RESUMEN
Despite the extensive use of biochar (BC) in soil and aqueous media for pollutant immobilization, the environmental behaviors and health risks of aged BC with multiple pollutants, especially with metal ions possessing various valence states, remain unexplored. Here, we prepared fresh banana peel BC (BP-BC) and aged BP-BCs by acidification (ABP-BC) and oxidation (OBP-BC). ABP-BC was then chosen to explore its environmental behaviors (i.e., adsorption, desorption, and arsenic valence transfer) towards As(III)-Cu(II) and the combined cytotoxicity of BCs with As(III)-Cu(II) was investigated in Human Gastric epithelium cells (GES-1). Our results demonstrate that the aging process notably alters the physicochemical properties of BP-BC, including surface morphology, elemental composition, and surface functional groups, which are key factors affecting the long-term environmental behaviors of BC with As(III)/Cu(II). Specifically, the aging process significantly enhanced the adsorption of As(III) on BC but reduced the adsorption of Cu(II). Although the oxidation of As(III) to As(V) did not change much, the aging process improved the stability of ABP-BC-metal ion complexes, alleviating the release of As(III) in acidic solution. Consequently, the combined cytotoxicity induced by ABP-BC-As(III)-Cu(II) was reduced compared to BP-BC-As(III)-Cu(II). The study highlights the critical roles of the aging process in regulating the As(III) adsorption/desorption dynamics on BCs and their combined cytotoxicity in the presence of multiple metal ions.
Asunto(s)
Arsénico , Carbón Orgánico , Carbón Orgánico/química , Carbón Orgánico/toxicidad , Humanos , Arsénico/toxicidad , Arsénico/química , Adsorción , Línea Celular , Cobre/toxicidad , Cobre/química , Supervivencia Celular/efectos de los fármacosRESUMEN
As both electron donors and acceptors, biochars (BCs) may interact with multivalent metal ions in the environment, causing changes in ionic valence states and resulting in unknown combined toxicity. Therefore, we systematically investigated the interaction between BCs and Cr (Cr(III) & Cr(VI)) or As (As(III) & As(V)) and their combined cytotoxicity in human colorectal mucosal (FHC) cells. Our results suggest that the redox-induced valence state change is a critical factor in the combined cytotoxicity of BCs with Cr/As. Specifically, when Cr(VI) was adsorbed on BCs, 86.4 % of Cr(VI) was reduced to Cr(III). In contrast, As(III) was partially oxidized to As(V) with a ratio of 37.2 %, thus reaching a reaction equilibrium. Meanwhile, only As(V) was released in the cell, which could cause more As(III) to be oxidized. As both Cr(III) and As(V) are less toxic than their corresponding counterparts Cr(VI) and As(III), different redox interactions between BCs and Cr/As and release profiles between BCs and Cr/As together lead to reduced combined cytotoxicity of BP-BC-Cr(VI) and BP-BC-As(III). It suggests that the valence state changes of metal ions due to redox effects is one of the parameters to be focused on when studying the combined toxicity of complexes of BCs with different heavy metal ions.
Asunto(s)
Arsénico , Contaminantes Químicos del Agua , Humanos , Arsénico/química , Cromo/química , Carbón Orgánico/química , Iones , Contaminantes Químicos del Agua/toxicidad , Contaminantes Químicos del Agua/análisis , AdsorciónRESUMEN
Biochar (BC) has been widely used for soil remediation and pollutant removal from environmental water. The pollutant-adsorbing BC often exerts different cytotoxicity from pollutant-free BC. However, how adsorption of multiple pollutants alters the cytotoxicity of BC and how to modulate such toxicity are still unclear. By preparing BCs from two different materials (Banana peel (BP) and corn stalk (CS)) at two pyrolysis temperatures (300 °C and 500 °C, namely BP300-BC, BP500-BC, CS300-BC, and CS500-BC, respectively), we systemically investigated factors that affect the combined cytotoxicity of pollutant-adsorbing BC in Human normal rectal mucosal cells (FHC). The reduction of Cr(VI) to Cr(III) occurred on BC, in particular on BC prepared at 300 °C, in which larger amount of organic matters were left. The presence of Cu(II) promoted the release of Cr from BC once entering cells, which was more obvious for BC prepared at 500 °C. The changes in valence states and release rates of Cr adsorbed on BC prepared at different pyrolysis temperatures together caused reduced cytotoxicity of BP300-BC-Cr-Cu but enhanced cytotoxicity of BP500-BC-Cr-Cu, compared to the same amount of mixture of Cr(VI)-Cu(II). Our findings offer insight understanding of how pyrolysis temperature and the adsorbed multiple pollutants affect the combined cytotoxicity of BC-pollutant complex, allowing for safe applications of BC in future.