Synthesis of tri-metallic surface engineered nanobiochar from cynodon dactylon residues in a single step - Batch and column studies for the removal of copper and lead ions

Abstract

Superparamagnetic nanocomposites integrated with multiple metals, and surface engineered nanoparticles play a vital role in the removal of heavy metals. In the present study, amino-functional silica-coated magnetic nanocomposites with biochar synthesised from Cynodon dactylon plant residues are prepared in a single step reaction process. The synthesised nanocomposites are characterized using various analytical techniques such as FTIR to determine their functional entities, SEM, TEM, EDX and VSM to analyse the size (~50 nm), elements and magnetic nature of the nanocomposites. Characterization reveals that the prepared nanobiochar was coated with silica and a specific amine group. The magnetic saturation value of 50 emu/g confirms the prepared sorbent was superparamagnetic. Kinetics, isotherm and thermodynamics parameters are evaluated to study the metal interaction mechanism with the nanocomposites where the system follows pseudo-second-order kinetics and the four-parameter Fritz Schlunder model for both metal ions. The nanocomposites showed the enhanced adsorption capacity of copper (Cu(II)) ions with 220.4 mg/g and 185.4 mg/g for lead (Pb(II)) ions. The nanocomposites also showed the excessive reusing ability of 15 times with the maximum removal efficiency for Cu(II) and Pb(II) metal ions. Column studies are evaluated to demonstrate the vital performance in the removal of Cu(II) ions and the breakthrough point was inferred for the parameters such as concentration (100–300 mg/L), bed height (1–3 cm) and flow rate (2–4 mL/min). The breakthrough point was attained at 1400 min and the removal efficiency of about 64.58% was obtained.