Facile and environmentally sustainable synthesis of bone waste derived biochar-based bimetallic-LDH nanocomposite for selected dyes removal from aqueous medium

Abstract

The disposal of bone waste can be effectively addressed utilizing a novel approach involving the synthesis of a bovine bone-derived biochar-based Mg/Al-layered double hydroxide (LDH) nanocomposite (B-Mg/Al-NC). This nanocomposite exhibits exceptional capabilities for removing specific dyes, such as Methylene Blue (MB) and Congo Red (CR), from aqueous media. Extensive characterization using techniques confirmed the successful formation of the B-Mg/Al-NC, which possesses a high surface area, high porosity, and abundant functional groups. The Langmuir monolayer biosorption capacity was 395.56 mg g⁻¹ and 328.25 mg g⁻¹ at 50 °C for MB and CR, respectively, with rapid dye removal achieved within 25 min under alkaline pH conditions. The experimental data fit well with the pseudo-second-order kinetics model for both dyes. The remarkable dye adsorption capacity of the B-Mg/Al-NC can be attributed to the combined basic properties of the bone biochar and Mg/Al-LDH. Proposed mechanisms for enhanced dye removal include hydrogen bonding interactions, anion exchange, surface complexation, electrostatic interactions, and pore filling. Furthermore, the nanocomposite exhibited excellent reusability. In addition to its dye removal capabilities, the B-Mg/Al-NC was found to have a positive effect on seed germination and growth and salient soil health parameters, as demonstrated by a rapid seed germination test using the spent composite. Overall, the facile synthesis of the B-Mg/Al-NC via co-precipitation and ultrasonication is a highly recommended and sustainable approach for producing an eco-friendly bio-sorbent with exceptional dye removal efficiency from wastewater while also addressing the issue of bone waste disposal.

Graphical abstract