H3PO4 Activation Research Articles

Activated carbon materials-derived from polyethylene terephthalate (PET) plastic waste using H3PO4 activation for Rhodamine B removal in aqueous solution

Plastic items, which offer convenience, are ubiquitous in several manufacturing sectors and in everyday life. Polyethylene terephthalate (PET) is a highly popular synthetic plastic that is seeing a growing demand. Annually, a substantial quantity of PET plastic garbage is released into the environment. Hence, it is imperative to devise an efficient remedy for the disposal of PET plastic waste. This work employed PET waste plastic to produce activated carbon by the chemical activation method. The activating agent utilized was H3PO4 acid. An investigation was conducted to determine the impact of the impregnation rate of PET waste plastic with H3PO4, as well as the activating temperature and activating time, on the surface areas of activated carbon. The activated carbon was thoroughly analyzed using scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and Brunauer-Emmett-Teller (BET) analysis. The resulting product has a porous structure, a developed pore system, and a specific surface area of 892 m2/g, with effective adsorption capacity for RhB solutions with concentrations below 80 ppm (efficiency above 90%) in a neutral environment according to the Langmuir adsorption isothermal model, with a maximum adsorption capacity of 45.45 mg/g.

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.

Spent coffee activated carbon via microwave-induced H3PO4 activation for brilliant green dye removal: statistical parametric optimization

Spent coffee activated carbon via microwave-induced H3PO4 activation for brilliant green dye removal: statistical parametric optimization

Phosphorous - Containing Activated Carbon Derived From Natural Honeydew Peel Powers Aqueous Supercapacitors.

The introduction of phosphorous (P), and oxygen (O) heteroatoms in the natural honeydew chemical structure is one of the most effective, and practical approaches to synthesizing activated carbon for possible high-performance energy storage applications. The performance metrics of supercapacitors depend on surface functional groups and high-surface-area electrodes that can play a dominant role in areas that require high-power applications. Here, we report a phosphorous and oxygen co-doped honeydew peel-derived activated carbon (HDP-AC) electrode with low surface area for supercapacitor via H3PO4 activation. This activator forms phosphorylation with cellulose fibers in the HDP. The formation of heteroatoms stabilizes the cellulose structure by preventing the formation of levoglucosan (C6H10O5), a cellulose combustion product, which would otherwise offer a pathway for a substantial degradation of cellulose into volatile products. Therefore, heteroatom doping has proved effective, in improving the electrochemical properties of AC-based electrodes for supercapacitors. The specific capacitance of HDP-AC exhibits greatly improved performance with increasing carbon-to-H3PO4 ratio, especially in energy density and power density. The improved performance is attributed to the high phosphorous doping with a hierarchical porous structure, which enables the transportation of ions at higher current rates. The high specific capacitance of 486, and 478 F/g at 0.6, and 1.3 A/g in 1 M H2SO4 electrolyte with a prominent retention of 98.5 % is observed for 2 M H3PO4 having an impregnation ratio of 1 : 4. The higher yield of HDP-AC could only be obtained at an activation temperature of 500 °C with an optimized amount of H3PO4 ratio. The findings suggest that the concentration of heteroatoms as surface functional groups in the synthesized HDP-AC depends on the chosen biomass precursor and the processing conditions. This work opens new avenues for utilizing biomass-derived materials in energy storage, emphasizing the importance of sustainable practices in addressing environmental challenges and advancing toward a greener future.

Exploring the adsorptive potential of chemically activated Nanoporous carbons derived from invasive goat weed for treatment of hospital wastewater

Nanoporous activated carbons synthesized from goat-weed (Ageratum Conyzoides) using single-step pyrolytic chemical-activation with ZnCl2 and H3PO4 at various ratios. Nano-textural properties of samples assessed through N2 adsorption/desorption, XRD, SEM, and FTIR. ZnCl2 activation led to a high microporosity and maximum surface-area of 1699 m2·g−1 and total pore-volume of 1.23 cm3·g−1 (Zn/biomass ratio 1:1), while H3PO4 activation yielded 866 m2·g−1 and 1.24 cm3·g−1, respectively (P/biomass ratio 1.5:1). The adsorption capacity of samples follows surface-area variations of samples. During treatment of hospital wastewater, ZnCl2-activated carbon removed 90–93 % of pollutants, comparable to commercial carbon, while H3PO4-activated carbon removed 85–88 %. The adsorption mechanism of carbons during interaction with HWW contaminants was discussed to explain variation in removal efficiency.

