We used discarded oyster shells to prepare vaterite calcium carbonate microparticles and explored the removal effects and the underlying mechanism toward several heavy metal ions. The removal ...efficiency for each ion type was: Pb2+ (99.9%), Cr3+ (99.5%), Fe3+ (99.3%), and Cu2+ (57.1%). With the exception of Cu2+, vaterite calcium carbonate particles exhibited excellent removal performance on all tested heavy metal ions, with exceptional results for Pb2+. The factor affecting the removal efficiency of heavy metal ions is shown to involve an ion exchange reaction between calcium and the heavy metal ions resulting in recrystallization. Vaterite calcium carbonate particles prepared by this method have the advantage of low price, easy synthesis, and reduction of environmental waste. Thus, this procedure for synthesizing vaterite CaCO3 provides an environmentally responsible method for preparing materials that can be economically incorporated into common consumer products such as household drinking water filtration systems.
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•Oyster shells-prepared CaCO3 has better removal efficiencies than commercial CaCO3.•Heavy metals removal could also be indirectly monitored via pH changes.•The CaCO3 remove heavy metal ions rapidly and be used in water treatments.
Macro- and microalgae-based foods are becoming popular due to their high nutritious value. The algal biomass is enriched with polysaccharides, protein, polyunsaturated fatty acids, carotenoids, ...vitamins and minerals. However, the most promising fraction is polysaccharides (PS) or their derivatives (as dietary fibers) which are not entirely fermented by colonic bacteria hence act as potential prebiotic. Primarily, algae become famous as prominent protein sources. Recently, these are widely adopted as functional food (e.g., desserts, dairy products, oil-derivatives, pastas etc.) or animal feed (for poultry, cattle, fish etc.). Besides prebiotic and balanced amino acids source, algae derived compounds implied as therapeutics due to comprising bioactive properties to elicit immunomodulatory, antioxidative, anticancerous, anticoagulant, hepato-protective, and antihypertensive responses. Despite the above potentials, broader research determinations are inevitable to explore these algal compounds until microalgae become a business reality for broader and specific applications in all health domains. However, scale up of algal bioprocess remains a major challenge until commercial affordability is accomplished which can be possible by discovering their hidden potentials and increasing their value and application prospects. This review provides an overview of the significance of algae consumption for several health benefits in humans and animals mainly as prebiotics, however their functional food and animal feed potential are briefly covered. Moreover, their potential to develop an algal-based food industry to meet the people's requirements not only as a sustainable food solution with several health benefits but also as therapeutics is inevitable.
4-Nonylphenol (4-NP), a phenolic endocrine disruptor chemical (EDC), is known to have high toxicity to aquatic organisms and humans. The remediation of 4-NP-contaminated marine sediments was studied ...using red algae-based biochar (RAB) thermochemically synthesized from Agardhiella subulata with simple pyrolysis process under different temperatures of 300–900 °C in CO2 atmosphere. The RAB was characterized by XRD, Raman, FTIR spectroscopy, and zeta potential measurements. The calcium in RAB efficiently activated sodium percarbonate (SPC) to generate reactive radicals for the catalytic degradation of 4-NP at pH 9.0. The oxygen-containing functional groups reacted with H2O2, which increased the generation of reactive radicals under alkaline pH condition. Ca2+ ion was the active species responsible for 4-NP degradation. CaO/CaCO3 on RAB surface enhanced direct electron transfer, increased HO production, and 4-NP degradation in marine sediments. Langmuir‒Hinshelwood type kinetics well described the 4-NP degradation process. Remediation of contaminated sediments using RAB could be a sustainable approach toward closed-loop biomass cycling in the degradation of 4-NP contaminants.
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•RAB was successfully prepared from red algae biomass.•Real marine sediments were treated with SPC oxidation for 4-NP removal.•Calcium-enriched RAB efficiently activated SPC to generate reactive radicals.•pH and RAB dose controlled 4-NP degradation.•Langmuir-Hinshelwood model described well the kinetics of 4-NP degradation.
