Activated Carbon Research Articles

Reduction of 2,4-dichlorophenoxy acetic acid herbicide toxicity from aqueous media by adsorption: Experimental and theoretical study using DFT method

This work studies the possibility of reducing the toxicity of water laden with 2,4-dichlorophenoxy acetic acid (2,4-D) using a commercial activated carbon (AC). Multiple structural and textural characterization techniques including Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM/EDS), point of zero charge (pHzpc) determination, Boehm titration, iodine number, Methylene blue index, and BET analysis measurements were performed on the commercial AC. Various parameters affecting adsorption were studied and well-known isotherms models in their linear and non-linear forms were applied for fitting equilibrium data. The kinetic data was analyzed using intraparticle diffusion, pseudo-first and second-order kinetic models. Density functional modeling (DFT) of 2,4-dichlorophenoxyacetic acid was used to investigate the origin of the reactivity. The AC surface area was found to be 1017 m2⋅g−1. A contact time of 30 min, an AC dose of 4 g⋅L−1 and a pH of 6.2 resulted in a maximum adsorption capacity of 235.55 ± 6.43 mg⋅g−1. The thermodynamic study revealed that the adsorption process was physical, spontaneous and endothermic. The adsorption process was governed by second-order kinetics and controlled by intraparticle diffusion.

Repurposing disposed surgical face masks into activated carbon for efficient sorption of bio recalcitrant malathion pesticide

Pesticides are essential for enhancing agricultural produce, but their excessive use poses risks to ecosystems due to persistence and toxicity. This study explores repurposing disposed surgical face masks (DSFMs), rich in polypropylene (PP), as a precursor for activated carbon (AC) synthesis, addressing plastic pollution. DSFM pieces were subjected to hydrothermal treatment with sulfuric acid and KOH activation, optimized via response surface methodology (RSM). Optimal AC preparation conditions were achieved at 800 °C, PP/KOH ratio 3 g/g, and 50 min resulting in AC (3AC800-50) with BET surface area 892.16 m2/g and pore volume 0.6353 cm3/g. The resulting carbon material demonstrated excellent adsorption affinity towards malathion pesticides (MP) with a capacity of 536.68 mg/g. The Freundlich adsorption model accurately fits the data with a high R2 of 0.9898. Kinetic analysis revealed the pseudo-second-order (PSO) model as the best fit, with negative ∆G° indicating the spontaneous nature of MP adsorption. These findings highlight the potential of utilizing ACs derived from DSFMs for sustainable plastic waste management and pesticide removal from water.

Flower-like and porous Ni3S2 nanosheets for high performance supercapacitors

Transition metal sulfides have received significant attention as electrode materials for their low cost and high specific capacitance. Herein, flower-like and porous Ni3S2-120-10 assembled by nanosheets is directly grown on nickel foams through a facile one-step hydrothermal method. Benefited from the porous structure, the flower-like compound offers respectable gravimetric specific capacitance of 1899.4F g−1 at a current density of 1 A/g in 6 M KOH aqueous electrolyte. Moreover, an asymmetric supercapacitor (ASC) was obtained using Ni3S2-120-10 as the positive electrode and active carbon as the negative electrode with 6 M KOH as the electrolyte. Ni3S2-120-10//AC displays a high power density of 1590.7 W kg−1 at the energy density of 17.6 Wh kg−1 accompanied with an outstanding cyclic stability (83.2 % of initial capacitance after 8000 cycles). This work provides a facile strategy for the next generation energy-storage applications with high stability and superior electrochemical capacity.

