Adsorption of nitroimidazole antibiotics from aqueous solutions on self-shaping porous biomass carbon foam pellets derived from Vallisneria natans waste as a new adsorbent

Powdered biomass adsorbents can potentially remove antibiotics from wastewater However, recovering or separating the adsorbents after use is difficult. The preparation of mold-assisted shaping of biomass carbon foam pellets (BCFPs) without compaction and addition of binder instead of powdered adsorbent, is rarely reported. Therefore, the study explored the formation mechanism of BCFPs by using Vallisneria natans (V. natans) waste as precursor and investigated the adsorption performance and mechanisms of metronidazole (MNZ) and dimetridazole (DMZ) onto BCFPs. The optimal preparation conditions were V. natans-and-ZnCl2 mass ratio of 1:2.4, carbonization temperature of 600 degrees C, and time of 90 min. BCFPs exhibited uniform size, excellent floatability, and abundant micropores. The Brunauer-Emmett-Teller specific surface area, total pore volume, and micropore volume of BCFPs were 92256 m(2) g(-1), 0.421 cm(3) g(-1),and 0.386 cm(3) g(-1) respectively. The adsorption process of MNZ and DMZ was both described well by pseudo-first-order kinetic model. However, the isotherm data fitted well with Langmuir for MNZ and Dubinin-Radushkevic model for DMZ, with a maximum monolayer adsorption capacity of 64.23 and 82.58 mg g(-1), respectively. The nature of the adsorption process is endothermic and spontaneous. The adsorption mechanisms of MNZ and DMZ onto BCFPs were mainly hydrogen bonding, pi-pi interactions, and micropore filling. Preparation of BCFPs with high mechanical strength and excellent adsorption capacity from V. natans waste without compaction and any binder is feasible. furthermore, BCFPs are easily separated and recyclable adsorbents, and their average recovery rate was 99.6%. (C) 2019 Elsevier B.V. All rights reserved.