There has been a significant increase in the microplastic (MP) polluting the ocean in recent time which is regarded as toxic for living organisms. In this study, Fluorescent red polyethylene ...microspheres (FRPE) were administered intramuscularly to Litopenaeus vannamei juveniles at the concentration of 0.1, 0.2, 0.5 and 1.0 μg (g shrimp)−1, and the survival rate was recorded. Analysis of the hepatopancreas for antioxidant enzyme activity and gene expression were done after seven days. Further tissue morphology and accumulation of FRPE was analysed. The results showed that FRPE at 0.5 and 1.0 μg (g shrimp)−1 reduce the survival rate of L. vannamei. FRPE at 0.5 and 1.0 μg (g shrimp)−1 reduced superoxide dismutase (SOD) activity; FRPE at different concentrations reduced catalase (CAT) activity; FRPE at 0.2, 0.5 and 1.0 μg (g shrimp)−1 increased the lipid peroxide thiobarbituric acid (TBARS) content. FRPE at 0.1, 0.2, and 0.5 μg (g shrimp)−1 significantly affect the performance of SOD and CAT genes; FRPE at 0.2 and 0.5 μg (g shrimp)−1 significantly improves GPx gene performance; FRPE at 1.0 μg (g shrimp)−1 significantly reduced the expression of GPx genes. Analysis of tissue morphology shows that FRPE cause muscle, midgut gland, and hepatopancreas, and gill damage at different concentrations. In the results of accumulation of microplastic, FRPE accumulated in gill tissue at 0.2 and 0.5 μg (g shrimp)−1; FRPE accumulated in gill, muscle and hepatopancreas tissue at 1.0 μg (g shrimp)−1. Based on the above results, FRPE at 0.5 and 1.0 μg (g shrimp)−1 can regulate the antioxidant enzymes of L. vannamei, increase lipid peroxide content, cause tissue damage by accumulating in the tissues. The rate of survival decreased in L. vannamei, and the impact of FRPE at 1.0 μg (g shrimp)−1 was significant.
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•FRPE when injected reduces the survival rate of Litopenaeus vannamei.•Injection of FRPE induce oxidative stress and histology damage in L. vannamei.•FRPE is accumulated in the muscle, hepatopancreas and gills of L. vannamei.
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•Rice husk derived biochar modified (RHMB) by hydrothermal auxiliary alkali.•RHMB exhibited improved performance in removing Malachite green (MG).•RHMB was efficient for MG removal ...from saline and non-saline wastewaters.•Major adsorption contacts were H bonding, π-π interactions at pH 6.•The maximum adsorption capacity of RHMB obtained was 373.02 mg g−1.
Extremely soluble Malachite green (MG) acts as potential carcinogen for aquatic life in polluted aqueous environments. Current study aims to modify rice husk derived biochar to improve its removal efficiency for MG from MG-containing wastewaters. The hydrothermal alkali activation was effective for preparing modified biochar (RHMB) from native biochar (RHB) derived from rice husk. After modification, surface area and pore volume of RHMB was determined respectively 434.62 m2g−1 and 287.28 cm3g−1, significantly improved from native RHB values 21.764 m2g−1 and 65.53 cm3g−1. Pseudo second order kinetic model fitted well. RHMB exhibits an equilibrium adsorption capacity of 373.02 mg g−1. RHMB showed an excellent MG removal ability and was not susceptible to ion interference even at highly saline environments. It has exhibited 96.96 ± 1.17% removal efficiency of MG and is expected to be used as potential adsorbent for MG remediation from aquaculture wastewater and other MG containing industrial wastewaters.
•Facile synthesis of novel MoS2/TiO2 nanohybrids is described.•Synergistic effect of the nanohybrids is improves the photodegradation efficiency.•Superoxide radicals are the most reactive species in ...a reductive degradation route.•Nanohybrids showed a high rate of tetracycline degradation and heavy metal reduction.•The degradation pathway and mechanism of TC were performed by liquid chromatography-mass spectrometry.
