Mg–Al-Layered Double Hydroxide (LDH) Modified Diatoms for Highly Efficient Removal of Congo Red from Aqueous Solution

Ganesan Sriram,U T Uthappa,Madhuprasad Kigga,Dusan Losic,Mahaveer D Kurkuri,Ho-Young Jung

doi:10.3390/app10072285

Ganesan Sriram, U T Uthappa + Show 4 more

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https://doi.org/10.3390/app10072285

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Abstract

In this work, diatomaceous earth (DE) or diatoms are modified with Mg–Al-layered double hydroxide (DE-LDH) using the facile co-precipitation method to demonstrate their application for the removal of toxic dyes such as Congo Red (CR), which was used as a model. Field emission scanning electron microscopy (FE-SEM) characterization confirms the successful modification of diatom microcapsules structures, showing their surface decorated with LDH nano patches with sheet-like morphologies. The surface area of the DE was enhanced from 28 to 51 m2/g after modification with LDH. The adsorption studies showed that the maximum CR removal efficiency of DE and DE-LDH was ~15% and ~98%, respectively at pH 7, which is a significant improvement compared with unmodified DE. The maximum adsorption capacities of DE-LDH were improved ten times (305.8 mg/g) compared with the bare DE (23.2 mg/g), showing very high adsorption performances. The recyclability study of DE-LDH up to five cycles, after desorbing CR either by methanol or by NaOH, showed the efficient removal of the CR by up to three cycles via adsorption. The presented study suggests the promising application of DE-LDH as an effective material for application in the removal of CR from aqueous solutions for industrial wastewater treatment.

Highlights

The purity of water, due to extensive industrialization, urbanization and agriculture, is critically diminished in many countries due contaminations by dye-based industries such as textiles, paint, plastics, paper, leather and so on
We present a new concept to modify diatomaceous earth (DE) material with Mg–Al-layered double hydroxide (DE-Layered double hydroxide (LDH)) to enhance the dye removal efficiency and adsorption capacity of DE
This study reveals that the reusability of diatoms are modified with Mg–Al-layered double hydroxide (DE-LDH) is capable for up to two to threeis capable to two toof three cycles desorbing for the adsorption of CRwith

Summary

Introduction

The purity of water, due to extensive industrialization, urbanization and agriculture, is critically diminished in many countries due contaminations by dye-based industries such as textiles, paint, plastics, paper, leather and so on. The dye-contaminated wastewater should be treated and dyes removed before releasing it into the environment or reusing it. Among many dyes used in these industries, water-soluble Congo Red (CR) is hazardous and used at high concentrations in textile and biochemistry based industries [1]. This benzidine based dye is very toxic, highly carcinogenic and can lead to serious health issues such as diarrhoea, vomiting and nausea [2].

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