Enhanced Adsorptive Removal of Tetracycline by Phosphomolybdic Acid-Modified Low-Temperature Sludge Biochar

Abstract

Increasing the adsorption capacity and reducing the energy consumption of sludge biochar during preparation is important. In this study, a new modification method was developed to prepare phosphomolybdic acid-modified sludge biochar through the low-temperature pyrolysis of sewage sludge using phosphomolybdic acid as a modifier. Tetracycline was used to assess the adsorption performance of sludge biochar, and phosphomolybdic acid-modified sludge biochar was prepared at different temperatures. The results showed that the adsorption capacity of sludge biochar improved from 84.49 to 120.86 mg/g through modification with phosphomolybdic acid at 200 °C. The maximum adsorption capacities of phosphomolybdic acid-modified sludge biochar (200 °C pyrolysis temperature) at 298, 308, and 318 K were 283.87, 421.39, and 545.48 mg/g, respectively. Both liquid film and intraparticle diffusion were the main rate-limiting steps of tetracycline adsorption by phosphomolybdic acid-modified sludge biochar. Furthermore, the adsorption of tetracycline by phosphomolybdic acid-modified sludge biochar was mainly attributed to π−π interactions, electrostatic interactions, hydrogen bonding, and pore filling.

Enhancing Cr (VI) Adsorption of Chestnut Shell Biochar through H3PO4 Activation and Nickel Doping

“…Recently, a variety of modification treatments, such as chemical activation, physical activation, and doping strategies, have been developed and applied to optimize biochar with enhanced heavy metal adsorption capacities. The most commonly used activating reagents are H 3 PO 4 , KOH, NaOH, K 2 CO 3, and ZnCl 2 [11]. As an example, Amali Herath et al developed modified biochar derived from Douglas fir using a KOH-assisted activation approach, and the highest Langmuir adsorption of Cr (VI) was 124.2 mg•g −1 [10].…”