Biochar Nanoparticles over TiO2 Nanotube Arrays: A Green Co-Catalyst to Boost the Photocatalytic Degradation of Organic Pollutants

Abstract

Biochar nanoparticles (BC NPs), produced by low temperature pyrolysis (350 °C) of microalgae (Nannochloropsis sp.) and nutshells, are proposed as low-cost and sustainable co-catalysts to promote the photocatalytic activity of TiO2 nanotube (NT) arrays towards the degradation of methylene blue (MB) used as an organic pollutant model molecule. BC NPs (size < 25 nm) were obtained by treating bulk BC (i.e., biomass after pyrolysis) by sonication–centrifugation cycles in a water solution. The filtered BC NPs dispersion was deposited by simple drop-casting on the TiO2 NT support. The BC loading was varied by performing multiple depositions. Photocatalytic experiments under UV light (365 nm) revealed that the decoration with BC NPs significantly improves the TiO2 photoactivity. Such enhancement is mainly influenced by the amount of BC deposited; upon optimizing the BC deposition conditions, the rate of photocatalytic degradation of MB increases approximately three times with respect to bare TiO2, almost irrespective of the nature of the raw material. The greater photocatalytic activity of BC-TiO2 can be attributed to the synergistic combination of reactant/product adsorption and catalytic degradation of the adsorbed organic pollutant, as well as an improved charge carrier separation and electron transfer.

Solvothermal Synthesis of ZnO Nanoparticles for Photocatalytic Degradation of Methyl Orange and p-Nitrophenol

“…When the catalyst dose was 2.0 g/L, the photodegradation rate of PNP decreased with an increasing catalyst amount. In this paper, the pseudo-first-order and pseudo-second-order kinetics models were used to evaluate the degradation kinetics of MO and PNP with different doses of ZnO NPs [25]. The kinetics equations were as follows:…”

“…In this paper, the pseudo-first-order and pseudo-second-order kinetics models were used to evaluate the degradation kinetics of MO and PNP with different doses of ZnO NPs [25]. The kinetics equations were as follows:…”

Removing the Oxamyl from Aqueous Solution by a Green Synthesized HTiO2@AC/SiO2 Nanocomposite: Combined Effects of Adsorption and Photocatalysis

“…Moreover, TiO2 doping, metal coating, surface sensitization, and support (immobilization by increasing the illuminated specific catalyst area [14]) are increasingly used to improve the photocatalytic response [12]. Moreover, attempts to employ an adsorbent such as silica, alumina, zeolite, or activated carbon have previously been made [13].…”

Preparation of TiO2/Black Talc Composite Photocatalyst and the Research on Its Adsorption-Degradation Coupling Effects

“…Non-metallic minerals, such as diatomite, zeolite, and sepiolite, have been widely used as carriers [22,23] due to their low cost, excellent stability, and large specific area. Biochar, such as biomass bamboo fiber [24], macroalgae [25], coconut shell biochar [26], microalgae, and nut shells [27], has also been shown to promote the catalytic effect of photocatalysts and enhance the adsorption of organic molecules [28]. Pinna et al [27] produced a biochar-decorated TiO 2 photocatalyst through a simple drop casting method.…”

“…Biochar, such as biomass bamboo fiber [24], macroalgae [25], coconut shell biochar [26], microalgae, and nut shells [27], has also been shown to promote the catalytic effect of photocatalysts and enhance the adsorption of organic molecules [28]. Pinna et al [27] produced a biochar-decorated TiO 2 photocatalyst through a simple drop casting method. The composite Biochar -TiO 2 material has a better catalytic effect than pure titanium dioxide, which proves that BC NPs have the ability to act as a promoter.…”