Original nanostructured bacterial cellulose/pyrite composite: Photocatalytic application in advanced oxidation processes

The development of an original catalytic composite of bacterial cellulose (BC) and pyrite (FeS2) for environ-mental application was the objective of this study. Nanoparticles of the FeS2 were synthesized from the hy-drothermal method and immobilized on the BC structure using ex situ methodology. In the BC, the FTIR and XRD analyzes showed the absorption band associated with the Fe-S bond and crystalline peaks attributed to the pyrite. Thus, the immobilization of the iron particles on the biopolymer was proven, producing the composite BC/FeS2. The use of the SEM technique also ratifies the composite production by identifying the fibrillar structure morphology of the cellulose covered by FeS2 particles. The total iron concentration was 54.76 +/- 1.69 mg L-1, determined by flame atomic absorption analysis. TG analysis and degradation tests showed respectively the thermal stability of the new material and its high catalytic potential. A multi-component solution of textile dyes was used as the matrix to be treated via advanced oxidative processes. The composite acted as the catalyst for the Fenton and photo-Fenton processes, with degradations of 52.87 and 96.82%, respectively. The material proved stability by showing low iron leaching (2.02 +/- 0.09 and 2.11 +/- 0.11 mg L-1 for the respective processes). Thus, its high potential for reuse is presumed, given the remaining concentration of this metal in the BC. The results showed that the BC/FeS2 composite is suitable to solve the problems associated with using catalysts in suspension form.

Automated summary

The study aimed to develop an original catalytic composite of bacterial cellulose (BC) and pyrite (FeS2) for environmental application. FeS2 nanoparticles were synthesized and immobilized on the BC structure. The FTIR and XRD analyzes confirmed the presence of Fe-S bonds and pyrite peaks in BC, indicating successful immobilization. SEM analysis showed the morphology of cellulose covered by FeS2 particles, further confirming the composite production.