Surface properties of activated carbon fibers obtained from polyacrylonitrile and methyl acrylate: Experimental and simulation studies for lead and acid blue 25 dye adsorption from water

Activated carbon fibers were prepared using a methyl acrylate/polyacrylonitrile (MA/PAN) system and H3PO4 activation. These fibers were assessed to adsorb AB25 and Pb2+ from aqueous solutions, and DFT calculations were carried out to determine the main surface interactions that caused the removal of both pollutants. The results showed that AB25 and Pb2+ adsorption on these activated carbon fibers was endothermic, with maximum experimental adsorption capacities of 0.012 − 0.023 and 0.248 − 0.306 mmol/g at 20 – 40 °C. Pb2+ adsorption properties of these fibers outperformed those of other carbonaceous materials utilized in the depollution of metallic cations, whereas their removal effectiveness was less competitive to separate AB25 dye molecules. A double-site monolayer model was applied to correlate the experimental Pb2+ isotherms, while AB25 adsorption on activated carbon fibers was simulated using a one-site multilayer model. Oxygenated acidic (i.e., carboxylic and phenolic) and phosphate-carbon functional groups were the main binding sites to adsorb these pollutants. The adsorption energies of the tested systems, the identification of the most feasible binding positions of the tested adsorbates on the activated carbon fiber surface, and the role of hydrogen bonding in the corresponding adsorption mechanisms were discussed using DFT calculations. These results contribute to the valorization and application of engineered materials such as activated carbon fibers for water depollution.

Activated carbon from hydrothermal carbonization of ice cream factory wastewater with H3PO4 activation. Synthesis, characterisation and adsorption properties

This work aims to treat ice cream wastewater (ICWW) by hydrothermal carbonization (HTC) and to produce activated carbon (AC). The HTC reduces COD, BOD5 and KTN by up to 80%, 55% and 93%, respectively. The obtained hydrochar was activated with H3PO4 at various impregnation ratios (1−4) and different temperatures (400−600 °C). The material with the best properties, named AC-2-500, was obtained at 500 °C with an acid impregnation rate of 2 and represents a spherical shape (specific surface area of 1432.44 m2 g−1, pore volume of 0.80 cm3g-1, and average pore diameter around 2.24 nm). The porous structure of AC-2-500 enabled to achieve high adsorption capacities of the order of 588.23 mg g−1 and 250 mg g−1 for rhodamine B (RhB) and acid red 97 (AR97), respectively. The adsorption equilibrium was reached in 30 min for RhB and 60 min for AR97. The linear forms of the Langmuir and Freundlich isotherms appear to produce reasonable models for the adsorption of dyes onto AC-2-500, with best results when applying Langmuir model. Both dyes adsorb spontaneously and endothermically, with an increase in the randomness at the solid/solution interface. Furthermore, the regeneration study revealed that during several adsorption-desorption cycles, AC-2-500 demonstrated a strong adsorption capability.

Blended tropical pineapple peel and crown fruit wastes as precursor for activated carbon by microwave-assisted H3PO4 activation: process optimization for methylene blue dye removal

Blended tropical pineapple peel and crown fruit wastes as precursor for activated carbon by microwave-assisted H3PO4 activation: process optimization for methylene blue dye removal

Adsorption study of methylene blue dye removal with activated carbon derived from Leucaena leucocephala wastes prepared via H3PO4 activation

Adsorption study of methylene blue dye removal with activated carbon derived from Leucaena leucocephala wastes prepared via H3PO4 activation

Interconnected pyrolysis and activation with in-situ H3PO4 activation of biochar from pear wood chips in a pilot scale dual fluidized bed

