Impregnation Ratio Research Articles

High surface area peat moss biochar and its potential for Chromium metal adsorption from aqueous solutions

Activated carbons (ACs) have been synthesized using local peat moss biomass for adsorption of heavy metal ions. Adsorbents with different surface areas and pore sizes were obtained using a chemical activation route with different impregnation ratios (20%, 30%, and 40%) of phosphoric acid. The carbonization process was carried out in a tubular furnace under flow of nitrogen (N2) at 500 °C, and 600 °C. Physicochemical properties of developed activated carbon have been evaluated by several techniques such as; X-ray diffraction, Scanning Electron Microscopic, Energy Dispersive X-ray Spectroscopy, Nitrogen adsorption isotherm, Pore size distribution analysis, and Fourier-transform analysis. Moreover, adsorption of chromium ions (Cr+2) from an aqueous solution under different variables was carried out. Heavy metal concentration (20 - 200) ppm, the dosage of adsorbent (0.1 – 0.5) g/L, the time of contact (0 - 220) min, and initial pH (2 - 8) were studied. Results showed that a synthesis route by chemical activation with 30% H3PO4 concentration at 600 °C for 3 h gave the highest BET surface area and pore volume (1692.6 m2/g and 1.55 cm3/g) respectively, compared with other prepared samples. As well as, the removal results show that the maximum adsorption capacity was 493.3 mg/g at 200 mg/L of initial heavy metal concentration, 6.5 pH, 0.3 g/L activated carbon dosage, and 180 min contact time. The Freundlich isotherm was the better description of the adsorption equilibrium data, while the pseudo-second-order model shows the most accurately describes of adsorption kinetics, which indicates that chemisorption is dominant in the adsorption process. Temperature and thermodynamics parameters were studied. The positive value of enthalpy indicates that the adsorption was endothermic.

Alteration of Tecoma chip wood waste into microwave-irradiated activated carbon for amoxicillin removal: Optimization and batch studies

Amoxicillin (AMOX) in wastewater can promote antibiotic resistance in bacteria and affecting aquatic ecosystems, due to inadequate removal by conventional wastewater treatment plants. This study aimed to (i) optimizing Tecoma chip wood based activated carbon (TCAC) to adsorb amoxicillin (AMOX) using response surface methodology (RSM) and (ii) evaluating AMOX adsorption through batch and continuous modes. The RSM revealed the optimum conditions to be 657 W, 20 min and 0.99 g/g for radiation power, radiation time and impregnation ratio (IR), respectively. These optimum conditions resulted in AMOX removal efficiency of 88.07 mg/g and 27.68 % of TCAC’s yield. The BET surface area and total pore volume of TCAC were 924.85 m2/g and 0.3485 cm3/g respectively. The surface of TCAC was occupied with several functional groups namely primary amine, hydroxy, alkyl carbonate and terminal alkyne. These functional groups enhanced the adsorption process by forming hydrogen bond with AMOX molecules. The isotherm study revealed that AMOX-TCAC adsorption system obeyed the Langmuir model and the maximum monolayer adsorption capacity, Qm is 357.14 mg/g. Pseudo-second order (PSO) model fitted the best for the adsorption of AMOX by TCAC in the kinetic studies. Boyd plot divulged that the rate limiting step in the adsorption process was the film diffusion. Thermodynamic study confirmed the adsorption process to be endothermic, spontaneous and controlled by physisorption. In bed column studies, the percentage removal of adsorbates was found to increase when the adsorbates flowrate decreased, adsorbates initial concentration decreased, and bed height increased. For the breakthrough curve model, the adsorption is best fitted to Yoon Nelson model. TCAC demonstrated its efficacy in the removal of AMOX, proving successful in both batch mode and continuous mode operations. These findings suggest the potential for scaling up TCAC production for industrial purposes, indicating its suitability for larger-scale applications.