Respiration rates and its relationship with ETS activity in euphausiids: implications for active flux estimations

Euphausiids, commonly known as krill, are crucial contributors to the ocean’s active carbon pump, impacting carbon export and sequestration through their diel vertical migration. These organisms feed on organic matter in the epipelagic layer at night and release inorganic carbon in the mesopelagic layer during the day via respiration. Measuring respiration in the mesopelagic layer is challenging due to the difficulties in obtaining direct measurements, as well as the lack of comprehensive data, and reliance on conservative estimates. The measurement of the electron transfer system (ETS) activity is used as a proxy to assess respiration in the mesopelagic layer. However, accurate calibration of respiration rates and ETS activity is imperative through experimental measurements and empirical data. Here, we compared the respiration rates with their respective ETS activities of different species of euphausiids captured at night in the epipelagic layer of the Atlantic Ocean along a latitudinal (42-29°N, 25°W) and a longitudinal (25-13°W, 29°N) transect. Our results revealed a spatial trend in respiration rates, and consequently in ETS activities, with rates decreasing southward and increasing slightly towards the African upwelling region. The Generalized Additive Model (GAM) demonstrated that epipelagic oxygen concentration, chlorophyll a, and the interaction between epipelagic temperature and mesopelagic oxygen concentration significantly influenced euphausiids respiration rates. Furthermore, we observed a strong correlation between respiration and specific ETS activities, with R/ETS ratios exceeding the conservative value of 0.5, which is typically used to estimate respiratory flux.

Salinity increases under sea level rise strengthens the chemical protection of SOC in subtropical tidal marshes

The rise in sea levels due to global warming could significantly impact the soil organic carbon (SOC) pool in coastal tidal marshes by altering soil salinity and flooding conditions. However, the effects of these factors on SOC protection in coastal tidal marshes are not fully understood. In this study, we employed a space-for-time approach to investigate the variations in soil active carbon components and mineral-associated organic carbon under different salinity gradients (freshwater and brackish) and flooding frequencies (high and low tidal flats).The soil organic carbon (SOC) and easily oxidizable organic carbon (EOC) contents at the low-flooding frequency sites were higher than those at the high-flooding frequency sites. The dissolved organic carbon (DOC) content was higher at the high-salinity sites compared to the low-salinity sites, while the soil microbial biomass carbon (MBC) content was higher at the low-salinity sites than at the high-salinity sites. The EOC/SOC and DOC/SOC ratios were greater at the high-salinity sites than at the low-salinity sites, whereas the MBC/SOC ratios were higher at the low-salinity sites than at the high-salinity sites. Iron (Fe) and aluminum (Al) mineral-associated organic carbon [Fe(Al)-OC] and calcium-associated organic carbon (Ca-OC) contents were higher at the high-salinity sites compared to the low-salinity sites, and at the low-flooding frequency sites compared to the high-flooding frequency sites.Meanwhile, Fe(Al)-OC was the dominant fraction among mineral-associated organic carbon at all sites. The dominant phyla of bacterial community included Proteobacteria (49.31 %–66.36 %), Firmicutes (2.67 %–28.44 %), Chloroflexi (3.81 %–9.54 %), and Acidobacteria (4.28 %–7.02 %). In addition, Desulfobacca, a sulfate-reducing bacterium, promoted the formation of mineral-associated organic carbon.Random forest analysis showed that SOC and DOC were key factors in promoting mineral-associated organic carbon formation. Partial least squares path modeling (PLS-PM) indicated that sea level rise affects DOC content by altering soil physicochemical properties, promoting the formation of mineral-associated organic carbon.In summary, while soil organic carbon activity increases, the chemical association of minerals with organic carbon is becoming increasingly crucial for the protection of organic carbon under rising salinity conditions driven by sea level rise.

Extraction of carbon and preparation of activated carbon from waste dry cell battery

The goal of this research was to synthesize activated carbon (AC) from discarded batteries, and the crystallographic characterization of the final product (AC), intermediate product, and raw sources were explored. The formation of activated carbon was confirmed by utilizing an X-ray diffractometer (XRD) that revealed the structure of activated carbon was hexagonal. The crystallite size of activated carbon was computed by applying several model equations (Linear straight-line method of Scherrer's equation, Monshi-Scherrer method, Sahadat-Scherrer method, Size-Strain plot method, Halder-Wagner method, Williamson-Hall method), and the range of calculated crystallite size was 5–28 nm. The weight loss occurred in the two stages those was explored by a thermogravimetric analyzer (TGA). Fourier Transform Infrared Spectrophotometer (FTIR) confirmed that there was no significant change in the peak position between intermediate product and activated carbon except for the intensity and peak separation difference. Field Emission Electron Microscope (FE-SEM) revealed several types of shapes of the waste source, intermediate product, and main product (AC).