Interconnected pyrolysis and activation is a novel technology for combustible gas and biochar production in dual fluidized bed (DFB). The study proposed one-step and two-step methods for pyrolysis and activation of biomass in a pilot scale DFB with capacity of 100 kg/h. Physical and chemical activation occurred simultaneously in DFB system by phosphoric acid (H3PO4) impregnation pretreatment of pear wood chips, and flowing hot flue gas and steam. Stable operating parameters were observed for both methods. The one-step method was superior to the two-step method in terms of the pyrolysis gas quality, biochar pore distribution, micro- and meso-pores structures of biochar, while one-step method reduced the biochar yields. As an activation agent, H3PO4 increased the yields of biochar and pyrolysis gas, promoted formation of micropores and enriched the surface functional groups of biochar with increasing ratio of H3PO4. H3PO4 to biomass ratio of 1:5 reached the maximum biochar yield of 42.3 wt% and highest iodine adsorption value of 648.5 mg/g, increasing by 70.6 % and 90.3 % compared to the biochar without H3PO4 pretreatment, respectively. This DFB system facilitated the diversified use of fluidized beds and the co-production of biochar and product gas with energy saving and CO2 emission reduction.

Composite of activated carbon-hydroxyapatite from corn (Zea mays L.) cob and catfish (Pangasius sp.) bones with H3PO4 activation for methylene blue dye adsorption

Methylene blue (MB) is a synthetic dye in wastewater that causes serious environmental problems due to its toxicity, carcinogenicity, and resistance to environmental degradation. To overcome this problem, activated carbon (AC) from corncob waste and natural Hydroxyapatite (HAp) from catfish bone were synthesized to generate a simple, cost-effective, and efficient composite adsorbent for removing MB dye in wastewater. The performance of the AC/HAp composite adsorbent was assessed under varying conditions, including initial dye concentration, contact time, adsorbent dosage, pH, and reusability. The scanning electron microscope (SEM) morphology and BET results showed that the composite had an irregular shape, with a specific surface area of 419.02 m2/g. The results showed that the isotherm model followed the Langmuir model with an adsorption capacity of 109.90 mg/g. Reusing the composite adsorbent after 3 cycles resulted in an insignificant decrease in the MB removal percentage from 73.52 % to 55.32 % at an initial dye concentration of 200 mg/L. Ion exchange, hydrogen bonding, Lewis acid-base interaction, electrostatic interaction, and π–π bond interactions were several adsorption mechanisms. Based on these findings, the composite had the potential to be an MB adsorbent by enhancing agricultural and aquaculture waste value and supporting the implementation of a circular economy and net zero carbon in Indonesia.

Oxygen and phosphorus-enriched mesoporous biowaste-based carbonaceous material: A sustainable solution for efficient removal of diclofenac and chromium (VI) from polluted water

In response to the current environmental crisis, this study focuses on converting biowaste into phosphorus-oxygen-rich activated hydrochar (AH) for removing persistent pollutants such as Diclofenac (DCF) and chromium (VI) (Cr (VI)) from polluted water. The AH was prepared via hydrothermal carbonization of argan nut shells followed by H3PO4 activation under an oxygen-rich atmosphere. The obtained AH was characterized by a high specific surface area of 1879 m2g−1, remarkable mesoporosity, and wide pore diameters. The AH was further analyzed revealing its highly aromatic nature, as well as the abundance of phosphorus and oxygen functional groups on its surface. These properties led to high adsorption capacities of diclofenac and chromium (VI) of 240 mgg−1 and 539 mgg−1, respectively. The investigations indicated that the AH applied physical and chemical forces for removing Cr (VI), while the uptake of DCF molecules was governed by physical forces. Indeed, the high aromaticity and oxygen functionality of AH facilitated the DCF adsorption through hydrogen bonding, π-π interactions, and pore-filling. Meanwhile, the oxygen functionality and the oxygen and phosphorus electron-providing sites on the AH’s surface favor the removal of Cr (VI) ions through physical and chemical interactions, including electrostatic attractions, ion exchange, complexation, and oxidation–reduction reactions. These findings highlight the effectiveness of AH in the elimination of DCF and Cr (VI) from polluted water.

Enhancing Cr (VI) Adsorption of Chestnut Shell Biochar through H3PO4 Activation and Nickel Doping.

