Residual Carbon Research Articles

Carbon residue from co-pyrolysis of cartons and plastics: Characteristics, environmental behaviors and applications.

The continuously growing of municipal solid waste (MSW) has posed a threat to human-being. Pyrolysis is a promising technique for MSW disposal, as it can reduce its volume and produce valuable products as well. This study evaluated the potential of carbon residue (CR) derived from waste carton as soil amendment. Additionally, considering the waste plastics, such as plastic bags, plastic tape, etc., can mix with carton in MSW, the effect of polyvinyl chloride (PVC) addition on the characteristics of CR and its environmental behavior was measured. Results showed that the CR derived from carton exhibited notable efficacy in adsorbing Cd2+ (56.111mg/g), pesticides and PO43- (0.231mmol/g), thereby mitigating pollutants and immobilizing nutrient in soil environment. The introduction of PVC was found to enhance the adsorption of CR for Cd2+ (65.623mg/g) and PO43- (0.524mmol/g), albeit exhibiting diminished performance in the removal of pesticides. Different from previous studies, this study revealed that the dissolved black carbon (DBC) released from CRs did not generate reactive oxygen species (ROS) effectively under solar irradiation, and the light screening of DBC can mitigate the photodegradation of pollutants. Furthermore, both CRs increased bacterial luminescence by approximately 70%, which indicated that no toxicity produced during the pyrolysis process. And gas chromatography-mass spectrometry (GC-MS) revealed the absence of polyaromatic hydrocarbon (PAH) in CRs. In summary, this study may provide some new insights on the disposal of MSW, and the CR made by MSW could be effective in soil amendment and reduce the leaching of pollutants and nutrient.

Stabilizing Layered Oxide Cathodes Based on Universal Surface Residual Alkali Conversion Chemistry for Rechargeable Secondary Batteries.

Layered transition metal oxides (LTMOs) are attractive cathode candidates for rechargeable secondary batteries because of their high theoretical capacity. Unfortunately, LTMOs suffer from severe capacity attenuation, voltage decay, and sluggish kinetics, resulting from irreversible lattice oxygen evolution and unstable cathode-electrolyte interface. Besides, LTMOs accumulate surface residual alkali species, like hydroxides and carbonates, during synthesis, limiting their practical application. Herein, a universal strategy is suggested to in situ convert surface residual alkali into a stable polymer coating layer for LTMOs, thus turning wastes into treasure. The formation process of polymer coating involves NH4F treatment to consume residual alkali, then utilizing generated fluorides to induce the ring-opening polymerization of tetrahydrofuran. Implementing this strategy to Li-rich Mn-based cathode materials (LRM) results in a notable reduction in voltage hysteresis, along with enhanced kinetics and cycling stability in lithium-ion batteries. With this layer of encapsulation, surface lattice oxygen release and layered-to-spinel phase transition of LRM are significantly alleviated with minimal mechanical degradation and surface parasitic reactions. Such strategy can also be applied to air-sensitive sodium-rich LTMOs in sodium-ion batteries,which showcases superior universality. This work might provide a promising solution to overcome residual alkali and interfacial instability issues for LTMOs in practical application.

Groundwater Quality Assessment for Irrigation in Durg District, Chhattisgarh, India: A Hydro Geochemical and GIS-Based Perspective

Groundwater quality is a critical factor for agricultural irrigation, as its chemical composition can directly impact soil structure and crop productivity. This study investigates the groundwater quality in Durg district, Chhattisgarh, with a focus on its suitability for irrigation. A comprehensive analysis of hydro geochemical parameters such as pH, electrical conductivity (EC), sodium adsorption ratio (SAR), sodium percentage (Na%), residual sodium carbonate (RSC), and other key elements was conducted. The study uses both chemical analysis and digital tools such as ERDAS IMAGINE and MapInfo Professional to assess the spatial variability of groundwater properties and their implications for agricultural use. The results indicate that while groundwater quality in Durg district is generally favourable for irrigation, local variations exist that require consideration for optimal water use in agriculture.

