Adsorptive Removal of Azo Dye New Coccine Using High-Performance Adsorbent-Based Polycation-Modified Nano-Alpha Alumina Particles

The azo dyes new coccine (NCC) were successfully removed through the adsorption onto PVBTAC-modified α-Al2O3 particles. The optimal conditions of both the surface modification by PVBTAC adsorption and the NCC adsorption were thoroughly investigated. Formerly, polycations PVBTAC were adsorbed onto the nanosized α-Al2O3 particles at pH 8, NaCl 100 mM, with a contact time of 2 h, and initial concentration of 1000 ppm to modify the α-Al2O3 surface. Latterly, the NCC adsorptive removal was conducted at pH 8, NaCl 10 mM, α-Al2O3 adsorbent dosage of 3 mg mL−1, and a contact time of 45 min. Interestingly, the optimal pH of 8 potentially applies to treat real wastewater as the environmental pH range is often about 7–8. High removal efficiency and adsorption capacity of the NCC azo dyes were, respectively, found to be approximately 95% and 3.17 mg g−1 with an initial NCC concentration of 10 ppm. The NCC adsorption on the modified α-Al2O3 particles was well fitted with a Freundlich model isotherm. A pseudo-second kinetic was more suitable for the NCC adsorption on the PVBTAC-modified α-Al2O3 surface than a pseudo-first kinetic. The NCC adsorptive removal kinetic was also affirmed by the FT-IR spectra, based especially on the changes of functional group stretch vibrations of −SO3− group in the NCC molecules and −N+(CH3)3 group in the PVBTAC molecules. The high reusability of the α-Al2O3 particles was proved to be higher than 50% after four generation times.


Introduction
Nowadays, the azo dyes have been diversely used in many industrial applications such as textile, clothing, printing, plastic, and paper productions. e azo dyes that contain a specific group −N � N− are the most popular and estimate to be about 50-70% of annual total dye production [1]. e azo dyes durably exist and are non-degraded in the aquatic environment. Moreover, the effluents from these industries often contain a large dye amount of 10-200 mg L −1 [2,3], which is likely dangerous to the ecosystem and human health, causing biohazard risks such as bioaccumulation and mutagenesis inducing genetical diseases, congenital NCC degraded up to 99.6% with the employment of the Fenton reagent combining with UV irradiation (UV/FR) at pH 3 and under 30 min of reaction time [14]. Among these techniques, adsorption is more effective with high removal efficiency, and simple and low cost. e use of carbon as an adsorbent seems to be popular. NCC was totally removed (higher than 99% in 10 consecutive cycles) from an aqueous solution through adsorbing on carbon nanotubes coated with chitosan at a high temperature of 323.15 K [15]. A maximum NCC removal efficiency reached 90.83% by adsorption onto the almond shell-synthesized activated charcoal at the optimal pH 2 [16]. It was found that the use of carbon nanotubes with multiple walls (MWCNTs) could remove 166.67 mg g −1 of the NCC from an aqueous solution at pH 3 [17]. On the other hand, other materials are also applied as adsorbents. NCC was removed from wastewater by means of adsorbing onto the powder of zero iron at an acidic condition of pH 3 [18]. However, strictly controlled conditions, such as high experimental temperature or/and acidic environment, have been requested as the removal efficiency is still low.
Furthermore, alumina has been well known as a potential adsorbent for organic pollutant treatment. Alpha alumina (α-Al 2 O 3 ) was characterized with a high specific surface area and existed as the most stable form at high temperature among various alumina forms such as beta (β)-and gamma (c)- [19][20][21]. Recently, the adsorptive removal potential of the organic pollutants was intensified through modifying the α-Al 2 O 3 surface by polyelectrolyte adsorption, even at room temperature, which was previously proved [22][23][24]. It was found that the sodium dodecyl sulfate (SDS) surfactant was strongly attached to the alpha alumina of a small specific surface area [23]. Continuously, oxytetracycline antibiotic was adsorptively removed with a high removal efficiency of higher than 90% by using SDS-modified α-Al 2 O 3 [24]. e modification of surface materials has been demonstrated to increase the total net surface charges, enhancing adsorptive removal of wastewater pollutants through electrostatic interactions [25][26][27][28]. e adsorption mechanism of the azo dyes were followed Langmuir [15,29], Freundlich [15,30], and two-step models [31], while adsorption kinetics were indicated by first-order and secondorder models [18,32,33].
In this study, attention was focused on removing NCC via adsorption onto polycation-modified α-Al 2 O 3 nanosized particles under different conditions at room temperature. e effectiveness parameters including pH, ionic strength, adsorbent dosage, contact time, and the initial concentration on both α-Al 2 O 3 modification process and the NCC removal were comprehensively investigated. e adsorption mechanism was discussed based on both the FT-IR spectra and the general adsorption isotherm models such as Langmuir, Freundlich and two-step. Adsorption kinetics were described by the pseudo-first and -second models.