A high-efficiency nickel-doped porous biochar (PCNi3) has been successfully synthesized from chestnut shell waste via a two-step chemical activation treatment with H3PO4. The influences of microstructure, surface morphology, elemental composition, surface functional groups, specific surface area, porosity, pore-size distribution, and chemical properties of the surface state on the removal of Cr (VI) from water were thoroughly investigated by using XRD, FESEM, FTIR, Raman, BET, and XPS testing methods, N2 adsorption, and XPS testing techniques respectively. The results indicate that the treatment of H3PO4 activation and nickel doping can effectively improve microstructure characteristics, thus promoting Cr (VI) adsorption capacity. The effects of initial solution pH, solution concentration, time, and temperature on remediation are revealed. The Cr (VI) uptake experiments imply that the adsorption curves of PCNi3 fit well with the Freundlich model, the pseudo-second-order kinetic model, and the Elovich model. The adsorption process of PCNi3 can be regarded as a spontaneous endothermic reaction limited by diffusion among particles and porosity. The adsorption mechanisms of PCNi3 are ion exchange, complexation, electrostatic adsorption, and coprecipitation with the assistance of surface active sites, porosity, Ni0 particles, and Ni7P3. With these advantages, PCNi3 reveals an extraordinary Cr (VI) removal capacity and a strong ability to reduce Cr (VI) to Cr (III).

Air-mediated phosphoric acid activation strategy for preparation of oxygenated functional groups rich activated carbon for capacitive deionization

Atmosphere during H3PO4 activation is vital to the texture structure and surface-interface properties of activated carbon (AC), but the researches are way out of sufficiency. In this work, it is found that the air in the H3PO4 activation process is not only conducive to the introduction of more-oxidized oxygenated functional groups on ACs, but also beneficial to the formation of micropores rather than mesopores. Besides, as the air content increases in H3PO4 activation, the ACs’ ash, phosphorous content and conductivity reduce, but their wettability, disorder degree and defect number increase. In addition, the potential of zero charge of the as-prepared ACs is positively correlated with the O-CO content, which show a pattern of first increasing and then decreasing with the increase of air content. Benefit from the improved hydrophilicity, electrolyte-affinity, additional adsorption sites for sodium ions, the optimal AC exhibits excellent salt adsorption capacity of 12.08 mg g−1 and good cycling stability at 1.0 V in single-pass capacitive deionization. This work not only establishes a novel and effective method for regulating the texture structure and surface properties of ACs, but also provides promising cathode candidates for capacitive deionization application.

Preparation of porous carbon from Cogongrass leaves as raw material for batteries (electrical energy)

Cogongrass (Imperata cylindrica) can be processed into a positive electrode as a battery component to generate electricity by utilizing its carbon element. This study used various activators, KOH and H3PO4, and characterized using XRD, FTIR, and SEM-EDX and electrical tests with electric conductivity analysis. The analysis results using XRD diffraction showed that when using both KOH and H3PO4 activators, Cogongrass carbon has graphite (C) and silicon (Si) crystals but at different peaks. The carbon has the same functional groups for both activators: OH-bending, C=C-bending, C-O-bending, and C=C-bending. Cogongrass carbon with KOH activator has a pore size of 235-980 nm with a percentage of carbon atoms of 71.29%, while with H3PO4 activator has a pore size of 110-960 nm with a higher percentage of carbon atoms of 75.04%. The elements contained in carbon are the same for both activators, namely carbon, oxygen, silicon, indium, potassium, calcium, iron, chlorine, phosphorus, magnesium, and sodium. EC analysis showed that carbon from Cogongrasss showed electric conductivity reaching 140 µs/cm at 60 minutes pyrolysis time.

