•The effect of microplastics on the chlorophyll a content of algae was studied.•The changes of photosynthetic activity were determined.•High concentrations of microplastics inhibited photosynthesis ...of algae.•Toxicity of polyvinyl chloride (PVC) is greater than that of polypropylene (PP).
Microplastics are widely distributed in freshwater environments. At present, most of the studies on the toxicity of microplastics are concentrated on aquatic feeding animals, but relatively few have addressed freshwater algae. This study investigated the effect of microplastics (polypropylene (PP) and polyvinyl chloride (PVC)) exposure on the photosynthetic system of freshwater algae over the logarithmic growth period. The results showed that both PVC and PP had a negative effect on chlorophyll a concentrations of Chlorella (C.) pyrenoidosa and Microcystis (M.) flos-aquae; among them, when the concentration of PVC exceeded 250 mg/L, compared with the control group, the chlorophyll a content of C. pyrenoidosa was reduced by 55.23%. For photosynthetic activity, higher concentrations of PVC and PP can induce lower values of Fv/Fm, Fv/F0, and Fv’/Fm’, suggesting a larger impact in algae. However, algae were able to adjust, with increased values of Fv/Fm, Fv/F0, and Fv’/Fm’. This dose-negative effect phenomenon also exists in the study of the rapid light-response curves. In addition, comparing the two microplastics, we could see that PVC greatly inhibits the photosynthesis system of freshwater algae. Our study confirmed that microplastics can affect algae growth under certain concentrations, which provides evidence for understanding the risks of microplastics.
Green plants (Viridiplantae) include around 450,000-500,000 species
of great diversity and have important roles in terrestrial and aquatic ecosystems. Here, as part of the One Thousand Plant ...Transcriptomes Initiative, we sequenced the vegetative transcriptomes of 1,124 species that span the diversity of plants in a broad sense (Archaeplastida), including green plants (Viridiplantae), glaucophytes (Glaucophyta) and red algae (Rhodophyta). Our analysis provides a robust phylogenomic framework for examining the evolution of green plants. Most inferred species relationships are well supported across multiple species tree and supermatrix analyses, but discordance among plastid and nuclear gene trees at a few important nodes highlights the complexity of plant genome evolution, including polyploidy, periods of rapid speciation, and extinction. Incomplete sorting of ancestral variation, polyploidization and massive expansions of gene families punctuate the evolutionary history of green plants. Notably, we find that large expansions of gene families preceded the origins of green plants, land plants and vascular plants, whereas whole-genome duplications are inferred to have occurred repeatedly throughout the evolution of flowering plants and ferns. The increasing availability of high-quality plant genome sequences and advances in functional genomics are enabling research on genome evolution across the green tree of life.
Display omitted
•A novel 3D reticular anti-fouling green bio-sorbent was prepared by introducing PEI and GDAC for the removal of U(VI).•The 3D HF-PEI-GDAC has multi-active sites, which exhibiting ...high adsorption capacity for uranium in the simulated seawater.•The 3D HF-PEI-GDAC exhibits excellent selectivity and cyclability.•HF-PEI-GDAC is an eco-friendly uranium adsorbent that can effectively block algae to contact the surface.
Plenty of uranium resources were consumed with the development of nuclear energy. Therefore, the effective collection of uranium resources has been received much focus. It is well known that the amount of uranium resources in the seawater is abundant. However, the extremely low concentration of U(VI) and complex environments pose are considerable challenges for the extraction of uranium. Herein, the polyethylenimine (PEI) and Guanidineacetic acid (GDAC) were covalently grafted onto the surface of the hemp fibers (HF) to prepare a novel 3D reticular anti-fouling green adsorption material. Subsequently, a series of adsorption batch experiments were performed to evaluate the performance of the adsorbent. The experimental results showed that the maximum adsorption capacity of HF-PEI-GDAC is 414.93 mg/g. Meanwhile, the adsorbent exhibited great adsorption properties in simulated seawater. In addition, the adsorbent still presents excellent resistance to the algae adhesion after 15 days. Therefore, the HF-PEI-GDAC can be considered as a highly promising adsorbent for the extraction of U(VI) from seawater.
Microstructured calcium alginate (Ca-Alg) hydrogel exhibiting superhydrophilicity and underwater superoleophobicity is prepared for high speed and highly efficient oil/water separation. The ...fabricated mesh works in highly acidic or basic, salty, and high-temperature environments because of the stability of Ca-Alg. Moreover, nonwoven fabric used as a template for Ca-Alg is capable of separation of an oil-in-water emulsion.
