Adsorption behaviors and mechanisms of metal endocrine disruptors (Pb2+, Cd2+, and Hg2+) by pyrogenic carbonaceous materials including engineered carbons (biochar and activated carbon) and carbon ...nanomaterials (multi-walled carbon nanotubes and graphene oxide) have been investigated by experimental and density functional theory (DFT) studies. The adsorption isotherms of metal endocrine disruptors on carbonaceous materials were better fitted by Langmuir models. The adsorption capacities were in the order as follows: GO > BC600 > BC300 > CNT > AC for Pb2+, GO > BC300 > AC > BC600 > CNT for Cd2+, and GO > BC300 ≥ AC > CNT > BC600 for Hg2+, respectively. The DFT-computed binding energy (kcal/mol) of different oxygen-containing functional groups with metal endocrine disruptors followed the orders: (ⅰ) CMCOCPb (−136.70) > CM-COO--Pb (−91.58) > CMCOPb (−33.57) > CMOHPb (−4.69), (ⅱ) CM-COO--Cd (−45.91) > CMCOCCd (−4.49) > CMOHCd (−3.68) > CMCOCd (1.08), (ⅲ) CM-COO--Hg (−25.51) > CMCOCHg (−3.58) > CMOHHg (−0.63) > CMCOHg (0.23). And COC has the highest binding energy for Pb2+, whereas COC has much lower binding energy for Cd2+ and Hg2+. Comprehensively considering DFT calculations, competitive adsorption results and the cost analysis, this work may provide insights into the design of selective adsorbent for specific contaminant.
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•Adsorption capacity of the adsorbents for metal endocrine disruptors was compared.•DFT calculation was used to study the effect of oxygen-containing groups.•COO- has the highest binding energy for Cd2+ and Hg2+.•COC has the highest binding energy for Pb2+, followed by COO-.•Biochar was found suitable for large scale environmental remediation.
Cadmium (Cd) contamination in river sediments becomes increasingly serious, and phytoremediation has been used to remediate Cd contaminated sediments, but the remediation efficiency needs to be ...improved. In this study, tea waste derived biochar (TB) was used to facilitate the phytoremediation of Cd contaminated sediments. Results showed that TB at 100, 500 and 1000 mg kg−1 increased Cd accumulation and translocation in ramie seedlings by changing Cd speciation in sediments and altering the subcellular distribution of Cd in plant cells. TB at low contents alleviated Cd induced toxicity in ramie seedlings by promoting plant growth and mitigating the oxidative stress. In addition, the activities of urease-, phosphatase-, and catalase-producing microbes in the Cd contaminated sediments were promoted by the application of TB. These findings demonstrated that biochar at low concentrations could improve the phytoremediation efficiency and mitigating Cd-induced toxicity to plants and microbes in Cd contaminated sediments. This study herein provides a novel technological application of waste biomass in controlling and mitigating risks of heavy metals.
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•TB was prepared according to the pyrolysis of tea waste.•TB changed Cd speciation in river sediments.•TB increased Cd accumulation and translocation in the plants.•TB alleviated Cd induced toxicity to plants and microbes.•TB enhanced the phytoremediation efficiency and reduced the risks of heavy metals.
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A novel adsorbent based on steel converter slag (SCS), useful for adsorbing cationic pollutants from water was prepared by a simple method. The characterization showed that salicylic ...acid–methanol (SAM) modification selectively removed calcium silicate minerals from the surface of SCS and lead to a prominent increase in the specific surface areas. The maximum adsorption capacity of SAM-modified SCS for methylene blue (MB) at initial pH of 7.0 and temperature of 293 K was 41.62 mg/g, which is 35.2-times higher than that of SCS (1.15 mg/g). Adsorption kinetics and isotherms of MB on the SAM-modified SCS can be satisfactorily fitted by pseudo-second order kinetic and Langmuir model, respectively, which suggest that single-layer chemical adsorption was mainly responsible for MB removal. Further studies showed that pH value and ionic strength of wastewater have minimal effects on the adsorption capacity of SAM-modified SCS. A small decrease (<10%) was found in the adsorption capacity of SAM-modified SCS after five cycles. These findings indicate that SAM-modified SCS is a promising adsorbent for the efficient removal of MB from aqueous solution due to its low cost, good thermal stability, excellent adsorption performance and simple separation.
