This study describes the synthesis of an innovative nanomaterial composed of cobalt ferrite functionalized in niobium pentoxide CoFe2O4@Nb2O5 synthesized by green synthesis using tangerine peel extract. The material values the combination of a magnetic material (which allows easy recovery after application) with niobium pentoxide (whose metal is abundant in Brazilian territory).
The first step to obtaining the catalyst is drying the tangerine peels in drying oven at 80 °C for 18 h. Sequentially, the tangerine peels were crushed in an analytical mill and sieved. To obtain the tangerine peels extract the following methodology was optimized, using an analytical balance, 4.0 g of crushed tangerine peels were placed in a round-bottom flask with 100 mL of distilled water, which was placed under magnetic stirring at room temperature for 3 h. After, the temperature was increased to 60 °C for 1 h, the dispersion further centrifuged at 4000 rpm for 5 minutes, to separate the tangerine peels from the supernatant. Finally, the obtained extract solution was stored in a freezer until use.
On the second step, the cobalt ferrite functionalized catalysts in niobium pentoxide (CoFe2O4@Nb2O5) have been synthesized. The salts Fe3+ (11.4 mmol) and Co2+ (5.7 mmol) were weighted in a Erlenmeyer. After were added 25 mL of tangerine peels extract, the resultant solution showing immediately black color. The Erlenmeyer was stirred in the shaker at 200 rpm, 25 °C for 15 minutes. So, niobium pentoxide was weighted and added in the Erlenmeyer and the mixture was stirred more 15 minutes under the same conditions. In sequence, the mixture was transferred to a porcelain crucible, which stayed in a drying oven for 4.5 hours at 100 °C, until forming a gel. Finally, the porcelain crucible with the gel was placed in a calcination furnace with a heating ramp until 600 °C. After calcination, the resulting material in the porcelain crucible is cobalt ferrite functionalized in niobium, CFNb (CoFe2O4@Nb2O5)
Besides the magnetic properties, the type of synthesis created has several advantages over other types of synthesis already reported in literature. Among the advantages can be highlighted: Utilization of biomass,
namely fruit peels; Extract production using only distilled water as a solvent and low temperatures; Incorporation of the niobium pentoxide support in the same stage of synthesis of cobalt ferrite; High support incorporation compared to other methods, without losing or decreasing the magnetic properties of cobalt ferrite; Added-value to a raw material abundant in Brazilian territory, Nb; Low cost synthesis, using common equipment of laboratory, and relatively low cost.
The nanomaterial in question is being optimized for the degradation of emerging pollutants (i.e. paracetamol, ibuprofen, salicylic acid), but preliminary tests indicated that the CoFe2O4@Nb5O2 nanocatalysts were efficient in the degradation of Paracetamol (up to 99% degradation), showing better results under conditions of pH 1.0, catalyst concentration 103 mg.L-1, under irradiation of the 250 W mercury vapor lamp (greater than 28 mW /cm²) at 240 minutes of the reaction.
Audience Take Away:
- Other faculty could use this research to expand their research or teaching on synthesis of magnetic nanocatalysts;
- This research offers a practical solution for recovering the nanocatalyst after use (with a magnet), allowing its reuse;
- It is possible to obtain the material with few resources, allowing its reproducibility.