Cross-upgrading of biomass hydrothermal carbonization and pyrolysis for high quality blast furnace injection fuel production:Physicochemical characteristics and gasification kinetics analysis

The paper proposes a biomass cross-upgrading process that combines hydrothermal carbonization and pyrolysis to produce high-quality blast furnace injection fuel.The results showed that after upgrading,the volatile content of biochar ranged from 16.19%to 45.35%,and the alkali metal content,ash content,and specific surface area were significantly reduced.The optimal route for biochar pro-duction is hydrothermal carbonization-pyrolysis(P-HC),resulting in biochar with a higher calorific value,C=C structure,and increased graphitization degree.The apparent activation energy(E)of the sample ranges from 199.1 to 324.8 kJ/mol,with P-HC having an E of 277.8 kJ/mol,lower than that of raw biomass,primary biochar,and anthracite.This makes P-HC more suitable for blast furnace injection fuel.Additionally,the paper proposes a path for P-HC injection in blast furnaces and calculates potential environmental benefits.P-HC of-fers the highest potential for carbon emission reduction,capable of reducing emissions by 96.04 kg/t when replacing 40wt%coal injec-tion.

Ultra-high specific surface area activated carbon from Taihu cyanobacteria via KOH activation for enhanced methylene blue adsorption

Cyanobacteria-based activated carbon(CBAC)was successfully prepared by pyrolysis-activation of Taihu cyanobacteria.When the impregnation ratio and activated temperature were 2 and 800-C,respectively,the optimal CBACs possessed an ultra-high specific surface(2178.90 m^(2)·g^(-1))and plenty of micro-and meso-pores,as well as a high pore volume(1.01 cm^(3)·g^(-1)).Ascribed to ultra-high surface area,π-π interaction,electrostatic interaction,as well as hydrogen-bonding interactions,the CBACs displayed huge superiority in efficient dye removal.The saturated methylene blue adsorption capacity by CBACs could be as high as 1143.4 mg·g^(-1),superior to that of other reported biomass-activated carbons.The adsorption was endothermic and modeled well by the pseudo-second-order kinetic,intra-particle diffusion,and Langmuir models.This work presented the effectiveness of Taihu cyanobacteria adsorbent ascribed to its super large specific surface area and high adsorption ability.

Achieving high-efficient photocatalytic persulfate-activated degradation of tetracycline via carbon dots modified MIL-101(Fe)octahedrons

The synergistic reaction of photocatalysis and advanced oxidation is a valid strategy for the degradation of harmful antibiotic wastewater.Herein,carbon dots(CDs)modified MIL-101(Fe)octahedrons to form CDs/MIL-101(Fe)composite photocatalyst was synthesized for visible light-driven photocatalytic/persulfate(PS)-activated tetracycline(TC)degradation.The electron spin resonance(ESR)spectra,scavenging experiment and electrochemical analysis were carried out to reveal that the high visible light-driven photocatalytic degradation activity of TC over CDs/MIL-101(Fe)photocatalysts is not only ascribed to the production of free active radicals in the CDs/MIL-101(Fe)/PS system(·OH,·SO_(4-),^(1)O_(2),h^(+)and·O_(2)^(-))but also attributed to the consumption of electrons caused by the PS,which can suppress the recombination of photo-generated carriers as well as strong light scattering and electron trapping effects of CDs.Finally,the possible degradation pathways were proposed by analyzing intermediates via liquid chromatography-mass spectrometry technique.This research presents a rational design conception to construct a CDs/PS-based photocatalysis/advanced oxidation technology with high-efficient degradation activity for the remediation of organic antibiotic pollutant wastewater and for the improvement of carrier transport kinetics of photocatalysts.

