High capacity adsorption of oxytetracycline by lignin-based carbon with mesoporous structure: Adsorption behavior and mechanism

In this study, an adsorbent with mesoporous structure and PO/PO bonds is prepared by hydrothermal and phosphoric acid activation from industrial alkali lignin for the adsorption of oxytetracycline (OTC). The adsorption capacity is 598 mg/g, which is three times higher than that of the adsorbent with microporous structure. The rich mesoporous structure of the adsorbent provides adsorption channels and filling sites, and π-π attraction, cation-π interaction, hydrogen bonds, and electrostatic attraction provide adsorption forces at the adsorption sites. The removal rate of OTC exceeds 98 % over a wide range of pH values (3–10). It has high selectivity for competing cations in water, with higher than 86.7 % removal rate of OTC from medical wastewater. After 7 consecutive adsorption-desorption cycles, the removal rate of OTC remains as high as 91 %. This efficient removal rate and excellent reusability indicate the strong potential of the adsorbent for industrial applications. This study prepares a highly efficient, environmentally friendly antibiotic adsorbent that can not only efficiently remove antibiotics from water but also recycle industrial alkali lignin waste. •High performance oxytetracycline adsorbent was synthesized from industrial lignin.•Mesoporous structure and PO/PO bonds promoted the adsorption of oxytetracycline.•The adsorption capacity of LCP for oxytetracycline is 598 mg/g at 298 K.•LCP has excellent selective adsorption and recycling ability for oxytetracycline.•Functionalized lignin is a promising material for the removal of pollutants.