Thermal stability, flame retardancy and mechanical properties of casein-based rigid polyurethane foam with starch and sepiolite as fillers

Casein-based rigid polyurethane foam (RPUF) with different ratios of starch and sepiolite were prepared by a one-step process. Thermogravimetric analysis, CONE analysis, scanning electron microscopy analysis, limiting oxygen index (LOI) analysis, vertical combustion analysis, and mechanical property analysis were used to explore the thermal stability, flame retardancy, and compressive properties of the modified RPUFs, respectively. The results showed that the initial decomposition temperature and activation energy (E) of RPUF-C5ST2SE3 (5 g casein, 2 g starch, and 3 g sepiolite) were the highest. Under the condition of radiant flux of 50 kW/m2, the peak heat release rate (PHRR), total heat release (THR), peak smoke production rate (PSPR), and total smoke release (TSR) were reduced by 35.92%, 10.83%, 36.67%, and 18.20%, respectively, compared with the RPUF without flame retardant. By analyzing the carbon residue, it was found that RPUF-C5ST2SE3 had the highest carbon residue and its carbon residue morphology was relatively intact. In addition, the RPUF-C5ST2SE3 had the highest LOI and a UL-94 rating of V-0. At the same time, it also had the best mechanical property. The present experimental results can provide a useful reference for future RPUF flame retardant studies.

Fabrication and Performance Enhancement of Wood Liquefaction-Based Carbon Fibers Modified with Alumina Nanoparticles.

In this paper, alumina-modified wood liquefaction (AL-WP) was prepared by blending nano-alumina (Al2O3) into wood liquefaction phenolic resin (WP) using a co-blending method. Alumina-modified wood liquefaction protofilament fiber (AL-WPF) was obtained by melt-spinning, curing, and thermo-curing processes, which were followed by carbonization to obtain alumina-modified wood liquefaction carbon fiber (AL-WCF). This paper focuses on the enhancement effect of nano-alumina doping on the mechanical properties and heat resistance of wood liquefaction carbon fiber (WCF), explores the evolution of graphite microcrystalline structure during the high-temperature carbonization process, and optimizes the curing conditions of AL-WPF. The results showed that the introduction of Al2O3 significantly improved the mechanical properties and heat resistance of carbon fibers. When 1.5% Al2O3 was doped and carbonized at 1000 °C, the tensile strength of AL-WCF was increased from 33.78 MPa to 95.74 MPa, there was an enhancement of 183%, its residual carbon rate could reach 79.2%, which was better than that of the undoped wood liquefaction (WCF), and it exhibited a more substantial heat-resistant property. In addition, the best curing process for alumina nanoparticle wood liquefiers was obtained by optimizing the curing conditions: hydrochloric acid concentration of 16%, formaldehyde concentration of 18.5%, temperature increase rate of 15 °C/min, holding time of 3 h, and holding temperature of 100 °C. These studies provide a theoretical basis and technical support for developing and applying carbon fibers from alumina-modified wood liquefiers.

Preparation of Fe3O4/C Composite Material from Red Mud for the Degradation of Acid Orange 7.

This study presents a novel Fe3O4/C composite material synthesized from red mud through a process of magnetic roasting and separation. The research explores the impact of Fe3O4/C dosages, sodium persulfate (PS) concentrations, and initial solution pH on the chemical oxygen demand (COD) removal efficiency using Acid Orange 7 as a model pollutant. Optimal conditions were identified as 3 g/L Fe3O4/C, 20 mM PS, and an initial pH of 2, achieving a 94.11% COD removal efficiency within 30 min. X-ray diffraction and photoelectron spectroscopy analyses confirmed that the magnetization roasting process effectively transformed red mud's ferric oxide (Fe2O3) into magnetite (Fe3O4). Concurrently, Fe3O4 interacted with residual carbon to form the Fe3O4/C composite. This composite demonstrated superior catalytic performance, along with excellent recyclability and reusability.

Residue carbon removal for the high-quality and sustainable direct regeneration of spent LiFePO4 materials

Residue carbon removal for the high-quality and sustainable direct regeneration of spent LiFePO4 materials

The Preparation of an Environmentally Friendly Novel Daidzein-Modified Lignin Phenolic Resin with High Performance and Its Application in Friction Materials.

