Enhanced adsorption of Congo red onto camphor leaf-derived biosorbents modified with lanthanum

A novel high-performance porous carbon material, lanthanum(iii)-doped camphor leaf-derived porous carbon (La/CPC), was synthesized and used as an adsorbent for the anionic dye Congo red (CR). The La/CPC composite was characterized by nitrogen adsorption and desorption isotherms, scanning electron microscopy, transmission electron microscopy and X-ray photoelectron spectroscopy. The adsorption performance of CR by the CPC and La/CPC composites with different contents of lanthanum(iii) was evaluated in fixed-bed breakthrough experiments and batch tests at room temperature (298 K). The La/CPC composite had a high CR uptake capacity, which was found to be superior to those previously reported for other adsorbents. The La/CPC sorbents could be easily regenerated using an ethanol elution technique, and after five cycles, the reused La/CPC sorbent maintained about 98% of its CR capacity. The adsorption kinetics of CR onto the lanthanum(iii)-doped CPC sorbent followed a pseudo-second-order kinetic model and fitted well with a Langmuir adsorption isotherm. La/CPC is a promising adsorbent for the removal of anionic dyes from wastewater.