Hollow Structured Kapok Fiber-Based Hierarchical Porous Biocarbons for Ultrahigh Adsorption of Organic Dyes

Abstract

The activated carbon (AC) adsorption technology has been widely used in wastewater purification. Natural fiber-based AC is a group of emerging biomass adsorbents for dye adsorption; however, poor adsorption performance and a high preparation cost bring many limitations to its large-scale applications. Kapok fiber (KF) is a desirable and promising carbon source due to its low cost, renewability, unique hollow structure, and rich carbon content. Herein, novel KF-derived hierarchical porous biocarbons (KHPBs) were fabricated through a feasible two-step carbonization approach for the high-performance removal of cationic and anionic dyes from wastewater. The combined hollow structure and hierarchical pore structure of KHPBs greatly enlarged the adsorption capacity and removal rate of organic dyes. Due to their outstanding specific surface area (1455 m2/g) and pH responsiveness, the KHPBs possessed a large adsorption capacity of 1983.39 mg/g to Congo Red (CR). Moreover, the flexible KHPB filter element showed remarkable continuous filtration capacity to a cationic binary dye system, and the removal rate of it was almost 100% after 10 continuous filtrations. Therefore, the as-prepared KHPBs have a great application prospect as a highly efficient, economical, and eco-friendly adsorbent in organic dye wastewater purification.