The preparation of biological phenolic resin (PF) with green recyclable biomaterials instead of phenol is a research hotspot for solving current resource and environmental problems. In this study, on the basis of introducing lignin into the phenolic system, daidzein of a renewable resource with a rigid structure was selected to modify lignin-based phenolic resin (LPF), and the improvement of the mechanical and thermal properties of the modified phenolic resin under different substitution ratios was studied. The friction materials were prepared with a daidzein-modified lignin-based phenolic resin (D-LPF) as the matrix binder, and their effects on the mechanics and friction and wear properties of friction materials were investigated. The results show that when the proportion of daidzein replacing phenol is 12%, the highest Tp can reach 152.4 °C, and the Tg of the modified D-LPF resins is significantly higher than those of PF and LPF. The highest Ts of D-LPF is 203.3 °C, which is also significantly higher than those of PF and LPF (184.7 °C and 174.6 °C, respectively). The maximum carbon residue rate at 800 °C is 64.2% and is greatly improved compared with the 55.1% and 56.7% of PF and LPF. The bending strength and impact strength of D-LPF-matrix friction materials are obviously higher than those of PF- and LPF-matrix friction materials. The specific wear rate of D-LPF-matrix friction materials is 0.70 × 10-4 mm3/Nm, which is obviously lower than those of PF- and LPF-matrix friction materials and shows good applicational prospect as a matrix resin in friction materials.

Assessment of irrigation water quality for groundwater in Semi-Arid Region, Bangalore, Karnataka

ABSTRACT Anthropogenic activities-related degradation of groundwater quality has emerged as a major concern. The variation in geomorphological, geological, and hydrogeological factors are assessed for the thirty groundwater samples, collected from Bangalore North, Bangalore Rural district, Karnataka, during the pre-monsoon season. The study’s goal is to evaluate major ion chemistry and several physicochemical parameters viz. salinity hazard (EC), sodium adsorption ratio (SAR), residual sodium carbonate (RSC), chloride hazard (CH), total hardness (TH), magnesium hazard (MH), permeability index (PI), percent sodium (%Na), kelly’s ratio/index (KR/KI), soluble sodium percent (SSP), chloro-alkaline index (CAI), and ion balance. The Principal Component Analysis (PCA) in performed to evaluate the Irrigation Water Quality Index (IWQI) considering and water quality parameters like EC, Na+ (sodium), HCO3 − (bicarbonates), Cl− (chlorides), SAR content of groundwater. To determine the overall water quality suitable for irrigation use, the irrigation water quality index ratings were computed. Along with this, Gibbs diagrams and Wilcox plots were created based on analytical results, and groundwater quality. The Gibbs diagram reveals that more than 83% of samples were evaporation dominates and regulate the mechanism for the chemistry of groundwater except few samples (R7, R8, T7, T8, U3) which accounts for nearly 17% , and have high sodium content. Whereas the Wilcox plot represents, most of the samples are within the permissible limits for irrigation use. Ten percent of the transition sample (T6) and almost 60% of the rural samples (R1, R2, R4, R5, R6, R10) had no irrigation restrictions. Low irrigation restriction was present in 20% of urban samples (U4, U7), 80% of transition samples (T1, T2, T4, T5, T7, T8, T9, T10), and 30% of rural samples (R3, R7, R9). Moderate restrictions on irrigation use were present in 10% of rural samples (R8), 10% of transition sample (T3), and 80% of urban samples (U1, U2, U3, U5, U6, U8, U9, U10). The natural resources of water bodies have been impacted by unplanned economic and industrial activities that have sped up urbanization, industrialization, infrastructural development, and population growth. Most of the rural samples had no toxicity risk for most of the crops, while transition samples had limited restriction and proper monitoring & judicious application for irrigation will be better for most of the crops except salt-sensitive crops. More than 80% of urban samples had moderate restriction only plants with moderate tolerance to salts may be grown.

