Low-cost pyrolysis of biomass-derived nitrogen-doped porous carbon: Chlorella vulgaris replaces melamine as a nitrogen source.

Porous carbon generated from biomass has a rich pore structure, is inexpensive, and has a lot of promise for use as a carbon material for energy storage devices. In this work, nitrogen-doped porous carbon was prepared by co-pyrolysis using bagasse as the precursor and chlorella as the nitrogen source. ZnCl2 acts as both an activator and a nitrogen fixer during activation to generate pores and reduce nitrogen loss. The thermal weight loss experiments showed that the pyrolysis temperatures of bagasse and chlorella overlap, which created the possibility for the synthesis of nitrogen-rich biochar. The optimum sample (ZBC@C-5) possessed a surface area of 1508 m2g-1 with abundant nitrogen-containing functional groups. ZBC@C-5 in the three-electrode system exhibited 244.1F/g at 0.5A/g, which was extremely close to ZBC@M made with melamine as the nitrogen source. This provides new opportunities for the use of low-cost nitrogen sources. Furthermore, the devices exhibit better voltage retention (39%) and capacitance retention (96.3%). The goal of this research is to find a low cost, and effective method for creating nitrogen-doped porous carbon materials with better electrochemical performance for highly valuable applications using bagasse and chlorella.

Circular economical approach of extracting nanocarbons from waste pea peel for sensing of p-nitrophenol and its conversion into paracetamol.

An important paradigm shift towards the circular economy is to prioritize waste prevention, reuse, recycling, and recovery before disposal is necessary. In this context, a sustainable protocol of converting waste pea peel (wPP) into low-cost carbon nanomaterials for sensing and conversion of p-nitrophenol (p-NP) into value-added paracetamol is being reported. Two fractions of the carbonaceous nanomaterials were obtained after the hydrothermal treatment (HT) of wPP, firstly an aqueous portion containing water-soluble carbon dots (wPP-CDs) and a solid residue, which was converted into carbonized biochar (wPP-BC). Blue-colored fluorescent wPP-CDs displayed excitation-dependent and pH-independent properties with a quantum yield (QY) of 8.82 %, which were exploited for the fluorescence sensing of p-NP with 4.20 µM limit of detection. Pyrolyzed biochar acting as an efficient catalyst effectively reduces p-NP to p-aminophenol (p-AP) in just 16 min with a 0.237 min-1 rate of conversion. Furthermore, the produced p-AP was converted into paracetamol, an analgesic and antipyretic drug, to achieve zero waste theory. Thus, this study provides the execution of sustainable approaches based on the integral valorization of biowaste that can be further recycled and reused, offering an effective way to attain a profitable circular economy.

Electrochemical determination of riboflavin in pharmaceuticals using unmodified screen printed carbon electrodes.

In this study, we have devised an efficient and rapid approach to detect riboflavin (also known as Vitamin B2 or VB2) utilizing an unaltered screen-printed carbon electrode (SPCE). The unmodified screen-printed electrodes are created within the laboratory, where carbon ink is applied to a ceramic substrate. All experiments pertaining to the investigation of electrochemical behavior and the fine-tuning of crucial experimental parameters were conducted through cyclic voltammetry (CV). For quantitative assessments, square wave voltammetry (SWV) was employed. The findings indicate that unaltered SPCEs exhibit robust current signals during the riboflavin redox reaction. Riboflavin displays a distinct oxidation peak at - 0.136 V (vs. Ag/AgCl, 3.0 M KCl) in a Britton-Robinson buffer solution (BRBS) at pH 2, which was employed for quantification. The electrode demonstrates a broad linear range from 0.05 to 10 µM, boasting a detection limit of 0.03 µM. Repeatability stands at 1.45%, while reproducibility is 6.61%. Testing the influence of common interfering compounds yielded negligible results. The sensor effectively determines riboflavin content in pharmaceutical formulations without any prior treatment. This method presents an economical, modifier-free sensor with exceptional sensitivity and cost-effectiveness, making it suitable for rapid riboflavin quantification.

Highly efficient heterogeneous electro-Fenton reaction for tetracycline degradation by Fe-Ni LDH@ZIF-67 modified carbon cloth cathode: Mechanism and toxicity assessment.

