Synthesis of biochar from iron-free and iron-containing microalgal biomass for the removal of pharmaceuticals from water

• Published in: Environmental research Vol. 214; no. Pt 3; p. 114041
• Main Authors: Nakarmi, Kanchan J., Daneshvar, Ehsan, Eshaq, Ghada, Puro, Liisa, Maiti, Abhijit, Nidheesh, P.V., Wang, Hailong, Bhatnagar, Amit
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier Inc 01-11-2022
• Subjects: Adsorption; Biomass; Charcoal - chemistry; Ciprofloxacin; Ciprofloxacin - chemistry; Diclofenac; Kinetics; Microalgae; Microalgal biochar; Pharmaceutical Preparations; Spectroscopy, Fourier Transform Infrared; Water; Water Pollutants, Chemical - analysis; Water treatment; Water treatment; Microalgal biochar; Adsorption; Ciprofloxacin; Diclofenac
• ISSN: 0013-9351; 1096-0953
• DOI: 10.1016/j.envres.2022.114041

The contamination of natural water bodies with pharmaceutical compounds has raised significant concerns about ecological and public health safety. In this study, biochars were synthesized from iron-free microalgal biomass (harvested by centrifugation) and iron-containing microalgal biomass (harvested by coagulation) and tested for the adsorption of ciprofloxacin (CIP) and diclofenac (DIC) from water in batch and fixed-bed column continuous studies. The physicochemical properties of synthesized biochars were analyzed using Brunauer, Emmett and Teller (BET) surface area analyzer, elemental analyzer, Fourier Transformed Infrared spectroscopy (FTIR), X-ray Diffractometer (XRD), and Scanning electron microscope with energy dispersive spectroscopy (SEM-EDS). The maximum monolayer adsorption capacities of iron-containing biochar (FBC750W) and iron-free biochar (MBC750W) based on the Langmuir model were obtained as 75.97 mg/g and 39.08 mg/g for CIP, and 40.99 mg/g and 6.77 mg/g for DIC, respectively. Comparatively, maximum monolayer adsorption capacities of commercial activated carbon (C-AC) were found to be 50.97 mg/g and 46.39 mg/g for CIP and DIC, respectively. In fixed-bed column continuous adsorption studies, the effects of flow rate (1 and 2 mL/min) and the adsorbent amount (50 and 100 mg) on adsorption performance were evaluated. Column kinetic models, such as Bohart-Adams model and Fractal-like Bohart-Adams model were examined. The adsorption mechanisms were proposed as pore filling, π-π interaction, and electrostatic interaction. Overall, the results of this study revealed that microalgal biomass, harvested with FeCl3, can be used for the direct synthesis of iron-containing biochar for the removal of pharmaceuticals from water.
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