A review of the ecotoxicological status of microplastic pollution in African freshwater systems.

Microplastics (MPs) have found extensive application globally due to their low cost, flexibility and light weight. Microplastic pollution is a growing environmental concern that poses significant threats to aquatic ecosystems worldwide, including African freshwater systems. Nevertheless, although Africa houses some of the deepest and largest freshwater rivers and lakes in the world such as Lake Tanganyika and Victoria, River Congo and the Nile, there is limited information available regarding the presence of MPs in these inland waters. Selected published data on MPs in African freshwater systems, including sediments, biota, rivers, and lakes, were incorporated in this review. The study discovered that the sampling technique employed has a major impact on the morphological characteristics and abundance of MPs in African freshwater systems. Fibers and fragments were the most common shapes; black, white, and transparent were the most prevalent colors; and polyethene terephthalate, polystyrene, and polypropylene were the frequently dominant polymers. As the distance between the sampling sites increased geographically, the polymer similarities declined. MPs have been found to translocate into body cells and tissues where they are capable of causing genetic mutations, cytotoxicity, oxidative stress and neurotoxicity. In Africa, MPs are poorly managed and monitored, and there has been insufficient research done on the possibility that they could be present in drinking water. Considering the fact that humans in the continent are exposed to freshwater and aquatic organisms, the risk assessment routes are currently unvalidated, therefore it was recommended that African nations should strengthen their capacity for plastic management and environmental monitoring. This review provides up to date information on the occurrence, prevalence, ecotoxicity and management of MPs across African freshwater systems.

Dual p-n Z-scheme heterostructure boosted superior photoreduction CO2 to CO, CH4 and C2H4 in In2S3/MnO2/BiOCl photocatalyst.

The creation of a Z-scheme heterojunction is a sophisticated strategy to enhance photocatalytic efficiency. In our study, we synthesized an In2S3/MnO2/BiOCl dual Z-scheme heterostructure by growing BiOCl nanoplates on the sheets of In2S3 nanoflowers, situated on the surface of MnO2 nanowires. This synthesis involved a combination of hydrothermal and solution combustion methods. Experiments and density functional theory (DFT) calculations demonstrated that the In2S3/MnO2/BiOCl composite exhibited notable photo reduction performance and photocatalytic stability. This was attributed to the pivotal roles of BiOCl and MnO2 in the composite, acting as auxiliaries to enhance the electronic structure and facilitate the adsorption/activation capacity of CO2 and H2O. The yield rates of CO, CH4, and C2H4 over In2S3/MnO2/BiOCl as the catalyst were 3.94, 5.5, and 3.64 times higher than those of pure In2S3, respectively. Photoelectrochemical analysis revealed that the dual Z-scheme heterostructure, with its oxygen vacancies and large surface area, enhanced CO2 absorption and active sites on the nanoflower/nanowire intersurfaces. Consequently, the dual Z-scheme charge transfer pathway provided efficient channels for boosting electron transfer and charge separation, resulting in high C2H4, CH4, and CO yields of formed and exihibits an promising photoreduction rate of CO2 to CO (51.2 µmol/g.h), CH4 (42.4 µmol/g.h) and C2H4 (63.2 µmol/g.h), respectively. DFT, in situ Diffuse reflectance infrared fourier transform spectroscopy, and temperature-programmed desorption tests were employed to verify the intermediates pathway. The study proposed a potential photocatalytic mechanism based on these findings.

Innovative dual-active sites in interfacially engineered interfaces for high-performance S-scheme solar-driven CO2 photoreduction.

The realization of 2D/2D Van der Waals (VDW) heterojunctions represents an advanced approach to achieving superior photocatalytic efficiency. However, electron transfer through Van der Waals heterojunctions formed via ex-situ assembly encounters significant challenges at the interface due to contrasting morphologies and potential barriers among the nanocomposite substituents. Herein, a novel approach is presented, involving the insertion of a phosphate group between copper phthalocyanine (CuPc) and B-doped and N-deficient g-C3N4 (BDCNN), to design and construct a Van der Waals heterojunction labeled as xCu[acs]/yP-BDCNN. The introduction of phosphate as a charge modulator and efficient conduit for charge transfer within the heterojunction resulted in the elimination of spatial barriers and induced electron movement from BDCNN to CuPc in the excited states. Consequently, the catalytic central Cu2+ in CuPc captured the photoelectrons, leading to the conversion of CO2 to C2H4, CO and CH4. Remarkably, this approach resulted in a 78-fold enhancement in photocatalytic efficiency compared to pure BDCNN. Moreover the findings confirm that the 2D-2D 4Cu[acs]/9P-BDCNN sheet-like heterojunction effectively boosts photocatalytic activity for persistent pollutants such as methyl orange (MO), methylene blue (MB), rhodamine B (RhB), and tetracycline antibiotics (TCs). The introduction of "interfacial interacting" substances to establish an electron transfer pathway presents a novel and effective strategy for designing photocatalysts capable of efficiently reducing CO2 into valuable products.