A biochar-based amendment improved cadmium (Cd) immobilization, reduced its bioaccumulation, and increased rice yield

Cadmium (Cd) contamination of soil threatens human health, food security, and ecosystem sustainability. The in situ stabilization of Cd has been recognized as a potentially economical technology for the remediation of Cd-contaminated soil. Recently, biochar (BC) and activated carbon (AC) have received widespread attention as eco-friendly soil amendments that are more beneficial for plant growth, soil health, and remediation of contaminated soil. An experiment was performed in a paddy field to investigate the effects of two different types of BC (maize straw biochar and bamboo biochar) and AC (coconut shell activated carbon) in combination with rape organic fertilizer (R), calcium magnesium phosphate fertilizer (P), and fulvic acid (F), respectively, on soil Cd immobilization, Cd accumulation in rice, and yield. The results indicated that the BC/AC-based amendments reduced soil bioavailable Cd (DTPA-Cd) and brown rice Cd by 9.58%–27.06% and 19.30%–71.77%, respectively. The transformation of exchangeable Cd (Ex-Cd) to carbonate-bound Cd (Ca-Cd), Fe-Mn oxide bond (Ox-Cd), and residual (Re-Cd) in soil accounted for the mitigation of Cd uptake and enrichment by rice. Additionally, BC-/AC-based amendments altered soil physicochemical properties, which significantly increased the soil pH and cation exchange capacity (CEC), total nitrogen (TN), total phosphorus (TP), soil organic carbon (SOC), and dissolved organic carbon (DOC), directly promoting soil health. All BC-/AC-based amendments significantly increased FeIMP and MnIMP concentrations by 47.31%–160.34% and 25.72%–73.09% in the Fe/Mn plaque (IMP), respectively. Maize straw and bamboo biochar-based amendments significantly increased rice yield by 10.46%–20.41% and 9.94%–16.17%, respectively, while coconut shell-activated carbon severely reduced rice yield by 65.06%–77.14%. The correlation analysis revealed that leaf Cd and IMP primarily controlled Cd uptake by rice, and soil pH, Eh, CEC, SOC, IMP, and TP influenced DTPA-Cd in soil. This field study demonstrated that maize straw and bamboo biochar-based amendments not only reduced soil DTPA-Cd in paddy fields but also decreased the accumulation of Cd in brown rice, as well as improved rice yield, which has potential application in Cd-contaminated agriculture fields. Coconut shell-activated carbon severely decreased rice yields, which is not appropriate for rice production.

Guiding nitrogen doped vanadium pentoxide nanoclusters on cobalt sulfide nano-flakiness as stable seamless interface anode toward highly energy density and durable asymmetric supercapacitors

Interaction of the interface-heterostructures is crucial to rapid ionic conductivity and highly energy density of electrode materials toward supercapacitors. Herein, a novel anode heterostructure is synthesized using cobalt sulfide (CoS) nanoflowers as a substrate for composite nitrogen doped vanadium pentoxide (denoted as N-V2O5@CoS) by combination of hydrothermal and calcination method. As expected, the N-V2O5@CoS electrode possesses superhigh specific surface area that significantly enhances the specific capacitance, and its unique porous interconnected structure not only reduces the volume effect during the cycles, but also greatly enhances the conductivity of electron transfer. The as-prepared N-V2O5@CoS electrode has a specific capacitance of up to 2413.6F/g at a current density of 1 A/g, and can still maintain 87.51 % of the initial capacitance after 5,000 cycles at a high current density of 10 A/g. More importantly, the partial density of states (PDOS) ares obtained through theoretical calculations reveal that the interaction of heterogeneous interfaces is contributed by the p-orbitals of C, O and S and d-orbitals of V and Co. In addition, asymmetric supercapacitor (ASC) with N-V2O5@CoS as the positive electrode and activated carbon (AC) as the negative electrode has a high voltage of 1.7 V, which achieves an outstanding energy density of 71.6 W h kg−1 at a power density of 849.8 W kg−1, showing excellent cycle stability (retain 90.6 % of the initial capacitance after 10,000 charge/discharge cycles). This paper offers novel paradigm for the doping of metal oxides and the development of heterostructures, which provides support for their use as advanced energy storage materials.

