Ambient nanoparticles/nanominerals and hazardous elements from coal combustion activity:Implications on energy challenges and health hazards

Coal is the most abundant fossil fuel in the world. Because of the growth of coal mining, coal-fired power plants and coal-burning industries, the increase of the emission of particulates(coarse, fine or ultrafine)is of great concern. There is a relationship between increasing human morbidity and mortality and progressive environmental air pollution caused by these types of particles. Thus, the knowledge of the physico-chemical composition and ambient concentrations of coal-derived nanoparticles will improve pollution control strategy. Given the current importance of this area of research, the advanced characterization of this coal combustion-derived nanoparticles/nanominerals as well as hazardous elements is likely to be one of the hottest research fields in coming days. In this review, we try to compile the existing knowledge on coal-derived nanoparticles/nanominerals and discuss the advanced level of characterization techniques for future research. This review also provides some of aspects of health risks associated with exposure to ambient nanoparticles. In addition, the presence of some of the hazardous elements in coal and coal combustion activities is also reviewed.

Catalytic Property of Nanostructured Titanium Minerals

Titanium minerals are of interest because they constitute the most important source of titanium,a strategic metal in modem industry.However, knowledge on their structure,composition,and properties of nanodisperse structures has been limited. Several studies have shown that synthetic analogs of natural titanium oxides have structural features and physico-chemical properties distinctly different

Biomineralized nanoparticles for the immobilization and degradation of crude oil-contaminated soil

Accidental oil leaks and spills often cause server soil pollution,and in situ remediation is a powerful and economical treatment technology.While during in situ remediation process,unpredicted migration of petroleum hydrocarbon in heterogeneous soil will lead to a long-term source of persistent aquifer contamination.To reduce the migration of petroleum hydrocarbon and effectively improve the in situ remediation efficiency,herein,fungal biomineralization strategy was proposed for the immobilization of petroleum contaminants.A ureolytic fungi strain with crude oil-degradation ability was screened and identified as Chaetomium globosum.When incubated in medium containing Ca2+and crude oil,a mineral corona with spiny nanoparticles was formed at the edge of oil and the interface characters were analyzed using fluorescent pH and dissolved oxygen(DO)sensing films,respectively.Results indicated that biominerals preferred to aggregate around the edge of crude oil,providing favorable microenvironment for fungal growth and then leading to the increase of pH in the microenvironment,eventually accompanied by the formation of mineral corona.The mineral corona with numerous nanoparticles may act as a solid and stable shell,limiting or reducing the mobility of crude oil,and providing enough time for fungal biodegradation.After 28 days incubation,oilcontaminated soil treated with fungal biomineralization showed better immobilization ability for total petroleum hydrocarbon(TPH)under simulated acid-rain condition and higher TPH removal efficiency.This is the first demonstration for the immobilization of oil through fungal biomineralized nanoparticles,thus providing a novel strategy for the in situ remediation of oilcontaminated sites.

Nanozyme-mediated elemental biogeochemical cycling and environmental effects

In Earth systems,thousands of terragrams(Tg)(1 Tg=10^(12) g)of mineral nanoparticles move around annually.Some mineral nanoparticles have exhibited unexpected intrinsic enzyme-like characteristics(so called“mineral nanozymes”),and are ubiquitously distributed in natural ecosystems such as the atmosphere,oceans,waters,and soils.Compared with natural enzymes,these mineral nanozymes have several advantages such as tunable catalytic efficiency and robustness to harsh conditions,e.g.,heat,acid,and alkaline conditions.As mineral nanozymes are new products of multidisciplinary cross-cutting,they have been widely applied in various fields.This review,for the first time,systematically introduces the species and properties of mineral nanozymes in Earth systems,discusses the critical roles played by nanozymes in environmental biogeochemical cycles,compiles the interfacial processes and mechanisms of mineral nanozymes,and provides an overview of the future prospects of mineral nanozymes.

Occurrence, Structure and Mineral Phases of Nanoparticles in an Anthrosol

Soils contain various kinds of crystalline to amorphous solid particles with at least one dimension in the nanoscale （〈 100 nm）. These nanoparticles contribute greatly to dynamic soil processes such as soil genesis, trace element cycling, contaminant transport, and chemical reaction. The nano-sized fraction of an Anthrosol was obtained to determine the occurrence, chemical composition, structure, and mineral phases of nanoparticles using high-resolution transmission electron microscopy （HRTEM） equipped with an energy-dispersive X-ray spectroscopy. Selected area electron diffraction or the fast Fourier transform of high-resolution images was used in structural characterization of the nanoparticles with HRTEM. Two nanoscale mineral types, i.e., mineral nanoparticles and nanomi- nerals, were observed in the Anthrosol. Mineral nanoparticles in soil included well crystalline aluminumsilicate nanosheets, nanorods, and nanoparticles. Nanosheets with a length of 120-150 nm and a width of about 10-20 nm were identified as chlorite/vermiculite series. The presence of clear lattice fringe spacing in HRTEM image of nanoparticles indicated that mineral nanoparticles had a relatively good crystallinity. The nanomineral ferrihydrite also existed in the Anthrosol. The HRTEM images and the particle size distribution histogram suggested that these ferrihydrite nanoparticles were quite homogeneous, and had a narrow size distribution range （1-7 nm） with a mean diameter of 3.6 4- 1.6 nm. Our HRTEM observation indicated that mineral nanoparticles and nanominerals were common and widely distributed in Anthrosols. HRTEM and selected area diffraction or lattice fringe spacing characterization provided further proofs to the structure of nanoparticles formed in soil.