In this work, a novel and efficient Fe-Ni LDH@ZIF-67 catalyst modified carbon cloth (CC) cathode was developed for tetracycline (TC) degradation in heterogeneous electro-Fenton (Hetero-EF) process. Compared to Fe-Ni LDH/CC (75.7%), TC degradation rate of Fe-Ni LDH@ZIF-67/CC cathode increased to 95.6% within 60 min. The synergistic effect of hetero-EF and anodic oxidation process accelerated electron transfer, the maximum H2O2 production of Fe-Ni LDH@ZIF-67/CC electrode reached 264 mg/L, improving utilization efficiency of H2O2. The cathode possessing a satisfied TC degradation performance over a wide pH (3-9). Free radical capture experiment revealed the collaboration of ·O2-, ·OH, and 1O2 play a significant role in TC degradation. The 5 cycles experiment and metal ion leaching experiment showed that the proposed Fe-Ni LDH@ZIF-67/CC has good recyclability and stability. In addition, the proposed Fe-Ni LDH@ZIF-67/CC cathode achieved satisfying performance in real water (tap water: 97.3%, lake water: 97.7%), demonstrating the possibility for practical application. TC degradation pathways were proposed by theory analysis and experimental results. The toxicity of TC intermediates was reduced by Hetero-EF degradation according to Toxicity Estimation Software Tool and Escherichia coli growth inhibition experiments. This work provides a novel modified cathode to improve removal efficiency of antibiotics in wastewater.

The High Stability and Selectivity of Electrochemical Sensor Using Low-Cost Diamond Nanoparticles for the Detection of Anti-Cancer Drug Flutamide in Environmental Samples.

In this study, a novel electrochemical sensor was created by fabricating a screen-printed carbon electrode with diamond nanoparticles (DNPs/SPCE). The successful development of the sensor enabled the specific detection of the anti-cancer drug flutamide (FLT). The DNPs/SPCE demonstrated excellent conductivity, remarkable electrocatalytic activity, and swift electron transfer, all of which contribute to the advantageous monitoring of FLT. These qualities are critical for monitoring FLT levels in environmental samples. Various structural and morphological characterization techniques were employed to validate the formation of the DNPs. Remarkably, the electrochemical sensor demonstrated a wide linear response range (0.025 to 606.65 µM). Additionally, it showed a low limit of detection (0.023 µM) and high sensitivity (0.403 µA µM-1 cm-2). Furthermore, the practicability of DNPs/SPCE can be successfully employed in FLT monitoring in water bodies (pond water and river water samples) with satisfactory recoveries.

Strategic Assessment of Boron-Enriched Carbon Dots/Naproxen: Diagnostic, Toxicity, and In Vivo Therapeutic Evaluation.

Cancer is a significant global public health concern, ranking as the leading cause of mortality worldwide. This study thoroughly explores boron-doped carbon dots (B-CDs) through a simple/rapid microwave-assisted approach and their versatile applications in cancer therapy. The result was highly uniform particles with an average diameter of approximately 4 nm. B-CDs exhibited notable properties, including strong fluorescence with a quantum yield of 33%. Colloid stability tests revealed their robustness within a pH range of 6-12, NaCl concentrations up to 0.5 M, and temperatures ranging from 30 to 60 °C. The study also delved into the kinetics of naproxen release from B-CDs as a drug delivery system. The loading efficacy of naproxen exceeded 55.56%. Under varying pH conditions, the release of naproxen from B-CDs conformed to the Peppas-Sahlin model, demonstrating the potential of Naproxen-loaded CDs for cancer drug delivery. In vitro cytotoxicity assessments, conducted using the CCK-8 Assay and flow cytometry, consistently indicated low toxicity with average cell viability exceeding 80%. An in vivo toxicity test on female mice administered 20 mg/kg of B-CDs for 31 days revealed reversible histological changes in the liver and kidneys, while the pancreas remained unaffected. Importantly, B-CDs did not impact the mice's physical behavior, body weight, or survival. In vivo experiments targeting benzo(a)pyrene-induced fibrosarcoma demonstrated the efficacy of B-CDs as naproxen carriers in the treatment of cancer. This in vivo study provides a thorough comprehension of B-CDs synthesis and toxicity and their potential applications in cancer therapy and drug delivery systems.

Investigation of the electrochemical properties of edoxaban using glassy carbon and boron-doped diamond electrodes and development of an eco-friendly and cost effective voltammetric method for its determination.