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In this study, MoS2/TiO2 nanohybrids, formed through hydrothermal synthesis technique, was considered as a superior heterojunction for the removal of tetracycline (TC) and Pb (II) reduction under visible light irradiation. The Z-scheme MoS2/TiO2 nanohybrids was easily synthesized with much narrower nanoparticles, ~10 times the outstanding charge separation, and greater specific surface area than bulk MoS2 or TiO2. The MoS2/TiO2 nanohybrids achieved a stronger photocatalytic activity, which could degrade 94% TC within 60 min. The optimized nanohybrids catalysts demonstrated outstanding efficiency with the apparent reaction rate constants of 0.05 min−1 for TC removal, about 3–4 times as bigger as the removal rate of bulk components. Superoxide radical (˙O2−) was presumed as the conduct active species in the potential improvement mechanism of organized MoS2/TiO2 nanohybrids for photocatalytic activities was introduced. These can admit to prefer photodegradation pathways and mechanism of tetracycline by nanohybrids with visible light activity. The novel nanohybrids photocatalysts have great structural stability, greater light absorption, and superior cycle performance, which could be utilized as an efficient process of antibiotics degradation and Pb (II) removal.
In recent years, the increase of microplastics in the sea exerted a negative impact on coral health. This study has been undertaken to analyze the impact of microplastics on corals. Here, Goniopora ...columna was exposed to different concentrations of polyethylene microplastics (PE-MP). The daily polyps length and adaptability were recorded. Analysis of the zooxanthellae density and antioxidant activity of coral was done after 1, 3, 5 and 7 days. Further tissue morphology and accumulation of PE-MP were analyzed. The results showed that PE-MP at different concentrations can be adsorbed on the surface of corals and enter inside corals after 7 days. PE-MP at different concentrations reduced polyps length, adaptability and cause the changes in the density of zooxanthellae to be the reason for unbalancing of corals. PE-MP at different concentrations reduced the superoxide dismutase (SOD) activity after exposure to 1 day. PE-MP increased the catalase (CAT) activity at 100 mg/L after exposure; even after reducing the concentration has the same effect. PE-MP at various concentrations increased the glutathione peroxidase (GPx) activity after exposure to 5 and 7 days. It also increased the glutathione transferase (GST) and glutathione (GSH) activity after exposure to 5 and 7 days. PE-MP at different concentrations increased the malondialdehyde (MDA) content after exposure from 1 to 7 days. Analysis of tissue morphology and tissue accumulation shows that different concentrations of PE-MP cause mesenteric atrophy, vacuole, and accumulation in the coral mesenteric. These results indicate that the PE-MP can impact the antioxidant system and hampers the function of enzymes responsible for detoxification of G. columna, increase lipid peroxide content and also cause tissue damage through accumulating in the coral mesenteric.
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•Polyethylene microplastics (PE-MP) cause oxidative damage of Goniopora columna.•PE-MP destroy the function of detoxification enzymes of G. columna.•PE-MP interfere with the anthozoan-algae symbiotic relationships of G. columna.•PE-MP cause mesenteric atrophy, vacuolar and accumulate in the G. columna.