Fabrication of Free-Standing Porous BaTiO Thick Films by Indirect Selective Laser Sintering

The fabrication of free-standing porous thick films of ferroelectric BaTiO3, using a laser-assisted technique, is presented as a novel alternative to conventional methods. This approach adapts Indirect Selective Laser Sintering (ISLS) to create green films in a single laser pass, avoiding the complexities of traditional processes. Using commercial BaTiO3 powder and polyamide 12 as raw materials, laser processing parameters such as scanning laser speed and power were optimized to produce green BaTiO3 thick films with different thicknesses. After laser processing, the films were conventionally sintered and characterized for phase composition, microstructure, porosity, and electrical properties. X-ray diffraction and Raman spectroscopy confirmed the tetragonal BaTiO3 phase, while mercury intrusion porosimetry revealed a bimodal pore distribution. Impedance spectroscopy demonstrated a positive temperature coefficient of resistivity (PTCR) effect, with a peak resistivity near the Curie temperature. The PTCR behavior is hypothesized to arise from better oxygen adsorption due to the porosity and oxygen vacancies generated during sintering by carbon residues from polyamide degradation. The results demonstrate that ISLS is a versatile technique for producing high-quality, free-standing porous ceramic thick films with potential for a wide range of applications.

Development of a Fire-Retardant and Sound-Insulating Composite Functional Sealant.

The use of traditional sealing materials in buildings poses a significant risk of fire and noise pollution. To address these issues, we propose a novel composite functional sealant designed to enhance fire safety and sound insulation. The sealant incorporates a unique four-component filler system consisting of carbon nanotubes (CNTs) decorated with layered double hydroxides (LDHs), ammonium dihydrogen phosphate (ADP), and artificial marble waste powder (AMWP), namely CLAA. The CNTs/LDHs framework provides structural support and enhances thermal stability, while the ADP layer acts as a protective barrier and releases non-combustible gases during combustion. AMWP particles contribute to sound insulation by creating impedance mismatches. The resulting composite functional sealant exhibits improved mechanical properties. In terms of flame retardancy, it boasts the lowest peak heat release rate (PHRR) of 224.83 kW/m2 and total smoke release (TSR) of 981.14 m2/m2, achieving the V-0 classification. Furthermore, its thermal degradation characteristics reveal a notably higher carbon residue rate. Additionally, the sound insulation capability has been significantly enhanced, with an average sound insulation level of 43.48 dB. This study provides a promising solution for enhancing the fire safety and acoustic properties of building sealing materials.

Assessment of Phytorid Treatment System Efficacy for Irrigation Water Quality in Bindapur, South-West Delhi, India

Constructed wetlands (CWs) offer an eco-friendly approach for treating diverse wastewaters, including sewage and industrial and agricultural effluents. This study evaluates the performance of a self-sustaining constructed wetland system using Phytorid treatment technology for decentralized wastewater treatment at Bindapur, South West Delhi. The government-operated system was monitored for twelve months (2022–2023), with inlet and outlet water samples collected fortnightly and analysed for irrigation water quality parameters. Key irrigation indices, such as Percent Sodium, Sodium Adsorption Ratio (SAR), Residual Sodium Carbonate (RSC), Electrical Conductivity (EC), Kelly’s Ratio (KR), Total Hardness (TH), Chloride-Bicarbonate Ratio (CB Ratio), Magnesium Hazard (MH), Permeability Index (PI), and Gibbs Ratio, were calculated to assess irrigation suitability. Results revealed that one inlet sample fell into the C4-S3 category (very high salinity, high sodium), while most samples were classified as C4-S2 (very high salinity, medium sodium). High EC and sodium levels indicated unsuitability for irrigation, particularly in poorly drained soils. The Wilcox Diagram confirmed most samples were unsuitable for irrigation due to high salinity. Diluting treated effluent with low TDS water (<500 mg/L) in a 2:1 ratio could improve suitability. This study provides insights to help policymakers and stakeholders manage treated sewage water for irrigation.