Materials.
Nanosized alpha alumina (α-Al 2 O 3 ) particles solvothermaly synthesized following the previous method, were used as adsorbents [34]. Accordingly, to precipitate alumina hydroxide, 4 M sodium hydroxide solution was added to 1 M aluminum nitrate solution, respectively prepared from NaOH pellets and (Al(NO 3 ) 3 (analytical reagent, Merk, Germany). e precipitates were dried at 80°C for 24 h after centrifugation and rising to neutral pH with ultrapure water. en, the collected precipitates were transformed to α-Al 2 O 3 at high temperature of 1200°C for 12 h. Finally, the α-Al 2 O 3 were dried and ground after activating by using the solution of 0.05 M NaOH and rising with ultrapure water several times. A high synthesis yield of the α-Al 2 O 3 particles was calculated to be approximately 97.23 ± 1.43%. e α-Al 2 O 3 particles synthesized were nanosized at about 27 nm determined by transmission electron microscopy (TEM, H7650, Hitachi, Tokyo, Japan). Homopolymer, poly(vinylbenzyl) trimethylammonium chloride) (PVBTAC) with a molecular weight of 343.45 g mol −1 (Hyogo, Japan) was applied as a surface modifier.
e stock PVBTAC solution of 10 4 ppm was prepared for adsorption experiments. New coccine with a molecular weight of 604.46 g mol −1 (NCC, purity >82% Merck, Germany) was used as azo dye. e polymer working solutions were diluted from the stock solution. e chemical structures of polycation PVBTAC and the NCC dye were described in Figure 1.
e NaCl solutions of 0.1 and 1 M (prepared from analytical reagent NaCl, Merk, Germany) were employed to control ionic strength after filtering through cellulose membranes of 0.2 μm pore size. Meanwhile, the solutions of 0.1 M HCl and 0.1 M NaOH (Merk, Germany) were used to adjust the pH of the solution under a pH meter (Hanna, USA). All experimental solutions were prepared with ultrapure water (resistance of 18.2 MΩ cm, Labconco, Kansai, MO, USA).

Modification of Alpha-Alumina Using Highly Positively
Charged Polycation

Alpha-alumina Modification by the PVBTAC
Adsorption. e nanosized α-Al 2 O 3 particles were strongly shaken for 2 h by an orbital shaker before using. To deaggregate particles, the nanosized α-Al 2 O 3 particles were sonicated for 30 min before conducting each experimental modification. To modify the particles, suitable PVBTAC stock solution volumes were added to the nanosized α-Al 2 O 3 particles. e modification experiments were carried out for about 2 h by vigorously shaking in investigating conditions of pH and ionic strength. en, the samples were centrifuged to separate the solid-liquid phases. Finally, the solutions were collected to determine PVBTAC-remaining concentration by ultraviolet-visible (UV-Vis) measurement.

NCC Adsorptive Removal Using PVBTAC-Modified Nanosized α-Al2O3 Particles.
e nanosized α-Al 2 O 3 particles modified by PVBTAC adsorption at optimal conditions were rinsed with ultrapure water to eliminate excess polycation PVBTAC after centrifuging to release remaining water. en, these modified materials were used to conduct dye removal experiments at room temperature and different conditional parameters such as pH, ionic strength, adsorption time, α-Al 2 O 3 adsorbent, and NCC adsorbate dosage. Similarly, the solution was pipetted after centrifugation of the sample. e NCC concentration remaining in the solution was measured by the UV-Vis method. Each experiment was at least triply repeated. Standard deviations were determined by at least triple experiments.

