Biochar from Waste Vineyard Pruning as a CO₂ Sorbent in Pressure Swing Adsorption: Experimental and Modeling Study

Vineyard pruning is an agro-industrial waste largely available in Italy. In this work, biochar from vineyard pruning pellets (previously produced by pyro-gasification at two Equivalence Ratios (<i>ER</i>)) was chemically activated and tested as a CO₂ sorbent by pressure swing adsorption (PSA), at room temperature and 5, 7, or 9 bar_a (<i>P</i>). As-received and activated biochar samples showed CO₂-sorption capacities (<i>Y</i>) comparable to or even higher than those of reference sorbents, emerging as good candidates for future PSA scale-up studies. A 2³ factorial design was adopted to study the dependency of measured <i>Y</i> on factors <i>P</i>, <i>ER</i>, and "activation". Empirical linear regression models and Langmuir adsorption isotherms were obtained from <i>Y</i> experimental data. The extrapolation of the empirical model gave <i>Y</i> values with admissible deviations (lower than ± 5%) from the Langmuir isotherm in the range of 4-11 bar_a. The proposed model is a good predictive tool for future PSA scale-up studies.