The growing number of industrial carbon emissions have resulted in a significant increase in the greenhouse gas carbon dioxide (CO2), which, in turn, will have a major impact on climate change. ...Therefore, the reduction, storage, and reuse of CO2 is an important concern in modern society. Calcium oxide (CaO) is known to be an excellent adsorbent of CO2 in a high-temperature environment. However, since deterioration of the adsorbent is likely to occur after repeated cycles of adsorption under high temperature conditions, it would be desirable to mitigate this phenomenon, in order to maintain the stability of CaO. In the present study, common eggshell waste was used as the starting material. The main component of eggshell waste is calcium carbonate (CaCO3), which was purified to produce CaO. Different surfactants and amino-containing polymers were added to synthesize CaO-based adsorbents with different configurations and pore sizes. The amount of CO2 adsorbed was determined using a thermogravimetric analyzer (TGA). The results showed that the CO2 adsorption capacity of the synthetic CaO recovered from purified eggshell waste could reach 0.6 g-CO2/g-sorbent, indicating a good adsorption capacity. CaO modified with a dopamine-containing polymer was shown to have an adsorption capacity of 0.62 g-CO2/g-sorbent. Moreover, it showed an excellent adsorption capacity of 0.40 g-CO2/g-sorbent, even after 10 cycles of CO2 adsorption. The present study suggests that using eggshell waste to synthesize CaO-based adsorbents for effective CO2 adsorption can not only reduce environmental waste, but also have the potential to capture greenhouse gas CO2 emissions, which conforms to the principles of green chemistry.
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•CaO prepared from eggshell was applied for CO2 gas adsorption.•Pore size and volume of CaO were varied by using surfactants and amino containing polymers.•Through thermogravimetry analysis amount of CO2 adsorbed were analyzed.•CaO prepare from dopamine containing polymer showed excellent adsorption capacity.
The effect of pyrolysis temperature on the generation of polycyclic aromatic hydrocarbons (PAHs) in sewage sludge biochar (SSB) and the removal of hazardous chemicals from esturine sediments by SSB ...and sodium percarbonate (SPC), exemplified by 4-nonylphenol (4-NP) were studied. SSB synthesized at 500 °C (SSB500) achieved the highest 4-NP degradation efficiency of 73%, at pH0 9.0 in 12 h of reaction time. The enhanced 4-NP degradation was attributed to the SSB500 activation activation of SPC that produced sufficient •OH and CO3−• due to electron-transfer interaction on the Fe–Mn redox pairs. The microbial community diversity and composition of the treated sediment were compared using high-throughput sequencing. Results showed SSB/SPC treatment increased the microbial diversity and richness in the sediments. Proteobacteria were the keystone phylum, while Thioalkalispira genera were responsible for 4-NP degradation in the SSB/SPC treatment. Over all, results revealed the change in the bacterial community during the environmental applications of SSB, which provided essential information for better understanding of the monitoring and improvement of sustainable sediment ecosystems.
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•SSB effectively activated SPC toward 4-NP degradation in estuarine sediments.•4-NP degradation efficiency was affected by pyrolysis temperature, SSB dose, and pH.•4-NP degradation process was well described by the pseudo-first-order kinetics equation.•Bacterial composition, richness, and diversity were changed after SSB/SPC treatment.
The adsorption of Pb ions, on high-density polyethylene (PE) microplastics (MPs) with the diameter of 48–500 μm, was examined in this study. According to the Langmuir isotherm, MP of the smallest ...size, 48 μm, had the greatest adsorption capacity of 0.38 μmol g−1. The mechanism of Pb ions adsorption onto PE MPs was chemical adsorption, in particular, hydrogen bonding and surface complexation. Pb adsorption onto PE particles was proceeded at a rapid rate, as predicted by the pseudo-second-order rate model (R2 > 0.99). The PE 48 μm had the maximum adsorption capacity of 0.44 μmol g-1 (or 0.2 mol m−2) at pH 5. While humic acid can operate as a bridging agent, boosting heavy metal adsorption on the surface of PE MPs, fulvic acid has the reverse effect. The findings indicated that PE particles may serve as a carrier of heavy metals in the aquatic environment, posing perceived risks to the environment and public health.
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•Adsorption of lead onto PE microplastic is size-dependent.•Surface charge of PE particles was controlled by the potential-determining ion, pH.•Pb adsorption followed the pseudo-second-order kinetics model (R2 > 0.99).•Specific chemical adsorption played a major role on Pb adsorption.•Natural organic matters have different bridging effect on lead adsorption.
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