Ultraviolet Visible (UV-Vis) Spectroscopy.
e PVBTAC and NCC concentrations were determined by an UV-Vis spectroscopy equipped with a spectrophotometer (UV-1650 PC, Shimadzu, Japan) at a wavelength of 224 and 508 nm, respectively. e PVBTAC adsorption efficiency and the NCC removal efficiency (H, %) were determined where C i and C e are initial and equilibrium polymer concentrations (ppm), respectively. e polymer adsorption capacities onto unmodified/ modified nanosized α-Al 2 O 3 particles were determined by equation (2): where Γ is the polymer adsorption capacity (mg g −1 ) at contact time t (min), M is polymer molecular weight (g mol −1 ), and m is the α-Al 2 O 3 adsorbent dosage (mg mL −1 ).

Adsorption
Mechanism. e adsorption isotherms of PVBTAC onto the α-Al 2 O 3 particles and NCC onto the PVBTAC-modified α-Al 2 O 3 particles were considered to be fit with some general adsorption isotherm models such as Langmuir, Freundlich, and two-step [26]. Each adsorption isotherm model was described as below.
First, the Langmuir model described by equation (3) was applicable for absorbate-formed monolayer on the absorbent. e adsorption favorite was evaluated by R L constant as in equation (4).
where K L is Langmuir constant. Second, the concept of the Freundlich model was developed, based on the experimental data, to evaluate that multiple adsorbate layer formed on the inhomogeneous adsorbent surface. It was subjected in where K f is Freundlich constant and n is the layer number. A general equation of the two-step model adsorption isotherm [34] is as follows: where k 1 and k 2 are equilibrium constants for in the first and second adsorption step, respectively.

Adsorption Kinetics.
Adsorption kinetics of polymer are often described by the pseudo-first and pseudo-second models proposed by Lagergren as follows [17,26]: where Γ is polymer adsorption capacity at contact time t (mg g −1 ), Γ e is the polymer adsorption capacity (mg g −1 ) at equilibrium state, and K 1 (min −1 ) and K 2 (g mg −1 min −1 ) are reaction rate constants of the pseudo-first and pseudosecond models, respectively.

Fourier Transform Infrared (FT-IR) Spectroscopy.
e mechanisms of adsorption of both PVBTAC onto the α-Al 2 O 3 particles and NCC onto the PVBTAC-modified α-Al 2 O 3 particles were discussed based on the FT-IR spectra.
e PVBTAC adsorption and the NCC adsorption were carried out for 2 h at pH 8 and at ionic strength of NaCl 100 and 10 mM, respectively. en, the residuals were collected and dried at 80°C after centrifugation and removal of the water excess. Five spectra of the α-Al 2 O 3 particles, PVBTAC, NCC, PVBTAC-modified α-Al 2 O 3 particles, and NCC-adsorbed-PVBTAC-modified α-Al 2 O 3 particles were recorded from 400 to 4000 cm −1 by an Affinity-1S spectrophotometer (20 scans averaging, Shimadzu, Japan) at room temperature (293 K).  Journal of Analytical Methods in Chemistry α-Al 2 O 3 particles. To modify the α-Al 2 O 3 particles, an initial PVBTAC concentration of 50 ppm was added to the particles of 5 mg mL −1 in the pH range of 4-12 under different ionic strength conditions of 1, 10, and 100 mM NaCl. Figure 2 shows that PVBTAC adsorption capacity (Γ PVBTAC ) increased with increasing pH until pH reached 8, then Γ PVBTAC decreased with continuous increment of the pH.

Results and Discussions
e α-Al 2 O 3 particles were characterized with −O and OH functional groups [19] and an isoelectric point (IEP) of approximately 6.7 [35]. It means that the charging sign of the α-Al 2 O 3 particles changed over the IEP point. At the pH higher than 6.7, the α-Al 2 O 3 particle surface was negatively charged due to the presence of O − groups while PVBTAC was positively charged, independently from the pH level. erefore, the PVBTAC adsorption onto the α-Al 2 O 3 particles was promoted due to electrostatic attractions at the solution pH greater than 6.7. Oppositely, at a pH lower than 6.7, the α-Al 2 O 3 particle surface was positively charged due to appearance of the OH + 2 groups. ese surface groups introduced the strong electrostatic repulsions between PVBTAC molecules and the α-Al 2 O 3 surface, resulting in the limitation of the PVBTAC adsorption. At the solution pH of 8, the Γ PVBTAC achieved maximum value at all ionic strengths. Hence, pH 8 was chosen to be the optimal modification condition.

