Degradation of thiocyanate by Fe/Cu/C microelectrolysis: Role of pre-magnetization and enhancement mechanism.

Thiocyanate (SCN-), a non-volatile inorganic pollutant, is commonly found in various types of industrial wastewater, which is resistant to hydrolysis and has the potential to be toxic to organisms. Premagnetized iron-copper-carbon ternary micro-electrolytic filler (pre-Fe/Cu/C) was prepared to degrade SCN-. Pre-Fe/Cu/C exhibited the most significant enhancement effect on SCN- removal when magnetized for 5 min with an intensity of 100 mT, and the SCN- removal rate was the highest at an initial pH of 3.0 and an aeration rate of 1.6 L/min. The electrochemical corrosion and electron transfer in the pre-Fe/Cu/C system were confirmed through SEM, XPS, FTIR, XRD, and electrochemical tests. This resulted in the formation of more corrosion products and multiple cycles of Fe2+/Fe3+ and Cu0/Cu+/Cu2+. Additionally, density functional theory (DFT) calculations and electron paramagnetic resonance (EPR) were utilized to illustrate the oxygen adsorption properties of the materials and the participation of reactive oxygen species (1O2, ·O2-, and ·OH) in SCN- removal. The degradation products of SCN- were identified as SO42-, HCO3-, NH4+, and N2. This study introduced the use of permanent magnets for the first time to enhance Fe/Cu/C ternary micro-electrolytic fillers, offering a cost-effective, versatile, and stable approach that effectively effectively enhanced the degradation of SCN-.

Spontaneous femoral neck fracture resulting from osteonecrosis involving lateral femoral head-neck junction: a retrospective study.

BACKGROUND: Spontaneous femoral neck fracture is a rare condition that remains controversial due to limited reported cases. This retrospective study aims to provide further insights into the etiology and characteristics of the disease. METHOD: We conducted a retrospective review of data from 963 patients with femoral neck fractures. The data encompassed demographic information, medical histories, radiographic records, bone mineral density (BMD) measurements, and pathological examinations. Patients were categorized into two groups: spontaneous femoral neck fracture (SFF) group (30 cases) and control group (933 cases), based on their medical histories. Logistic regression analysis was employed to identify risk factors for SFF. Statistical analysis was performed to compare and elucidate the characteristics of SFF within each group. RESULTS: Logistic regression analysis revealed osteonecrosis of the femoral head, steroid use, and osteoporosis as three significant risk factors for SFF. Furthermore, a higher proportion of Garden type I and II fractures, as well as Pauwels type I fractures, were observed in the SFF group compared to the control group. Within the SFF group, a higher proportion of patients with osteonecrosis exhibited Garden type III and IV fractures compared to those with osteoporosis. Additionally, both magnetic resonance imaging (MRI) and pathological examinations demonstrated that osteonecrosis in the SFF group predominantly occurred at the lateral femoral head-neck junction. CONCLUSIONS: Osteonecrosis of the femoral head, particularly involving the lateral head-neck junction, was confirmed as a major risk factor for SFF. Furthermore, SFF exhibits internal heterogeneity based on its different causes.

In-situ preparation of yeast-supported Fe0@Fe2O3 as peroxymonosulfate activator for enhanced degradation of tetracycline hydrochloride.

Nano zero-valent iron (nZVI) is extensively used as a peroxymonosulfate (PMS) activator but suffers from the ease of oxidation and agglomeration due to its high surface energy and inherent magnetism. Here, green and sustainable yeast was selected as a support material to firstly in-situ prepare yeast-supported Fe0@Fe2O3 and used for activating PMS to degrade tetracycline hydrochloride (TCH), one of the common antibiotics. Due to the anti-oxidation ability of the Fe2O3 shell and the support effect of yeast, the prepared Fe0@Fe2O3/YC exhibited a superior catalytic activity for the removal of TCH as well as some other typical refractory contaminants. The chemical quenching experiments and EPR results demonstrated SO4•- was the main reactive oxygen species while O2•-, 1O2 and •OH played a minor role. Importantly, the crucial role of the Fe2+/Fe3+ cycle promoted by the Fe0 core and surface iron hydroxyl species in PMS activation was elucidated in detail. The TCH degradation pathways were proposed by LC-MS and density functional theory (DFT) calculation. In addition, the outstanding magnetic separation property, anti-oxidation ability, and high environmental resistance of the catalyst were demonstrated. Our work may inspire the development of green, efficient, and robust nZVI-based materials for wastewater treatment.