Photosynthetic splitting of water into oxygen by plants, algae, and cyanobacteria is catalyzed by the oxygen-evolving center (OEC). Synthetic mimics of the OEC, which is composed of an asymmetric ...manganese-calcium-oxygen cluster bound to protein groups, may promote insight into the structural and chemical determinants of biological water oxidation and lead to development of superior catalysts for artificial photosynthesis. We synthesized a Mn4Ca-cluster similar to the native OEC in both the metal-oxygen core and the binding protein groups. Like the native OEC, the synthetic cluster can undergo four redox transitions and shows two magnetic resonance signals assignable to redox and structural isomerism. Comparison with previously synthesized Mn3CaO4-cubane clusters suggests that the fourth Mn ion determines redox potentials and magnetic properties of the native OEC.
Display omitted
•A 3D rice-like hierarchical nanocomposite was designed by anchoring La species into LDH matrix.•La@MgAl achieved high adsorption capacities for both phosphate and ...fluoride.•Satisfactory selectivity and reusability of the adsorbent were proved.•Interlayer sorption and inner-sphere complexation were main mechanisms for excellent adsorption performance.•La@MgAl was effective for synchronous phosphate and fluoride remediation in real wastewater.
The frequent occurrence of algae boom and skeletal fluorosis has drawn global attention to developing feasible technologies for phosphate and fluoride removal from water bodies. This study reported the synthesis of novel three-dimensional rice-like La@MgAl nanocomposites by anchoring La species into Mg-Al LDH matrix to achieve effective and synchronous phosphate and fluoride capture. Results from multiple detection methods including XRD, SEM, FTIR, and XPS revealed the introduced La cations could serve as a structural inducer to regulate the crystallinity of the La@MgAl composites and rice-like nanocomposite La@MgAl-1 was fabricated under optimal La loading amount. La@MgAl-1 possessed high adsorption capacities for both phosphate and fluoride (101.59 mg/g and 51.03 mg/g, respectively). The effective adsorption performance also sustained even after five adsorption-desorption cycles, indicating favorable reusability. The adsorption mechanism analysis revealed that the presence of unique hydrotalcite-like structure triggered memory effect to exert strong adsorption of P and F anions into the interlayered gallery. Besides, an optimum amount of La species organized on the composite wielded specific anion adsorption to phosphate and fluoride through inner-sphere complexation and ligand exchange. These encouraging results highlight the positive consequence of combining the strategic La species and LDH matrix to render a nanostructured Mg/Al/La ternary metal assembly in which various components are united in a controllable way to exert collective properties for accumulative anion adsorption properties. Besides, this study offered promising candidates for real water purification against phosphate and fluoride pollution.
•Carrageenans are a source of renewable, sustainable polymers derived from seaweeds.•Limitations of carrageenan films arise from their inherent hydrophilicity.•Blending, reinforcement, and ...multi-layering can enhance film properties and extend potential applications.•Blends with nanocellulose can improve tensile strength by 50%.•Films layered with poly(lactic acid) can reduce water vapor permeability by 24-fold.
Carrageenan, a polysaccharide extracted from marine algae, is becoming increasingly regarded as a promising renewable biomaterial that has strong potential as a substitute for conventional synthetic plastics. Materials derived from carrageenans have been widely investigated over the recent decades for use in pharmaceutical and biomedical applications through to edible films and coatings. In the area of flexible films, carrageenans suffer from limitations that are primarily a result of their inherent hydrophilicity. Considerable research efforts have been devoted to the improvement of the properties of carrageenan films in order to extend the range of suitable applications. These include blending with other polymers, the use of plasticizers, and reinforcements with nanomaterials. This review comprehensively assesses the current status of carrageenan-based film development including material characteristics and strategies to obtain desirable film properties with particular regard to real applications.
