Functionalized Cellulose for the Controlled Synthesis of Novel Carbon-Ti Nanocomposites: Physicochemical and Photocatalytic Properties.

Hesham Hamad,Esther Bailón-García,Agustín F Pérez-Cadenas,Sergio Morales-Torres,Francisco Carrasco-Marín,Francisco J Maldonado-Hódar

doi:10.3390/nano10040729

Abstract

Carbon–Ti nanocomposites were prepared by a controlled two-step method using microcrystalline cellulose as a raw material. The synthesis procedure involves the solubilization of cellulose by an acid treatment (H3PO4 or HNO3) and the impregnation with the Ti precursor followed of a carbonization step at 500 or 800 °C. The type of acid treatment leads to a different functionalization of cellulose with phosphorus- or oxygen-containing surface groups, which are able to control the load, dispersion and crystalline phase of Ti during the composite preparation. Thus, phosphorus functionalities lead to amorphous carbon–Ti composites at 500 °C, while TiP2O7 crystals are formed when prepared at 800 °C. On the contrary, oxygenated groups induce the formation of TiO2 rutile at an unusually low temperature (500 °C), while an increase of carbonization temperature promotes a progressive crystal growth. The removal of Orange G (OG) azo dye in aqueous solution, as target pollutant, was used to determine the adsorptive and photocatalytic efficiencies, with all composites being more active than the benchmark TiO2 material (Degussa P25). Carbon–Ti nanocomposites with a developed micro-mesoporosity, reduced band gap and TiO2 rutile phase were the most active in the photodegradation of OG under ultraviolet irradiation.

Highlights

The occurrence of organic contaminants at very low levels in different water sources, including drinking water, has emerged as a global concern
Azo dyes represent about 70% of the synthetic chemical dyes and possess a relatively stable chemical structure [1], composed by aromatic rings, which confer them with carcinogenic and mutagenic properties [2]. Effluents containing this contaminant need to be treated by advanced oxidation processes (AOPs), because conventional treatments used in municipal wastewater treatment plants (MWWTPs) are not completely efficient for their removal
Microcrystalline cellulose (MCC) and titanium (IV) isopropoxide (TTIP) were purchased from Merck (Darmstadt, Germany), while o-phosphoric acid (85% w/w), nitric acid (70% w/w) and heptane were acquired from VWR chemicals (Leuven, Belgium)

Summary

Introduction

The occurrence of organic contaminants at very low levels in different water sources, including drinking water, has emerged as a global concern. Azo dyes represent about 70% of the synthetic chemical dyes and possess a relatively stable chemical structure [1], composed by aromatic rings, which confer them with carcinogenic and mutagenic properties [2]. Effluents containing this contaminant need to be treated by advanced oxidation processes (AOPs), because conventional treatments used in municipal wastewater treatment plants (MWWTPs) are not completely efficient for their removal. Its practical application is severely compromised by the low quantum yield and the poor light-harvesting ability as consequence of its wide band gap (i.e., 3.2 or 3.0 eV for anatase or rutile phases, respectively) [7]

Objectives

Methods

Results

Conclusion