Dual functionality of malt bagasse-based carbonaceous material for obtaining carbon dots and adsorbent: removing and...

Malt bagasse was used as a precursor to produce a carbonaceous material (CM) with dual functionality: adsorbing tetracycline (TC) from aqueous solutions and serving as raw material for carbon dots (CDs) capable of detecting TC qualitatively. A 2³ experimental design evaluated the effects of temperature (200-500 °C), heating rate (2-8 °C/min), and carbonization time (30-180 min) on the adsorption capacity of CM and the quantum yield of CDs. Adsorption capacity was evaluated in an aqueous solution of tetracycline (30 mg/L) and 1 g/L of CM. The use of CD as a qualitative sensor was studied in TC solutions (30 μM), based on the comparison of the areas under the fluorescence spectrum between samples with and without the antibiotic. Temperature was the most significant factor, followed by carbonization time. The material obtained at 350 °C for 30 min with a heating rate of 5 °C/min had a TC adsorption capacity of 7.0 mg/g ± 0.6 mg/g and a quantum yield ranging from 4.90% to 7.62%. These samples also achieved TC detection above 58%. This material had a heterogeneous mesoporous structure, with low graphitization and a greater presence of defects and/or disorder. Additionally, the CD particles exhibit an almost spherical morphology and good dispersion, with an average diameter ranging between 1 nm and 3 nm. These results demonstrate the innovative use of malt bagasse as a precursor for multi-functional carbonaceous materials. The results highlight the potential of lignocellulosic biomass as a versatile and sustainable resource for environmental applications, paving the way for future advances in integrated pollutant management strategies.