Intrinsic pentagon defect engineering in multiple spatial-scale carbon frameworks for efficient triiodide reduction

Intrinsic topological defect engineering has been proven as a promising strategy to elevate the electrocatalytic activity of carbon materials.However,the controllable construction of high-density and specific topological defects in carbon frameworks to reveal the relationship between reactivity and defect structure remains a challenging task.Herein,the intrinsic pentagon carbon sites that can favor electron overflow and enhance their binding affinity towards the intermediates of catalytic reaction are firstly presented by the work function and the p-band center calculations.To experimentally verify this,the cage-opening reaction of fullerene is proposed and utilized for synthesizing carbon quantum dots with specific pentagon configuration(CQDs-P),subsequently utilizing CQDs-P to modulate the micro-scale defect density of three-dimensional reduced graphene oxide(rGO)viaπ-πinteractions.The multiple spatial-scale rGO-conjugated CQDs-P structure simultaneously possesses abundant pentagon and edge defects as catalytic active sites and long-range-orderedπelectron delocalization system as conductive network.The defects-rich CQDs-P/rGO-4 all-carbon-based catalyst exhibits superb catalytic activity for triiodide reduction reaction with a high photoelectric conversion efficiency of 8.40%,superior to the Pt reference(7.97%).Theoretical calculations suggest that pentagon defects in the carbon frameworks can promote charge transfer and modulate the adsorption/dissociation behavior of the reaction intermediates,thus enhancing the electrocatalytic activity of the catalyst.This work confirms the role of intrinsic pentagon defects in catalytic reactions and provides a new insight into the synthesis of defects-rich carbon catalysts.

Thermal pretreatment of willow branches impacts yield and pore development of activated carbon in subsequent activation with ZnCl_(2) via modifying cellulose structure

Development of pore structures of activated carbon(AC)from activation of biomass with ZnCl_(2) relies on content and structure of cellulose/hemicellulose in the feedstock.Thermal pretreatment of biomass could induce dehydration and/or aromatization to change the structure of cellulose/hemicellulose.This might interfere with evolution of structures of AC,which was investigated herein via thermal pretreatment of willow branch(WB)from 200 to 360℃and the subsequent activation with ZnCl_(2) at 550℃.The results showed that thermal pretreatment at 360℃(WB-360)could lead to substantial pyrolysis to form biochar,with a yield of 31.9%,accompanying with nearly complete destruction of cellulose crystals and remarkably enhanced aromatic degree.However,cellulose residual in WB-360 could still be activated to form AC-360 with specific surface area of 1837.9 m~2·g^(-1),which was lower than that in AC from activation of untreated WB(AC-blank,2077.8 m~2·g^(-1)).Nonetheless,the AC-200 from activation of WB-200 had more developed pores(2113.9 m~2·g^(-1))and superior capability for adsorption of phenol,due to increased permeability of ZnCl_(2) to the largely intact cellulose structure in WB-200.The thermal pretreatment did increase diameters of micropores of AC but reduced the overall yield of AC(26.8%for AC-blank versus 18.0%for AC-360),resulting from accelerated cracking but reduced intensity of condensation.In-situ infrared characterization of the activation showed that ZnCl_(2) mainly catalyzed dehydration,dehydrogenation,condensation,and aromatization but not cracking,suppressing the formation of derivatives of cellulose and lignin in bio-oil.The thermal pretreatment formed phenolic-OH and C=O with higher chemical innerness,which changed the reaction network in activation,shifting morphology of fibrous structures in AC-blank to“melting surface”in AC-200 or AC-280.

Properties of Activated Carbons from Sugarcane Leaves and Rice Straw Derived Charcoals by Activation at Low Temperature via KMnO_(4)Pre-Oxidation-Hydrolysis

Activated carbon preparation from sugarcane leaves and rice straw by carbonization(250℃–400℃)and activation at 500℃were studied.The effects of pre-oxidation,hydrolysis of derived charcoals by boiled KMnO4 aqueous solution were evaluated.The derived charcoals products were pretreated using oxidation-hydrolysis with 1–5 wt.%KMnO4 at 100℃and then activated at 500℃.The derived charcoal and activated carbon products were characterized by FTIR,XRD,SEM-EDS and BET.Iodine number and methylene blue number of derived products were also used for the analysis of the products.It was found that fabricated charcoal materials made at 350℃–400℃possess good characteristics with low content of surface functional groups and high carbon content.After pre-oxidation-hydrolysis and activation at 500℃,the resulting derived activated carbon materials from charcoals with 400℃carbonization temperature have high content of oxygen containing surface functional groups such as Mn-O,Si-O,Si-O-Si,C-O,or O-H.In addition,MnO_(2) accumulated on the surface of the derived activated carbon products.The surface area and pore volume of the activated carbon products have also increased with increasing of KMnO_(4) concentration from 1 to 3 wt.%and then decreased with 5 wt.%used during activation.Therefore,activated carbon products made by pre-oxidation-hydrolysis with 3 wt.%KMnO_(4) were used for Fe(Ⅲ)adsorption experiments.It was found that Fe(Ⅲ)adsorption on the activated carbon materials can be fitted with both the Freundlich and the Langmuir models.The calculated maximum Fe(Ⅲ)adsorption capacities of sugarcane leaves derived activated carbon and rice straw derived activated carbon products were 50.00 and 39.37 mg/g,respectively.It was shown that the effect of pre-oxidation-hydrolysis by KMnO_(4) and activation at 500℃are beneficial for activated carbon preparation with environmentally friendly and low-cost simplified operation.

