Abstract

The combination of adsorption and photodegradation processes is an effective technique for the removal of dye contaminants from water, which is motivating the development of novel adsorbent-photocatalyst materials for wastewater treatment. Herein, novel nanocomposite porous beads were developed using titanium dioxide (TiO2) nanotubes embedded in a sodium alginate (SA)/polyvinylpyrrolidone (PVP) matrix using calcium chloride solution as a crosslinker. The prepared nanocomposite beads’ performance was examined as an adsorbent-photocatalyst for the breakdown of methylene blue in aqueous solutions. Several operation factors influencing the dye decomposition process, including photocatalyst dosage, illumination time, light intensity, and stability were investigated. The findings demonstrated that the removal activity of the beads changed with the TiO2 weight ratio in the composite. It was found that SA/PVP/TiO2-3 nanocomposite beads presented the greatest deterioration efficiency for methylene blue dye (98.9%). The cycling ability and reusability of the prepared SA/PVP/TiO2 nanocomposite beads recommend their use as efficient, eco-friendly materials for the treatment of wastewaters contaminated with cationic dyes.

Highlights

  • The release of dye-contaminated wastewaters from different industries [1] into the environment leads to dramatic effects on the living life of our planet, as dyes and their sub-products are often toxic or mutagenic agents [2]

  • Sodium alginate (SA), polyvinylpyrrolidone (PVP), and titanium (IV) dioxide rutile powder (TiO2,

  • Under illumination of an unfiltered commercial LED visible light, tw 1 g L−1 of the sodium alginate (SA)/PVP/TiO2 nanocomposite beads was suspended in methylene blue (MB) dye solution

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Summary

Introduction

The release of dye-contaminated wastewaters from different industries [1] into the environment leads to dramatic effects on the living life of our planet, as dyes and their sub-products are often toxic or mutagenic agents [2]. By using cross-linked sodium alginate (SA) with TiO2 , forming a SA–TiO2 hydrogel, an adsorption efficiency for methyl violet dye of 99.6% was reported, whereas SA-based film only achieved 85%. This effect was attributed to the electrostatic attraction between the methyl violet dye and TiO2 , which behaves as an anionic center in the hybrid hydrogel [15]. SA is suitable for chemical modification and can be shaped as hydrogel beads by cross-linking the α-L-guluronic acid units with poly- or divalent cations [17,18] It is frequently employed as a polymeric matrix that can support catalysts [10]. TiO2 nanoparticles, which cause secondary pollution in the water treatment process

Preparation of Polymeric Beads
Characterization
Discussion
The band at about 500 for the
Adsorption and Photocatalytic Removal of MB
Effect of Illumination Time on the Decay of MB
Effect of two Intensity on MB
Effect of the MB Dye Initial Concentration on its Photocatalytic Decay
Reaction
Kinetic Models
Conclusions
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