Phosphoric Acid-activated Carbon Research Articles

Phosphoric acid-activated carbons as catalysts for 5-hydroxymethylfurfural synthesis

Phosphoric acid-activated carbons as catalysts for 5-hydroxymethylfurfural synthesis

Selenite Adsorption and Reduction via Iron(II) Impregnated Activated Carbon Produced from the Phosphoric Acid Activation of Construction Waste Wood.

Chemical activation of waste materials, to form activated carbon, (AC) is complicated by the large amounts of chemical activating agents required and wastewater produced. To address these problems, we have developed an optimized process for producing AC, by phosphoric acid activation of construction waste. Waste wood from construction sites was ground and treated with an optimized phosphoric acid digestion and activation that resulted in high surface areas (> 2000 m2/g) and a greater recovery of phosphoric acid. Subsequently the phosphoric acid activated carbon (PAC), was functionalized with iron salts and evaluated for its efficacy on the adsorption of selenite and selenate. Total phosphoric acid recovery was 96.7% for waste wood activated with 25% phosphoric acid at a 1:1 ratio, which is a substantially higher phosphoric acid recovery, than previous literature findings. Post activation impregnation of iron salts resulted in iron(II) species adsorbed to the PAC surface. The iron(II) chloride impregnated AC removed up to 11.41 ± 0.502mg selenium per g Iron-PAC. Competitive ions such as sulfate and nitrate had little effect on selenium adsorption, however, phosphate concentration did negatively impact the selenium uptake at high phosphate levels. At 250ppm, approximately 75% of adsorption capacity of both the selenate and the selenite solutions was lost, although selenium was still preferentially adsorbed. Peak adsorption occurred between a pH of 4 and 11, with a complete loss of adsorption at a pH of 13.

Paracetamol and amoxicillin adsorptive removal from aqueous solution using phosphoric acid activated-carbon

Abstract Charcoal-based materials have attracted much attention for the removal of pharmaceutical agents. The charcoal-based carbon materials have green synthetic routes, high surface area, numerous active site with active functional groups available for physico-chemical interactions with adsorbate for surface-adsorptive removal of toxins. In this study, acid treated activated carbon was developed from the peach seeds using thermal pyrolysis approach. Phosphoric acid activated carbon (PAC) was further modified by HNO3 and employed as an adsorbent for the removal of amoxicillin and paracetamol and process variables were optimized for enhanced removal of amoxicillin and paracetamol. The adsorption of pharmaceutical agents was significantly affected by temperature, pH and reaction time. The amoxicillin and paracetamol sorption process onto PCA followed a pseudo second order kinetics and Langmuir isotherm model with a maximum removal capacity of 51.8 mg/g and 51.1 mg/g, respectively. The results revealed that acid activated carbon has promising efficiency for the removal of amoxicillin and paracetamol from aqueous medium and peach seeds derived PCA could be employed for the removal of these pharmaceutical agents from effluents and PAC is also extendable for the removal of other drugs from pharmaceutical wastewater streams.

Chemically Activated Carbon Based on Biomass for Adsorption of Fe(III) and Mn(II) Ions from Aqueous Solution.

Rice husk was converted into activated carbon (AC) as a byproduct of agricultural waste in an electric furnace at 700 °C and chemically activated using three distinct processes: NaOH AC(C), acetic acid AC(C-1), phosphoric acid AC(C-2), and carbonization AC(C-3) without any chemical activation. To characterize the activated carbon and the removal efficiencies of Fe(III) and Mn(II) from aqueous solutions, various analytical tools were used. The results revealed that the capacities of the four adsorbents to adsorb Fe(III) or Mn(II) from an aqueous solution differ significantly. AC(C-3) was chosen for additional research. The impact of different operational factors, including pH, contact time, adsorbent dosage, starting metal ion concentration, interfering ions, and temperature, were investigated. The optimum pH values for Fe(III) and Mn(II) adsorption were found to be pH 3 and pH 6, respectively. The results obtained were utilized to assess the kinetics and thermodynamics of the adsorption process. The sorption of Fe(III) and Mn(II) ions was found to be a pseudo-second-order kinetic process, and the equilibrium data were fitted with the Langmuir isotherm. Additionally, the evidence suggests that an endothermic mechanism governs the adsorption process. The maximum adsorption capacities of Fe(III) and Mn(II) were 28.9 and 73.47 mg/g, respectively.