A Review on Tetrabromobisphenol A: Human Biomonitoring, Toxicity, Detection and Treatment in the Environment.

Tetrabromobisphenol A (TBBPA) is a known endocrine disruptor employed in a range of consumer products and has been predominantly found in different environments through industrial processes and in human samples. In this review, we aimed to summarize published scientific evidence on human biomonitoring, toxic effects and mode of action of TBBPA in humans. Interestingly, an overview of various pretreatment methods, emerging detection methods, and treatment methods was elucidated. Studies on exposure routes in humans, a combination of detection methods, adsorbent-based treatments and degradation of TBBPA are in the preliminary phase and have several limitations. Therefore, in-depth studies on these subjects should be considered to enhance the accurate body load of non-invasive matrix, external exposure levels, optimal design of combined detection techniques, and degrading technology of TBBPA. Overall, this review will improve the scientific comprehension of TBBPA in humans as well as the environment, and the breakthrough for treating waste products containing TBBPA.

Highly Enhanced Photocatalytic Hydrogen Production Performance of Heterostructured Ti3C2/TiO2/rGO Composites.

There has been a dire need for the exploration of renewable clean hydrogen energy recourses in recent years. In this work, we investigated the photocatalytic hydrogen production of heterostructured Ti3C2/TiO2/rGO composites. Ti3C2/TiO2/rGO heterojunction nanocomposites were synthesized using two-step calcination and hydrothermal methods, and the optimum in situ growth ratio of TiO2 of 71.8% (nTi-O/nTi) and rGO mass ratio (mRGO/mTiO2/mTi3C2) of 12% were obtained. The target photocatalyst presented an outperforming photocatalytic hydrogen production performance of 1671.85 µmol·g-1 hydrogen production capacity in 4 h, with the maximum hydrogen production rate of 808.11 µmol·g-1·h-1 in the first hour being 3.08 times the maximum hydrogen production rate of bare TiO2 (262.66 µmol·g-1·h-1). The excellent hydrogen production performance was due to the formed rutile TiO2 and the constructed heterojunction of Ti3C2/TiO2/rGO, where rGO provided different electron transport channels, and made charge transfer easier, and restrained the recombination efficiency of electrons and holes.

One-pot synthesis of magnetic Ni@Mg(OH)2 core-shell nanocomposites as a recyclable removal agent for heavy metals.

A surfactant-assisted hydrothermal route has been presented to one-pot synthesized Ni nanoparticles encapsulated in Mg(OH)2 hollow spheres. The diameter of Ni cores and the thickness of Mg(OH)2 shells are about 60-80 and 15 nm, respectively, and the size of a whole composite sphere is approximately 70-100 nm. Benefiting from the ferrimagnetic behavior of Ni cores and the high surface area of Mg(OH)2 shells, Ni@Mg(OH)2 nanocomposites exhibit excellent heavy metals adsorption capacity and recyclable property. The first removal efficiency is almost 100% for target metals, and after five cycles, the adsorption capacity remains 95%. A series of experiments show the adsorption of heavy metal ions on Ni@Mg(OH)2 follows a pseudo-second order kinetic equation and can be described by a Langmuir isotherm model.

Preparation, physical-chemical characterisation and cytocompatibility of calcium carbonate cements.

The feasibility of calcium carbonate cements involving the recrystallisation of metastable calcium carbonate varieties has been demonstrated. Calcium carbonate cement compositions presented in this paper can be prepared straightforwardly by simply mixing water (liquid phase) with two calcium carbonate phases (solid phase) which can be easily obtained by precipitation. An original cement composition was obtained by mixing amorphous calcium carbonate and vaterite with an aqueous medium. The cement set and hardened within 2h at 37 degrees C in an atmosphere saturated with water and the final composition of the cement consisted mostly of aragonite. The hardened cement was microporous and showed poor mechanical properties. Cytotoxicity tests revealed excellent cytocompatibility of calcium carbonate cement compositions. Calcium carbonates with a higher solubility than the apatite formed for most of the marketed calcium phosphate cements might be of interest to increase biomedical cement resorption rates and to favour its replacement by bone tissue.