Adsorptive Removal of Anionic Azo Dye New Coccine Using Silica and Silica-gel with Surface Modification by Polycation.

Tien Duc Pham,Van Hoi Bui,Kim Thuy Nguyen,Viet Phuong Bui,The Dung Nguyen,Thi Mai Dung Le,Thuy Nga Pham

doi:10.3390/polym13101536

Abstract

In the present work, adsorption of anionic azo dye, new coccine (NCC) on silica and silica-gel in an aquatic environment was discovered. Effective conditions such as adsorption time, pH, the influence of dosage on NCC adsorption using strong polycation, poly-diallyl-dimethylammonium chloride (PDADMAC) modified silica (PMS) and PDADMAC modified silica-gel (PMSG) were systematically studied. The removal of NCC using PMS and PMSG were much higher than that using raw silica and silica-gel without PDADMAC in all pH ranges from 3 to 10. The adsorption of NCC onto PMS and PMSG was achieved maxima at the same conditions of contact time 30 min, pH 6. The optimum adsorbent dosages of PMS and PMSG for NCC removal were 10 and 20 mg·mL−1, respectively. Experimental results of NCC adsorption isotherms onto PMS and PMSG at different ionic strength were fitted by Langmuir and Freundlich models. The NCC removal efficiencies using PMS and PMSG were higher than 87%, indicating that PMS and PMSG are novel and reusable adsorbents for removal of anionic dye. Based on adsorption isotherms, and surface group changes after PDADMAC modification and NCC adsorption examined by Fourier transform infrared spectroscopy (FTIR), we demonstrate that electrostatic interaction between positively charged adsorbents’ surfaces and negative sulfonic groups of NCC are the main driving force for anionic azo dye adsorption onto PMS and PMGS adsorbents.

Highlights

Dyes are important chemicals for many industrial activities related to textiles, paper, cosmetics, paint, etc
Various hybridized materials have been investigated for removal of dye through adsorption techniques, such as nanofibrous membrane [18] or porous g-C3N4 nanosheet [19]
High purity silica-gel with a diameter of about 50 μm was calcinated at 800 ◦C to form silica

Summary

Introduction

Dyes are important chemicals for many industrial activities related to textiles, paper, cosmetics, paint, etc. Different techniques have been investigated and further developed for treatment to remove dyes from aqueous solution [3,4], such as photocatalysis [5,6,7], advanced oxidation [8,9], flocculation and coagulation [10], biological processes [11], and adsorption [12,13,14,15]. Adsorption is one of the most suitable and effective methods for dye removal when using low-cost adsorbents such as minerals, clays or agricultural subproducts [2,16,17]. Various hybridized materials have been investigated for removal of dye through adsorption techniques, such as nanofibrous membrane [18] or porous g-C3N4 nanosheet [19]. In order to produce novel adsorbents, materials can be modified by surface coating [20] or pre-adsorption with active chemical agents [21]

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Conclusion