Competitive adsorption analysis of antibiotics removal from multi-component systems using chemically activated spent tea waste: effect of operational parameters, kinetics, and equilibrium study.

In this study, spent tea powder waste was chemically treated for the synthesis of adsorbent using two activating agents, i.e., sulfuric acid and phosphoric acid, to obtain sulfuric acid activated carbon (SAC) and phosphoric acid activated carbon (PAC). The performance of PAC and SAC for the sorption of tetracycline (TCY) and sulfadiazine (SDZ) antibiotics from mono-component (SDZ/TCY) and multi-component (SDZ + TCY) adsorption systems was investigated. Synergistic and antagonistic effects were studied in removing target pollutants in SDZ + TCY systems. Kinetic and equilibrium studies were modeled by different kinetic and isotherm models. The adsorption capacity was assessed using Langmuir's competitive model in a [Formula: see text]. Pseudo-first-order kinetic and Langmuir isotherm models best fit the experimental kinetic and equilibrium data to remove antibiotics. The Langmuir's maximum adsorption capacity (qm) of PAC for the removal of SDZ and TCY in a [Formula: see text] was found to be 16.75 and 10.87mg/g, and qm of SAC for the removal of SDZ and TCY was found to be 24.69 and 23.20mg/g, respectively. In SDZ + TCY multi-component system, adsorption of TCY was synergistic in nature for both PAC and SAC. Sorption of SDZ displayed an antagonistic effect in the SDZ + TCY system for both SAC and PAC. In conclusion, the activated carbons synthesized from spent tea waste could be effectively adopted for the simultaneous adsorption of SDZ and TCY from multi-component systems.

Enhanced production of levoglucosenone from pretreatment assisted catalytic pyrolysis of waste paper

A new method was developed for the selective production of levoglucosenone (LGO) from catalytic pyrolysis of waste paper. Copy paper (CP) was selected as the representative waste paper and subjected to single or combined pretreatment with ethanol and HCl solutions. The influences of pretreatment method, acid concentration, and pretreatment temperature were systematically investigated to reveal their impacts on the physicochemical properties and pyrolytic characteristics of CP as well as LGO formation. The catalytic pyrolysis experiments of pretreated CP were conducted using pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) and lab-scale device under different pyrolysis temperatures and sample/catalyst ratios. The results showed that the combined ethanol-HCl pretreatment was the most conducive to LGO production, with the optimal pretreatment conditions of acid concentration of 23% and pretreatment temperature of 80 °C. With phosphoric acid-activated carbon (PAC) as the catalyst, the maximum yields of LGO reached 18.15 wt% and 14.76 wt% at 260 °C from Py-GC/MS and lab-scale experiments with sample/catalyst ratios of 4 and 5, respectively. Compared with cellulose and biomass materials, catalytic pyrolysis of pretreated CP had the advantages of high LGO yield and low production temperature.

Fluoride removal in drinking water using activated carbon prepared from palmyrah (Borassus flabellifer) nut shells

Fluoride is a useful ion for human health and fluoride related health problems can occur due to the deficiency or excess intake. Human intake of fluoride is consumed mainly from drinking water. The removal of fluoride ions from its aqueous solutions and water samples using activated carbon, was conducted in this study. For the preparation of activated carbon dried palmyrah (Borassus flabellifer) nut shells were used as a low cost adsorbent. Activation of dried palmyrah nut shell charcoal was done with concentrated H3PO4 and 25% NaOH separately as activating agents. Characterization of the non-activated carbon (NAC), phosphoric acid activated carbon (PAC) and sodium hydroxide activated carbon (SHAC) was conducted using different parameters. Fluoride removal efficiency of PAC was investigated for a synthesized fluoride solution which was prepared using NaF and deionized water in four different conditions such as contact time, adsorbent dosage, initial fluoride concentration and temperature. Fluoride concentration in samples was measured by SPADNS method. Then seven different field water samples were collected from Nochchiyagama area, Anuradhapura district which is a major fluoride contaminated ground water containing area in Sri Lanka. The physicochemical characteristics of PAC was found to be high compared to NAC and SHAC.Optimum conditions for the highest fluoride removal efficiency of PAC were observed as 45 ​min contact time, 0.2g adsorbent dosage, 1 ​mg/L initial fluoride concentration at 30 ​°C temperature with 61% adsorption efficiency. The pseudo-first order and pseudo second order kinetic models were applied in this experiment. The pseudo second order exhibited the best fit for the kinetics studies that indicates the chemisorption process. The experimental isotherm data were analysed by different models; the adsorption follows the Freundlich model providing better fit for the equilibrium data. PAC from palmyrah nut shells would make an alternative source of activated carbon and low cost adsorbent for the fluoride ions.