Over the last two decades, the hydrothermal liquefaction (HTL) of algae has emerged as a promising technology for producing liquid bio-oil to meet increasing energy demands and reduce environmental ...pollution. In this article, the present research status of the catalytic HTL of algae and the catalytic hydrothermal upgrading of biocrude (crude bio-oil) is systematically reviewed and analyzed. The corresponding catalytic characteristics (such as the catalytic effect on the biocrude yield and quality and the related influencing factors) and catalytic mechanisms (e.g., hydrogenation, deoxygenation, decarboxylation, denitrogenation and desulfurization) during algae HTL as well as the approaches for upgrading of biocrude are summarized and analyzed comprehensively. Another potential technological flow for bio-oil production from algae HTL is proposed, and a comparison between direct catalytic HTL and the two-step production method is presented for the first time. Moreover, contemporary problems and subsequent research directions are presented.
•Analyze catalytic performances of various catalysts on algae HTL and biocrude upgrading.•Summarize catalytic reaction mechanisms of hydrogenation and heteroatom removal.•Compare the characteristics of direct catalytic HTL and the two-step producing method.•Propose a potential whole technological flow concerning bio-oil production from algae HTL.•Recommend some future research directions on catalytic algae HTL and biocrude upgrading.
Biofuels from biomass gasification are reviewed here, and demonstrated to be an attractive option. Recent progress in gasification techniques and key generation pathways for biofuels production, ...process design and integration and socio-environmental impacts of biofuel generation are discussed, with the goal of investigating gasification-to-biofuels’ credentials as a sustainable and eco-friendly technology. The synthesis of important biofuels such as bio-methanol, bio-ethanol and higher alcohols, bio-dimethyl ether, Fischer Tropsch fuels, bio-methane, bio-hydrogen and algae-based fuels is reviewed, together with recent technologies, catalysts and reactors. Significant thermodynamic studies for each biofuel are also examined. Syngas cleaning is demonstrated to be a critical issue for biofuel production, and innovative pathways such as those employed by Choren Industrietechnik, Germany, and BioMCN, the Netherlands, are shown to allow efficient methanol generation. The conversion of syngas to FT transportation fuels such as gasoline and diesel over Co or Fe catalysts is reviewed and demonstrated to be a promising option for the future of biofuels. Bio-methane has emerged as a lucrative alternative for conventional transportation fuel with all the advantages of natural gas including a dense distribution, trade and supply network. Routes to produce H2 are discussed, though critical issues such as storage, expensive production routes with low efficiencies remain. Algae-based fuels are in the research and development stage, but are shown to have immense potential to become commercially important because of their capability to fix large amounts of CO2, to rapidly grow in many environments and versatile end uses. However, suitable process configurations resulting in optimal plant designs are crucial, so detailed process integration is a powerful tool to optimize current and develop new processes. LCA and ethical issues are also discussed in brief. It is clear that the use of food crops, as opposed to food wastes represents an area fraught with challenges, which must be resolved on a case by case basis.
It is increasing clear that biofuels can be a viable source of renewable energy in contrast to the finite nature, geopolitical instability, and deleterious global effects of fossil fuel energy. ...Collectively, biofuels include any energy-enriched chemicals generated directly through the biological processes or derived from the chemical conversion from biomass of prior living organisms. Predominantly, biofuels are produced from photosynthetic organisms such as photosynthetic bacteria, micro- and macro-algae and vascular land plants. The primary products of biofuel may be in a gas, liquid, or solid form. These products can be further converted by biochemical, physical, and thermochemical methods. Biofuels can be classified into two categories: primary and secondary biofuels. The primary biofuels are directly produced from burning woody or cellulosic plant material and dry animal waste. The secondary biofuels can be classified into three generations that are each indirectly generated from plant and animal material. The first generation of biofuels is ethanol derived from food crops rich in starch or biodiesel taken from waste animal fats such as cooking grease. The second generation is bioethanol derived from non-food cellulosic biomass and biodiesel taken from oil-rich plant seed such as soybean or jatropha. The third generation is the biofuels generated from cyanobacterial, microalgae and other microbes, which is the most promising approach to meet the global energy demands. In this review, we present the recent progresses including challenges and opportunities in microbial biofuels production as well as the potential applications of microalgae as a platform of biomass production. Future research endeavors in biofuel production should be placed on the search of novel biofuel production species, optimization and improvement of culture conditions, genetic engineering of biofuel-producing species, complete understanding of the biofuel production mechanisms, and effective techniques for mass cultivation of microorganisms.
•Challenges and opportunities of biofuels in addressing global energy demands were investigated.•Third generation biofuels using microalgae seems to be promising energy sources in the long run.•Improving microalgae species and achieving more in-depth understanding of biofuel production mechanisms is essential.
PDF
