulation6 biodegradation11 and adsorption meth-od12 Among these the adsorption method is a promising

technology for the removal of berberine from water due to itssimple operation high removal efficiency and low cost13 Theadsorbents used for berberine removal mainly includemesoporous carbon214 resin315 and some minerals1617

However because of the high acidity and complex compositionof berberine wastewater the capacities of these materials forberberine is usually low which limits the application of theseadsorbents in berberine wastewater treatment Thus it isnecessary and important to develop efficient adsorbents forberberine removalMetalminusorganic frameworks (MOFs) are an emerging class of

porous materials which are constructed from metal ions andorganic ligands18 MOFs have the advantages of ultrahighporosity good chemical stability high thermal stability andtunable structure and function1920 Thus the potentialapplication of MOFs has gained more and more attentionfrom the researchers At present MOFs have been widely used

Received July 17 2020Accepted October 8 2020

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in gas storage21minus23 toxic gas removal24 separation2526

photocatalysis27 chemical sensors28 and so on In recentyears some water-stable MOFs have been used for the removepollutants from wastewater including removal of organicdyes2930 heavy metal ions3132 and pharmaceuticals andpersonal care products3334 from water The possiblemechanisms for adsorptive removal of pollutants over MOFsmainly include electrostatic adsorption acidminusbase reactionπminusπ complexation and hydrogen bond35 Previous studieshave shown that berberine is mainly removed throughhydrogen-bonding formation with berberine acting as a Hacceptor15 while it is reported that MOFs could be good Hdonors36 Thus MOFs might be promising materials forberberine adsorption However the use of MOFs for berberineremoval has not been reportedThe overall objective of the current study is to explore the

possibility of removing berberine from water by MOFs MIL-101(Fe) was synthesized and used for berberine removal inthis study The effect of temperature adsorbent dosagesolution pH and chloride on the materialrsquos properties forberberine adsorption was examined The capacity and thekinetics of the material for berberine removal were studied byconducting batch experiments Also the associated mechanismfor berberine removal by the material was proposed togetherwith experimental results and theoretical calculations

2 RESULTS AND DISCUSSION21 Effect of Temperature and Adsorbent Dosage on

the Adsorption of Berberine by MIL-101(Fe) Theinfluence of temperature on berberine removal was studiedunder the temperature of 298 308 and 318 K as shown inFigure 1a The results showed that the removal of berberineincreased with the increase of temperature When thetemperature increased from 298 to 308 K the adsorptionamount of berberine increased from 6155 to 8203 mggFurther increasing the temperature to 318 K could increase theadsorption amount of berberine to 10338 mgg Howeverconsidering the energy consumption of temperature increasethis study mainly focused on the removal of berberine at roomtemperatureFurthermore the thermodynamic parameters including the

standard Gibbs free energy change (ΔGdeg) enthalpy change(ΔHdeg) and entropy change (ΔSdeg) were calculated for theadsorption of berberine on MIL-101(Fe) according to themethod reported in the previous study29 As shown in Table 1the Gibbs free energy changes were positive at 298 and 308 Kindicating that the adsorption process is not spontaneous forthe adsorption of berberine on MIL-101(Fe) While the Gibbsfree energy change was negative at 318 K which indicates thatthe adsorption process is spontaneous under 318 K Also ΔHdegand ΔSdeg were positive for the adsorption of berberine on MIL-101(Fe) indicating that the adsorption process wasendothermicThe effect of the dosage of MIL-101(Fe) on the adsorption

of berberine was also studied as shown in Figure 1b It can beseen that the adsorption amount of berberine for per unit ofadsorbent decreased with the increase of adsorbent dosageHowever the concentration of removed berberine increasedwith the increase of adsorbent dosage as seen in Figure S1When the dosage of MIL-101(Fe) increased from 02 to 1 gLthe removed berberine concentration increased from 2168 to6155 mgL However when the dosage of MIL-101(Fe) washigher than 10 gL further increase in the adsorbent dosage

resulted in less increase in berberine adsorption Especiallywhen the MIL-101(Fe) dosage increased from 2 to 3 gL theremoval of berberine increased from 8007 to 8627 mgLThus considering the adsorption capacity of the material andthe removal efficiency of berberine the dosage of 10 gLwould be used in the following study