Ionic Strength Effect.
In addition to the pH effect, the ionic strength is one of the most effective parameters that influences to the adsorption capacity. e electrolyte shielding effect prevents the hydrophilic interactions and promote the hydrophobic interactions [36][37][38]. e Γ PVBTAC on the α-Al 2 O 3 particles was determined at the four NaCl concentrations of 1, 10, 100 and 150 mM at pH 8, PVBTAC initial concentration of 50 ppm, contact time of 2 h and a α-Al 2 O 3 adsorbent dosage of 5 mg mL −1 .
As obviously seen in Figure 3, the Γ PVBTAC increased with increasing the NaCl concentration from 1 to 100 mM and decreases with continuous salt increment. It was subjected to contributions of different interaction kinds on the PVBTAC adsorption such as electrostatic interactions, including electrostatic attraction and electrostatic repulsion, and nonelectrostatic interactions such as hydrogen bonding and Van der Waals. e Van der Waals not only between PVBTAC and the α-Al 2 O 3 particles, but also between PVBTAC molecules, might take responsibility for the Γ PVBTAC increment as the NaCl concentration went up from 1 to 100 mM. On the other hand, the electrolyte ions screened the electrostatic attraction between PVBTAC and the absorbent, the Γ PVBTAC quickly dropped while the NaCl concentration passed 100 mM. A maximum Γ PVBTAC of 3.24 mg g −1 was obtained at NaCl 100 mM. Hence, the ionic strength of 100 mM NaCl was employed to modify the α-Al 2 O 3 surface.

PVBTAC Initial Concentration Effect.
e polycation initial concentration effect on the α-Al 2 O 3 modification efficiency was examined with the PVBTAC initial concentration from 25 to 1000 ppm at pH 8, NaCl 100 mM, contact time of 2 h. As shown in Figure 4, the Γ PVBTAC considerably raised from 2.46 to 37 mg g −1 by increasing the PVBTAC initial concentration in the range of 25-1000 ppm. e results can infer that more PVBTAC molecules were diffused and attached to the α-Al 2 O 3 surface, due to main electrostatic interactions at high PVBTAC initial concentration and vice versa [38]. For the next experiments, the PVBTAC initial concentration of 1000 ppm was used to sufficiently modify the α-Al 2 O 3 surfaces.
Summarily, the α-Al 2 O 3 particle modification through PVBTAC adsorption was optimized at pH 8, ionic strength of 100 mM, contact time of 2 h, and PVBTAC initial concentration of 1000 ppm.

NCC Adsorptive Removal by Using PVBTAC-Modified α-Al 2 O 3 Particles Confirmed by FT-IR Measurement.
e successful α-Al 2 O 3 surface modification by adsorbing polycation PVBTAC, and the NCC dye adsorptive removal through adsorption onto the PVBTAC-modified particles were confirmed based on the changes of functional groups determined by FT-IR spectroscopy. Formerly, the PVBTAC adsorption onto the α-Al 2 O 3 particles was affirmed by comparing the FT-IR spectra of the pure α-Al 2 O 3 particles  Lately, the S � O vibration at 1173 and 1144 cm −1 and the symmetrical −SO 3 stretching vibration at 1040 cm −1 of the NCC molecule disappeared in the PVBTAC-modified α-Al 2 O 3 spectrum [43][44][45]. In addition to that, the R 3 N + -C vibration at 1800-3400 cm −1 and C-N peak at 976 cm −1 of PVBTAC in the spectrum of NCC-adsorbed-PVBTACmodified α-Al 2 O 3 [41,42] were absent, strongly confirming the electrostatic attractions between −SO 3 of NCC and −N + R 3 of PVBTAC. At the optimal pH 8 and NaCl 10 mM, the −OH group in the NCC was partly transferred to OH + 2 as the pK a is 11.38 [46], reducing its total negative charges as well as the electrostatic repulsion between the NCC molecules. We might imply that hydrogen bonding was formed among -OH groups between the NCC molecules because the peak at 3399 cm −1 corresponding to −OH vibration in the NCC molecule, disappeared in the spectrum of NCCadsorbed-PVBTAC-modified α-Al 2 O 3 [16,44].

