Synthesis of highly porous ferric hydroxide-bacterial cellulose nanocomposites via in-situ mineralization for efficient glyphosate removal
摘要
Research on the use of nanoparticles for pollutant adsorption has received increasing attention. However, there are problems with the recovery and persistence of nanoparticles in pollutant removal processes. Herein, ferric hydroxide-bacterial cellulose (BC) nanocomposites with high porosity were synthesized via in situ mineralization and employed to efficiently remove glyphosate from wastewater. The prepared BC@Fe(OH)3 nanocomposites were comprehensively characterized using scanning electron microscopy, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy, which indicated that the Fe(OH)3 nanoparticles were well positioned on the surface of BC, and the specific surface area of the BC@Fe(OH)3 nanocomposites reached 179.14 m2 g−1, with a pore volume and average pore diameter (0.766 m2 g−1 and 21.6 nm) much larger than those of pristine BC (0.412 m2 g−1 and 12.6 nm) and unsupported Fe(OH)3 (0.016 m2 g−1 and 20.7 nm). Batch adsorption experiments revealed that the synthesized BC@Fe(OH)3 nanocomposites had better adsorption performance than unsupported Fe(OH)3 and pristine BC; the maximum glyphosate adsorption capacity was 180.48 mg g−1 according to the fitting results of the Langmuir adsorption isotherm. We also investigated the kinetics and adsorption mechanism of glyphosate on BC@Fe(OH)3. The results showed that the adsorption of glyphosate involved multiple physical and chemical processes, such as electrostatic interactions, ligand exchange, hydrogen bond formation, and pore diffusion. Moreover, this material showed a high reuse rate and maintained approximately 50% of its adsorption capacity after four consecutive adsorption–desorption cycles. Thus, BC@Fe(OH)3 nanocomposites are expected to be promising, eco-friendly adsorbents for effectively removing glyphosate from wastewater.