High performance self-assembled nano-chlorapatite in the presence of lactonic sophorolipid for the immobilization of cadmium in polluted sediment.

A novel lactonic sophorolipid (LS) self-assembled nano-chlorapatite (LS-nClAP) was prepared for the immobilization of severe cadmium (Cd) in sediment. The experimental results indicated that the introduction of LS not only improved the dispersed performance of chlorapatite, but also brought massive hydroxyl and carboxyl groups, which significantly improved the immobilization efficiency of Cd and reduced its eco-toxicity in sediment. LS can significantly increase the effective utilization rate of phosphorus in chlorapatite, and reduce the content of available phosphorus (AP) by half after remediation compared with ClAP. Additionally, the participation of LS possessed a significant impact on the enzyme activities in the sediment, especially for urease, which was closely related to the effective stability of Cd and the introduction of LS. All experimental results of this study provided new insights into the possible effects of Cd immobilization by chlorapatite in contaminated sediments, demonstrating great application potential for sediment remediation in the future.

Pyrolysis kinetics and environmental risks of oil-based drill cuttings at China's largest shale gas exploitation site.

Chongqing Fuling shale gas field, the largest shale gas exploration site in China, produces a large amount of oil-based drill cuttings (OBDC) every year, which is a hazardous waste. Traditional treatment methods such as solidification/stabilization did not recycle the valuable components such as petroleum hydrocarbons. Pyrolysis is proven to be an efficient method that can recover those components. This study firstly investigated the pyrolysis kinetics by two different methods on the basis of detailed material characterization, and then taking the workers and the surrounding ecological environment as the analysis object, the human health risk assessment (HHRA) and ecological risk assessment were evaluated respectively before and after pyrolysis. The results showed that the pyrolysis of OBDC was divided into three stages, and the cracking of light hydrocarbons stage was the key control step for pyrolysis process. The activation energy E increased gradually during the pyrolysis progress. The HHRA results showed that pyrolysis could greatly reduce the non-carcinogenic risk, carcinogenic risk and ecological risk by 59.6 %, 62.8 % and 75 % respectively. However, the carcinogenic risk after pyrolysis was still higher than the critical value 10-6.

Roasting mechanism of lightweight low-aluminum-silicon ceramisite derived from municipal solid waste incineration fly ash and electrolytic manganese residue.

Municipal solid waste incineration (MSWI) fly ash and electrolytic manganese residue (EMR) belong to hazardous waste, and must be disposed of before processing. It was found that the low content of silicon and aluminum at low roasting temperature can meet the expansion mechanism of lightweight aggregates. A low-aluminum-silicon lightweight ceramisite was successfully prepared from MSWI fly and EMR, the formation mechanism of which was that the viscosity of molten stuffs in pellet was the function of temperature and chemical composition and had enough capacity of capturing the emerged gas over roasting. The resulting ceramisite met with the requirement of Lytag commercial lightweight aggregate. The content of heavy metal in ceramisite accorded with the requirement of soil environmental quality for development GB 36600-2018 Class I, and PCDD/Fs in ceramisite was 2.0 ng I-TEQ/kg, which was safe. The collaboration of thermal simulation and characterization (SEM-EDS, FTIR and XRD) elaborated the formation mechanism of ceramisite, with six stages provided.

Co-stabilization/solidification of heavy metals in municipal solid waste incineration fly ash and electrolytic manganese residue based on self-bonding characteristics.

Municipal solid waste incineration (MSWI) fly ash and electrolytic manganese residue (EMR) were classified as hazardous waste, must be harmlessly processed prior to subsequent treatment or disposal. The competition between massive free manganese ions of raw EMR and other heavy metals was found, thus raw EMR was pretreated by calcining to eliminate competition of manganese with other heavy metals for stabilizer complexation. MSWI fly ash was successfully solidified with 6% NaH2PO4, 6% H2NCSNH2 and 20% sintered EMR (800 °C). The addition of sintered EMR enhanced solidification/stabilization of heavy metals in fly ash and the resulting product had a higher compressive strength for further reutilization like trench backfilling, structural fill and void filling. The stabilization/solidification mechanism of heavy metals was attributed to the combined interaction of heavy metal precipitation in stabilizers and ion exchange or physical encapsulation in silicate compounds like calcium silicate, which is a feasible and valuable approach to co-disposal of MSWI fly ash and EMR.

