A novel role of various hydrogen bonds in adsorption, desorption and co-adsorption of PPCPs on corn straw-derived biochars

Nana Li; Yifan Liu; Cong Du; Yue Wang; Lijun Wang; Xiaoyun Li

doi:10.1016/j.scitotenv.2022.160623

A novel role of various hydrogen bonds in adsorption, desorption and co-adsorption of PPCPs on corn straw-derived biochars

Sci Total Environ. 2023 Feb 25:861:160623. doi: 10.1016/j.scitotenv.2022.160623. Epub 2022 Nov 29.

Authors

Nana Li¹, Yifan Liu¹, Cong Du¹, Yue Wang¹, Lijun Wang², Xiaoyun Li³

Affiliations

¹ Department of Environmental Science, School of Geography and Tourism, Shaanxi Normal University, Xi'an 710119, China.
² Department of Environmental Science, School of Geography and Tourism, Shaanxi Normal University, Xi'an 710119, China; International Joint Research Centre of Shaanxi Province for Pollutants Exposure and Eco-environmental Health, Xi'an 710119, China.
³ Department of Environmental Science, School of Geography and Tourism, Shaanxi Normal University, Xi'an 710119, China; International Joint Research Centre of Shaanxi Province for Pollutants Exposure and Eco-environmental Health, Xi'an 710119, China. Electronic address: lxy518@snnu.edu.cn.

PMID: 36460113
DOI: 10.1016/j.scitotenv.2022.160623

Abstract

The effect of various hydrogen bonds with different strength on the environmental behaviors of PPCPs remains unclear. In this study, three pharmaceutical pollutants including clofibric acid (CA), sulfamerazine (SMZ), and acetaminophen (ACT) with different functional groups and pK_a, were selected as representative of PPCPs to investigate the pivotal role of hydrogen bonds in adsorption/desorption and co-adsorption behaviors of PPCPs on two corn straw-derived biochars prepared at 300 °C (BCs-300) and 600 °C (BCs-600), respectively. The results indicated that charge-assisted hydrogen bond (CAHB) and ordinary hydrogen bond (OHB) with different intensities were the pivotal mechanisms responsible for the adsorption of three PPCPs on biochars, which was further confirmed by FTIR, but their immobilization effects of PPCPs on biochars were completely different. Compared with OHB formed between CA and BCs-600, the stronger CAHB (formed between CA and BCs-300, and SMZ/ACT and BCs-300/BCs-600) with covalent bond characteristics that derived from the smaller |ΔpK_a| (<5.0), resulted in the greater adsorption capacity (Q_s) and affinity (K_f) of the three PPCPs on BCs-300 (Q_s ≥ 195 μmol·g^-1, K_f ≥ 1.9956) than that on BCs-600 (Q_s ≤ 92 μmol·g^-1, K_f ≤ 0.5192), thereby making the better immobilization effect of PPCPs by biochar. In addition, in the coexisting systems, either SMZ coexisting with CA/ACT on BCs-300, or ACT coexisting with CA/SMZ on BCs-600, both implied that when the |ΔpK_a| between the target PPCPs and biochar is smaller than that between the coexisting compound and biochar, the target PPCPs can preferentially occupy the shared hydrogen bond sites on the biochar surface, and hard to be replaced by the coexisting compound. This work not only expand the application of designed biochar as engineering adsorbents to control and removal of the specific PPCPs in the environment, but also facilitate accurate assessment of the environmental risk of co-existing PPCPs.

Keywords: Biochar; Hydrogen bond; Hysteresis index; Immobilization; PPCPs.

MeSH terms

Adsorption
Charcoal* / chemistry
Hydrogen Bonding
Zea mays*

Substances

biochar
Charcoal