Ionic Strength Effect.
e removal efficiency of 10 ppm initial NCC concentration was more significantly enhanced by using the PVBTAC-modified α-Al 2 O 3 adsorbents compared with using the unmodified nanosized α-Al 2 O 3 particles at the same ionic strength of 10 mM NaCl and all pH ( Figure 6). e modification of the α-Al 2 O 3 adsorbents by PVBTAC adsorption improved the surface net charge, inducing additional electrostatic attractions between the positively charged PVBTAC covered on the α-Al 2 O 3 surfaces and the negatively charged NCC molecules. Following this, the common effect factors to optimize the NCC removal through adsorbing onto the PVBTAC-modified α-Al 2 O 3 adsorbents were comprehensively investigated.
As represented in Figure 6, two trends of the ionic strength effect on the NCC removal efficiency were observed. First, the ionic strength increment from 0 to 10 mM NaCl impulsed the NCC removal efficiency through adsorption onto the PVBTAC-modified α-Al 2 O 3 particles at all pH. It can be explained that the promotion of the hydrogen bonding, and limitation of electrostatic repulsion between the NCC molecules, due to the condenser presence of electrolyte ions mainly controlled the NCC adsorption. However, the NCC removal efficiency decreased as the salt concentration was higher than 100 mM NaCl. e phenomenon suggested the significant shielding electrolyte ion effect on screening the electrostatic attractions between −N + R 3 of the PVBTAC and −SO 3 − of the dye NCC. It was consistent with our previous findings [36][37][38]. Herein, the NCC removal efficiency strongly depended on the interaction types between the NCC molecules and the PVBTACmodified α-Al 2 O 3 surface. erefore, in all experiments, the ionic strength was controlled at NaCl 10 mM because the removal efficiency of the NCC was up to approximately 96% at almost all pH, and the standard deviation was lowest. Figure 7, the NC removal efficiency, H NCC and the adsorption amount, Γ NCC unremarkably changed with the wide change of pH from 3 to 12. PVBTAC is highly positively charged and independent on pH. Normally, the −OH group of the NCC molecule more becomes −OH + 2 in lower pH, reducing the NCC net negative charge. As a result, the electrostatic attraction between PVBCTAC and NCC is less strong at low pH than at high pH. However, as observed, the OH + 2 formation contribution was negligible at pH lower than pK a of NCC (pK a 11.38) [46]. It is suggested that the NCC net charge was mainly decided by the sulfate groups. On the other hand, at the same salt concentration, the Γ NCC got maximum at pH 8. e NCC removal was carried out at pH 8 and 10 mM NaCl.

Absorbent Dosage Effect.
Normally, the total specific area significantly rises with an increment of absorbent dosage, enhancing more effectively adsorptive removal. e removal efficiency gradually changed from 53.94% to 99.25% with a 12-fold increment of the α-Al 2 O 3 adsorbent dosage from 0.25 to 3 mg mL −1 (Figure 8). en it was noticeably unchanged at the adsorbent dosage over 3 mg mL −1 . Herein, the adsorbent amount of 3 mg mL −1 was sufficient for the adsorptive removal of NCC.

Contact Time Effect.
e contact time effect on the NCC removal efficiency can be clearly observed in Figure 9.
e NCC removal efficiency raised rapidly in each 15 min of the first 30 min. In the contact time range of 30-45 min, the removal efficiency continuously slowly raised from 96.25 to 97.40%. en the removal efficiency was kept constant at the high removal efficiency of about 96% from 45 min to 120 min of the contact time. Accordingly, the NCC adsorption on the PVBTAC-modified α-Al 2 O 3 surface reached an equilibrium state at the contact time of 45 min. erefore, the optimal contact time of 45 min was applied for the next investigation.

NCC Adsorption Isotherm Model.
e fitness of the NCC adsorption on the PVBTAC-modified α-Al 2 O 3 particles with Langmuir, Freundlich and two-step models was examined. It can be seen clearly in Figure 10    gradually raised from about 1.62 to 13.5 mg g −1 as the NCC initial concentration increased from 5 to 600 ppm. A maximum NCC adsorption capacity of 13.5 mg g −1 determined proves that PVBTAC-modified α-Al 2 O 3 was high-performance adsorbents in the NCC removal compared with other materials. e NCC adsorption capacity by using PVBTAC-modified α-Al 2 O 3 particles was higher than using activated carbon as adsorbents (Table 1) [47][48][49]. Moreover, it might suggest that more numerous surface sites were available for NCC adsorption at low NCC initial concentration, intensifying the electrostatic attractions between NCC and adsorbed PVBTAC. Oppositely, the repulsive interactions between the NCC molecules were dominant at high NCC initial concentration. e NCC adsorptive removal only followed the Freundlich model with the fitting parameters calculated as K f of 2.8341 and n of 0.1983 and not adapted with the Langmuir and two-step models ( Figure 10).