High adsorption selectivity of activated carbon and carbon molecular sieve boosting CO_(2)/N_(2) and CH_(4)/N_(2) separation

Flue gas and coal bed methane are two important sources of greenhouse gases.Pressure swing adsorption process has a wide range of application in the field of gas separation,and the selection of adsorbent is crucial.In this regard,in order to assess the better adsorbent for separating CO_(2) from flue gas and CH_(4) from coal bed methane,adsorption isotherms of CO_(2),CH_(4) and N_(2) on activated carbon and carbon molecular sieve are measured at 303.15,318.15 and 333.15 K,and up to 250 kPa.The experimental data fit better with Langmuir 2 compared to Langmuir 3 and Langmuir-Freundlich models,and Clausius-Clapeyron equation was used to calculate the isosteric heat.Both the order of the adsorbed amount and the adsorption heat on the two adsorbents are CO_(2)>CH_(4)>N_(2).The adsorption kinetics are calculated by the pseudo-first kinetic model,and the order of adsorption rates on activated carbon is N_(2)-CH_(4)>CO_(2),while on carbon molecular sieve,it is CO_(2)-N_(2)>CH_(4).It is shown that relative molecular mass and adsorption heat are the primary effect on kinetics for activated carbon,while kinetic diameter is the main resistance factor for carbon molecular sieve.Moreover,the adsorption selectivity of CH_(4)/N_(2) and CO_(2)/N_(2) were estimated with the ideal adsorption solution theory,and carbon molecular sieve performed best at 318.15 K for both CO_(2) and CH_(4) separation.The study suggested that activated carbon is a better choice for separating flue gas and carbon molecular sieve can be a strong candidate for separating coal bed methane.

MIL-100(V) derived porous vanadium oxide/carbon microspheres with oxygen defects and intercalated water molecules as high-performance cathode for aqueous zinc ion battery

The development of aqueous zinc ion battery cathode materials with high capacity and high magnification is still a challenge.Herein,porous vanadium oxide/carbon(p-VO_(x)@C,mainly VO_(2) with a small amount of V_(2)O_(3)) core/shell microspheres with oxygen vacancies are facilely fabricated by using a vanadium-based metal-organic framework(MIL-100(V)) as a sacrificial template.This unique structure can improve the conductivity of the VO_(x),accelerate electrolyte diffusion,and suppress structural collapse during circulation.Subsequently,H_(2)O molecules are introduced into the interlayer of VO_(x) through a highly efficient in-situ electrochemical activation process,facilitating the intercalation and diffusion of zinc ions.After the activation,an optimal sample exhibits a high specific capacity of 464.3 mA h g^(-1) at0.2 A g^(-1) and 395.2 mA h g^(-1) at 10 A g^(-1),indicating excellent rate performance.Moreover,the optimal sample maintains a capacity retention of about 89.3% after 2500 cycles at 10 A g^(-1).Density functional theory calculation demonstrates that the presence of oxygen vacancies and intercalated water molecules can significantly reduce the diffusion barrier for zinc ions.In addition,it is proved that the storage of zinc ions in the cathode is achieved by reversible intercalation/extraction during the charge and discharge process through various ex-situ analysis technologies.This work demonstrates that the p-VO_(x)@C has great potential for applications in aqueous ZIBs after electrochemical activation.

