The use of a forest waste biomass, cone of Pinus brutia for the removal of an anionic azo dye Congo red from aqueous medium

Cone biomass of Pinus brutia, a novel low-cost adsorbent prepared from forest waste has been utilized as an adsorbent for the removal of Congo red (CR) dye from an aqueous solution. The adsorbate concentration, pH, time, and temperature were examined in batch tests. Maximum biosorption capacity was 102.8 mg/g, showing that cone biomass of P. brutia was more efficient than most of the other adsorbents. Experimental data were analyzed by Langmuir, Freundlich, and Sips adsorption isotherms models and showed that the adsorption process followed a Sips model. Pseudo-first-order, pseudo-second-order, and intraparticle diffusion models were used to fit experimental data, showing that the adsorption of CR could be described by a pseudo-second-order equation and that intraparticle diffusion was not the only rate-limiting mechanism for the biosorption of CR. Thermodynamic parameters such as ΔGo, ΔHo, and ΔSo were also evaluated and it was found that the sorption process was feasible, spontaneous, and endothermic in nature. These results indicated that cone biomass of P. brutia is promising as a low-cost alternative compared to other commercial adsorbents for the removal of dyes from wastewater.