Iron Minerals Mediated Interfacial Hydrolysis of Chloramphenicol Antibiotic under Limited Moisture Conditions

Abstract

Iron minerals are important soil components; however, little information is available for the transformation of antibiotics on iron mineral surfaces, especially under limited moisture conditions. In this study, we investigated the catalytic performance of four iron minerals (maghemite, hematite, goethite, and siderite) for the hydrolysis of chloramphenicol (CAP) antibiotic at different moisture conditions. All the iron oxides could efficiently catalyze CAP hydrolysis with the half-lives <6 days when the surface water content was limited, which was controlled by the atmospheric relative humidity of 33–76%. Different minerals exhibited distinctive catalytic processes, depending on the surface properties. H-bonding or Lewis acid catalysis was proposed for surface hydrolytic reaction on iron oxides, which however was almost completely inhibited when the surface water content was >10 wt % due to the competition of water molecules for surface reactive sites. For siderite, the CAP hydrolysis was resistant to excessive surface water. A bidentate H-bonding interaction mechanism would account for CAP hydrolysis on siderite. The results of this study highlight the importance of surface moisture on the catalytic performance of iron minerals. The current study also reveals a potential degradation pathway for antibiotics in natural soil, which has been neglected before.

Facet effect of hematite on the hydrolysis of phthalate esters under ambient humidity conditions

“…2c, d ). The excessive surface water molecules would compete for the reactive sites 10 , 12 , and reduce the Lewis acidity of the exposed Fe (Fig. 3 ).…”

“…PAEs are hydrolysable, however, at slow hydrolysis rates with the hydrolysis half-lives ( t 1/2 ) even up to several years under neutral pH conditions 9 . In our previous studies, we found that chloramphenicol antibiotic could be rapidly hydrolyzed by clay minerals and iron oxides under limited surface moisture conditions, attributing to the strong Brønsted-/Lewis-acidities of the dry mineral surface 10 – 12 . By contrast, under water-oversaturated conditions, the surface reactions were completely suppressed due to the shielding effect of surface water layers 10 – 12 .…”

“…In our previous studies, we found that chloramphenicol antibiotic could be rapidly hydrolyzed by clay minerals and iron oxides under limited surface moisture conditions, attributing to the strong Brønsted-/Lewis-acidities of the dry mineral surface 10 – 12 . By contrast, under water-oversaturated conditions, the surface reactions were completely suppressed due to the shielding effect of surface water layers 10 – 12 . Therefore, moisture plays an important role on surface-mediated reactions.…”

“…Hematite can catalyze the hydrolysis of organic contaminants, e.g., antibiotics and organophosphorus esters 12 , 16 . The catalytic activity of hematite is occasionally dependent on its facet constitution 17 .…”

Cu Nanoparticle-Decorated Boron–Carbon–Nitrogen Nanosheets for Electrochemical Determination of Chloramphenicol

“…Residues of pollutants such as CAP in medical wastewater adversely affect human health . CAP is often used in pharmaceutical and aquaculture industries as a broad-spectrum antibacterial antibiotic. , The increasing use of CAP , has resulted in CAP residues being found in aquatic environments and animals. CAP is banned in many countries because it can cause aplastic anemia and leukemia after entering the human body .…”