Insights into the Adsorption Mechanism of Chlorpyrifos on Activated Carbon Derived from Prickly Pear Seeds Waste: An Experimental and DFT Modeling Study

The removal of chlorpyrifos (CPF) from water was achieved using activated carbon (AC) derived from prickly pear seeds (PPS) wastes, developed through chemical activation with phosphoric acid. Several physico-chemical characterization methods were employed. The determination of surface functions using the Boehm assay indicated that the processed AC predominantly possesses acidic functions. The results obtained from the Boehm assay were corroborated by the pH value of the point of zero charge (pHpzc), which was equal to 2.5. Specific area calculation by the BET (Brunauer Emmett Teller) method revealed a large specific area (SBET) of 1077.66 m2 g⁻1. Adsorption experiments of CPF on AC demonstrated that the pseudo-second order (PSO) model and the Freundlich model were the most suitable for kinetic and isothermal modeling, respectively. The maximum CPF adsorption capacity of the PPS AC was found to be approximately 35 mg g⁻1. A theoretical study employing the density functional theory (DFT) was conducted using the B3LYP/6-311G (d, p) method. The most reliable adsorption energy (Eads) and Gibbs free energy (ΔGads) values between CPF and the functional groups on the AC surface were calculated. Results indicated a strong interaction between the lactone group of AC and CPF (ΔGads = -7.15 kcal mol⁻1, ΔEads = -21.55 kcal mol⁻1) and the hydroxyl group (ΔGads = -6.61 kcal mol⁻1, ΔEads = -20.66 kcal mol⁻1). This study demonstrates that activated carbon possesses significant adsorption power, making it highly effective for depolluting water contaminated by pesticides. The application of the theoretical DFT method enhances the understanding of the adsorption phenomenon of CPF on AC.

Influence of Phosphoric Acid Activation on Physiochemical Characteristics of Activated Carbons and Their Performance as Supercapacitor

ABSTRACTWe investigate the influence of phosphoric acid (H3PO4) activation on physiochemical characteristics of activated carbons (ACs) as a function of number of activation steps such as two‐step and three‐step and impregnation ratio (IR). Scanning electron microscopy observations identified that different morphologies in the forms of graphene sheet‐like, nano‐granular, and flake‐like carbon structure in the cases of ACs. FTIR spectroscopy confirmed that successful incorporation of phosphorous group in the ACs by H3PO4 activation. X‐ray diffraction (XRD) profile exposed that irrespective of the activation method and IR, all AC samples showed narrow and sharp XRD crystalline peak along with the amorphous signals. Raman scattering analysis suggested that three‐step activation create more defective structure as compared to two‐step activation route. Nitrogen adsorption–desorption isotherm measurements indicated that upon fabricating ACs via three‐step and two‐step activation approach, around 6.5 times and 3‐fold enhancement in the value of surface area of ACs as compared to that of carbon before activation. In addition, higher the IR value, lower the textural properties of ACs. This study demonstrated that three‐step activation methodology is capable of generating highly porous AC when compared to two‐step activation route. Cyclic voltammetry analysis showed that for the electrode developed from AC that fabricated via three‐step activation, capacitance retention of 50% is achieved upon tuning the scan rate by 10 times. The same electrode exhibited the capacitance retention of 45% upon increasing the current density by 10 times. We have also compared the electrochemical performance of symmetric and asymmetric supercapacitors. Electrochemical capacitance retention of symmetric and asymmetric supercapacitors is determined to be 100% and 92% respectively after 1000 cycles at the current density of 1 A g−1. Based on the Ragone plot study, it is observed that the maximum energy density of 5 W h kg−1 and the maximum power density of 943 W kg−1 are attained for the case of symmetric supercapacitors. Asymmetric supercapacitor displayed improved energy density of 7.15 W h kg−1 and modest power density of 432 W kg−1.