In this study, the highly risky drug Edoxaban (EDX), which can threaten life and cause bleeding, was electro analytically evaluated. The electrochemical behavior of EDX was investigated using glassy carbon electrode (GCE) and boron-doped diamond electrode (BDDE). In this study, for the first time, a simple, rapid, sensitive, and selective voltammetric technique was developed by using different electrodes for the electrochemical characterization and detection of EDX. The optimized voltammetric technique showed anodic signals of EDX at +1.09 V and +1.08 V on GCE and BDDE, respectively, in BR (pH 5.0) solution. The developed voltammetric method provided a very good analytical working range for EDX in BR (pH 5.0) solution on GCE and BDDE, covering concentration ranges from 1.84 µM to 12.88 µM and from 3.68 µM to 14.72 µM, respectively. The limits of detection for EDX on GCE and BDDE under these experimental conditions were calculated as 0.24 µM and 0.57 µM, respectively. The developed voltammetric methods on both electrodes were successfully applied to urine and tablet samples. Additionally, the obtained voltammetric results were compared with UV-Vis spectroscopy results.

Assessment of the Long-Range NMR C,H Coupling of a Series of Carbazolequinone Derivatives.

Synthesis, the complete 1H- and 13C-NMR assignments, and the long-range C,H coupling constants (nJC,H) of some hydrogen-deficient carbazolequinones, assessed by a J-HMBC experiment, are reported. In these molecules, the protons, used as entry points for assignments, are separated by several bonds with non-protonated atom carbons. Therefore, the use of long-range NMR experiments for the assignment of the spectra is mandatory; we used HSQC and HMBC. On the other hand, the measured heteronuclear (C,H) coupling constants 2J to 5J) allow us to choose the value of the long-range delay used in the HMBC experiment less arbitrarily in order to visualize a desired correlation in the spectrum. The chemical shifts and the coupling constant values can be used as input for assignments in related chemical structures.

Biomass directional pyrolysis based on element economy to produce high-quality fuels, chemicals, carbon materials - A review.

Biomass is regarded as the only carbon-containing renewable energy source and has performed an increasingly important role in the gradual substitution of conventional fossil energy, which also contributes to the goals of carbon neutrality. In the past decade, the academic field has paid much greater attention to the development of biomass pyrolysis technologies. However, most biomass conversion technologies mainly derive from the fossil fuel industry, and it must be noticed that the large element component difference between biomass and traditional fossil fuels. Thus, it's necessary to develop biomass directional pyrolysis technology based on the unique element distribution of biomass for realizing enrichment target element (i.e., element economy). This article provides a broad review of biomass directional pyrolysis to produce high-quality fuels, chemicals, and carbon materials based on element economy. The C (carbon) element economy of biomass pyrolysis is realized by the production of high-performance carbon materials from different carbon sources. For efficient H (hydrogen) element utilization, high-value hydrocarbons could be obtained by the co-pyrolysis or catalytic pyrolysis of biomass and cheap hydrogen source. For improving the O (oxygen) element economy, different from the traditional hydrodeoxygenation (HDO) process, the high content of O in biomass would also become an advantage because biomass is an appropriate raw material for producing oxygenated liquid additives. Based on the N (nitrogen) element economy, the recent studies on preparing N-containing chemicals (or N-rich carbon materials) are reviewed. Moreover, the feasibility of the biomass poly-generation industrialization and the suitable process for different types of target products are also mentioned. Moreover, the enviro-economic assessment of representative biomass pyrolysis technologies is analyzed. Finally, the brief challenges and perspectives of biomass pyrolysis are provided.

Assessment of biomass-derived carbon dots as highly sensitive and selective templates for the sensing of hazardous ions.

