Fabrication of lanthanum methanoate on sucrose-derived biomass carbon nanohybrid for the efficient removal of arsenate from water

Abstract

Herein, we have designed and synthesized a metal-organic framework (MOF)-like lanthanum-methanoate (LaMe) nanocomplex for the remediation of arsenate (AsO₄^3-) from aqueous environment, in which AsO₄^3- replaces the formic acid from LaMe through ligand exchange, partially disintegrates the crystal lattice, and is re-precipitated as LaAsO₄. Consequently, the sucrose-derived biomass carbon (SBC) was utilized as supporting material to develop nanohybrid of LaMe@SBC to inhibit the solubility of lanthanum from LaMe, and enhance the adsorption ability towards AsO₄^3- from water. The maximum adsorption densities of AsO₄^3- on SBC and LaMe were (0.059 and 0.793) mmol/g, respectively. On the other hand, the synergistically re-constructed LaMe@SBC nanohybrid possesses AsO₄^3- adsorption density of 0.918 mmol/g at 25 °C. The studies, including contact time, solution pH, competitive anions, and initial AsO₄^3- concentration, were optimized for maximum AsO₄^3- removal. The adsorption density of the LaMe@SBC for AsO₄^3- removal was pH-dependent, and possesses the maximum adsorption density at pH (4.0 and 5.0); moreover, the removal process was highly selective in the presence of common co-existing anions, except PO₄^3- ion. The adsorption isotherm and kinetics of the LaMe@SBC nanohybrid closely fitted the Langmuir isotherm and pseudo-second-order kinetic models, respectively. The surface interactions among the LaMe@SBC nanohybrid and AsO₄^3- were revealed through FTIR and PXRD analyses. The adsorption of AsO₄^3- on the LaMe@SBC nanohybrid was primarily a chemisorption, namely ligand exchange and electrostatic interactions. The results reported in this research work highlight the feasibility of the LaMe@SBC nanohybrid as a real adsorbent for the removal of AsO₄^3- from aqueous environment.

Keywords: Application; Arsenate adsorption; Biomass carbon; Lanthanum methanoate; Sucrose.