Machine learning-based prediction of adsorption capacity of metal-doped and undoped activated carbon: Assessing the role of metal doping

This research developed five ensemble-based machine learning (ML) models to predict the adsorption capacity of both pristine and metal-doped activated carbon (AC) and identified key influencing features. Results indicated that Extreme Gradient Boosting (XGB) model provided the most accurate predictions for both types of AC, with metal-doped AC exhibiting 1.7 times higher adsorption capacity than pristine AC showing 254.66 and 148.28 mg/g, respectively. Feature analysis using SHAP values revealed that adsorbent characteristics accounted for 53.5 % of the adsorption capacity in pristine AC, while experimental conditions were crucial for metal-doped AC (61.3%), with surface area and initial concentration being the most significant features, showing mean SHAP values of 0.317 and 0.117, respectively. Statistical comparisons of adsorbent characteristics between pristine and metal-doped AC showed that metal doping significantly altered surface area (p-value = 0.0014), pore volume (p-value = 0.0029), and elemental composition (C% (p-value = 3.9513∗10^−7) and O% (p-value = 0.0007)) of AC. Despite the reduction in surface area and consistent pore volume after metal doping, the enhanced adsorption capacity of metal-doped AC was attributed to increased oxygen content from 10.89% to 17.28 % as mean values. This suggests that oxygen-containing functional groups play a critical role in the improved adsorption capacity of metal-doped AC. This research lays the groundwork for optimizing AC adsorbents by identifying key factors in metal-doped AC and suggest further studies on the interaction between specific metal dopants and resulting functional groups to improve adsorption capacity and reduce repeated labor work.

Preparation and characterization of high performance super activated carbon based on coupled coal/sargassum precursors

High electrochemical performance supercapacitors require activated carbon with high specific surface area, suitable pore size distribution and surface properties, and high electrical conductivity as electrode materials, whereas there exists a trade-off relationship between specific surface area and electrical conductivity, which is not well met by a single type of carbon source. To solve this problem, the coal and sargassum are adopted to obtain the coupling product via co-thermal dissolution, followed by carbonization and KOH activation. The effects of mixing mass ratio and activation temperature on the prepared activated carbon (AC) are investigated using single factor experimental method. The experimental results show that AC1/3-800 has abundant micropore and mesopore content, good pore structure connectivity, high electrical conductivity and good wettability, and superior electrochemical properties compared with other activated carbons prepared in this experiment. Its total specific surface area is up to 2098.5 m2·g–1, the pore volume is up to 1.33 cm3·g–1, the content of mespores with diameter of 6–8 nm is significantly increased, and the pore size distribution is wide and uniform. When the current density increases from 0.1 A·g–1 to 10 A·g–1, the gravimetric capacitance decreases from 219 F·g–1 to 186 F·g–1 with a capacitance retention of 84.9%, the equivalent series resistance is very small, and the rate performance and reversibility of charging and discharging have also been excellent.

Synergistic photocatalytic degradation of methylene blue using TiO2 composites with activated carbon and reduced graphene oxide: a kinetic and mechanistic study