Access to safe drinking water and a hygienic living environment are the basic necessities that encourage healthy living. However, the presence of various pollutants (especially toxic heavy metal ions) at high concentrations in water renders water unfit for drinking and domestic use. The presence of high concentrations of heavy-metal ions (e.g., Pb2+, Hg2+, Cr6+, Cd2+, or Cu2+) greater than their permissible limits adversely affects human health, and increases the risk of cancer of the kidneys, liver, skin, and central nervous system. Therefore, their detection in water is crucial. Due to the various benefits of "green"-synthesized carbon-dots (C-dots) over other materials, these materials are potential candidates for sensing of toxic heavy-metal ions in water sources. C-dots are very small carbon-based nanomaterials that show chemical stability, magnificent biocompatibility, excitation wavelength-dependent photoluminescence (PL), water solubility, simple preparation strategies, photoinduced electron transfer, and the opportunity for functionalization. A new family of C-dots called "carbon quantum dots" (CQDs) are fluorescent zero-dimensional carbon nanoparticles of size < 10 nm. The green synthesis of C-dots has numerous advantages over conventional chemical routes, such as utilization of inexpensive and non-poisonous materials, straightforward operations, rapid reactions, and renewable precursors. Natural sources, such as biomass and biomass wastes, are broadly accepted as green precursors for fabricating C-dots because these sources are economical, ecological, and readily/extensively accessible. Two main methods are available for C-dots production: top-down and bottom-up. Herein, this review article discusses the recent advancements in the green fabrication of C-dots: photostability; surface structure and functionalization; potential applications for the sensing of hazardous anions and toxic heavy-metal ions; binding of toxic ions with C-dots; probable mechanistic routes of PL-based sensing of toxic heavy-metal ions. The green production of C-dots and their promising applications in the sensing of hazardous ions discussed herein provides deep insights into the safety of human health and the environment. Nonetheless, this review article provides a resource for the conversion of low-value biomass and biomass waste into valuable materials (i.e., C-dots) for promising sensing applications.

Miniaturized Rapid Electrochemical Immunosensor Based on Screen Printed Carbon Electrodes for Mycobacterium tuberculosis Detection.

In 2019, over 21% of an estimated 10 million new tuberculosis (TB) patients were either not diagnosed at all or diagnosed without being reported to public health authorities. It is therefore critical to develop newer and more rapid and effective point-of-care diagnostic tools to combat the global TB epidemic. PCR-based diagnostic methods such as Xpert MTB/RIF are quicker than conventional techniques, but their applicability is restricted by the need for specialized laboratory equipment and the substantial cost of scaling-up in low- and middle-income countries where the burden of TB is high. Meanwhile, loop-mediated isothermal amplification (LAMP) amplifies nucleic acids under isothermal conditions with a high efficiency, helps in the early detection and identification of infectious diseases, and can be performed without the need for sophisticated thermocycling equipment. In the present study, the LAMP assay was integrated with screen-printed carbon electrodes and a commercial potentiostat for real time cyclic voltammetry analysis (named as the LAMP-Electrochemical (EC) assay). The LAMP-EC assay was found to be highly specific to TB-causing bacteria and capable of detecting even a single copy of the Mycobacterium tuberculosis (Mtb) IS6110 DNA sequence. Overall, the LAMP-EC test developed and evaluated in the present study shows promise to become a cost-effective tool for rapid and effective diagnosis of TB.

Valorisation of spent tire rubber as carbon adsorbents for Pb(II) and W(VI) in the framework of a Circular Economy.

Spent tire rubber-derived chars and their corresponding H3PO4 and CO2-activated chars were used as adsorbents in the recovery of Pb(II) ion and (W(VI)) oxyanion from synthetic solutions. The developed chars (both raw and activated) were thoroughly characterized to have insight about their textural and surface chemistry properties. H3PO4-activated chars presented lower surface areas than the raw chars and an acidic surface chemistry which affected the performance of these samples as they showed the lowest removals of the metallic ions. On the other hand, CO2-activated chars presented increased surface areas and increased mineral content compared to the raw chars, having presented higher uptake capacities for both Pb(II) (103-116 mg/g) and W(VI) (27-31 mg/g) ions. Cation exchange with Ca, Mg and Zn ions was appointed as a mechanism for Pb removal, as well as surface precipitation in the form of hydrocerussite (Pb3(CO3)2(OH)2). W(VI) adsorption might have been ruled by strong electrostatic attractions between the negatively charged tungstate species and the highly positively charged carbons' surface.The results shown in this work allow concluding that the valorisation of spent tire rubber through pyrolysis and the subsequent activation of the obtained chars is an alternative and a feasible option to generate adsorbent materials with a high uptake capacity of critical metallic elements.

Silk Fibroin-Based Piezoelectric Sensor with Carbon Nanofibers for Wearable Health Monitoring Applications.