Removal of oxytetracycline promoted by manganese-doped biochar based on density functional theory calculations: Comprehensive evaluation of the effect of transition metal doping.

The regulation of surface electrons by non-metal doping of biochar (BC) is environmentally and ecologically significant. However, systematic studies on the regulation of surface electrons by transition metal doping are lacking. The present study is based on the observation that the removal efficiency of oxytetracycline (OTC) by Mn-doped BC is eight times higher than that of undoped BC in 20 min. The effects of Mn doping on the crystal phase formation, persistent free radicals (PFRs), electron density, molecular orbitals, and nucleophilic active sites of BC are investigated, and the intermediate products of OTC are evaluated. Mn doping enhances the signal for sp2-hybridised carbon-carbon double bond, forms more delocalised π-bonds, and promotes the formation of free radicals centred on the carbon atoms. The specific surface area of BC increases, and manganese oxide is formed on the its surface. Density functional theory calculations show that Mn doping accelerates the electron transfer of BC, provides additional electrons for the BC system, and makes this system more ionised. OTC molecules preferentially attack the nucleophilic reaction sites near Mn atoms based on molecular electrostatic potential measurements. Therefore, this study provides new insights into the surface electronic structures regulated by transition metal elements.

Electrodialytic remediation of municipal solid waste incineration fly ash as pre-treatment before geopolymerisation with coal fly ash.

Municipal solid waste incineration (MSWI) fly ash is classified as hazardous waste and needs to be disposed of according to strict regulations. By disposal, valuable resources in the MSWI fly ash is lost, and other solutions are sought for. The effect of electrodialytic remediation (ED) as a pre-treatment for removing heavy metals from MSWI fly ash before using the treated ash in geopolymerization with coal fly ash was explored. ED pre-treatment for MSWI fly ash increased the Si reactivity and the Si/Al ratio. The mixture of 80% coal fly ash and 20% ED treated fly ash with 8 M NaOH (L/S 0.37 mL/g) was found optimal, with a resulting compressive strength of 15.3 MPa, which was higher than the reference coal fly ash geopolymer. The leaching concentrations of Pb, Zn, Cr, Cu and Ni were below 0.02 mg/L with Mn and Cd at 0.023 and 0.027 mg/L, respectively. The enhanced mechanism for ED treated MSWI fly ash in geopolymer was confirmed by FTIR analysis and SEM images. The resistance against extreme leaching environments for treated fly ash geopolymer was stronger than raw fly ash geopolymer, and physical encapsulation of geopolymeric gels contributed to the heavy metal immobilization.

Co-sintering MSWI fly ash with electrolytic manganese residue and coal fly ash for lightweight ceramisite.

The MSWI fly ash (FA) is classified as hazardous waste and electrolytic manganese residue (EMR) as the harmful industrial waste. FA, water-washed FA (WFA), EMR and coal fly ash (CFA) were co-recycled to form lightweight MFCE ceramisites. The effects of FA, WFA and mixed MSWI fly ash on ceramisites were discussed. The approach to mixing FA and WFA increased the recycling amount of MSWI fly ash. The optimal mixture of 34.5% EMR, 24.1% CFA, 20.7% FA and 20.7% WFA sintered at 1160 °C for 12 min with a procedural heating rate (10 °C/min) and belonged to Class 800 artificial lightweight aggregate (GB/T 17431.1-2010); the quantity of MSWI fly ash in ceramisite was as high as 41.4%. Volatilization rates of Cd, Pb, Cu, Zn, Mn and Cr for ceramisite were higher 75.0, 24.2, 62.7, 133, 343 and 764% than FA respectively, attributed to the co-existence of chlorides and sulfates. The remained Zn, Cu, Pb, Mn and Cr were exchanged with Mg2+/Ca2+/Al3+ of diopside and wollastonite to form residual fractions. Our findings provided a feasibility method of co-recycling MSWI fly ash and electrolytic manganese residue to produce green lightweight aggregates.