NCC Adsorption Kinetics on PVBTAC-Modified α-Al 2 O 3 Particles.
Two kinetic models including pseudofirst and pseudo-second were considered for the NCC adsorption on PVBTAC-modified α-Al 2 O 3 particles, as indicated in Figure 11. e NCC adsorption kinetics on the PVBTAC-modified α-Al 2 O 3 surface were better followed with the pseudo-second model with a higher correlation coefficient (R 2 ) of 0.9964 than the pseudo-first model with a lower R 2 of 0.7972 ( Figure 11). It was proposed that there were some interactions between the adsorbed NCC molecules. In detail, the interactions might be resulted from hydrogen bondings between −OH groups in the NCC suggested by the FT-IR spectra above. e fitted parameters were shown in Table 2. en the concentration of the NCC desorbed was determined by the UV-Vis method at the wavelength of 508 nm. As shown in Figure 12, the NCC desorption efficiency in the first HCl treatment was low. After HCl treatment twice, the NCC adsorption efficiency reached higher than 90% at all HCl concentration. Moreover, the NCC desorption efficiency slightly raised with increasing 2-fold HCl concentration from 1 to 2 M, and reached maximum (approximately 97%) at the HCl higher than 5 M. It was referred to elute almost the NCC from the adsorbent surface. More presence of OH + 2 groups on the particle surface under acidic condition led to stronger electrostatic repulsion between the positively charged PVBTAC and the positively charged α-Al 2 O 3 . As a result, the NCC were desorbed. erefore, the regeneration of the α-Al 2 O 3 adsorbent was carried out twice by using the HCl solution of 5 M. Each procedure of the HCl treatment twice was considered to be a regeneration time. e regeneration treatment of the α-Al 2 O 3 adsorbents with strong acid at high concentration confirmed strong interactions between NCC and PVBTAC-modified surface, and the high synthesized adsorbent stability.

Regeneration of α-Al
Lately, the regenerated α-Al 2 O 3 particles were modified by the PVBTAC adsorption. en the PVBTAC-modifiedregenerated adsorbents were applied to adsorptively remove NCC. It was seen in Figure 13 that the NCC removal efficiency by using PVBTAC-modified-regenerated adsorbents decreased with rising the regeneration time. However, the NCC removal efficiency, achieved about 53% after four regeneration times, still was high. It was clarified that high reusability of the α-Al 2 O 3 adsorbents.    Figure 11: Kinetics of the PVBTAC adsorption isotherm on the α-Al 2 O 3 particles following (a) pseudo-first and (b) pseudo-second at conditions of C i, NCC of 10 ppm, pH 8, NaCl 10 mM, and m α-Al2O3 of 3 mg mL −1 . Table 2: Fitting parameters for the NCC adsorption onto the PVBTAC-modified α-Al 2 O 3 particles following the pseudo-first and pseudo-second kinetic.

Conclusions
In the present study, it was the first time the azo dye NCC was highly adsorptively removed from aqueous solutions by using the PVBTAC polycation-modified α-Al 2 O 3 particles. Both PVBTAC adsorption and NCC adsorption were comprehensively investigated. To sufficiently modify the α-Al 2 O 3 particles, polycations PVBTAC of 1000 ppm initial concentration were adsorbed onto α-Al 2 O 3 for 2 h at pH 8 under ionic strength of NaCl 100 mM. en, the NCC adsorption on the PVBTAC-modified α-Al 2 O 3 particles was optimized at conditions including pH 8, NaCl 10 mM, contact time of 45 min, and an α-Al 2 O 3 dosage of 3 mg g −1 .
e adsorption of both PVBTAC and NCC was controlled by the electrostatic and non-interaction that also affirmed by the FT-IR spectra. e mechanism and kinetics of the NCC adsorption isotherm onto the PVBTAC-modified α-Al 2 O 3 particles were clarified. e NCC adsorption isotherm mechanism was in accordance with the Freundlich model, while the NCC adsorption kinetics was more suitably followed by the pseudo-second than the pseudo-first model. e nanosized alpha alumina was proved to be a highly reusable adsorbent.

Data Availability
All the data and supporting materials are included within the article.

Conflicts of Interest
All authors declare that there are no conflicts of interest regarding the publication of this paper. Journal of Analytical Methods in Chemistry 9