Comparative adsorption study of malachite green dye on acid-activated carbon

ABSTRACT Activated carbon produced from coconut shells has been gaining interest in wastewater treatment as a potential carbon source for adsorption with desired porosity, surface area, and stability requirements. Acid activation has been preferred for activated carbon production due to its superiority over adsorption of malachite green dye. This study involved in the acid activation of coconut shell derived carbon and its characterisation was performed to study the surface functionalities, thermal stability, textural and structural morphologies. The activated carbon was used for the adsorption of malachite green dye from aqueous solutions and with a special insight by varying contact time (20–220 min) and initial dye concentration (20–80 mg L−1) for adsorption study. Phosphoric acid-activated carbon has shown maximum adsorption capacity (Xm) of 32.787 mg g−1 at initial malachite dye concentration of 20 mg L−1 after 3 hours. All the adsorbents followed Freundlich isotherm with intra particle diffusion model as the rate-limiting step.

Flexible Type Symmetric Supercapacitor Electrode Fabrication Using Phosphoric Acid-Activated Carbon Nanomaterials Derived from Cow Dung for Renewable Energy Applications.

Porous-activated carbon (PAC) materials have been playing a vital role in meeting the challenges of the ever-increasing demand for alternative clean and sustainable energy technologies. In the present scenario, a facile approach is suggested to produce hierarchical PAC at different activation temperatures in the range of 600 to 900 °C by using cow dung (CD) waste as a precursor, and H3PO4 is adopted as the nonconventional activating agent to obtain large surface area values. The as-prepared cow dung-based PAC (CDPAC) is graphitic in nature with mixed micro- and mesoporous textures. High-resolution scanning electron microscopy depicts the morphology of CDPAC as nanoporous structures with a uniform arrangement. High-resolution transmission electron microscopy reveals spherical carbon dense nanoparticles with dense tiny spherical carbon particles. N2 adsorption–desorption isotherms show a very high specific surface area of 2457 m2/g for the CDPAC 9 (CD 9) sample with a large pore volume of 1.965 cm3/g. Electrochemical measurements of the CD 9 sample show a good specific capacitance (Cs) of 347 F/g at a lower scan rate (5 mV/s) with improved cyclic stability, which is run up to 5000 cycles at a low current density (0.5 A/g). Hence, we choose an activated carbon prepared at 900 °C to fabricate the modified electrode material. In this regard, a flexible type symmetric supercapacitor device was fabricated, and the electrochemical test results show a supercapacitance value (Cs) of 208 F/g.

Removal of the Hazardous Crystal Violet Dye by Adsorption on Corncob-Based and Phosphoric Acid-Activated Carbon

In this work, the decolorization of crystal violet dye in aqueous solution by corncob-based and phosphoric acid-activated carbon was addressed. Equilibrium data were successfully applied to study the kinetics and mechanism of adsorption of dye onto both carbons. Adsorption increases with pH increase from 2 to 5, but a further increase in pH has no effect on adsorption. Quantitative removal of dye at a higher initial pH of the dye solution reveals the basic nature of the crystal violet and the acidic nature of the activated carbons. Langmuir equation gave good fitting for adsorption results, with a high removal capacity of 320.0 mg/g. Kinetic results indicate that adsorption process followed a pseudo-second-order equation (R2 = 0.998) and intra-particle diffusion is the most probable operating mechanism. This suggests that corncob-based and phosphoric acid-activated carbon is an efficient crystal violet adsorbent and that it possess good potential for crystal violet removal in wastewater treatment.

