Pyrolysis of Biomass Wastes into Carbon Materials

Abstract

This study presents the results of the biomass pyrolysis process focusing on biochar production and its potential energetic (as solid fuel) and material (as adsorbent) applications. Three kinds of biomass waste were investigated: wheat straw, spent coffee grounds, and brewery grains. The pyrolysis process was carried out under nitrogen atmosphere at 400 and 500 °C (residence time of 20 min). A significant increase in the carbon content was observed in the biochars, e.g., from 45% to 73% (at 400 °C) and 77% (at 500 °C) for spent coffee grounds. In addition, the structure and morphology were investigated using scanning electron microscopy. Thermal properties were studied using a simultaneous thermal analysis under an oxidising atmosphere. The chemical activation was completed using KOH. The sorption properties of the obtained biochars were tested using chromium ion (Cr3+) adsorption from liquid solution. The specific surface area and average pore diameter of each sample were determined using the BET method. Finally, it was found that selected biochars can be applied as adsorbent or a fuel. In detail, brewery grains-activated carbon had the highest surface area, wheat straw-activated carbon adsorbed the highest amount of Cr3+, and wheat straw chars presented the best combustion properties.

Pyrolysis of Waste Biomass – Technical and Process Achievements, and Future Development – A Review

“…The obtained biochars had a significant increase in carbon content (up to c.a. 70% of C) and a lower O/C ratio [74].…”

Actual Trends in the Usability of Biochar as a High-Value Product of Biomass Obtained through Pyrolysis

“…In addition to biomass, there are many other organic wastes that, might be applied to pyrolysis. To these group belongs chars with high carbon content, including plastics, car tires, sewage sludge, railroad sleepers, resins from ion exchangers, and textile waste [135][136][137]. Char from these wastes, obtained by pyrolysis, has been studied as a raw material for obtaining activated carbons to be used as adsorbents [133].…”

Evaluation of Physical and Chemical Properties of Residue from Gasification of Biomass Wastes

“…%/min), average mass loss rate ((dW/dT) av , wt. %/min) the temperature of the highest peak of DTG (T DTG , • C), time corresponding to the parameters mentioned above, such as the ignition time (t i , min), burnout time (t b , min), time range = 0.5 (∆t 1/2 , min) and the maximum peak time (t p , min) were obtained and used in the calculation of key combustion parameters for all studied samples [44,45].…”