22 Effect of pH on the Adsorption of Berberine byMIL-101(Fe) The pH of the solution is usually very importantfor the adsorption of organics In this study the influence ofthe initial pH on berberine removal by MIL-101(Fe) wasconducted at pH from 4 to 10 as shown in Figure 2 Asillustrated the initial pH did not have much influence on theremoval of berberine by MIL-101(Fe) The adsorption amountof berberine was almost the same at the initial pH from 4 to 10This result is different from that of other studies Shan et al3

found that the initial pH had a great influence on the removalof berberine by resin H103 This is because the adsorption ofberberine onto resin is highly dependent on the size ofberberine in the solution Berberine molecules dissociate intoR+ and Clminus when the pH is lower than 70 but form RminusOH2+

ions when the pH is higher than 70 Also at a pH of 70

Figure 1 Effect of temperature (a) and adsorbent dosage (b) on theadsorption of berberine by MIL-101(Fe) Experimental conditions(a) the dosage of MIL-101(Fe) = 10 gL initial concentration ofberberine = 200 mgL initial pH = 70 and equilibration time of 12h and (b) initial concentration of berberine = 200 mgL initial pH =70 equilibration time of 12 h and temperature of 298 K

Table 1 Thermodynamic Parameters for the Adsorption ofBerberine on MIL-101(Fe)

temperature ΔG (kJmol) ΔH (kJmol) ΔS (kJ(mol K)) R2

298 204 3437 011 09999308 097318 minus013

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berberine exists as neutral molecules3 Therefore the initial pHwould affect the size of berberine in the solution resulting inthe initial pH having a great influence on the adsorption ofberberine by resin H103 In this study the pH of the solutionwith different initial pH was all about 3 after the adsorption ofberberine by MIL-101(Fe) as shown in Figure 2 The pH ofthe solution decreased rapidly after the addition of MIL-101(Fe) due to the strong acidity of the material Thereforethe initial pH did not have much influence on the removal ofberberine by MIL-101(Fe)In particular berberine wastewater is usually highly acidic

with pH in the range from 006 to 12937 However theadsorbents used to remove berberine in the current studies areusually less effective in removing berberine under acidicconditions For example the adsorption capacity of polymericresin H103 for berberine decreased obviously when the pHwas less than 53 Similarly the adsorption capacity of berberineon ZSM-5 molecular sieves reached the maximum at pH 8 anddecreased with the decrease in pH38 However MIL-101(Fe)synthesized in this study is suitable for the removal ofberberine under acidic conditions which is favorable for itspractical application23 Effect of Chloride on the Removal of Berberine

by MIL-101(Fe) Because berberine wastewater usuallycontains high concentrations of chloride (Clminus) in the rangefrom 6555 to 12670 mgL3940 it is necessary to investigate theinfluence of chloride on the adsorption of berberine by MIL-101(Fe) The removal of berberine by MIL-101(Fe) in thepresence of chloride was examined at different concentrationsas shown in Figure 3 It can be seen that Clminus had little effect onthe adsorption of berberine at low concentrations However itwas found that chloride could promote berberine removal byMIL-101(Fe) when the concentration of chloride was morethan 50 mM (2922 mgL) This result indicated that thepresence of chloride was advantageous for the adsorption ofberberine from berberine wastewater by MIL-101(Fe) Thismight be because berberine molecules dissociate into R+ andClminus under reaction conditions The presence of highconcentrations of Clminus may lead to the formation of neutralberberine molecules which is favorable for the adsorption ofberberine3 Thus the high concentration of chloride inberberine wastewater could promote the adsorption ofberberine by MIL-101(Fe) which is beneficial for theapplication of MIL-101(Fe) in berberine wastewater treat-ment

