Reactivity towards Na of biochars produced from date palm residues with different oxygen proportions during pyrolysis

Abstract The use of biochar produced from the rachis of date palm leaves could help fight soil salinization while using under-utilized crop residues. To improve the specific surface area of the biochars produced and therefore their adsorption capacity, the addition of oxygen (3 and 7%) during pyrolysis was tested. The amount of Na adsorbed was relatively low (between 15 and 20% of Na added) whatever are the biochar considered (produced with or without O 2 ). The release of this adsorbed Na in contact with water was quite important, from 100% for the lowest concentrations of Na added to 30-40% for the highest concentrations added, highlighting a low retention of Na by the biochars studied and a limited impact of the presence of O 2 during pyrolysis.