Characterization of Natural Resources in the Narmada Canal Project Area of Rajasthan for their Management under Canal Command Irrigation

A systematic investigation was undertaken to assess the state of natural resources i.e. soils, landform, and water in response to continuous canal irrigation in the Narmada Canal Project area in two arid districts of arid Rajasthan. Soils in the NCP area in Rajasthan were found very deep, slightly to strongly alkaline in reaction (pH 7.62 to 9.98), sandy to silty loam in texture at surface and loamy sand to sandy loam in texture at the subsurface. Five soil series were characterized and mapped in the course of the investigation. Four soil series belonged to the aeolian plains covering 74% area of NCP and these are Sanchore, Dhorimana, Chohtan and Dune complex whereas one soil series i.e. Chitalwana was identified belonging to alluvial plains covering 10% area of NCP. Organic carbon content ranged from 0.03 to 0.42% in the surface soils with a decreasing trend along the depth. Available N, P and K content in surface soils ranged from 61.9 to 191.0 kg ha-1, 1.41 to 47.84 kg ha-1 and 56.25 to 652.50 kg ha-1, respectively. Similarly, Fe, Mn, Zn and Cu ranged from 0.85 to 13.46 mg kg-1, 1.72 to 14.55 mg kg-1, 0.08 to 2.40 mg kg-1 and 0.02 to 1.38 mg kg-1, respectively. Based on visual interpretation of satellite images and subsequent ground truthing, ten types of landforms have been characterized in the area, which have been categorised under fluvial, aeolian and coastal kinds. Among the landforms of fluvial origin, alluvial plains occur in about 37% of total area under NCP and have been further mapped as younger and older alluvial plain types. Analysis of groundwater in the NCP area of Rajasthan revealed medium sodicity of groundwater with the value of sodium adsorption ratio ranging from 0.15 to 36.31. The residual sodium carbonate of groundwater ranged from almost nil to 5.7 me L-1 with a mean value of 1.1 me L-1. Among the cations and anions, Na+ and Cl- are the dominant ions and their concentrations ranged from 0.27 to 95.50 me L-1 and 1.40 to 92.40 me L-1, respectively. Benchmark characterization of these soil and water resources will help in future assessment and best management of natural resources specifically in canal command area located in arid landscape.

Impact of oxygen content on debinding of binder jetted 17-4 PH stainless steel: Part I – Debinding

Binder jetting (BJT) utilises a sacrificial binder to shape green parts in a metal powder bed. The binder must be removed during debinding at elevated temperatures without contaminating the powder material. Efficient binder removal often requires oxygen in the atmosphere to aid the decomposition of the binder, but oxygen causes oxidation of the metal powders and hence negatively impacts the final material properties. Therefore, the use of tailored oxygen contents in the atmosphere during a standard debinding cycle performed at 300°C for 2 h was investigated for BJT printed 17-4 PH stainless steel. The change in bulk chemistry (carbon, oxygen, nitrogen, and hydrogen) from green parts to brown parts was thoroughly analysed and compared to the virgin powder subjected to the same conditions as used for debinding. While inert argon was beneficial for protecting the powder from oxidation, the removal of only ∼34% of binder was insufficient, resulting in 0.47 wt.% of residual carbon in the brown part. Debinding in atmospheres containing 3 vol.% O2 to 20 vol.% O2 led to almost complete binder removal, but also caused significant oxygen pickup by the powder between 1734 ppm and 1820 ppm. Furthermore, the brittleness of the brown parts increased, leading to undesirable powder losses during handling. The best debinding was obtained in Ar + 1 vol.% O2, which allowed the best combination of binder removal of ∼74% and lower oxygen pickup by the powder of 1617 ppm, together with sufficient brown part strength for handling.

Study on dissociation mechanism and process of regenerated cryolite

Solid waste produced in the process of aluminum electrolysis is a substantial secondary source of fluorine, the fluoride electrolyte in aluminum electrolysis carbon slag accounts for about 75%. Regenerative cryolite, extracted from anode carbon residue through flotation or calcination, possesses a significant potential for fluorine recovery. The fluoride in regenerated cryolite is mainly insoluble, making its efficient dissociation crucial for utilizing the solid waste from aluminum electrolysis. This study uses regenerative cryolite and sodium carbonate to examine how roasting temperature, time, and the reagent-to-cryolite ratio (R/C) affect cryolite dissociation. Dissociation efficiency is measured using indices like baking loss, leaching loss, fluoride ion concentration in the leachate, and fluoride ion conversion rate. Optimal dissociation is achieved at 780°C–820°C, 2.0–2.5 h roasting time, and an R/C ratio of 1.0–1.2. Orthogonal experimental results highlight the predominant influence of R/C, with roasting temperature being the secondary factor and roasting time having the least impact. Notably, at 780°C, 2.0 h, and an R/C ratio of 1.2:1, the fluoride ion conversion rate reaches a peak of 94.23%. This allows for recycling and production of high-value fluoride products, benefiting both the environment and the economy.