The continuous real-time monitoring of human health using biomedical sensing devices has recently become a promising approach to the realization of distant health monitoring. In this paper, the piezoelectric characteristics of the silk fibroin (SF) natural polymer were analyzed as the material used for obtaining sensing information in the application of distance health monitoring. To enhance the SF piezoelectricity, this paper presents the development of a novel SF-based sensor realized by combining SF with different carbon nanofiber (CNF) densities, and for such newly developed SF-based sensors comprehensive performance analyses have been performed. Versatile methods including the scanning electron microscope, Fourier transform infrared spectroscopy, Raman and X-ray diffraction measurements and impedance analysis were used to study the morphologic, mechanical and electrical properties of the developed SF-based sensor. The SF with CNF samples was analyzed for three different pressure loads (40 N, 60 N and 80 N) in 500 compression test cycles. The analyses thoroughly describe how combining natural polymer SF with different CNF densities impacts the piezoelectricity and mechanical strength of the proposed SF-based sensor. The developed piezoelectric SF-based sensors were further tested on humans in real medical applications to detect generated piezoelectric voltage in versatile body movements. The maximum piezoelectricity equal to 2.95 ± 0.03 V was achieved for the jumping movement, and the SF sample with a CNF density equal to 0.4% was tested. Obtained results also show that the proposed SF-based sensor has an appropriate piezoelectric sensitivity for each of the analyzed body movement types, and that the proposed SF-based sensor can be applied in real medical applications as a biomedical sensing device. The proposed SF-based sensor's practical implementation is further confirmed by the results of cytotoxicity analyses, which show that the developed sensor has a non-toxic and biocompatible nature and can be efficiently used in skin contact for biomedical wearable health monitoring applications.

Cost effective porous areca nut carbon nanospheres for adsorptive removal of dyes and their binary mixtures.

Novel porous nanospheres from areca nuts (ACNPs) were synthesized via one-step pyrolysis without the use of any chemical treatment and the materials were used as adsorbents for the removal of cationic methylene blue (MB) and anionic methyl orange (MO) as well as their binary mixtures. Around, 6-7 tonnes of areca nut biowaste is generated every year which are then burnt due to their slow rate of decomposition resulting in higher carbon footprints. Biosorbents are generally a preferable alternative for dye adsorption but involve chemical modification for surface enhancement and complex sample treatment. In this work, ACNPs, were investigated for their efficiency in the raw form and were characterized by SEM, EDS, FTIR, XRD, and BET techniques before and after subjecting to the dye adsorption studies. The BET analysis of the adsorbents showed a high specific surface area of 693.8 m2/g when prepared at 1000 °C, while the N2 adsorption-desorption plot showed type-IV isotherm, suggesting the microporous nature of the carbon matrix. Batch equilibrium studies showed the removal efficiency of >95% for both the dyes and their binary mixtures under the optimum conditions of 0.15 g/L dosage, 10 µM concentration and contact time of 70 min. Due to the synergistic effects of the binary dyes, higher removal efficiency of MB compared to MO was observed in the binary mixture. Adsorption results were tested using Langmuir, Freundlich, Temkin, Redlich-Peterson, and Elovich isotherms to assess the best fit of the models. The qm value of MB was found to be 97.37 mg/g, while that of MO was 71.22 mg/g which is higher compared to individual dye components having lower values of 86.12 mg/g and 50.35 mg/g, respectively. Extended Langmuir and Jain and Snoeyink isotherms were used for binary data interpretation. The kinetic results showed good agreement with the Pseudo-second order equation, indicating internal diffusion. The possible mechanism involved electrostatic and á´¨-á´¨ interactions between the dye molecules and ACNPs. This approach is comprehensible and cost effective and can be utilized for dye removal in textile industries.

Biomass-based adsorbents for post-combustion CO2 capture: Preparation, performances, modeling, and assessment.