Squamous cell carcinoma (SCC) is a prevalent malignancy affecting multiple organs in the human body, including the oral cavity, esophagus, cervix, and skin. Given its significant incidence and ...mortality rates, researchers are actively seeking effective diagnostic and therapeutic strategies. In recent years, exosomes and their molecular cargo, particularly circular RNA (circRNA), have emerged as promising areas of investigation in SCC research. Exosomes are small vesicles released into the extracellular environment by cells that contain biomolecules that reflect the physiological state of the cell of origin. CircRNAs, known for their unique covalently closed loop structure and stability, have garnered special attention in oncology and are closely associated with tumorigenesis, progression, metastasis, and drug resistance. Interestingly, exosomal circRNAs have been identified as ideal biomarkers for noninvasive cancer diagnosis and prognosis assessment. This article reviews the progress in research on exosomal circRNAs, focusing on their expression patterns, functions, and potential applications as biomarkers in SCC, aiming to provide new insights and strategies for the diagnosis and treatment of SCC.
There is a continuously increasing worldwide concern for the development of wastewater and contaminated soil treatment technologies. Fenton processes and biological treatments have long been used as ...common technologies for treating wastewater and polluted soil but they still need to be modified because of some defects (high costs of Fenton process and long remediation time of biotreatments). This work first briefly introduced the Fenton technology and biotreatment, and then discussed the main considerations in the construction of a combined system. This review shows a critical overview of recent researches combining Fenton processes (as pre-treatment or post-treatment) with bioremediation for treatment of wastewater or polluted soil. We concluded that the combined treatment can be regarded as a novel and competitive technology. Furthermore, the outlook for potential applications of this combination in different polluted soil and wastewater, as well as the mechanism of combination was also discussed.
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•The combination of Fenton process and biotreatment is novel and useful.•Toxicity and biodegradability tests are significant to design a combined system.•No matter which technology at first stage, they would be called combined methods.•Wastewater contains PPCPs or EDCs.•Use of combination system in wastewater and polluted soil.
Owning to the potential in carbon sequestration and other environmental benefits, biochar has been widely used for in-situ environmental remediation. Understanding the biological effects of biochar ...is essential. The goal of this study was to explore the response of indigenous microbes under the stress of different concentrations of biochar. The results showed that biochar could significantly change physicochemical properties, enzymes activity and microbial community composition depending on biochar concentration and incubation time. When the concentration of biochar was 50 mg kg−1, the activities of invertase and alkaline phosphatase were obviously inhibited. Meanwhile, bacterial 16S rRNA and fungal 18S rRNA coding gene copies were decreased by 74% and 25%, respectively after 90 days of incubation. Additionally, the bacterial community succession occurred and the relative intensity of dominant species decreased when treated with high concentration of biochar. However, the activity of urease and alkaline phosphatase, as well as bacterial and fungal abundance, were increased when sediment was treated with 10 mg kg−1 biochar. Relationships among physicochemical properties, heavy metals and microbes were analyzed by correlation analysis and redundancy analysis (RDA). Correlations between invertase activity and pH value in the experiment were significantly negative. Redundancy analysis showed physicochemical properties and heavy metals explained 92% of the variation in the bacterial DGGE profiles and organic matter content explained the majority (45%) of the variation. This study indicated that indigenous microbes could be affected by biochar either directly or indirectly via changing the physicochemical properties and heavy metals of sediment.
•Invertase and alkaline phosphatase were decreased by high concentration of biochar.•Intensities of dominant bacteria declined when biochar rate was 50 mg kg−1.•pH might be related to the decreases in enzymes activity and microbial abundance.•OM explained the 45% of the variations of microbial community structure by RDA.
