• Energy Research

The mass production of graphene oxide (GO) unavoidably elevates the chance of human exposure, as well as the possibility of release into the environment with high stability, raising public concern as to its potential toxicological risks and the implications for humans and ecosystems. Therefore, a thorough assessment of GO toxicity, including its potential reliance on key physicochemical factors, which is lacking in the literature, is of high significance and importance. In this study, GO toxicity, and its dependence on oxidation level, elemental composition, and size, were comprehensively assessed. A newly established quantitative toxicogenomic-based toxicity testing approach, combined with conventional phenotypic bioassays, were employed. The toxicogenomic assay utilized a GFP-fused yeast reporter library covering key cellular toxicity pathways. The results reveal that, indeed, the elemental composition and size do exert impacts on GO toxicity, while the oxidation level exhibits no significant effects. The UV-treated GO, with significantly higher carbon-carbon groups and carboxyl groups, showed a higher toxicity level, especially in the protein and chemical stress categories. With the decrease in size, the toxicity level of the sonicated GOs tended to increase. It is proposed that the covering and subsequent internalization of GO sheets might be the main mode of action in yeast cells.

Although various hydrometallurgical and solvometallurgical efforts have been made to extract REEs from end-of-life (EoL) products and waste, a systematic and statistical analysis of the impacts of leaching parameters to optimize the leaching process using organic acids is necessary, but lacking in the literature. This study employed the response surface methodology to develop mathematical models for optimal leaching by levulinic acid (LevA) of REEs in two waste materials, namely red mud and spent fluorescent lamp phosphors. The established models exhibited excellent statistical properties, in terms of significance, fitting, prediction, and error distribution. For red mud, the optimal conditions of liquid-to-solid ratio (L/S; v/w) of 40, temperature of 70 °C, and duration of 60 h led to 100% leaching of REEs excluding Sc. At the same L/S and temperature, >98.7% of REEs were leached from fluorescent phosphors after 96 h. The SEM–EDS analysis of the waste materials revealed and confirmed morphological and compositional changes after leaching under the optimal conditions.

AbstractLoss of basic utilities, such as drinking water and electricity distribution, were sustained for months in the aftermath of Hurricane Maria’s (HM) landfall in Puerto Rico (PR) in September 2017. The goal of this study was to assess if there was deterioration in biological quality of drinking water due to these disruptions. This study characterized the microbial composition of drinking water following HM across nine drinking water systems (DWSs) in PR and utilized an extended temporal sampling campaign to determine if changes in the drinking water microbiome were indicative of HM associated disturbance followed by recovery. In addition to monitoring water chemistry, the samples were subjected to culture independent targeted and non-targeted microbial analysis including quantitative PCR (qPCR) and genome-resolved metagenomics. The qPCR results showed that residual disinfectant was the major driver of bacterial concentrations in tap water with marked decrease in concentrations from early to late sampling timepoints. WhileMycobacterium aviumandPseudomonas aeruginosawere not detected in any sampling locations and timepoints, genetic material fromLeptospiraandLegionella pneumophilawere transiently detected in a few sampling locations. The majority of metagenome assembled genomes (MAGs) recovered from these samples were not associated with pathogens and were consistent with bacterial community members routinely detected in DWSs. Further, whole metagenome-level comparisons between drinking water samples collected in this study with samples from other full-scale DWS indicated no significant deviation from expected community membership of the drinking water microbiome. Overall, our results suggest that disruptions due to HM did not result in significant and sustained deterioration of biological quality of drinking water at our study sites.Graphical Abstract

Single-walled carbon nanotubes (SWCNTs) have caused increasing public concerns associated with their potential toxicological effects. This study demonstrated that the physicochemical properties of SWCNTs have impacts on their toxicological effects.