In-situ construction of abundant active centers on hierarchically porous carbon electrode toward high-performance phosphate electrosorption: Synergistic effect of electric field and capture sites

Phosphate removal is crucial for eutrophication control and water quality improvement.Electro-assisted adsorption,an eco-friendly elec-trosorption process,exhibited a promising potential for wastewater treatment.However,there are few works focused on phosphate electro-sorption,and reported electrodes cannot attach satisfactory removal capacities and rates.Herein,electro-assisted adsorption of phosphate via in-situ construction of La active centers on hierarchically porous carbon(LaPC)has been originally demonstrated.The resulted LaPC composite not only possessed a hierarchically porous structure with uniformly dispersed La active sites,but also provided good conductivity for interfacial electron transfer.The LaPC electrode achieved an ultrahigh phosphate electrosorption capability of 462.01 mg g^(-1) at 1 V,outperforming most existing electrodes.The superior phosphate removal performance originates from abundant active centers formed by the coupling of electricfield and capture sites.Besides,the stability and selectivity toward phosphate capture were maintained well even under comprehensive conditions.Moreover,a series of kinetics and isotherms models were employed to validate the electrosorption process.This work demonstrates a deep understanding and promotes a new level of phosphate electrosorption.

Fate and Behavior of Tetracycline Resistance Genes in Activated Carbon Adsorption

The accessibility of tetracycline resistance gene (tetG) into the pores of activated carbon (AC), as well as the impact of the pore size distribution (PSD) of AC on the uptake capacity of tetG, were investigated using eight types of AC (four coal-based and four wood-based). AC showed the capability to admit tetG and the average reduction of tetG for coal-based and wood-based ACs at the AC dose of 1 g·L-1 was 3.12 log and 3.65 log, respectively. The uptake kinetic analysis showed that the uptake of the gene followed the pseudo-second-order kinetics reaction, and the uptake rate constant for the coal-based and wood-based ACs was in the range of 5.97 × 10-12 - 4.64 × 10-9 and 7.02 × 10-11 - 1.59 × 10-8 copies·mg-1·min-1, respectively. The uptake capacity analysis by fitting the obtained experiment data with the Freundlich isotherm model indicated that the uptake constant (KF) values were 1.71 × 103 - 8.00 × 109 (copies·g-1)1-1/n for coal-based ACs and 7.00 × 108 - 3.00 × 1010 (copies·g-1)1-1/n for wood-based ones. In addition, the correlation analysis between KF values and pore volume as well as pore surface at different pore size regions of ACs showed that relatively higher positive correlation was found for pores of 50 - 100 Å, suggesting ACs with more pores in this size region can uptake more tetG. The findings of this study are valuable as reference for optimizing the adsorption process regarding antibiotic resistance-related concerns in drinking water treatment.

A general descriptor for guiding the electrolysis of CO_(2)in molten carbonate

Molten carbonate is an excellent electrolyte for the electrochemical reduction of CO_(2)to carbonaceous materials.However,the electrolyte–electrode-reaction relationship has not been well understood.Herein,we propose a general descriptor,the CO_(2)activity,to reveal the electrolyte–electrode-reaction relationship by thermodynamic calculations and experimental studies.Experimental studies agree well with theoretical predictions that both cations(Li^(+),Ca^(2+),Sr^(2+)and Ba^(2+))and anions(BO_(2)^(-),Ti_(5)O_(14)^(8-),SiO_(3)^(2-))can modulate the CO_(2)activity to control both cathode and anode reactions in a typical molten carbonate electrolyzer in terms of tuning reaction products and overpotentials.In this regard,the reduction of CO_(3)^(2-)can be interpreted as the direct reduction of CO_(2)generated from the dissociated CO_(3)^(2-),and the CO_(2)activity can be used as a general descriptor to predict the electrode reaction in molten carbonate.Overall,the CO_(2)activity descriptor unlocks the electrolyte–electrode-reaction relationship,thereby providing fundamental insights into guiding molten carbonate CO_(2)electrolysis.