The adsorbents are critical carriers in the process of adsorption-based post-combustion CO2 capture. Biomass-based adsorbents (BAs) are considered to have great potential because of their high efficiency, low cost, and good sustainability. To understand the methods, theories, and technologies of BAs-based CO2 capture, this work analyzes their preparation and activation/modification, influencing factors, mechanisms, thermodynamics/kinetics, regeneration and cycle performances, and the pathway to application. It is found that BAs prepared by pyrolysis, chemical activation, and modification with dual heteroatoms are more conducive to improving adsorption sites. CO2 adsorption capacity positively correlates with elemental C and fixed carbon of feedstocks, but negatively with moisture. The BAs prepared at 550-600 °C have high performance. The specific surface area (SSA) increases as the preparation time increases by 9.4%-93.4%. The adsorption capacity is positively correlated to the SSA (R = 0.880) and microporous volume (R = 0.773). Moreover, it decreases linearly with increasing operating temperature with the slope of -0.6 mmol/(g·°C) but increases exponentially with increasing operating pressure and CO2 concentration with the power of 0.824. The adsorption process includes physical and/or physicochemical adsorption. Freundlich isotherm equation and pseudo-second-order model characterize the adsorption thermodynamics and kinetics more effectively with R2 = 0.985-1.000 and R2 = 0.894-1.000. The quantum chemistry indicates that most BAs modified with non-metallic belong to physisorption. The regeneration of BAs has low energy consumption (<3.44 MJ/kg CO2) and loss rate (<8%). Furthermore, the technical pathway is proposed for application. Finally, the challenges are also presented to facilitate the development of BAs-CO2 capture.

Nitrogen-doped magnetic porous carbon material from low-cost anion-exchange resin as an efficient adsorbent for tetracyclines in water.

In this work, nitrogen-doped magnetic porous carbon material (N-MPC) was prepared through the high-temperature calcination of low-cost [Fe(CN)6]3--loaded anion-exchange resin, which was experimentally demonstrated to have significant adsorption performance for tetracycline (TC) in water. The N-MPC adsorbent with a large specific surface area (781.1 m2 g-1) was able to maintain excellent performance in a wide pH range from 4 to 10 or in high ionic strength solution. The adsorption of TC on N-MPC was found to be more consistent with the pseudo-second-order model and Langmuir adsorption model, and the maximum adsorption capacity (qm, cal) was calculated to be 603.4 mg g-1. As a recoverable magnetic adsorbent, the N-MPC remained a TC removal rate higher than 70% after four adsorption cycles. The adsorption mechanism was speculated on the basis of characterizations, where pore filling, hydrogen bonding interaction, and π-π electron donor-acceptor (EDA) interaction were crucial adsorption mechanisms. A variety of antibiotics were selected for adsorption, and excellent performance was found especially for TCs, indicating that the N-MPC can be used for the efficient removal of TCs from water.

Physicochemical, structural analysis of coal discards (and sewage sludge) (co)-HTC derived biochar for a sustainable carbon economy and evaluation of the liquid by-product.

This study focused on the hydrothermal treatment (HTC) of coal tailings (CT) and coal slurry (CS) and the co-hydrothermal treatment (Co-HTC) of CT, CS and sewage sludge to assess the potential for increasing the carbon content of the hydrochar produced as an enabler for a sustainable carbon economy. The optimal combination methodology and response surface methodology were used to study the relationship between the important process parameters, namely temperature, pressure, residence time, the coal-to-sewage-sludge ratio, and the carbon yield of the produced hydrochar. The optimized conditions for hydrochar from coal tailing (HCT) and hydrochar from coal slurry (HCS) (150 °C, 27 bar, 95 min) increased fixed carbon from 37.31% and 53.02% to 40.31% and 57.69%, respectively, the total carbon content improved from 42.82 to 49.80% and from 61.85 to 66.90% respectively whereas the ash content of coal discards decreased from 40.32% and 24.17% to 38.3% and 20.0% when compared CT and CS respectively. Optimized Co-HTC conditions (208 °C, 22.5bars, and 360 min) for Hydrochar from the blend of coal discards and sewage sludge (HCB) increased the fixed carbon on a dry basis and the total carbon content from 38.67% and 45.64% to 58.82% and 67.0%, when compared CT and CS respectively. Carbonization yields for HCT, HCS, and HCB were, respectively, 113.58%, 102.42%, and 129.88%. HTC and Co-HTC increase the calorific value of CT and CS, to 19.33 MJ/kg, 25.79 MJ/kg, respectively. The results further show that under Co-HTC conditions, the raw biomass undergoes dehydration and decarboxylation, resulting in a decrease in hydrogen from 3.01%, 3.56%, and 3.05% to 2.87%, 2.98%, and 2.75%, and oxygen from 8.79%, 4.78, and 8.2% to 5.83%, 2.75%, and 6.00% in the resulting HCT, HCS, and HCB, respectively. HTC and Co-HTC optimal conditions increased the specific surface area of the feedstock from 6.066 m2/g and 6.37 m2/g to 11.88 m2/g and 14.35 m2/g, for CT and CS, respectively. Total pore volume rose to 0.071 cm3/g from 0.034 cm3/g, 0.048 cm3/g, and 0.09 cm3/g proving the ability of HTC to produce high-quality hydrochar from coal discards alone or in conjunction with sewage sludge as precursors for decontamination of polluted waters, soil decontamination applications, solid combustibles, energy storage, and environmental protection.