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•The MMBC composites were used in PS activation for TC degradation.•MMBC-900–2 h exhibited the best adsorption and catalytic abilities.•Pyrolysis temperatures and residence times ...effected catalytic abilities of catalysts.•SO4•− and •OH were generated in MMBC-PS system.•The catalysts exhibit high performance, stability and reusability.
Recently, biochar (BC) has been frequently used to degrade organic contaminants in advanced oxidation processes (AOPs). In this study, Mn doped magnetic biochar (MMBC) was prepared to activate persulfate (PS) for the degradation of tetracycline (TC). The activation of PS by MMBC was affected by the doping amount of Mn, pyrolysis temperature and residence time. The degree of defects and the formation of metal oxides of MMBC were mainly affected by the pyrolysis temperature. The removal efficiency of TC reached 93%, which was much higher than that of the original BC (64%). Electron spin resonance (ESR) and quenching results showed that SO4− and OH were generated in MMBC-PS system and the dominated free radical was OH. In addition, the results of linear sweep voltammetry (LSV) proved that MMBC was highly conductive and the existence of electron transport in the degradation. X-ray diffractometer (XRD), Raman, X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectrum (FT-IR) analysis jointly implied that surface oxygen-containing functional groups, the defect structure of the material and iron-manganese oxide provided active sites for activation of PS with MMBC. In addition, MMBC exhibited an excellent reusability and did not cause secondary pollution to the environment due to its excellent magnetic properties. This study confirmed that the presence of transition metals can promote the activation of PS by BC, and the pyrolysis temperature can affect its catalytic performance by affecting the properties of carbon materials (oxygen functional groups, degree of defects, etc.), providing a new idea for the application of carbon materials in AOPs.
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•Mechanisms about phosphate-induced Pb-immobilization are summarized.•Precipitation of Pb-phosphates is the main mechanism along with the adsorption effect and rhizosphere effect.•The ...relationships between the three mechanisms were discussed.•How to overcome the adverse impacts during the P application is of great importance.
Lead (Pb) is one of the most toxic heavy metals that pose a direct threat to organisms and it can not been degraded through microbial activities or chemical reaction. Bioavaibility and eco-toxicity of Pb which mostly depend on Pb chemical speciation play an important role in the remediation of Pb-contaminated soils. Phosphate (P) amendments which could transfer Pb from unstable fraction to stable fraction are commonly used to immobilize Pb in soils and have been extensively studied by researchers during decades. Based on the previous study, it can be concluded that three principal mechanisms may be responsible for P-induced Pb immobilization: 1) the precipitation of Pb-phosphates, including direct precipitation, ion-exchange (or substitution) effect and liming effect; 2) the adsorption of Pb, including the direct adsorption and the adsorption of Pb to iron (hydr)oxides; 3) the rhizosphere effect, including acidification effect and mycorrhizae effect. In this review, these mechanisms have been completely discussed and the internal relationships among them were summarized to give a better understanding of P-induced Pb immobilization in soils and promote the development of P-based remediation technology.
Nanoparticles can be absorbed by plants, but their impacts on phytoremediation are not yet well understood. This study was carried out to determine the impacts of starch stabilized nanoscale ...zerovalent iron (S-nZVI) on the cadmium (Cd) accumulation and the oxidative stress in Boehmeria nivea (L.) Gaudich (ramie). Plants were cultivated in Cd-contaminated sediments amended with S-nZVI at 100, 500, and 1000 mg/kg, respectively. Results showed that S-nZVI promoted Cd accumulation in ramie seedlings. The subcellular distribution result showed that Cd content in cell wall of plants reduced, and its concentration in cell organelle and soluble fractions increased at S-nZVI treatments, indicating the promotion of Cd entering plant cells by S-nZVI. In addition, the 100 mg/kg S-nZVI alleviated the oxidative damage to ramie under Cd-stress, while 500 and 1000 mg/kg S-nZVI inhibited plant growth and aggravated the oxidative damage to plants. These findings demonstrate that nanoparticles at low concentration can improve the efficiency of phytoremediation. This study herein develops a promising novel technique by the combined use of nanotechnology and phytoremediation in the remediation of heavy metal contaminated sites.
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