24 Isothermal Adsorption of Berberine by MIL-101(Fe) Adsorption isotherm of berberine by MIL-101(Fe) atpH 7 is shown in Figure 4 It can be seen that the adsorption ofberberine increased with the increase of berberine concen-tration To further analyze the adsorption behavior ofberberine on MIL-101(Fe) Langmuir isotherm modelFreundlich isotherm model and Temkin isotherm modelwere used to analyze the batch adsorption results The fittingparameters of Langmuir Freundlich and Temkin isotherm arelisted in Table 2 The fitting results showed that the Langmuirequation was better to analyze the isotherm data than theFreundlich equation or the Temkin equation The correlationcoefficients from the Langmuir equation were higher than 099Based on the fitting of the Langmuir equation the synthesizedmaterial had a maximum capacity of 16393 mgg forberberine which is higher than those of the previouslyreported adsorbents (Table 3) These results demonstrate thatMIL-101(Fe) has good prospects for the removal of berberinefrom water

25 Kinetics of Berberine Removal by MIL-101(Fe)Kinetics of berberine adsorption by MIL-101(Fe) wasexamined at pH 7 as shown in Figure 5 It can be seen thatthe berberine was adsorbed by MIL-101(Fe) quickly in thefirst 30 min and the concentration of berberine decreased fastThe adsorption of berberine by MIL-101(Fe) reached anequilibrium in about 6 h At the beginning of the reactionMIL-101(Fe) contained a lot of adsorption sites on the surfaceof the material and the berberine in the solution can beadsorbed quickly However the reaction sites on the surface ofthe material were consumed gradually with the increase in thereaction time and the decrease in the concentration ofberberine in the solution resulted in a slower reaction rateFurther the typical kinetic models including intraparticlediffusion pseudo-first-order and pseudo-second-order modelswere used to fit the experimental results and analyze theadsorption kinetics of berberine on MIL-101(Fe) The kineticparameters and coefficients of the three models are shown inTable 4 It can be seen that the correlation coefficient of thepseudo-second-order model is greater than 099 which ismuch higher than that of the two other models Thus theexperimental data can be fitted well to the pseudo-second-order kinetic model rather than to the intraparticle diffusionequation or the pseudo-first-order equation This indicatedthat the rate-limiting step for the adsorption of berberine onMIL-101(Fe) may be a chemisorption process

Figure 2 Effect of pH on the removal of berberine by MIL-101(Fe)(the dosage of MIL-101(Fe) = 10 gL initial concentration ofberberine = 200 mgL equilibration time of 12 h and temperature of298 K)

Figure 3 Effect of chloride on berberine removal by MIL-101(Fe)(the dosage of MIL-101(Fe) = 10 gL initial concentration ofberberine = 200 mgL initial pH = 70 and temperature of 298 K)

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26 Characterization of MIL-101(Fe) before and afterAdsorption To observe the changes in the material beforeand after the adsorption of berberine scanning electronmicroscopy (SEM) X-ray power diffraction (XRD) Fouriertransform infrared spectroscopy (FTIR) and X-ray photo-electron spectroscopy (XPS) analysis were conducted Themorphologies of the MIL-101(Fe) before and after theadsorption of berberine were observed by SEM as shown inFigure 6 The synthesized MIL-101(Fe) had typical octahedralshapes before the adsorption of berberine which is in

accordance with the previous reports41 The morphology ofthe material changed obviously after the adsorption ofberberine as presented in Figure 6b After the reaction withberberine the octahedron shape of MIL-101(Fe) was de-pressed This result indicated that the metal site of MIL-101(Fe) may not participate in the reaction with berberineThe XRD spectra of the material before and after the

adsorption of berberine are shown in Figure 7 The XRDspectra of the synthesized MIL-101(Fe) were well inagreement with the previously reported data42 which indicatedthat MIL-101(Fe) was successfully synthesized in this studyAfter the adsorption of berberine the XRD spectra of thematerial changed However the typical main diffraction peaksdid not change Shown in Figure 8 are the FTIR spectra ofMIL-101(Fe) before and after the adsorption of berberine atpH 7 for 12 h The FTIR spectra of the synthesized materialconfirmed the successful synthesis of MIL-101(Fe)43 Thebands in the region of 1600minus1400 cmminus1 represent theasymmetrical and symmetrical stretchings of OminusCminusO whichare the typical characteristic peaks of MIL-10144 The peaks at590 and 790 cmminus1 can be attributed to the vibration of FeminusO4445 and CminusH bending vibrations of the benzene46

respectively After the adsorption of berberine the mainpeaks of the FTIR spectra for the material weakened while the