Hydro-geochemistry of the Bindal River Catchment: water suitability for irrigation and drinking in the Doon Valley outer Himalaya

ABSTRACT The hydrogeochemical analysis of surface water and groundwater in the Bindal river catchment was conducted in the Doon Valley of Uttarakhand, situated in the Outer Himalayan region. The surface and ground water samples were collected from 13 sampling stations located at the Bindal river catchment. The pH ranged from 6.93 to 7.62, with an average value of 7.23, signifying a slightly alkaline nature. The electric conductivity concentration varied from 655 µs/cm to 1309 µs/cm, with a mean value of 865.54 µs/cm. The equivalent ratio of Ca2+ + Mg2+ (µEq/l vs total cation (TZ+) was varied from 1.05 to 10.7 with a mean value of 1 and the equivalent ratio of Ca2+/Mg2+ was 1.04 and the ratio of Ca2+ + Mg2+ (µEq/l) vs Na + K (µEq/l) was 10 indicating the dominance of carbonate weathering. As per Piper diagram, the dominance of weak acids (HCO3 −) over strong acids (SO4 2-, Cl−) was observed and majority of samples were alkaline earth and the alkaline earths (Ca2+ + Mg2+) were dominant over alkalis (Na+ + K+). The scatter plot Ca2+ + Mg2+ (µeq/l) and HCO3 − showed that few of the points fell along the 1:1 equiline, indicating that Ca2+ + Mg2+ in most of the sampling locations were almost balanced by HCO3 −. However, few points also fall away from 1:1 equiline indicating Ca2+ + Mg2+ are to balances by other ions, possibly sulphate ions, which were the second-largest ions in the study area. Two principal components were selected in this region and their eigenvalues were >1 and accounted 73% of cumulative variability in the data. The aptness of water for irrigation purposes was calculated via SAR value, Kelly’s Index, Wilcox, residual sodium carbonate, Na%, etc. The Piper plot indicated carbonate weathering is the dominant source of ions in the water, attributed to the prevalence of high-concentration dolomite and calcite rocks in the study area. Total order of ions follows HCO3 − > Ca2+ > Mg2+ > SO4 2- > Cl− > Na+ > NO3 − > K+ > PO4 3- > F− order. Apart from TDS, Ca2+, SO4 2- and K+, all the other parameters were within the acceptable limits as per Bureau of Indian Standards (BIS) for drinking water quality.

Assessing the suitability of water for irrigation purposes using irrigation water quality indices in the Irob catchment, Tigray, Northern Ethiopia

ABSTRACT Irrigation alleviates poverty in arid and semi-arid regions, such as Ethiopia, necessitating a water suitability assessment. This study evaluates irrigation water quality in the Irob catchment, Northern Ethiopia. It differs by using combined parameters of the irrigation water quality index (IWQI) for comprehensive assessment beyond standard comparisons. Eighteen water samples were collected and analyzed using ultraviolet spectrometry, titration, and atomic absorption spectrometry. The evaluation included parameters such as salinity, total dissolved solids (TDS), total hardness (TH), sodium adsorption ratio, sodium percentage, residual sodium carbonate, permeability index, magnesium ratio, Kelly's index, potential salinity, and the IWQI. The findings revealed that 22.2, 38.9, 88.8, 66.7, 83.3, 66.7, 100, 72.2, and 55.6% of samples exceeded recommended standards for electrical conductivity, TDS, TH, permeability index, manganese, cobalt, copper, cadmium, and nickel, respectively. Most water quality parameters meet standards, but improved irrigation management is crucial to reduce risks. The IWQI indicates that 22.2% of water samples have minor restrictions, while 77.8% have no restrictions. This method provides key insights for evaluating irrigation water quality in similar hydrogeological and environmental conditions, particularly in semi-arid and arid regions. The findings enhance the understanding of sustainable water quality, supporting local authorities in developing resilient irrigation strategies for regional agricultural sustainability.