Exploring a New Method to Study the Effects of Surface Functional Groups on Adsorption of CO2 and CH4 on Activated Carbons.

The commercial coconut shell-activated carbon was modified to change the number of oxygen-containing functional groups. N2 adsorption/desorption isotherms, Fourier transform infrared (FT-IR), and Boehm titration were adopted to describe the physical and chemical properties of the samples. The adsorption isotherms of CO2 and CH4 on both the unmodified and modified samples were measured. To better understand the effects of surface oxygen-containing functional groups on adsorption of CO2 and CH4, the overall adsorption could be considered as the result of adsorption within the pores and adsorption onto the oxygen-containing functional groups. Thus, a new way to understand different adsorption mechanisms by calculation was proposed. On the basis of the results, there is a significant correlation between the saturation adsorption capacity of CO2 and the number of oxygen-containing functional groups, especially carboxyl and hydroxyl. According to the values of enthalpy (-12.2 to -20 kJ/mol), it can be known that the adsorption caused by oxygen-containing functional groups is exothermic and belongs to physisorption. A semiempirical relationship between the variation of the surface oxygen-functional groups and the variation of the adsorbed amount was established. The method proposed in this paper provides a new way to study the effects of surface functional groups on the adsorption of CO2 and CH4 and can be even promoted in studying the adsorption mechanism of other adsorbates.

Response mechanism of microbial community to the environmental stress caused by the different mercury concentration in soils.

Despite the toxicity of mercury for mammal has been widely studied in recent years, little is known on its impact on the soil microbiome. In this paper, the effects of mercury in soils microbial communities along a gradient of contamination from no to high concentration was assessed by the richness and diversity of microbial community using high throughput sequencing method. The richness of microbial community decreased gradually with the increase of culture time, while the low and medium concentration of mercury had little effect on the evenness of soil microbial community. Proteobacteria tolerated the mercury contamination, while Acidobacteria, Planctomycetes and Chloroflexi were sensitive to mercury pollution in phylum level. Omnitrophica and Ignavibacteriae microorganisms were very sensitive to mercury contamination and dead quickly when contaminated with mercury. Mercury contamination selected two mercury tolerance genuses which were Massilia and Burkholderia in genus level and at least 22 microorganisms such as Alkanindiges, Geothrix, Polycyclovorans and Sporichthya in genus which mainly from the Acidobacteria, Proteobacteria, Bacteroides, Chloroflexi and Omnitrophica phylum were sensitive to mercury. The bacteria tolerant to mercury in soil were Massilia and Burkholderia from Betaproteobacteria and Lysobacter, Luteimonas from Gammaproteobacteria, separately, they were Gram-negative bacteria with thin cell walls and complex ingredients that responded quickly to pollution stress.

Enhanced geopolymeric co-disposal efficiency of heavy metals from MSWI fly ash and electrolytic manganese residue using complex alkaline and calcining pre-treatment.

The predominant heavy metals in MSWI fly ash and electrolytic manganese residue (EMR) were determined to be Zn, Pb, Cd, and Mn, with lesser amounts of Cu and Cr. The curing efficiency of heavy metals in MSWI fly ash and EMR was improved using complex alkaline activators (NaOH and KOH), base addition (calcium hydroxide and complex Portland cement), and EMR calcining (at 800 °C for 3 h) based on a geopolymeric system. The best formulation of the geopolymeric system was composed of 75 wt% MSWI fly ash and 25 wt% EMR with a KOH/NaOH (1:1) complex solution (7.5 M OH-)/solid of 0.5. Calcium ions were dissolved aluminosilicate under the strongly basic conditions to form complex products (ternesite) which further improved the strength. The primary curing mechanism of heavy metals (Pb, Zn, Cd, Mn, Cr, and Cu) mainly was primarily influenced by the acid-base buffering capacity of geopolymers, followed by the physical encapsulation of geopolymeric gels.

Characterization of typical heavy metals in pyrolysis MSWI fly ash.

