T9 Characteristics, Reactivity, and the Role of Natural Organic Matter (NOM) in Mobilizing Trace Elements of Health Concern in the Environment

Sunday, 9 October 2022
8:00 AM - 12:00 PM
506

UNDERSTANDING THE IMPACTS OF BIOCHAR NANOPARTICLES (BCNPS) ON THE SPECIATION AND TOXICITY OF CD TOWARD DAPHNIA SP

Paper number: T9-12
Program: Technical Sessions
Time: 10:30 AM – 10:45 AM

Authors

Abstract

Biochar Nanoparticles (BCNPs) are generated in the environment due to the weathering and degradation of bulk pyrolytic carbon (often called biochar). Problematically, the recent development of bulk biochar application as a soil amendment and for water treatment will lead to the release of anthropogenic BCNPs into the environment. The diverse sources of biomass and pyrolysis methods applied during biochar production profoundly impact the physicochemical properties of BCNPs and their fate and transport in the environment. This research aims to characterize the surface reactivity and metal complexation of BCNPs produced from willow and bamboo biomass, and then determine their toxicity towards Daphnia magna in the presence and absence of cadmium (Cd), a potentially toxic divalent cation. Experiments were conducted by pyrolyzing biochar feedstocks at 500oC, followed by mechanical grinding using a shatter box to produce BCNPs. The size distribution of BCNPs particles was confirmed through zeta sizer analysis and the development of particle charge as a function of pH measured using zeta potential analysis. Furthermore, potentiometric titrations were conducted, and the resulting data was modeled to calculate protonation constants (pKa values) and corresponding site concentrations of the BCNPs. Toxicity tests with D. magna at various exposure levels were conducted on three systems: Cd, BCNPs, and combination Cd+BCNPs to determine the median-lethal concentration (LC50) levels. The results show that BCNPs are effective sorbents for Cd removal, in line with their elevated surface reactivity and surface area. However, due to their small size and mobility, BNCPs may act as a transport vector for contaminants in soils and water. In addition, the presence of Daphnia in the process of metal removal can be used as an initial observation of how organic nanoparticles affect the lives of the organism and their adaptation mechanism during exposure.

Keywords:

Potentiometric titration, Colloids, Metal toxicity, biochar, nanoparticles, Daphnia, toxicity test, surface complexation models

Geological Society of America Abstracts with Programs. Vol. 54, No. 6

doi: 10.1130/abs/2022AM-382704

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