Figure 4 Adsorption isotherms of berberine by MIL-101(Fe) (a) and fitting of Langmuir (b) Freundlich (c) and Temkin (d) models (the dosageof MIL-101(Fe) = 10 gL initial pH = 70 equilibration time of 12 h and temperature of 298 K)

Table 2 Langmuir Freundlich and Temkin Parameters for the Adsorption of Berberine on MIL-101(Fe)

Langmuir = +QK Q C

K Ce 1L max e

L eFreundlich Qe = KF Ce

1n Temkin Qe = B ln KT + B ln Ce

Qmax (mgg) KL R2 n KF R2 B KT R2

16393 00044 0 9914 1574 22105 09698 30597 00705 09603

Table 3 Comparison of Maximum Berberine AdsorptionCapacities of Various Adsorbents

adsorbents conditionsQmax

(mgg) reference

molecularly imprinted polymer AD-10

303 K 12 h 795 58

berberine hydrochloride imprintedpolymers

298 K 5 h 1011 12

macroporous resin AB-8 303 K 28 h 655 59macroporous resin HPD722 303 K 28 h 898 59macroporous resin HPD100B 303 K 28 h 971 59macroporous resin HPD300 303 K 28 h 1178 59mIL-101(Fe) 298 K 12 h 16393 this

work

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position of the main peaks did not change indicating nochanges in the chemical bondFurthermore to analyze the surface chemistry of MIL-

101(Fe) before and after the adsorption of berberine XPS wasconducted as shown in Figure 9 Figure 9a shows the full-survey spectrum of MIL-101(Fe) in which the signals of Fe Cand O could be detected Before the adsorption the XPS

spectra of Fe 2p showed two peaks at 71180 and 72560which can be assigned to Fe3+ Because that the Fe species inMIL-101 was Fe3+4747 the presence of Fe3+ validated theformation of MIL-101(Fe) with Fe as the metal site After theadsorption the XPS spectra of Fe 2p consist of two subpeaks at71147 and 72531 which were also attributed from Fe3+ Thisresult indicated that Fe as the metal site of the material did

Figure 5 Adsorption kinetics of berberine by MIL-101(Fe) (a) and fitting of the intraparticle diffusion model (b) pseudo-first-order model (c)and pseudo-second-order model (d) (the dosage of MIL-101(Fe) = 10 gL initial concentration of berberine = 200 mgL initial pH = 70temperature of 298 K)

Table 4 Kinetic Parameters and Coefficients of the Intraparticle Diffusion Pseudo-First-Order and Pseudo-Second-OrderModel for the Adsorption of Berberine on MIL-101(Fe)

intraparticle diffusion modelQt = Kpt

12 + C pseudo-first-order model Ct = C0 eminusK1t pseudo-second-order model = +t

Q K Qt

Q1

t 2 e2

e

Kp R2 K1 (minminus1) R2 Qe(mgg) K2 (g(mg min) R2

13049 08529 00003 06520 5848 00013 09985

Figure 6 SEM images of MIL-101(Fe) before (a) and after (b) adsorption of berberine

