Mesoporous biobased carbonaceous adsorbent for dye removal from water: Eutectic molten salts effect and adsorption mechanisms
Ji-Young Do, Hiresh Moradi, Dongsu Kim, Jae‐Kyu Yang, Yoon‐Young Chang, Suk Soon Choi
Abstract
Dye-polluted wastewater is released from various industries, such as textile and paint industries. Among different reclamation techniques, adsorption has been widely used for dye removal . Carbonaceous adsorbents , such as graphene, are among the most sought-after compounds for adsorption applications because of their high specific surface area and adjustable surface features. In this study, graphene-like carbon (GLC) was prepared from biomass as it is a facile and eco-friendly approach. Biomass-derived GLC was prepared by pyrolyzing waste wood in the presence of FeCl 3 /ZnCl 2 as a eutectic binary mixture . Brunauer–Emmett–Teller (BET) and Raman analyses revealed that FeCl 3 had a template effect during pyrolysis , whereas ZnCl 2 acted as a pore former. Moreover, FeCl 3 and ZnCl 2 concentrations positively affected the BET value, regardless of the salt type. Further, waste wood-derived graphene-like carbon (WGLC) pyrolyzed at 900 °C with biomass: FeCl 3 : ZnCl 2 at a ratio of 1:2:1 (WGLC-121) showed the highest specific surface area (2073.78 m 2 g −1 ) and could remove >90 % of rhodamine B (RhB) and Congo red (CR) dyes. The pseudo-second order kinetic model showed a stronger correlation with the experimental data than the pseudo-first order model. While intra-particle diffusion was the rate-determining step in RhB adsorption, it did not influence CR adsorption. Further, the Freundlich model better explained the RhB (q max = 633.86 mg g −1 ) and CR (q max = 141.28 mg g −1 ) adsorption and revealed the superiority of WGLC-121 in dye removal compared to the previously reported adsorbents. The adsorption isotherm , energy, and thermodynamic parameters confirmed that the dyes were adsorbed through physisorption . Furthermore, the inter-molecular interaction between the RhB and CR molecules influenced the dye adsorption rate and isotherm. The findings of this study demonstrate the high potential of a binary mixture of FeCl 3 and ZnCl 2 for preparing carbonaceous adsorbents from waste wood to remove dyes from industrial wastewater.