Conversion of Lignin into Porous Carbons for High-Performance Supercapacitors via Spray Drying and KOH Activation: Structure-Properties Relationship and Reaction Mechanism

Lignin-derived porous carbons have emerged as promising electrode materials for supercapacitors.However,the challenge remains in designing and controlling their structure to achieve ideal electrochemical performance due to the complex molecular structure of lignin and its intricate chemical reactions during the activation process.In this study,three porous carbons were synthesized from lignin by spray drying and chemical activation with vary-ing KOH ratios.The specific surface area and structural order of the prepared porous carbon continued to increase with the increase of the KOH ratio.Thermogravimetric-mass spectrometry(TG-MS)was employed to track the molecular fragments generated during the pyrolysis of KOH-activated lignin,and the mechanism of the thermochemical conversion was investigated.During the thermochemical conversion of lignin,KOH facili-tated the removal of H2 and CO,leading to the formation of not only more micropores and mesopores,but also more ordered carbon structures.The pore structure exhibited a greater impact than the carbon structure on the electrochemical performance of porous carbon.The optimized porous carbon exhibited a capacitance of 256 F g-1 at a current density of 0.2 A g-1,making it an ideal electrode material for high-performance supercapacitors.

Preparation and Electrochemical Performance Study of Catalytic Cracking Oil Slurry-based Porous Carbon Materials

Catalytic cracking oil slurry is a by-product of catalytic cracking projects,and the efficient conversion and sustainable utilization of this material are issues of continuous concern in the petroleum refining industry.In this study,oxygen-enriched activated carbon is prepared using a one-step KOH activation method with catalytic cracking oil slurry as the raw material.The as-prepared oil slurry-based activated carbon exhibits a high specific surface area of 2102 m^(2)/g,welldefined micropores with an average diameter of 2 nm,and a rich oxygen doping content of 32.97%.The electrochemical performance of the nitrogen-doped porous carbon is tested in a three-electrode system using a 6 mol/L KOH solution as the electrolyte.It achieves a specific capacitance of up to 230 F/g at a current density of 1 A/g.Moreover,the capacitance retention rate exceeds 89%after 10000 charge and discharge cycles,demonstrating excellent cycle stability.This method not only improves the utilization efficiency of industrial fuel waste but also reduces the production cost of supercapacitor electrode materials,thereby providing a simple and effective strategy for the resource utilization of catalytic cracking oil slurries.

Adsorption of Malachite Green Using Activated Carbon from Mangosteen Peel: Optimization Using Box-Behnken Design

In this research,activated carbon from mangosteen peel has been synthesized using sulfuric acid as an activator.The adsorption performance of the activated carbon was optimized using malachite green dye as absorbate.Mala-chite green dye waste is a toxic and non-biodegradable material that damages the environment.Optimization of adsorption processes was carried out using Response Surface Methodology(RSM)with a Box-Behnken Design(BBD).The synthesized activated carbon was characterized using FTIR and SEM instruments.The FTIR spectra confirmed the presence of a sulfonate group(-SO_(3)H)in the activated carbon,indicating that the activation pro-cess using sulfuric acid was successful.SEM characterization shows that activated carbon has porous morphology.Optimization was carried out for three adsorption parameters,namely contact time(20,60,and 120 min),adsor-bent mass(0.005,0.025,and 0.05 g),and initial concentration of malachite green solution(5,50,and 100 mg·L^(-1)).The concentration of the malachite green solution was determined using a UV-Vis spectrophotometer at the max-imum wavelength of malachite green,618 nm.The optimum of malachite green adsorption using mangosteen peel activated carbon was obtained at a contact time of 80 min,an adsorbent mass of 0.032 g,and malachite green initial concentration of 25 mg·L^(-1),with a maximum removal percentage and maximum adsorption capacity of 93.66%and 19.345 mg·g^(-1),respectively.

Activity Data and Emission Factor for Forestry and Other Land Use Change Subsector to Enhance Carbon Market Policy and Action in Malawi

Activity data and emission factors are critical for estimating greenhouse gas emissions and devising effective climate change mitigation strategies. This study developed the activity data and emission factor in the Forestry and Other Land Use Change (FOLU) subsector in Malawi. The results indicate that “forestland to cropland,” and “wetland to cropland,” were the major land use changes from the year 2000 to the year 2022. The forestland steadily declined at a rate of 13,591 ha (0.5%) per annum. Similarly, grassland declined at the rate of 1651 ha (0.5%) per annum. On the other hand, cropland, wetland, and settlements steadily increased at the rate of 8228 ha (0.14%);5257 ha (0.17%);and 1941 ha (8.1%) per annum, respectively. Furthermore, the results indicate that the “grassland to forestland” changes were higher than the “forestland to grassland” changes, suggesting that forest regrowth was occurring. On the emission factor, the results interestingly indicate that there was a significant increase in carbon sequestration in the FOLU subsector from the year 2011 to 2022. Carbon sequestration increased annually by 13.66 ± 0.17 tCO2 e/ha/yr (4.6%), with an uncertainty of 2.44%. Therefore, it can be concluded that there is potential for a Carbon market in Malawi.