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not participate in the reaction with berberine Combined withthe results of XRD and FTIR the chemical composition of thematerial may not change after the adsorption of berberine27 Adsorption Mechanism It is important to under-

stand the plausible mechanism of the interactions between theadsorbent and adsorbate Several adsorption mechanisms suchas electrostatic interaction acidbase complexing πminusπinteractions and hydrogen bonding have been used to explainthe adsorption of organics over MOFs35 From the character-ization results of MIL-101(Fe) before and after adsorption itcan be concluded that no obvious chemical reaction occurredbetween MIL-101(Fe) and berberine To further understandthe mechanism of the adsorption of berberine by MIL-101(Fe) theoretical calculations were performed to analyzethe weak interactions between MIL-101(Fe) and berberineFigure 10 shows the possible adsorption site of MIL-101(Fe)for berberine (Figure 10aminusc) and the isosurface of δg (Figure10d) The green area in the isosurface of δg between MIL-101(Fe) and berberine represents πminusπ interactions and theblue area represents hydrogen bonding It can be seen thatthere is a weak hydrogen bond between MIL-101(Fe) andberberine while πminusπ interactions play the main role in theadsorption of berberine by MIL-101(Fe) Thus it can beinferred that berberine is mainly adsorbed on MIL-101(Fe)through πminusπ interactions

3 CONCLUSIONSMIL-101(Fe) was used for berberine removal from water inthis study As a new type of porous materials MIL-101(Fe)showed some advantages in the removal of berberine FirstMIL-101(Fe) can be used for berberine removal under acidicconditions Second a high concentration of chloride couldpromote the removal of berberine by MIL-101(Fe) ThirdMIL-101(Fe) has a high capacity for berberine with themaximum sorption capacity of 16393 mgg at pH 7 For theremoval mechanism of berberine by MIL-101(Fe) thecharacterization results indicate that no chemical reactionoccurred between berberine and MIL-101(Fe) Throughtheoretical calculation it can be inferred that the mainmechanism for the adsorption of berberine by MIL-101(Fe)can be attributed to πminusπ interactions The findings of thisstudy suggest that MIL-101(Fe) is a promising sorbent forberberine removal from water For future research the capacityof MIL-101(Fe) for berberine can be further improvedthrough the modification of nitrogen-containing functionalgroups to enhance the hydrogen-bonding reaction betweenadsorbent and berberine

4 MATERIALS AND METHODS41 Materials The following reagents were used in this

study ferric chloride hexahydrate and terephthalic acid (TPA)were purchased from Shanghai Macklin Biochemical Co LtdNaCl NaNO3 Na2SO4 NaHCO3 NaOH HCl NN-dimethylformamide (DMF) and ethanol were provided bySinopharm Group China

Figure 7 XRD of MIL-101(Fe) before and after the adsorption ofberberine

Figure 8 FTIR spectra of MIL-101(Fe) before and after theadsorption of berberine

Figure 9 XPS spectra of MIL-101(Fe) before and after theadsorption of berberine full-survey (a) and Fe 2p (b)

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42 Preparation of MIL-101(Fe) MIL-101(Fe) wassynthesized through a hydrothermal synthesis method reportedpreviously with slight modifications43 First ferric chloridehexahydrate and terephthalic acid were dissolved in DMFsolution in a ratio of 21 Then the mixture was transferred toa Teflon-lined autoclave and put into a preheated (at 110 degC)electric oven and maintained for 20 h The autoclave wascooled to room temperature after the reaction and a solidproduct was recovered by centrifugation The product waswashed with DMF and ethanol 2 times respectively And thenthe product was vacuum-dried at 60 degC for 24 h The preparedMIL-101(Fe) had a BrunauerminusEmmettminusTeller (BET) surfacearea of 1312 m2g43 Characterization of Materials The synthesized

