In this study, the efficiency of biochar (BC) produced from sugarcane bagasse at different pyrolysis temperatures (300, 400, 500 and 600 ºC) for simultaneous removal of CdII, PbII, CuII, CrIII, NiII and ZnII ions from aqueous solutions was assessed. All BC were characterized using scanning electron microscopy (SEM), Fourier transform infrared (FTIR), 13C nuclear magnetic resonance (13C NMR) and pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS). The effects of pyrolysis temperature, initial adsorbate concentration and adsorbent dosage on adorption capacity of BC were examined through batch experiments. The BC efficiency was also evaluated after a desorption cycle. The maximal adsorptions (CdII: 51.50%, CrIII: 74.35%, CuII: 91.18%, NiII: 47.05%, PbII: 96.17% and ZnII: 40.50%) were observed for BC produced at 500 ºC, probably because of its higher porosity and presence of functional groups detected by SEM and FTIR. The maximum adsorption capacity for CdII, CrIII, CuII, NiII and ZnII (ions fitted to Langmuir model) were 175, 303, 455, 156 and 128 µg g-1, respectively. The predominance of phenolic groups observed in Py-GC-MS data may explain the high percentage of multi-element removal. Experimental data were best fitted to pseudo-second order, Sips and Freundlich models. The BC presented good removal results after a desorption cycle.

The biofuel properties of biomass play an important role in achieving their utilization on agro-systems and industries. In this context the biomass waste of maize, corncob husk, and its biochars were taken into account to be investigated by thermogravimetric analysis, thermodynamic parameters for non-isothermal analyses using the Ozawa-Flynn-Wall kinetic isoconversional model in order to comprehend its possible fuels features. It was also investigated the compounds generated after pyrolysis and their relation with oxidation reactions for the safe-handling and storage. It was found that corncob husk biochar produced at 300 °C shows the best qualities as a solid biofuel, since it requires less energy input through pyrolysis to be produced. Finally, analysing the compounds generated and remained on the biochar’s surface, by Fourier transform infrared spectroscopy (FTIR) analysis, biochars produced at low temperatures present one of the lowest features prone to oxidation reactions.

Atomic force spectroscopy, a technique derived from Atomic Force Microscopy (AFM), allowed us to distinguish nonspecific and specific interactions between the acetolactate synthase enzyme (ALS) and anti-atrazine antibody biomolecules and the herbicides imazaquin, metsulfuron-methyl and atrazine. The presence of specific interactions increased the adhesion force (Fadh) between the AFM tip and the herbicides, which made the modified tip a powerful biosensor. Increases of approximately 132% and 145% in the Fadh values were observed when a tip functionalized with ALS was used to detect imazaquin and metsulfuron-methyl, respectively. The presence of specific interactions between the atrazine and the anti-atrazine antibody also caused an increase in the Fadh values (approximately 175%) compared to those observed when using an unfunctionalized tip. The molecular modeling results obtained with the ALS enzyme suggest that the orientation of the biomolecule on the tip surface could be suitable for allowing interaction with the herbicides imazaquin and metsulfuron-methyl.