Preparation of activated carbon from sunflower straw through H_(3)PO_(4) activation and its application for acid fuchsin dye adsorption

With the development circular economy, the use of agricultural waste to prepare biomass materials to remove pollutants has become a research hotspot. In this study, sunflower straw activated carbon (SSAC) was prepared by the one-step activation method, with sunflower straw (SS) used as the raw material and H3PO4 used as the activator. Four types of SSAC were prepared with impregnation ratios (weight of SS to weight of H3PO4) of 1:1, 1:2, 1:3, and 1:5, corresponding to SSAC1, SSAC2, SSAC3, and SSAC4, respectively. The adsorption process of acid fuchsin (AF) in water using the four types of SSAC was studied. The results showed that the impregnation ratio significantly affected the structure of the materials. The increase in the impregnation ratio increased the specific surface area and pore volume of SSAC and improved the adsorption capacity of AF. However, an impregnation ratio that was too large led to a decrease in specific surface area. SSAC3, with an impregnation ratio of 1:3, had the largest specific surface area (1 794.01 m2/g), and SSAC4, with an impregnation ratio of 1:5, exhibited the smallest microporosity (0.052 7 cm3/g) and the largest pore volume (2.549 cm3/g). The adsorption kinetics of AF using the four types of SSAC agreed with the quasi-second-order adsorption kinetic model. The Langmuir isotherm model was suitable to describe SSAC3 and SSAC4, and the Freundlich isotherm model was appropriate to describe SSAC1 and SSAC2. The result of thermodynamics showed that the adsorption process was spontaneous and endothermic. At 303 K, SSAC4 showed a removal rate of 97.73% for 200-mg/L AF with a maximum adsorption capacity of 2 763.36 mg/g, the highest among the four types of SSAC. This study showed that SAAC prepared by the H3PO4-based one-step activation method is a green and efficient carbon material and has significant application potential for the treatment of dye-containing wastewater.

Adsorption behavior of activated carbon for the elimination of zearalenone during bleaching process of corn oil

Zearalenone is a mycotoxin produced by Fusarium species.It frequently contaminates cereals used for foods or animal feeds,especially deposited in crude corn oil.Certain amounts of zearalenone can be removed during refining processes.In this study,we studied the influence of activated carbon and six industial absorbents(zeolite,diatomite,attapulgite,perlite,montmorillonite and activated clay)on the elimination of zearalenone during bleaching process of corn oil and explored the absorption mechanism of activated carbon.Results showed that activated carbon had an excellent adsorption capacity of zearalenone compared with the other six industrial adsorbents.For activated carbon,a high removal rate of zearalenone(exceeding 83%)from heavily zearalenone-polluted corn oil was achieved and the removal rate of zearalenone was kept above 60%after five regeneration cycles.The research on the adsorption mechanism of activated carbon showed that Freundlich adsorption isotherm model and pseudo-second-order kinetic model could well described the adsorption process.The thermodynamic study demonstrated that adsorption process was spontaneous and exothermic.Fourier transform infrared spectroscopy and Raman spectroscopy further revealed that activated carbon was effectively combined with zearalenone viaπ-πinteraction.Thus,activated carbon is an efficient and suitable adsorbent to control the levels of zearalenone during bleaching process of corn oil.This study not only proposed a systematic research scheme for the mechanism study of activated carbon for the elimination of zearalenone in corn oil,but also provided the scientific basis for developing effective methods to eliminate zearalenone in refined vegetable oils.

