Synergistic effect of the presence of suspended and dissolved matter on the removal of cyanide from coking wastewater by TiO₂ photocatalysis

Abstract

This study assesses the influence of the presence of suspended and dissolved matter on the efficiency of TiO photocatalysis for the removal of cyanide from coking wastewater. Photocatalytic processes were carried out at basic pH (pH 9) with titanium dioxide (1 g/L), artificial radiation (290-800 nm) and during different time periods (20-100 min). The first assays applied in aqueous solutions achieved promising results in terms of removing cyanide. The maximum cyanide removal obtained in coking wastewater was 89% after 80 min of irradiation in the presence of suspended and dissolved matter. The presence of suspended matter composed of coal improves the efficiency of the photocatalytic process due to the synergistic effect between carbon and TiO. The absence of dissolved matter also improves the process due to the minimization of the hydroxyl radical scavenging effect produced by carbonate and bicarbonate ions. On the other hand, the presence of certain species in the real matrix such as silicon increases the activity of the titanium dioxide catalyst. In consequence, the improvement achieved by the photocatalytic process for the removal of cyanide in the absence of dissolved matter is counteracted.

Enhanced photocatalytic efficiency of layered CdS/CdSe heterostructures: Insights from first principles electronic structure calculations

“…Most of the significant developments in this area are mainly based on titanium dioxide (TiO 2 ), which exhibits strong redox potential and excellent photocatalytic activity. However, a wide band gap of 3.2 eV in this material hinders its applicability as it can only be driven through UV light radiation which is only 3% of solar spectrum [5,[8][9][10][11][12][13][14]. Therefore designing and investigation of efficient visible light responsive materials for photocatalytic activity has attracted researcher with a considerable attention from the viewpoint of cost, availability and environmental friendliness [15][16][17][18][19][20].…”

Synthesis of Si, N co-Doped Nano-Sized TiO2 with High Thermal Stability and Photocatalytic Activity by Mechanochemical Method

“…The strong and increasing presence of organic contaminants currently in the environment leads to many studies about photocatalytic degradation of photocatalytic materials. Titanium dioxide (TiO 2 ) is a very popular material in such applications and it owes its existence to its non-toxicity, high chemical stability, low cost, and good optoelectronic properties [ 1 , 2 , 3 , 4 , 5 ]. Anatase, which is one of the mineral forms of TiO 2 , is more active under ultraviolet (UV) light irradiation than the other TiO 2 crystalline phases such as brookite and rutile [ 6 , 7 , 8 ].…”

Nanomaterial híbrido (TiO2-MWCNT): Síntese, Caracterização e Ecotoxicidade aquática

“…O princípio dos POAs é o uso de um semicondutor como fotocatalisador (ex. TiO2), para produzir radicais hidroxilas em água, sendo este um oxidante muito poderoso, capaz de oxidar uma ampla gama de compostos orgânicos (DAGHRIR; DROGUI; ROBERT, 2013).Atualmente, o processo fotocatalítico, utilizando o TiO2, sob irradiação ultravioleta (UV) tem sido extensivamente aplicado para a oxidação de vários poluentes orgânicos e inorgânicos(CHATTERJEE;DASGUPTA, 2005;FUJISHIMA;ZHANG, 2006;BINAS;VENIERI;KOTZIAS, 2017;PUEYO et al, 2017).Figura 10 -Mecanismo proposto para a atividade fotocatalítica do nanomaterial hibrido TiO2-MWCNT Fonte: Do autor. A síntese de nanomateriais híbridos, como o TiO2-MWCNT pode ser feita a partir de dois métodos de funcionalização: covalente e não covalente.…”