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Ionic liquids (ILs), characterized by their tunable miscibility, negligible vapor pressure, and wide electrochemical window, have emerged as a prevalent substitute for organic solvents in diverse environmental and industrial applications. This work provides a critical review on environmental applications of newly developed ILs in recent years, emphasizing their roles in removal of pollutants from wastewater and exhaust gas, and environmental analysis. Furthermore, the combination of ILs with novel materials such as metal-organic frameworks (MOFs) and graphene is recapitulated. Moreover, the toxicological profile and mechanisms of newly developed ILs were also explored. It updates the recent research progress in the design of less toxic ILs and the development of novel mitigation methods for toxic ILs in the environment. In the end, future research directions and perspectives in the application of ILs are proposed.

The rapid development of nanotechnology has raised concern regarding the environmental toxicity of nanoparticles (NPs). However, little is known about the molecular mechanisms underlying NP toxicity in plants. Broad bean (Vicia fabaL.) plants were cultivated in soil amended with 0, 10, and 100 mg cadmium sulfide (CdS)-NPs per kg soil for 4 weeks, and then the phenotypic, biochemical, and metabolic responses of the plants to CdS-NP stress were evaluated. Metabolomics analysis revealed the significant up-regulation (1.2- to 39.2-fold) of several antioxidative metabolites, including N-acetyl-5-hydroxytryptamine, 2-hydroxybutanoic acid, putrescine, and flavone, upon CdS-NP exposure, but no negative phenotypic effects were visible (plant biomass, photosynthetic pigment contents, and lipid peroxidation). This observation was in accordance with the observed regulation of antioxidative-defense-related metabolic pathways (tyrosine pathway and phenylpropanoid biosynthesis) that were identified by biological pathway analysis. Importantly, twice as many metabolites were modulated in leaves than in roots, including three nitrogen-related (purine metabolism; alanine, aspartate, and glutamate metabolism; β-alanine metabolism) and two carbon-related (pantothenate and CoA biosynthesis and carbon fixation) metabolic pathways. These results indicate that to alleviate the toxicity of CdS-NP exposure in soil, plants significantly reprogram the metabolic profiles of leaves rather than of roots, which might subsequently impact both harvest and crop quality.

The soil environment is an important sink for penicillin antibiotics released from animal manure and wastewater, but the mineral-catalyzed transformation of penicillins in soil has not been well studied. To simulate this environmental process, we systematically investigated the behavior of penicillin G and amoxicillin, the two most widely-used penicillin antibiotics, in the presence of goethite and metal ions. The results demonstrated that Zn ions significantly promoted the hydrolysis of penicillins in goethite suspensions, as evidenced by the degradation rate nearly 3 orders of magnitude higher than that of the non-Zn-containing control. The spectroscopic analysis indicated that the specific complexation between penicillins, adsorbed Zn, and goethite was responsible for the enhanced degradation. Metastable interactions, involving hydrogen bonds between carbonyl groups in the β-lactam ring and the double/triple hydroxyl groups on goethite surface, and coordination bonding between carboxyl groups and surface irons were proposed to stabilize the ternary reaction intermediates. Moreover, the surface zinc-hydroxide might act as powerful nucleophile to rapidly rupture the β-lactam ring in penicillins. This study is among the first to identify the synergic roles of Zn ion and goethite in facilitating penicillin degradation and provides insights into β-lactam antibiotics to assess their environmental risk in soil.

Engineered nanoparticles (NPs) with activities that mimic antioxidant enzymes have good prospects in agriculture because they can increase photosynthesis and improve stress tolerance. Here, the interaction between cerium oxide NPs with spinach plants (Spinacia oleracea) was investigated by integrating phenotypic and metabolomic analyses. Soil-grown, four-week-old spinach plants were foliar exposed for 3 weeks to CeO2NPs at 0, 0.3, and 3 mg per plant. Phenotypic parameters (chlorophyll fluorescence, photosynthetic pigment contents, plant biomass, lipid peroxidation, and membrane permeability) were not affected. However, metabolomics analysis revealed that both doses of CeO2NPs induced metabolic reprogramming in leaves and roots in a non-dose-dependent manner. The low dose of CeO2NPs (0.3 mg per plant) induced stronger metabolic reprogramming in spinach leaves than high dose of CeO2NPs. However, the high dose of CeO2NPs triggered more metabolic changes in roots, compared to the low dose. Foliar spray of CeO2NPs at 3 mg/plant induced marked down-regulation of a number of amino acids (threonine, tryptophan, l-cysteine, methionine, cycloleucine, aspartic acid, asparagine, tyrosine, and glutamic acid). In addition, Zn decreased by 44% and 54% in leaves and Ca decreased by 38% and 32% in roots under exposure to CeO2NPs at 0.3 and 3 mg/plant, respectively. These results provide better understanding of the intrinsic phenotypic and metabolic changes imposed by CeO2NPs in spinach plants.