Preparation of carbon adsorbents from lignosulfonate by phosphoric acid activation for the adsorption of metal ions

Activated carbons were prepared from sodium lignosulfonate by phosphoric acid activation at carbonization temperatures of 400–1000°C. The resulting materials were characterized with regard to their surface area, pore volume, pore size distribution, distribution of surface groups and ability to adsorb copper ions. Activated carbons were characterized by nitrogen adsorption, scanning electron microscopy, Fourier transform infrared spectroscopy and thermal gravimetric analyses. The results indicate that with increasing carbonization temperature, the surface area decreased from 770m2/g at 400°C to 180m2/g at 700°C and increased at higher temperatures to 1370m2/g at 1000°C. The phosphorus content peaked at 11% for carbon obtained by carbonization at 800°C. Potentiometric titration revealed the acidic character of all the phosphoric acid-activated carbons, which were found to have total concentrations of surface groups of up to 3.3mmol/g. The carbons showed a high adsorption capacity for copper ions even at pH values as low as 2.

Effects of Heat Pretreatment During Impregnation on the Preparation of Activated Carbon from Chinese Fir Wood by Phosphoric Acid Activation

Activated carbons were prepared from Chinese fir wood by phosphoric acid activation. The effects of heat pretreatment from 80 to 180 °C during impregnation on the properties of fir wood and its activated carbons were discussed. The crystallinity index and surface chemistry of the pretreated fir wood were characterized by X-ray diffraction and Fourier transform infrared spectroscopy (FT-IR). The porous texture of activated carbons was investigated by N2 adsorption–desorption isotherms. The results showed that with increasing pretreatment temperature, the crystallinity of the pretreated samples decreased, which gave rise to a significant development of pores, especially micropores as high as 97.2 %. FT-IR results revealed that the carbonyl-containing and phosphorus-containing groups of the pretreated samples increased with increasing pretreatment temperature. For a temperature of 140 °C, the specific surface area, the total pore volume, and the micropore volume reached a maximum of 1603.0 m2/g, 0.792 cm3/g, and 0.770 cm3/g, respectively. However, a higher pretreatment temperature was not beneficial for activation. Thus, heat pretreatment during impregnation can be regarded as an excellent method for manufacturing phosphoric acid-activated carbon with a high micropore volume.

Impact of the Carbonization Atmosphere on the Properties of Phosphoric Acid-Activated Carbons from Fruit Stones

Activated carbons were obtained by phosphoric acid activation of a mixture of fruit stones (apricot and peach) in two different atmospheres (argon and air) at various temperatures in the 400–1000°C range. The evolution of several characteristic parameters of the resulting carbons (bulk density, yield, BET surface area, ultramicropore, supermicropore and mesopore volumes and cation-exchange capacity) with activation temperature was examined. The above parameters were re-calculated on a volume basis (practical effectiveness) and a volume-yield basis (economic efficiency). It was concluded that carbons obtained in an argon atmosphere exhibit some practical advantages over those obtained in air regarding cation adsorption, although those obtained in air may represent an interesting alternative regarding porous structure.

Adsorption of Methylene Blue and Phenol by Wood Waste Derived Activated Carbon

The phosphoric acid activated carbon (PAC) was derived from waste wooden pallets by a two-step chemical activation technique, carbonization and phosphoric acid activation in sequence. A widely used commercial activated carbon, Calgon Filtrasorb 400 (F400), was studied in parallel for comparison. The physical properties and surface chemistry of the activated carbons were characterized using BET- N2 adsorption, elemental analysis, Boehm’s titration, Fourier transform infrared spectroscopy, and x-ray photoelectron spectroscopy. PAC possessed physical properties (surface area and pore volume) that were comparable to those of F400, but displayed distinct surface chemistry in terms of pHPZC , surface acidity and basicity, and surface functional groups. Batch studies were conducted to evaluate the methylene blue (MB) and phenol adsorption capacity of PAC and F400 and their dependence on pH, contact time, and initial adsorbate concentration. Experimental results showed that the solution pH slightly influenced the...