MIL-101(Fe) was characterized by BrunauerminusEmmettminusTeller(BET) surface area scanning electron microscopy (SEM) X-ray power diffraction (XRD) Fourier transform infraredspectroscopy (FTIR) and X-ray photoelectron spectroscopy(XPS) For the characterization of MIL-101(Fe) afteradsorption of berberine the material after the reaction waswashed with water and ethanol two times respectively Andthen the product was vacuum-dried at 60 degC for 24 h and usedfor characterizationThe specific surface area of MIL-101(Fe) was calculated by

the BET equation from N2 adsorptiondesorption isothermswhich was conducted by Quadrasorb SI-MP The morphology

of the material before and after the adsorption of berberine wasobserved by SEM (Hitachi SU8010 Japan) The synthesizedsamples were also characterized by FTIR (Excalibur 3100Varian) in the range of 400minus4000 cmminus1 to identify thefunctional groups on the adsorbent surface X-ray diffractionanalysis of the samples before and after reaction with berberinewas conducted using X-ray power diffraction in the range from3 to 50deg In addition to determine the surface chemicalcomposition of the material before and after the adsorption ofberberine XPS (ESCALAB-MKII VG Co Bruker Germany)analysis was performed

44 Batch Experiments 441 Effect of Temperature onBerberine Removal The effect of temperature on the removalof berberine by MIL-101(Fe) was conducted In a typical test20 mg of MIL-101(Fe) was mixed with 20 mL of 200 mgLberberine solution at an initial pH of 70 Then the mixturereacted in a shaking table for 12 h at temperatures of 298 308and 318 K respectively After reaching equilibrium themixture was filtered through a 022 μm syringe filter and theconcentration of berberine in the filtrate was determined usingan ultravioletminusvisible (UVminusvis) spectrophotometer at 345 nmThe experiment was repeated three times

442 Effect of Adsorbent Dosage on Berberine RemovalThe effect of adsorbent dosage on the removal of berberine byMIL-101(Fe) was also conducted at a temperature of 298 KThe test procedures were similar to the above experiment

Figure 10 Weak interactions between MIL-101(Fe) and berberine the possible adsorption site of MIL-101(Fe) for berberine (aminusc) and theisosurface of δg (d)

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except that a different adsorbent dosage was used Theexperiment was also repeated three times443 Effect of pH on Berberine Removal Batch experi-

ments were carried out at 298 K to investigate the berberineadsorption as a function of the initial pH The pH of thesolution was adjusted by HCl or NaOH All other experimentalconditions and procedures were similar to the aboveexperiments The experiment was also repeated three times444 Effect of Chloride on Berberine Removal The

influence of chloride on berberine removal by MIL-101(Fe)was also studied at initial pH 7 Different levels ofconcentration of Clminus (1 3 5 10 20 50 100 and 200 mM)were tested All other experimental conditions and procedureswere similar to the above experiments The experiment wasalso repeated three times445 Adsorption Isotherms The capacity of MIL-101(Fe)

for berberine removal was examined at an initial pH of 7 byconducting the batch equilibrium experiment The testprocedures were similar to the above experiment except thatvaried berberine concentrations were used The experimentwas repeated three times Equilibrium sorption data wereplotted using the Langmuir Freundlich and Temkin modelsand the adsorption capacity (Qmax mgg) of the sorbent wasobtained from the fitting parameters446 Kinetics Study The sorption kinetics of berberine by

MIL-101(Fe) was examined at pH 7 in a conical flask thatcontained 200 mL of 200 mgL berberine solution at the startof the test All other experimental conditions were identical tothe above experiments The test mixture was sampled at thedesired time interval with a 5 mL syringe and filteredimmediately through a 022 μm membrane filter for ananalysis of residual berberine The experiment was alsorepeated three times45 Theoretical Calculations Theoretical calculations

were conducted to analyze the weak interactions betweenadsorbent and berberine Multiwfn 37 software48 was used tocalculate the isosurface of the δg function of the independentgradient model (IGM)49 after geometry optimization Theoptimization of the molecular geometry with a default solventmodel under the level of PBE1PBE6-311G50minus54 was carriedout by Gaussian software55 The images of molecular structureand isosurface of the δg function were obtained by VMDsoftware56 In addition the molecular docking was realized byAutoDockTools and Vina Because the structure file of MIL-101(Fe) was not found in the Cambridge CrystallographicData Center (CCDC) while the structure of MIL-101(Fe) isthe same as that of MIL-101(Cr)57 the crystal file of MIL-101(Fe) was obtained by replacing Cr of MIL-101(Cr) comingfrom CCDC