Rock mass quality in the study area of Cijurey dam diversion tunnel, Bogor Regency, West Java Province, Indonesia

Abstract This study investigated the rock mass quality in the diversion tunnel of the Cijurey Dam through a detailed case study. Detailed examinations of the geological conditions were carried out on the surface and subsurface of the designated area, including residual soil, sandstone, carbonate sandstone, and carbonate mudstone layer. The method of this study is based on the classification of the Rock Mass Rating (RMR) and Geological Strength Index (GSI). RMR was the basis for determining the strength of rock masses in the form of shear strength of discontinuity surfaces, which depends on several factors such as distance, orientation, continuity, surface characteristics, separation, thickness, and nature of the filling material, while GSI was related to the level of fractures and surface conditions of discontinuities (9). The study area consists of three types of rock mass classes, namely poor to fair-quality sandstone with an RMR range between (41-60), poor to fair-quality carbonate mudstone with an RMR range between (37-63), and fair to good-quality carbonate sandstone with an RMR range between (60-63). Equations were derived to express this correlation GSI = 1.9845RMR-41.039 (R2=0.939), which had similarities with the linear line of the empirical equation of Wijaya et al. (27). Further analysis was needed, including the evaluation of the slope stability of the portal, the determination of the excavation methodology, and the formulation of the tunnel support system based on the rock mass characterization results obtained from this study.

Effect of Phenolic Resin Pyrolysis on Thermal Properties of SiFRP Composites under High Heating Rates

Abstract During the ablation process of resin-based composite materials, residual carbon generated from pyrolysis of phenolic resin change the thermal performance of the material. Phenolic resin pyrolysis process depends on temperature and heating rate. Based on the mass loss curves of phenolic resin under high heating rates (5K/s, 50K/s, 100K/s), the study analyzes the variations in thermal performance parameters of SiFRP composite materials with temperature assuming phenolic resin and silica fibres are in parallel in heat transferring. As temperature rising, the pyrolysis conversation ratio of phenolic resin increases, thermal conductivity and specific heat capacity of the composites increase accordingly. The greater the heating rates, the smaller the change of thermal conductivity and specific heat capacity of composites at the same temperature. The complete pyrolysis temperature of phenolic resin is positively correlated with the temperature rise rate. When the temperature rise rate is very large (such as 100K/s), the influence of pyrolysis on the thermal properties of composites can be ignored at medium and low temperature.

Transforming waste into multifunctional nanomaterials: Mg-doped carbon dots from cow dung for Y(III) detection and biomedical applications

Rare earth metal Yttrium (Y3+) plays a vital role in many electronic devices however, discarding these devices eventually contaminates the environmental sources. Herein, we have developed a Mg-doped carbon dots (M-CDs) as a fluorescent probe for selective and sensitive determination of Y3+ in water bodies. The M-CDs having maximum emission at 420 nm upon 310 nm excitation with 20 % quantum yield and which was synthesized from upcycling of agricultural waste i.e., cow dung by simple carbonization followed by hydrothermal method. M-CDs were confirmed using different analytical and characterization techniques as well as stable in different pH and ionic strength solutions. The M-CDs was highly selective towards Y3+ ions over different metal ions with significant blue shift. This fluorescent probe performs a good linear relationship between the different concentrations of Y3+ ion and fluorescence intensity (R2 = 0.99) within the range of 0.2 to 20 μg/mL with a detection limit of 0.019 µg/mL. The study indicates quenching of Y3+ was result of dynamic quenching and the Inner Filter Effect (IFE) effect. Also, the cytotoxicity of M-CDs was checked via CAM assay and significant growth in blood vascularization with healthy growth of chick embryo confirmed the M-CDs were biocompatible. The nontoxic M-CDs was employed for MCF-7 breast cancer cell imaging which gives bright blue fluoresce under UV light excitation. Further, aiming to a circular economy approach the residual carbon remaining after hydrothermal was used as reactivated carbon for the abatement of environmental pollutants. The sustainable, cost-effective and agricultural waste-derived Mg-doped CDs have potential applications in analytical, environmental, forensic as well as biomedical fields.