Preparation and Characterization of Activated Carbons from Palm Nut Shells: Effects of Calcination Temperature on Porosity and Chemical Properties

Activated carbons (ACs) calcined at 400˚C, 500˚C, and 600˚C (AC-400, AC-500, and AC-600) were prepared using palm nut shells from Gabon as raw material and zinc chloride (ZnCl2) as a chemical activating agent. Prepared ACs were characterized by physisorption of nitrogen (N2), determination of diode and methylene blue numbers for studies of porosity and by quantification and determination of surface functional groups and pH at point of zero charge (pHpzc) respectively, for studies of chemical properties of prepared ACs. Then, effects of calcination temperature (Tcal) on porosity and chemical properties of prepared ACs were studied. The results obtained showed that when the calcination temperature increases from 500˚C to 600˚C, the porosity and chemical properties of prepared ACs are modified. Indeed, the methylene blue and iodine numbers determined for activated carbons AC-400 (460 and 7.94 mg·g−1, respectively) and AC-500 (680 and 8.90 mg·g−1, respectively) are higher than those obtained for AC-600 (360 and 5.75 mg·g−1, respectively). Compared to the AC-500 adsorbent, specific surface areas (SBET) and microporous volume losses for AC-600 were estimated to 44.7% and 45.8%, respectively. Moreover, in our experimental conditions, the effect of Tcal on the quantities of acidic and basic functional groups on the surface of the ACs appears negligible. In addition, results of the pHpzc of prepared ACs showed that as Tcal increases, the pH of the adsorbents increases and tends towards neutrality. Indeed, a stronger acidity was determined on AC-400 (pHpzc = 5.60) compared to those on AC-500 and AC-600 (pHpzc = 6.85 and 6.70, respectively). Also according to the results of porosity and chemical characterizations, adsorption being a surface phenomenon, 500˚C appears to be the optimal calcination temperature for the preparation of activated carbons from palm nut shells in our experimental conditions.

Improving the Quality of Baobab Oil by Filtration on Activated Carbon from the Fruit Capsules

The baobab, Adansonia digitata L., plays an important role in the economy of local populations. Nowadays, baobab seed oil is highly prized for its many cosmetic and therapeutic applications, and for its composition of unsaturated fatty acids, sterols, and tocopherols. However, it undergoes numerous reactions during production, processing, transport, and storage, leading to undesirable products that make it unstable. The aim of this study was to provide local processors with innovative solutions for the treatment of unrefined vegetable oils. To this end, an experimental device for filtering crude oil on activated carbon made from fruit capsules was designed. The results obtained after the treatment show a significant decrease at (p < 5%) in acid value (1.62 to 0.58 mg KOH/g), peroxide value (4.40a to 0.50c mEqO2/Kg), chlorophyll concentration (1.81 to 0.50 mg/Kg) and primary and secondary oxidation products. According to these results, activated carbon’s adsorptive power eliminates oxidation products and certain pro-oxidants such as chlorophyll, resulting in a cleaner, more stable and better storable oil.

Simultaneous Adsorption of Aqueous Pb2+, Cu2+, Zn2+, and Cd2+ Using Surfactant-Modified and Unmodified Activated Carbon in a Fixed Bed Column

The goal of this work is to improve the simultaneous removal of Pb2+, Cu2+, Zn2+, and Cd2+ ions from synthetic wastewater in a fixed bed column by incorporating sodium dodecyl sulfate (SDS) onto the surface of activated carbon made from coconut shells. The activated carbons were characterized using Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy-energy dispersive x-ray (SEM-EDX). The adsorption column dynamics were studied by varying the flow rates (5, 10 and 15 mL/min), bed heights (10, 15 and 20 cm), and initial concentrations (50, 150, and 250 mg/L). The activated carbon has a pore volume of 0.715 cm3/g and a BET-specific surface area of 1410 m2/g. Sodium dodecyl sulfate (SDS) surfactant incorporation onto the surface of the activated carbon enhances its capacity for simultaneous adsorption of Pb2+, Cu2+, Zn2+, and Cd2+ from the aqueous medium. The affinity of the heavy metals to both unmodified (AC) and modified (AC-SDS) activated carbons followed the order of Pb2+ > Cu2+ > Zn2+ > Cd2+. The dynamic adsorption of the column depends on the flow rate, bed height, initial metal concentration, and SDS surface modification. With a 5 mL/min flow rate, a 20 cm bed height, and a 50 mg/L initial metal concentration, a maximum break-through time of 150 minutes for the unmodified activated carbon (AC) and 180 minutes for the SDS-modified activated carbon (AC-SDS) was reached.