ASSOCIATED CONTENTsı Supporting InformationThe Supporting Information is available free of charge athttpspubsacsorgdoi101021acsomega0c03422

Effect of adsorbent dosage on the removal of berberineby MIL-101(Fe) (PDF)

AUTHOR INFORMATIONCorresponding AuthorPing Zeng minus Chinese Research Academy of EnvironmentalSciences Beijing 100012 China orcidorg0000-0002-4022-2551 Email zengpingcraesorgcn

AuthorsJuan Li minus Chinese Research Academy of Environmental SciencesBeijing 100012 China

Liangjie Wang minus Chinese Research Academy of EnvironmentalSciences Beijing 100012 China

Yongqiang Liu minus Faculty of Engineering and Physical SciencesUniversity of Southampton SO17 1BJ Southampton UnitedKingdom

Yan Wang minus Chinese Research Academy of EnvironmentalSciences Beijing 100012 China

Yizhang Zhang minus Chinese Research Academy of EnvironmentalSciences Tianjin Branch Tianjin 300457 China

Complete contact information is available athttpspubsacsorg101021acsomega0c03422

NotesThe authors declare no competing financial interest

ACKNOWLEDGMENTSThis work was supported by the China Postdoctoral ScienceFoundation (2019M650798) the National Major Scientificand Technological Projects for Water Pollution Control andManagement (2017ZX07402003) and the National NaturalScience Foundation of China (41671033)

REFERENCES(1) Wang J Wang S Removal of pharmaceuticals and personalcare products (PPCPs) from wastewater A review J Environ Manage2016 182 620minus640(2) Li Y Lu X Yang R Tong W Xu L de Bondelon LWang H Zhu J Ge Q Adsorption of berberine hydrochloride ontomesoporous carbons with tunable pore size RSC Adv 2016 628219minus28228(3) Shan Y Song Y Liu Y Liu R Du J Zeng P Adsorption ofberberine by polymeric resin H103 kinetics and thermodynamicsEnviron Earth Sci 2015 73 4989minus4994(4) Liu S Zhang Y Zeng P Wang H Song Y Li J Isolationand Characterization of a Bacterial Strain Capable of EfficientBerberine Degradation Int J Environ Res Public Health 2019 16No 646(5) Qin W Song Y Dai Y Qiu G Ren M Zeng P Treatmentof berberine hydrochloride pharmaceutical wastewater by O3UVH2O2 advanced oxidation process Environ Earth Sci 2015 73 4939minus4946(6) Ren M Song Y Xiao S Zeng P Peng J Treatment ofberberine hydrochloride wastewater by using pulse electro-coagu-lation process with Fe electrode Chem Eng J 2011 169 84minus90(7) Letasiova S Jantova S Cipak L Muckova M Berberine-antiproliferative activity in vitro and induction of apoptosisnecrosisof the U937 and B16 cells Cancer Lett 2006 239 254minus262(8) Hu Y Davies G E Berberine inhibits adipogenesis in high-fatdiet-induced obesity mice Fitoterapia 2010 81 358minus366(9) Cui X Zeng P Qiu G Liu Y Song Y Xie X Han LPilot-scale treatment of pharmaceutical berberine wastewater byFenton oxidation Environ Earth Sci 2015 73 4967minus4977(10) Komorsky-Lovric S Adsorption and Reduction of Berberine ata Mercury Electrode Electroanalysis 2000 12 599minus604(11) Qiu G Song Y-h Zeng P Duan L Xiao SCharacterization of bacterial communities in hybrid upflow anaerobicsludge blanket (UASB)-membrane bioreactor (MBR) process forberberine antibiotic wastewater treatment Bioresource Technol 2013142 52minus62(12) Li H Li Y Li Z Peng X Li Y Li G Tan X Chen GPreparation and adsorption behavior of berberine hydrochlorideimprinted polymers by using silica gel as sacrificed support materialAppl Surf Sci 2012 258 4314minus4321

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