This comprehensive study explored the removal of methylene blue (MB) from aqueous solutions as a model pollutant, utilizing solar-driven photocatalysis with nano-sized titanium dioxide (TiO2) and composites with activated carbon (AC) and reduced graphene oxide (RGO). This research introduces continuous solar reactor instead of conventional batch experiments investigating its design configuration. Utilizing response surface methodology (RSM), the study determined the optimal process conditions (MB concentration at 30 mg/L, pH 8.82, irradiation time 138 min), under which TiO2 achieved a 93.13% MB removal efficiency. The study further revealed that the integration of TiO2 with AC and RGO (5% wt.) significantly enhanced the MB photocatalytic degradation. The TiO2/AC composite achieved 98.3% MB degradation in 138 min of solar exposure, related to its large specific surface area of 146 m2/g and a pore volume of 0.439 cm3/g. Likewise, the TiO2/RGO composite demonstrated 97% removal with a surface area of 102 m2/g and a pore volume of 0.476 cm3/g, significantly better than nano-TiO2. Additionally, the research investigated the role of the solar reactor configuration on MB removal. Using 26 mm Pyrex tube diameter with 15 cm long on parabolic aluminum concentrator inclined at 30° optimally achieved the peak MB degradation efficiency. Recyclability tests shown a noticeable decrease in nano-TiO2 efficiency to 56.03% without regeneration; however, after regeneration following the third cycle, the efficiency significantly recovered to 70.07%. Thereby, this paper introduces an innovative, continuous, and well-designed solar reactor system for dye removal, employing nano-TiO2 and its composites with AC and RGO for improved photocatalytic efficiency under statistically optimized process conditions.

Adsorption of dibenzofuran by modified biochar derived from microwave gasification: Impact factors and adsorption mechanism

Dioxins, emanating from the waste incineration, constitutes an organic pollutant that poses considerable risks to the human health and environment. In this study, the corn straw char (CSC) and oak char (OC) derived from the electric heating or microwave gasification, and the coconut-shell activated carbon (AC) are employed as absorbents for the adsorption of dibenzofuran (DBF, dioxins model compound). Characterization techniques, including BET, X-ray CT, SEM-EDS, FTIR, and XPS, are performed to identify the DBF adsorption mechanism on the biochar. The results show that the biochar prepared by the microwave gasification has a more well-developed pore structure than that of the electric heating gasification. The higher porosity (16.94 %) and lower mineral content (1.75 %) are responsible for the effective adsorption of DBF onto AC. The adsorption capacity of CSC is proportional to the modified concentration of KOH. It is mainly ascribed to the decrement of carboxyl and lactone groups and the enhancement of alkaline functional groups on the biochar surface, which augments the hydrophobicity and π–π electron donor–acceptor (EDA) interaction. Instead, DBF adsorption capacity on the biochar is adversely affected by the HNO3 modification. For all biochar samples, the corresponding maximum adsorption ratios are AC (87.11 %) > KOH-modified CSC (77.14 %) > unmodified CSC (49.11 %) > unmodified OC (39.70 %) > HNO3-modified CSC (36.09 %). The adsorption mechanisms of DBF on the gasified biochar encompass the pore filling, hydrophobicity, and π–π EDA interaction. A desirable adsorption capacity of DBF on the biochar prepared by the microwave gasification is attainable through augmenting the specific surface area while diminishing the oxygen-containing groups of the surface simultaneously.

Preparation of hydrilla verticillata activated carbon adsorbent for remediation of wastewater containing the active metal chromium

Abstract This research aims to determine the capacity of Hydrilla Verticillata activated carbon adsorbent in absorbing the heavy metal chromium. The method used in making Hydrilla Verticillata activated carbon is by carbonization at a temperature of 3000C and chemically activated. Activated carbon was contacted with a solution of the heavy metal chromium with a concentration of 100 ppm with contact times of 15, 30, 45, 60, 90 and 120 minutes. The structure of hydrilla verticillata active carbon from the XRD results is graphite and BET BJH characterization data shows that activated carbon has a surface area of 53.143 m2/g, an average pore size of 0.2764 nm and a pore volume of 0.0789 cc/g. The SEM- Edx characterization results show that the size distribution is not homogeneous but forms agglomerations like plate particles consisting of slitted pores. Test results using AAS show that the ability of hydrilla verticillata activated carbon to remediate the heavy metal chromium based on contact time is around 47.35%, 46.77%, 49.08%, 54.85%, 61.30% and 69.69% and the adsorption capacity is around 13.94 mg/g.

