Macro- and micro-algae-based carbon composite for pharmaceutical wastewater treatment: Batch adsorption and mechanism study

Abstract

Biochar synthesized from algal biomasses acts as an efficient adsorbent to remove tetracycline (TC) from aqueous solutions. In this study, a mixture of Enteromorpha (EN) and Chlorella vulgaris (CV) was pyrolyzed at 500 °C, then activated with NaOH at 800 °C to prepare composite biochar (ECA-B). The effects of TC concentration (50–500 mg·L−1), pH (3–11), temperature (30 °C–50 °C), and contact time (0–960 min) on TC absorption were investigated. Results revealed that in aqueous solutions, the biochar (EC4:1-0.5)prepared with CV and EN at the mass ratio of 4:1 and the impregnation ratio of 0.5 had the optimal TC adsorption capacity (Qm = 376.878 mg·g−1). The removal rate of EC4:1-0.5 remained above 80 % after five cycles. The surface area of EC4:1-0.5 (583.329 m2·g−1) increased by three and four times that of EN and CV, respectively. Intraparticle diffusion was considered as the major limitation for the adsorption of TC onto EC4:1-0.5. This investigation provides a method for the synthesis and optimization of algal biomass-based activated carbon for the absorption of organic pollutants in wastewater.