•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.
Hydrothermal carbonization (HTC) is a thermochemical conversion technique which is attractive due to its ability to transform wet biomass into energy and chemicals without predrying. The solid ...product, known as hydrochar, has received attention because of its ability to prepare precursors of activated carbon in wastewater pollution remediation, soil remediation applications, solid fuels, and other carbonaceous materials. Besides the generally lignocellulose biomass used as sustainable feedstock, HTC has been applied to a wide range of derived waste, including sewage sludge, algae, and municipal solid waste to solve practical problems and generate desirable carbonaceous products. This review presented the critical hydrothermal parameters of HTC, including temperature, residence time, heating rate, reactant concentration, and aqueous quality. The chemical reaction mechanisms involved in the formation of hydrochar derived from single components and representative feedstock, lignocellulose, and sludge termed as N-free and N-rich biomass, were elucidated and summarized to better understand the hydrochar formation process. Specifically, hydrochar physicochemical characteristics such as surface chemistry and structure were investigated. Current knowledge gaps, and new perspectives with corresponding recommendations were provided to further exploit the great potential of the HTC technique and more practical applications for hydrochar in the future.
•Hydrothermal carbonization of biomass waste receives great deal attention.•Hydrothermal conditions during HTC process are critical to hydrochar production.•The chemical reaction mechanisms involved in hydrochar formation are reviewed.•Hydrochar physicochemical characteristics from biomass waste are summarized.
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.
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•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.
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.
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.
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•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.
•Composition and properties of algae and algae ash were summarized.•Comparative characterization between algae and other solid fuels was given.•Advantages of algae composition and properties were ...described.•Disadvantages and challenges of algae composition and properties were discussed.
Algae-based fuels are considered to be the most sustainable, renewable, effective and environment friendly response to climate change and food–feed security, as well as the only renewable energy resource that has the capacity to meet the global demand for fuels in the long-term. Therefore, an extended overview of the composition, properties and challenges of algae biomass for biofuel application was conducted based on reference peer-reviewed data plus own investigations. Initially, some general considerations such as current bioenergy situation and significance of biofuel generations, as well as different aspects related to biomass use as biofuels are discussed. Then, common issues concerning taxonomical classification, habitat environment, carbon reserve capacity, production, use, and main advantages and disadvantages of algae or algae biofuel are addressed. Further, more than 135 characteristics related to the chemical, phase and mineral composition and properties of algae and algae ash are evaluated and compared to those of terrestrial biomass, coal and their ashes. As a result specific benefits and obstacles connected with the composition and properties of algae and algae ash are discussed. The behaviour of organic and inorganic matter during algae combustion is also described. Finally, the major technological and environmental challenges related to algae-based fuels are emphasized. The present data demonstrate that the high contents of inorganic matter with unfavourable modes of element occurrences (chlorides, sulphates, carbonates, oxalates, nitrates and some oxyhydroxides, phosphates and amorphous material) in algae and algae ash provoke the most critical technological and environmental challenges during algae processing for biofuel application and especially during algae thermochemical conversion. Another very important challenge addressed is the indefinite availability of sustainable algae resources for production of biofuels and biochemicals and certain recommendations are given. It was found that the disadvantages of algae biofuel application prevail significantly over the advantages; however, the major economic, environmental and social benefits appear to compensate the technological and other barriers caused by the unfavourable composition and properties of algae.
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