Synthesis and characterization of Zr(IV) doped immobilized cross-linked chitosan/perlite composite for acid orange II adsorption

https://doi.org/10.1016/j.ijbiomac.2018.06.065Get rights and content

Highlights

  • A novel adsorbent, zirconium(IV)-immobilized cross-linked chitosan/perlite was synthesized.

  • Characterization of the samples was done by using XRD, FTIR and SEM analysis.

  • Adsorption mechanism and adsorption capacity of Zr(IV)-CS-PT composite was investigated.

Abstract

To enhance the adsorption capacity of chitosan for acid orange II (AOII) adsorption, a novel adsorbent, zirconium(IV) doped immobilized cross-linked chitosan/perlite (Zr(IV)-CS-PT) composite was synthesized and characterized. Batch studies were conducted to analyze the effect of different parameters on AOII adsorption, such as Zr (IV) loading amount, pH, adsorbent dosage and temperature. Also, kinetic data revealed that AOII adsorption was well described by pseudo-second order kinetic model. Langmuir adsorption isotherm model was best described the isotherm data and maximum adsorption capacity was found 476.2 mg/g at natural pH. The thermodynamic data showed that the AOII adsorption occurred spontaneously and endothermic nature. Desorption and recycle experiments showed that after six cycle the adsorption efficiency was decreased from 95.6% to 90.1%, which shows the Zr(IV)-CS-PT is a reusable, cost-effective and high adsorption capacity adsorbent.

Introduction

Synthetic dyes have been used in industries such as cosmetic, pharmaceutical, textile, leather, plastics, etc. Discharge of the dye effluents pollutes the aquatic systems. The synthetic dyes include complex aromatic molecules in their structures, such as benzene, toluene, xylene, etc., which makes them more stable and more difficult to biodegrade [1]. Azo dyes are the most popular dyes which contains one or more azo group(single bondNdouble bondNsingle bond). Azo dyes are highly toxic and carcinogenic; therefore, wastewaters containing dyes is one of the most important environmental problem [2].

Removal of dyes from wastewater was studied by using several methods such as chemical degradation, photocatalysis, coagulation, sorption, etc. [[3], [4], [5]]. Adsorption is one of the efficient and cost-effective method for the dye removal. Zeolite, chitosan, biomass are the some of the materials that were used for dye adsorption [[6], [7], [8], [9]]. Chitosan is an abundant biopolymer, which is nontoxic, biodegradable material and also has high adsorption capacity. Numerous studies have investigated the immobilization of chitosan using clay minerals for removal of dyes or heavy metals [[10], [11], [12], [13], [14]]. To increase the adsorption capacity of chitosan was modified with various metal ions such as iron [[15], [16]] and zirconium [[17], [18], [19], [20], [21]]. Zirconium is a nontoxic, biologically inert material and has high ion-exchange capacity. In the literature, there is only one research about AOII adsorption onto Zr(IV)-chitosan [22]. They found the maximum adsorption capacity was 926 mg/g using 0.2 g L−1 solid/liquid ratio. AOII was chosen as adsorbate in this study. AOII is an acidic dye, which contains an azo group, a sulfonated group and two aromatic rings. As a result of industrial applications, AOII is released into the aquatic system and causes serious environmental problems. Therefore, highly effective adsorbent, Zr(IV)-CS-PT, was synthesized. The novel adsorbent was characterized and the adsorption capacity was evaluated. The effects of experimental conditions such as solution pH, contact time and temperature on adsorption were investigated in batch system. Furthermore, the regeneration of Zr(IV)-CS-PT was also investigated using multicycle adsorption/desorption tests.

Section snippets

Materials

Chitosan was obtained from Sigma Aldrich with a degree of deacetylation of 91% and medium molecular weight. Zirconium oxychloride octahydrate (analytical grade) was purchased from Sigma-Aldrich. Gluteraldehyde was purchased from Merck. Acid Orange II (C16H11N2NaO4S, purity>99%) was obtained from Sigma-Aldrich. All the reagents used in this study were of analytical grades.

Synthesis of zirconium(IV) doped immobilized cross-linked chitosan/perlite composite

2.0 g chitosan was dissolved in 100 mL of 2% (v/v) acetic acid aqueous solution. 0.30 M ZrOCl2·8H2O solution was prepared by

Characterization of the Zr(IV)-CS-PT composite

The XRD spectra of CS-PT, Zr(IV)-CS-PT and AOII adsorbed Zr(IV)-CS-PT were shown in Fig. 1. The spectra from 2θ = 17o to 2θ = 37o corresponds amorphous nature of perlite [23]. The peak at 2θ = 27o in CS-PT showed the crystalline structure of CS. After CS-PT interacted with Zr(IV), the XRD pattern of Zr(IV)-CS-PT showed that the typical peak of CS shifted from 2θ = 27o to 2θ = 26o which indicates the intercalation of Zr(IV) into CS-PT structure by changing the symmetry of the clay mineral. The

Conclusions

In this work, a novel composite, Zr(IV)-CS-PT, was prepared and characterized for AOII adsorption. Adsorption capacity of Zr(IV)-CS-PT was compared with pure CS, Zr(IV)-CS and CS-PT and found the Zr(IV) loaded CS-PT had the highest adsorption capacity. Also, AOII adsorption capacity of Zr(IV)-CS-PT effected from temperature raising. From thermodynamic data and isotherm data, it was found that increasing of the temperature was resulted with an increase in adsorption capacity and the adsorption

References (26)

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