Facile phosphorus and oxygen heteroatom functionalization of biochar based on biomass prepared by microwave pyrolysis for adsorption process of cadmium in aqueous solution

AbstractIn this study, in the first stage, biochar is produced from green pistachio hulls (PGHMAC) by microwave heating method, which saves energy, time and cost. In the second step, with the activation of phosphoric acid (H3PO4), the surface properties of the biochar were modified by phosphorus (P) and oxygen (O) doping (O- and P-doped PGHMAC). This adsorbent obtained was applied to remove cadmium (Cd(II)) from wastewater. FTIR, SEM, EDX, and ICP-OES analyses were used for the characterization of the samples. FTIR, EDX, and ICP-OES analysis results showed the presence of oxygen and phosphorus groups on the surface of the relevant adsorbent. The contents of C and O atoms for P- and O-doped PGHMAC were found to be 62.54% and 36.12%, respectively. Also, about 1.29% of P atoms were found with H3PO4 activation. The kinetic, isotherm, and thermodynamic parameters of the adsorption studies were investigated. Maximum Cd(II) adsorption capacities of P- and O-doped PGHMAC at 298 K, 308 K, and 318 K temperatures were calculated as 78.74, 109.89, and 133.33 mg/g by Langmuir model, respectively. The mechanism of Cd(II) adsorption on O- and P-doped PGHMAC has been proposed.

Thermochemical treatment of mixed mandarin peel and algae via microwave and H3PO4 activation: process optimization and adsorption mechanism for methylene blue dye

Thermochemical treatment of mixed mandarin peel and algae via microwave and H3PO4 activation: process optimization and adsorption mechanism for methylene blue dye

Production of activated carbon from coal with H3PO4 activation for adsorption of Fe(II) and Mn(II) in acid mine drainage

Acid Mine Drainage (AMD) contains Fe(II) and Mn(II) metals, which can cause environmental pollution. This research aimed to investigate the potency of activated carbon made from coal as an adsorbent in AMD treatment. The carbon was made of coal and activated with H3PO4 in a weight ratio of 40%, 800 °C for 120 minutes while supplying 1.5 L/min of nitrogen during the carbonization process. The result shows that BET surface area, total pore volume, and iodine number were 296.4 m2/g, 0.156 cc/g, and 1205 mg/g, respectively. The surface contained many fractures, channels, and big holes, as evidenced by the FT-IR and SEM investigations, and it also had acidic surface functional groups. The optimum contact time adsorption for AMD treatment was 30 minutes, and the first concentration of Fe(II) and Mn(II) metals affected the adsorption. The optimum removal of Fe(II) in AMD treatment was 95.27% at an initial concentration of 3.51 ppm, while the optimum removal of Mn(II) was 99.82% at an initial concentration of 5.71 ppm. This activated carbon has a considerable potency to be used as the adsorbent in AMD treatment to reduce Fe(II) and Mn(II) levels.

Mixed fruit Citrullus lanatus and Citrus sinensis wastes for mesoporous activated carbon via microwave assisted H3PO4 activation: Optimization for methylene blue dye removal

Mixed fruit Citrullus lanatus and Citrus sinensis wastes for mesoporous activated carbon via microwave assisted H3PO4 activation: Optimization for methylene blue dye removal

Inspired by the Seeking Knowledge Strategy for Analects of Confucius to Screen Highly Electrochemically Active Porous Carbon: The Critical Source of Electroactive Sites

In this work, the forestry wastes are converted into a series of porous carbons using H3PO4 activation. These porous carbons feature a large specific surface area (1045.20 m2 g−1) and porosity that combines micro‐, meso‐, and macropores in various amounts depending on the fuel properties recorded for precursors used. Importantly, the C content recorded for forestry waste is one of the crucial factors in defining the specific surface area of the derived porous carbons. In addition, the total capacitance of the pine‐sawdust‐based porous carbon (PS‐C) sample is the highest, such as 220.55 F g−1 upon 5 mV s−1. Notably, the electrical double‐layer capacitance recorded for the samples remains essentially constant with increasing scan rates, such as ≈91.50 F g−1 for the olive‐shell‐based porous carbon, ≈123.70 F g−1 for PS‐C, and ≈105.66 F g−1 for the pine‐needle‐based porous carbon. Encouragingly, the pore‐associated sp3 site holds significant roles in the electrochemical application of the porous carbons. More importantly, the O/C value recorded for the precursor can be employed as a universal predictor of electrochemically active sites produced in porous carbons. In the findings, crucial insights are exhibited into the optimized fabrication of porous carbon with target electrochemically active sites for other applications such as catalysis.