Layer-by-layer WS2-Cr heterojunction as a positive working electrode material for high-performance supercapattery applications

This study investigates the impact on the electrochemical performance of pristine sputtered WS2 through the strategic integration of a highly conductive chromium interfacial layer. This study involves the fabrication of two different samples via magnetron sputtering: type I, WS2-sputtered and type II, WS2/Cr (sputtering of Cr as an interfacial layer between sputtered-WS2 and NF). Afterward, structural, topographic and elemental composition of as-synthesized samples were inspected via XRD, SEM, Raman, and EDX. Following this, the energy storage performance were evaluated by employing CV, GCD, and EIS in three and two electrode assembly sequentially. In three electrode testing WS2 and WS2/Cr exhibited the specific capacity (Qs) of 661.79C g−1 and 1600C g−1 at 3 mV/s along with the capacity retention of 61.37 % (WS2) and 83.04 % (WS2/Cr), respectively. Similarly, through GCD WS2 shows the Qs of 637.34C g−1 at 0.8 A/g conversely, WS2/Cr exhibited the Qs of 1220C g−1 at 1.3 A/g. Besides, the WS2/Cr demonstrated long-term longevity (capacity retention of 83.13 %) after 5000 GCD cycles. Based on exclusive electrochemical performance of type II of two samples, an asymmetric battery-type hybrid supercapacitor (WS2/Cr//AC) was fabricated by incorporating WS2/Cr and activated carbon (AC) as working and counter electrodes. WS2/Cr//AC revealed the Qs of 352C g−1 (785F g-1) at 0.7 A/g. Besides, it deliberately delivered 81 Wh kg−1 and 1750 W kg−1 energy and power. The device exhibits excellent cyclic stability by maintaining its capacity after 5000 GCD cycles and illustrated 87.30 % capacity retention. Following that, semi-empirical approach was applied to quantify the capacitive and diffusive currents’ contribution in overall device’s performance. The results highlight that WS2/Cr hold colossal potential to fill the proficiency gap between presently keep-going devices and stern demands of future energy storage applications.

Simultaneous removal of E1, E2, EE2 and levonorgestrel from water using TiO2 catalyst anchored on activated carbon: Processes optimization, materials characterization, and assessment of the estrogenicity reduction

Removal of estrogen hormones from water matrices is crucial owing to its adverse effects on aquatic ecosystems and human health. The present investigation applies an advanced approach to assess the effectiveness of combined processes (adsorption and visible-light-driven photo-degradation) for simultaneous removal of estrone (E1), 17β-estradiol (E2), 17α-ethinylestradiol (EE2), and levonorgestrel (LEVO) in water, applying TiO2-activated carbon composite selected through design of experiment (DoE) for process optimization. Based on a central composite rotatable design (CCRD), composites were synthesized with percentages of activated carbon (AC) ranging from 2.93% to 17.07% (wt.) and calcination temperatures between 259 and 541 °C. The composite with the best performance TiO2-AC15%-541 (15% wt. AC, calcined at 541 °C), achieved a total removal of 98.3 ± 1.15% for E1, 99.0 ± 1% for E2, 99.3 ± 1.15% for EE2, and 96.0 ± 2.65% for LEVO at the initial concentration of 100 μg L−1 under simulated solar irradiation. Further optimization using once more CCRD involved three independent variables: pH; hormone concentration/TiO2-AC15%-541 loading ratio; and the intensity of simulated solar irradiation. Under optimized conditions (pH 2.64, hormone concentration/TiO2-AC15%-541 loading ratio of 3.8 mg g−1, and irradiation intensity of 41 W m−2 UV-A), the TiO2-AC15%-541 composite removed 99.8% of E1, 99.8% of E2, 99.0% of EE2, and 92.1% of LEVO. Furthermore, the process achieved a 99.9% reduction in estrogenic activity, assessed with yeast estrogen screen (YES) assay. These results demonstrate that TiO2-AC15%-541 is an efficient and cost-effective remediation agent for treating mixed estrogen compounds in water, with significant potential for commercial applications.