In situ modification of activated carbons developed from a native invasive wood on removal of trace toxic metals from wastewater

Activated carbons were developed by phosphoric acid activation of sawdust from Prosopis ruscifolia wood, an indigenous invasive species of degraded lands, at moderate conditions (acid/precursor ratio = 2, 450 °C, 0.5 h). For in situ modification of their characteristics, either a self-generated atmosphere or flowing air was used. The activated carbons developed in the self-generated atmosphere showed higher BET surface area (2281 m 2/g) and total pore volume (1.7 cm 3/g) than those obtained under flowing air (1638 m 2/g and 1.3 cm 3/g). Conversely, the latter possessed a higher total amount of surface acidic/polar oxygen groups (2.2 meq/g) than the former (1.5 meq/g). To evaluate their metal sorption capability, adsorption isotherms of Cu(II) ion from model solutions were determined and properly described by the Langmuir model. Maximum sorption capacity ( X m) for the air-derived carbons ( X m = 0.44 mmol/g) almost duplicated the value for those obtained in the self-generated atmosphere ( X m = 0.24 mmol/g), pointing to a predominant effect of the surface functionalities on metal sequestering behaviour. The air-derived carbons also demonstrated a superior effectiveness in removing Cd(II) ions as determined from additional assays in equilibrium conditions. Accordingly, effective phosphoric acid-activated carbons from Prosopis wood for toxic metals removal from wastewater may be developed by in situ modification of their characteristics operating under flowing air.

Removal of Pesticide (Endosulphan) from Water via Adsorption onto Activated Carbons Developed from Date Pits

Activated carbons were prepared by impregnation of crushed clean date pits in concentrated solutions of phosphoric acid or zinc chloride followed by carbonization in absence of air at <TEX>$600^{\circ}C$</TEX>. Steam-activated carbon was prepared by gasifying <TEX>$600^{\circ}C$</TEX>-carbonization product at <TEX>$950^{\circ}C$</TEX> to a burn-off = 50%. KOH- activated carbon was prepared by impregnating date pitscarbonization product obtained at <TEX>$450^{\circ}C$</TEX> in concentrated KOH solution followed by carbonization at <TEX>$840^{\circ}C$</TEX>. Textural properties of these carbons were determined from nitrogen adsorption at <TEX>$-196^{\circ}C$</TEX> and the chemistry of the carbon surface was investigated by determination and of the surface carbon-oxygen (C-O) groups using bases of variable strength and dilute HCl. The adsorption of endosulphan at <TEX>$27^{\circ}C$</TEX> on all the carbons prepared was undertaken. Adsorption of this pesticide at 32 and <TEX>$37^{\circ}C$</TEX> was also undertaken for steam-activated and KOH-activated carbons. Phosphoric acid-activated carbons and steamactivated carbons are mainly microporous and have high surface concentration of C-O groups of acidic nature. Steamactivated and KOH-activated carbons exhibited surface areas > 1000 <TEX>$m^2/g$</TEX> and contain micro and non-micrpores. The adsorption of endosulphan was related to the surface area of non-micropores and was retarded by the high concentration of surface C-O groups. The thermodynamic properties indicated the feasibility of the adsorption process and the possible regeneration of the carbon for further use.

On the chemical structure of phosphorus compounds in phosphoric acid-activated carbon

Chemical structure of phosphorus species in polymer-based phosphoric acid-activated carbon SP800 was investigated by X-ray photoelectron spectroscopy. It has been shown that most probable structure for phosphorus species is condensed phosphates bound to carbon lattice via C O P bonding.

Chemical Activation of a South African Coal using Phosphoric Acid

The potential of a South African coal, Bosjesspruit, as a precursor for a phosphoric acid-activated carbon has been assessed using the adsorption of nitrogen at 77 K and mercury porosimetry. Column cleaning of the coal by froth flotation reduced the ash content from 22 to 12 wt.% and caused maceral separtion, resulting in an intertinite-rich product. Reaction of the column-cleaned coal with phosphoric acid in the range 450–550°C produced an activated carbon which was dominantly microporous. The notional BET surface area of the coal reached a maximum of 600 m2/g at a reaction temperature of 550°C.