Influence of feedstock and operational conditions on bio-chars derived from the pyrolysis of selected biomasses

The proprieties of bio-char, the solid product from biomass pyrolysis, depends on both the feedstock and process conditions during thermochemical conversion[1]. As regards the interaction of the char with soil (i.e. as soil amendment), surface areas, size and shape of pores are among the most important factors to be considered. [1] P. R. Bonelli , G. Nunell , M. E. Fernández , E. L. Buonomo & A. L. Cukierman (2012) The Potential Applications of the Bio-char Derived from the Pyrolysis of an Agro-industrial Waste. Effects of Temperature and Acid-pretreatment, Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 34:8, 746-755, DOI: 10.1080/15567031003681937 Please click Additional Files below to see the full abstract

Biochar from lab-scale pyrolysis: influence of feedstock and operational temperature

AbstractBiochar properties are highly dependent on the feedstock type and operational conditions during thermochemical processing, in particular slow pyrolysis. To clarify this aspect, nine biochars were produced by pyrolyzing in a macro TGA at 400, 550, and 650 °C three different decorticated and chopped biomasses. The studied biomasses are representative of conifer (black pine) and deciduous (poplar and willow) woods. Biochar surface area, size, and shape of pores were investigated by means of nitrogen adsorption isotherm, Hg porosimetry, and electron microscopy. The results indicate that biochars with high surface area can be obtained at high temperature, especially starting from pine feedstock. Regarding porosity, micro-pores (1–10 nm) are not remarkably affected by the starting feedstocks, while macro-pores (> 10 nm) are strictly connected with the morphology of the starting wood. More than the surface area, we found a strong correlation between the chemical composition (elemental composition and FTIR) of the biochars and their retention and release capacity of ions (cation exchange capacity, CEC). The trend in the CEC, determined via coupled approach by spectrophotometric and ion chromatography, reveals that the increase in the processing temperature has the effect of reducing the number of functional groups able of exchanging the cations with the equilibrium solution. This work represents a step forward in the characterization of the char produced by pyrolysis of biomass thanks to the development of a multi-technique approach allowing to obtain a structure-property correlation of the biochars. Our results and experimental approach can help in the optimization of the parameters used in the preparation of these materials.Graphical abstrac

New fluorescent reporters capable of Ultra-sensitively detecting trinitrotoluene on surfaces: A proof-of-concept for finding hidden nitroaromatics in the workroom

We describe the proof of concept of a portable testing setup for the detection of trinitrotoluene (TNT), a common component in hidden explosive devices. The system allows for field-testing and generation of real-time results to test for TNT traces in surfaces by simply using a filter paper and a fluorescent reporter. In this way, the controlled trapping and detection of the analyte by a chemical sensor gives reliable results at extremely low concentrations of TNT on surfaces under real life conditions suitable for daily use in ordinary sampling for example at airlines luggage storage or sport locker rooms. The reported fluorescent methodology is very sensitive and selective, allowing for the trapping and detection of TNT by a fluorescent reporter to give reliable results at very low concentrations. As a complement, we report the preparation of a modified Sylgard film that is useful under real conditions for qualitative fluorescent detection of hidden traces of TNT on surfaces or fingers by a swab method. The combination of quantitative and qualitative detection of TNT traces on surfaces constitutes a comprehensive new method for the detection of hidden nitroaromatic explosives in the workplace.This research was funded by the NATO Science for Peace and Security Programme (Grant SPS G5536) and the Ministerio de Ciencia e Innovación (Grants PID2019-111215RB-I00 and PDC2022-133955-I00). A. R. C. thanks Secretaría General de Universidades for a FPU18/03225 Grant