Thermal treatment methods are used extensively in the process of municipal solid waste incineration fly ash. However, the characterization of heavy metals during this process should be understood more clearly in order to control secondary pollution. In this paper, the content, speciation and leaching toxicity of mercury (Hg), plumbum (Pb), cadmium (Cd) and zinc (Zn) in fly ash treated under different temperatures and time were firstly analysed as pre-tests. Later, pilot-scale pyrolysis equipment was used to explore the concentration and speciation changes in the heavy metals of fly ash. Finally, the phase constitution and microstructure changes in fly ash were compared before and after pyrolysis using X-ray diffraction (XRD) and scanning electron microscope (SEM), respectively. The results showed that (a) The appropriate processing temperature was between 400°C and 450°C, and the processing time should be 1 h. (b) The stability of heavy metals in fly ash increased after pyrolysis. (c) XRD and SEM results indicated that phase constitution changed a little, but the microstructure varied to a porous structure similar to that of a coral reef after pyrolysis. These results suggest that pyrolysis could be an effective method in controlling heavy metal pollution in fly ash.

Co-disposal of MSWI fly ash and electrolytic manganese residue based on geopolymeric system.

MSWI fly ash (MSWI FA) and electrolytic manganese residue (EMR) were successfully co-disposed by use of a geopolymeric system. Alkaline products of MSWI FA and NaOH were used to elicit chemical reactions to promote solidification. The best performing formulation of EMR-based geopolymer for immobilization of heavy metals was composed of 75 wt% MSWI FA and 25 wt% EMR with NaOH solution (7.5 M)/solid of 0.5. Solidification was most effective for the heavy metals: Pb > Cu > Cr > Zn > Mn, respectively. The EMR-based geopolymer had high structural stability likely due to the high ratio of SiO2/Al2O3. The Solidification/Stabilization (S/S) mechanism for heavy metals of geopolymers is likely due to alkaline conditions and geopolymeric encapsulation, highlighting the utility and feasibility of this approach.

Heavy metal pollution of oil-based drill cuttings at a shale gas drilling field in Chongqing, China: A human health risk assessment for the workers.

With the flourish of shale gas industry in China, the characteristic hazardous waste, oil-based drill cuttings (OBDC), was also produced in large quantities. Unlike traditional petroleum industry, shale gas exploitation covers a wider area and there are more well sites, the adverse effects of OBDC piled up around well sites are even greater. This study investigated the pollution status and leaching toxicity of eight heavy metals (Cd, Cr, Cu, Hg, Mn, Ni, Pb and Zn) in OBDC of shale gas exploitation, and evaluated the health risks of the drilling workers. The results showed that heavy metal pollution in OBDC was moderate, and the leaching toxicity was far below the standard value. Non-carcinogenic and carcinogenic risks of drilling workers were within an acceptable range. Meanwhile, in order to reduce the health risks of drilling workers, some suggestions are proposed to reduce the exposure risks of workers and the content of heavy metals in OBDC.

Intervention using a novel biodegradable hollow stent containing polylactic acid-polyprolactone-polyethylene glycol complexes against lacrimal duct obstruction disease.

Lacrimal duct obstruction disease (LDOD) is a common ophthalmologic disease. Stent implantation surgery is one of the most effective therapies. In this study, we intended to find out the satisfactory biodegradable stents containing poly-L-lactic acid-polycaprolactone-polyethylene glycol (PLLA- PCL- PEG) complexes for therapeutic application in LDOD. Stents made of PLLA- PCL- PEG complexes in various ratios, were prepared and used in vitro to determine stents with appropriate mechanical properties and shorter range of bio-degradation for study in vivo. Thirty-two rabbits were randomized into eight groups of four eyes each in advance for test in vivo. The selected stents were implanted into the left lacrimal ducts of 16 rabbits and silica gel stents as the control for the other 16 rabbits. At four points in time (1, 4, 10 and 16 weeks after the implantation), weight loss rate (WLR) of the stents was measured and analysed. To access the change of lacrimal duct, fluorescein excretion test, lacrimal duct endoscopy and histopathological testing were conducted. The stent containing PLLA: PCL6: 4+ 15%PEG was selected for study in vivo. Analysis of weight loss rate (WLR), fluorescein excretion test, lacrimal duct endoscopy and histopathological testing indicated that the selected stent was biodegradable and caused minimal stimulation and earlier tissue restoration in the lacrimal epithelium compared with the silica gel stent used as the control. The study results suggest that the PLLA: PCL6: 4+ 15% PEG stent is a satisfactory biodegradable stent as a promising alternative for therapeutic application in LDOD, which showed tissue compatibility, biodegradation and adequate mechanical intensity.