A template-free assembly of Cu,N-codoped hollow carbon nanospheres as low-cost and highly efficient peroxidase nanozymes.

Developing carbon-based materials with high catalytic performance and sensitivity has significance in low-cost and highly efficient nanozymes. Herein, for the first time, Cu,N-codoped hollow carbon nanospheres (CuNHCNs) with highly active Cu-Nx sites were successfully assembled through a template-free strategy, in which Cu2+-poly(m-phenylenediamine) (Cu-PmPD) nanospheres were utilized as the source of Cu, N and C. Benefiting from the synergistic effect of the hollow spherical structure and optimized composition, the CuNHCN exhibits high affinity for 3,3',5,5'-tetramethylbenzidine and H2O2 with 0.0655 mM and 0.918 mM, respectively, which are superior to those of HRP and most metal-based nanozymes. Moreover, by employing glucose and ascorbic acid (AA) as biomolecule models, a CuNHCN-based colorimetric detection platform is developed. The CuNHCN exhibits superior peroxidase mimicking activity and sensitivity in detecting glucose and AA with a detection limit of 0.187 µM and 68.9 nM (S/N = 3), respectively. Also, the colorimetric detection based on the CuNHCN towards glucose and AA in human serum presents superior practicability and accuracy. The assay provides a new avenue for designing and fabricating low-cost peroxidase nanozymes with high performance in bioassays.

Recent Advances in Nondestructive Method and Assessment of Corrosion Undercoating in Carbon-Steel Pipelines.

Carbon-steel pipelines have mostly been utilized in the oil and gas (OG) industry owing to their strength and cost-effectiveness. However, the detection of corrosion under coating poses challenges for nondestructive (ND) pipeline monitoring techniques. One of the challenges is inaccessibility because of the pipeline structure, which leads to undetected corrosion, which possibly leads to catastrophic failure. The drawbacks of the existing ND methods for corrosion monitoring increase the need for novel frameworks in feature extraction, detection, and characterization of corrosion. This study begins with the explanations of the various types of corrosion in the carbon-steel pipeline in the OG industry and its prevention methods. A review of critical sensors integrated with various current ND corrosion monitoring systems is then presented. The importance of acoustic emission (AE) techniques over other ND methods is explained. AE data preprocessing methods are discussed. Several AE-based corrosion detection, prediction, and reliability assessment models for online pipeline condition monitoring are then highlighted. Finally, a discussion with future perspectives on corrosion monitoring followed by the significance and advantages of the emerging AE-based ND monitoring techniques is presented. The trends and identified issues are summarized with several recommendations for improvement in the OG industry.

Harmless Treatment of High Arsenic Tin Tailings and Environmental Durability Assessment.

The treatment of arsenic (As) in tin tailings (TT) has been an urgent environmental problem, and stabilization/solidification (S/S) treatment is considered an effective technology to eliminate contamination of As. In this study, we developed a low-carbon and low-alkalinity material to S/S of As, and the results showed that the leaching concentration of As after treatment was lower than the Chinese soil environmental quality standard (0.1 mg/L). Based on a series of characterization tests, we found that OH- promoted the dissolution of As(III)-S, Fe-As(V), and amorphous As(III)-O species and formed Ca-As(III) and Ca-(V) species with Ca2+. Simultaneously, hydration produces calcium silicate hydrate (C-S-H) gel and ettringite by the form of adsorption and ion exchange to achieve S/S of As. We also assessed the durability of this material to acidity and temperature, and showed that the leaching concentration of As was below 0.1 mg/L at pH = 1-5 and temperature 20-60 °C. The method proposed in this study, S/S of As, has excellent effect and environmental durability, providing a new solution for harmless treatment of TT and its practical application.