Highly-efficient recovery of silver from industrial cyanide-based plating effluent on TiO2/activated carbon composites

The release of silver-containing wastewater is an economic loss. In this works, the silver ions in the cyanide-based plating effluent of jewelry effluent was systematic recovered by the photocatalytic process using commercial semiconductors (TiO2, ZnO, Bi2O3 and WO3) and activated carbon (AC) enhanced semiconductors as the photocatalysts. The preliminary results demonstrated that the highest photocatalytic silver recovery was achieved via the use of TiO2 nanoparticles (NPs), ascribing to its better textural property that provided abundant active sites to undergo the reaction. The intrinsic property and activity of TiO2 were significantly improved in the presence of proper content of AC. Approximately 94% of silver was recovered within 45 min through the TiO2/AC with 14.9 wt.% AC (TiO2/AC1) under the UV-vis irradiation due to the act of AC as the conductive pathway for electron migration from CB of TiO2 along its surface, thus prolonging the lifetime of electron-hole pairs. Although a marked decrease in photocatalytic activity of the best composite was detected after the 4th use (∼50%), it exhibited an outstanding antibacterial ability compared with TiO2 and fresh one in dark environment. The work offers the avenue to design the photocatalyst for recovering the precious metals from industrial effluent and broaden the application of such recovered metal decorated photocatalyst for practical use.

Electronic synergy between NiCo2O4 and adjacent carbon defects to enhance styrene cracking activity for styrene-saturated activated carbon regeneration

The design and construction of catalysts featuring abundant electron transfer and defect structures for the regeneration of styrene-saturated activated carbon (AC) pose a significant challenge. This paper presents successful preparation of a regenerated adsorbent with synergistic catalytic active sites of NiCo2O4 spinel and carbon defects using a simple impregnation method. Enhanced catalytic activity is attributed to the electronic synergy between NiCo2O4 and carbon defects in 2.5Ni-2.5Co-900, involving substantial electron transfers, abundant acidic sites, and strong reducibility. Reactive oxygen species and the robust oxygen transfer facilitate the deep oxidation of intermediates and carbon elimination. The optimized regenerated adsorbent achieved a styrene adsorption capacity of 446.4mg/g with a recovery of 92.4% of the fresh sample, which is 1.5 times higher than 5Ni-900 and about 1.8 times higher than the unmodified regenerated activated carbon sample, RAC-900. The mechanism of styrene cracking and the evolution of intermediates were investigated using thermogravimetric-infrared coupling, and the effects of catalytic temperature and active sites on styrene cracking, deep oxidation of intermediates, and elimination of carbon deposits were explored. Kinetic analysis demonstrated that the adsorption of styrene on regenerated samples entailed a multifaceted process integrating both physical and chemical adsorption. The significance of chemical adsorption became increasingly evident as the concentration of defective sites grew. Intra-pore diffusion is the main determining step of the adsorption process. After five cycles, the adsorption capacity of 2.5Ni-2.5Co-900 decreased to below 25%, suggesting promising strategies to overcome challenges of regenerating styrene-saturated AC.

A hierarchical Cu2SnO4@NiCo-LDH nanofilament structure as a new-potent electrode for energy storage

Our research continues to explore innovative, efficient electrode materials and new production processes for electrochemical devices. Supercapacitors remain at the forefront of energy storage solutions, thanks to their exceptional power density, cycling durability, and mechanical robustness. For the first time, we have developed a hierarchical Cu2SnO4@NiCo-LDH nanocomposite using a straightforward hydrothermal technique coupled with an annealing process on a nickel foam substrate. This study introduces the novel Cu2SnO4@NiCo-LDH (CSO@NC-LDH) material, distinguished by its unique nanofilament structure and impressive electrochemical properties, including a high specific capacitance of 2791.5 F g−1 at 1 A g−1. Additionally, we created an asymmetric supercapacitor using CSO@NC-LDH for the positive electrode and activated carbon (AC) for the negative electrode. This system showcases an outstanding energy density of 108.67 Wh kg−1 and a notable power density of 1.05 kW kg−1 at an operating voltage of 1.6 V. These exciting results highlight the promising potential of CSO@NC-LDH nanofilaments as advanced electrodes for next-generation energy storage devices.