Synthesis, characterization of novel protein-modified rice husk biochar and their applications for highly adsorptive removal azo dye in water
Thi Kim Chi Tran, Thi Thuy Trang Truong, An Van Le, Duc M, Thu Giang Nguyen, Thi Duyen Tran, Tien Duc Pham
Abstract
This study investigates the removal of anionic dye New Coccine (NCC) using a new bio-based adsorbent protein lysozyme-modified rice husk biochar (Lys-RHB). Rice husk biochar (RHB) which was synthesized through a simple pyrolysis process, was characterized structurally and chemically using XRD, FT-IR, SEM, EDX, BET and ζ potential. The RHB was modified with lysozyme at pH 11 to increase the positive surface charge, enhancing electrostatic attraction to negatively charged pollutants. The major breakthrough of our study is optimization of conditions for the removal of NCC were obtained at pH 3, contact time 120 min and adsorbent dosage of 1.5 mg/mL; achieving the maximum adsorption capacity of 32.15 mg/g and the highest NCC removal efficiency of 97.3 %. Our findings reveal that the adsorption mechanisms of lysozyme on RHB and NCC on Lys-RHB were dominated by electrostatic forces, facilitating strong interactions between oppositely charged molecules. The adsorption of NCC on Lys-RHB was most accurately fitted by Freundlich isotherm, while the adsorption kinetics corresponded to the feature of pseudo-second-order model. Significantly, the Lys-RHB demonstrates as highly effective in removal of dyes, highlighting its potential as a sustainable and eco-friendly solution for wastewater treatment applications. These results present groundbreaking advancements in environmental science by providing an economical and effective method for dye pollution. Moreover, this study paves the way for future research on utilizing biochar for various environmental purposes. • The Lysozyme coating synthesized rice husk biochar was successfully fabricated. • The Lys-RHB was an excellent adsorbent for removal of anionic azo dye New Coccine. • Adsorption was fitted well with Freundlich isotherm and pseudo-second kinetic models. • High removal efficiency of 92 % retained after 5 regenerations.