Ferrihydrite is omnipresent in nature, and its adsorption of As(III/V) decides the migration of arsenic. Although As(III) is commonly recognized as the more mobile species of inorganic arsenic, it sometimes exhibits less mobility in ferrihydrite systems, which calls for further insights. In this study, we elucidated the adsorption behavior and mechanisms of As(III/V) on ferrihydrite under different loading levels (molar ratio As/Fe = 0–0.38), solution pH (3–10), and coexisting ions [P(V) and Ca(II)] based on batch adsorption experiments, surface complexation modeling, density functional theory calculations, and X-ray photoelectron spectroscopy. Our results show that As(III) exhibits weaker adsorption affinity but a larger capacity compared with that of As(V). On ferrihydrite, As(III) and As(V) are adsorbed mainly as bidentate mononuclear complexes at type-a sites [≡Fe(OH–0.5)2] and bidentate binuclear complexes at type-b sites (2≡FeOH–0.5), respectively. As the dosage increases, As(III) further forms mononuclear monodentate complexes at both surface sites, resulting in a higher site utilization efficiency, while As(V) does not due to repulsive electrostatic interaction. The difference in surface species of As(III/V) also leads to complex responses when coexisting with high concentrations of P(V) and Ca(II). This study helps us to understand environmental behavior of As(III/V) and develop remediation strategy in As(III/V) contaminated systems.

Cadmium (Cd) geochemical behavior is strongly influenced by its adsorption onto natural phyllomanganates, which contain both layer edge sites and vacancies; however, Cd isotope fractionation mechanisms at these sites have not yet been addressed. In the present work, Cd isotope fractionation during adsorption onto hexagonal (containing both types of sites) and triclinic birnessite (almost only edge sites) was investigated using a combination of batch adsorption experiments, extended X-ray absorption fine structure (EXAFS) spectroscopy, surface complexation modeling, and density functional theory (DFT) calculations. Light Cd isotopes are preferentially enriched on solid surfaces, and the isotope fractionation induced by Cd2+adsorption on edge sites (Δ114/110Cdedge-solution= −1.54 ± 0.11‰) is smaller than that on vacancies (Δ114/110Cdvacancy-solution= −0.71 ± 0.21‰), independent of surface coverage or pH. Both Cd K-edge EXAFS and DFT results indicate the formation of double corner-sharing complexes on layer edge sites and mainly triple cornering-sharing complexes on vacancies. The distortion of both complexes results in the negative isotope fractionation onto the solids, and the slightly longer first Cd–O distances and a smaller number of nearest Mn atoms around Cd at edge sites probably account for the larger fractionation magnitude compared to that of vacancies. These results provide deep insights into Cd isotope fractionation mechanisms during interactions with phyllomanganates.

Sunlight-induced photoformation of silver nanoparticles (nAg), mediated by natural organic matter (NOM), is significantly affected by the concentration of Ag(I) and chloride. The initial photoformation rates of nAg in Suwannee River humic acid (SRHA) and Suwannee River natural organic matter (SRNOM) solutions were examined under simulated sunlight irradiation. A critical induction concentration (CIC) of Ag(I) (10 mg/L for SRHA and 5 mg/L for SRNOM, respectively) was observed, below which the nAg formation was minimal. The threshold is attributed to the interplay of reduction and oxidation reactions mediated by NOM, reflecting the need to achieve sufficiently fast growth of silver clusters to outcompete oxidative dissolution. The CIC can be reduced by scavenging oxidative radicals or be increased by promoting singlet oxygen and hydrogen peroxide generation. The presence of chloride effectively reduced the CIC by forming AgCl, which facilitates reduction reactions and provides deposition surfaces. SRNOM is more efficient in mediating photoformation of nAg than SRHA, owing to their differed phototransient generation. These results highlight prerequisites for the photoformation of nAg mediated by NOM, in which the photochemistry and solution chemistry are both important.

Osteosarcoma (OS) is one of the most serious malignancies along with a high incidence in children and teenagers. Although the neoadjuvant chemotherapy of OS has made great progress and prolongs the five-year survival rates of patients to some extent, drugs are restrained from clinical application due to the unsatisfactory efficacy and severe side effects, especially for the systemic therapy through intravenous injection. The polymeric nanoparticles as anti-cancer drug nanocarriers make OS treatment more promising and effective. Specifically, various polymeric nanoparticles have been developed to overcome the difficulties in targeting delivery of drugs to OS tissue and/or cells through passive and/or active strategies. This review presents an overview on the development of polymeric nanoparticles for anti-cancer drug delivery in OS treatment, and briefly describes the challenge and opportunity for future development.