LAUSR

Abstract A new biochar derived from pecan nutshell was prepared, characterized, and applied as an alternative and low – cost adsorbent for removing Reactive Red 141 (RR141) from aqueous solutions. The yield from raw pecan nutshell to biochar was approx. 30%. The biochar presented a micro/mesoporous structure with a surface area of 93 m 2  g − 1 , which is considered high for biomass derived materials. For both, raw pecan nutshell and its biochar, the RR141 adsorption was favored under acid conditions (pH of 2 and 3, respectively). The dye removal percentage was 85% using the biochar as an adsorbent, and was only 23% when raw pecan nutshell was used. The adsorption kinetics of RR141 on the biochar followed the pseudo–second order model. The equilibrium isotherms were well represented by the Freundlich model. The maximum adsorption capacity was approx. 130 mg g −1 . The adsorption was spontaneous, favorable, and exothermic (ΔH 0  = −56.42 kJ mol −1 ). These findings indicated that the new biochar prepared in this work is an alternative, low – cost, and eco – friendly adsorbent that can be used to remove dyes from colored effluents.