Macro- and micro-algae-based carbon composite for pharmaceutical wastewater treatment: Batch adsorption and mechanism study

Biochar synthesized from algal biomasses acts as an efficient adsorbent to remove tetracycline (TC) from aqueous solutions. In this study, a mixture of Enteromorpha (EN) and Chlorella vulgaris (CV) was pyrolyzed at 500 °C, then activated with NaOH at 800 °C to prepare composite biochar (ECA-B). The effects of TC concentration (50–500 mg·L−1), pH (3–11), temperature (30 °C–50 °C), and contact time (0–960 min) on TC absorption were investigated. Results revealed that in aqueous solutions, the biochar (EC4:1-0.5)prepared with CV and EN at the mass ratio of 4:1 and the impregnation ratio of 0.5 had the optimal TC adsorption capacity (Qm = 376.878 mg·g−1). The removal rate of EC4:1-0.5 remained above 80 % after five cycles. The surface area of EC4:1-0.5 (583.329 m2·g−1) increased by three and four times that of EN and CV, respectively. Intraparticle diffusion was considered as the major limitation for the adsorption of TC onto EC4:1-0.5. This investigation provides a method for the synthesis and optimization of algal biomass-based activated carbon for the absorption of organic pollutants in wastewater.

Box–Behnken design with desirability function for methylene blue dye adsorption by microporous activated carbon from pomegranate peel using microwave assisted K2CO3 activation

This research aims to convert pomegranate peel (PP) into microporous activated carbon (PPAC) using a microwave assisted K2CO3 activation method. The optimum activation conditions were carried out with a 1:2 PP/K2CO3 impregnation ratio, radiation power 800 W, and 15 min irradiation time. The statistical Box–Behnken design (BBD) was employed as an effective tool for optimizing the factors that influence the adsorption performance and removal of methylene blue (MB) dye. The output data of BBD with a desirability function indicate a 94.8% removal of 100 mg/L MB at the following experimental conditions: PPAC dose of 0.08 g, solution pH of 7.45, process temperature of 32.1 °C, and a time of 30 min. The pseudo-second order (PSO) kinetic model accounted for the contact time for the adsorption of MB. At equilibrium conditions, the Freundlich adsorption isotherm describes the adsorption results, where the maximum adsorption capacity of PPAC for MB dye was 291.5 mg g−1. This study supports the utilization of biomass waste from pomegranate peels and conversion into renewable and sustainable adsorbent materials. As well, this work contributes to the management of waste biomass and water pollutant sequestration.

Preparation of Tetraethylenepentamine (TEPA) and Imidazole (Ims)-Modified Activated Carbon using Response Surface Methodology for Carbon Capture Applications

Introduction: Carbon capture and storage (CCS) is the most mature technology to capture CO2 from flue gas stream through the adsorption process. The commercial adsorbent, though efficient, is cost-inhibitive. An alternative adsorption approach is by utilizing a palm kernel shell (PKS) as adsorbent. To enhance the adsorption capacity of CO2, impregnation with Tetraethylenepentamine (TEPA) and imidazoles (Ims) were introduced to increase the selectivity and capacity of CO2. The response surface methodology (RSM) technique was utilized to optimize the operating conditions for the preparation of modified AC-PKS for carbon capture applications. Method: The main process variables for this study were impregnation ratio (TEPA: Ims) and impregnation temperature. The 2 Factorial 1 model was developed for iodine number which was selected as the investigated response. The optimum conditions for modified AC-PKS had been identified to be an impregnation ratio 0.17 and a temperature of 90°C which gave a maximum of iodine number 1062.95 mg/g. Based on this optimum condition, the experimental value of iodine number is 1027.58 mg/g and is found to agree adequately with that (1062.95 mg/g) predicted from the model. The higher the iodine number, the greater the surface area available for adsorption. With the high surface area of activated carbon allows it to have more adsorption sites, increasing its capacity to remove contaminants from liquids or gases. According to Scanning electron microscope (SEM), TEPA and Ims molecules were attached to the surface of ACs and stimulated the chemisorption process for excellent adsorption process. Result: Two prominent adsorption peaks were also observed at 3100 cm-1 and 2800 cm-1, corresponding to the stretching of the N-H functional group and confirmed the successfulness of impregnation between TEPA and Ims. Based on elemental analysis (EA), the addition of TEPA and imidazole resulted in an increase in the number of amine groups on the surface of the adsorbent. Conclusion: Hence, this modified AC-PKS with optimum impregnation ratio and temperature increased the adsorption capacity and selectivity of CO2 adsorption from the simulated flue gas with 4.239 mol/kg AC compared to the previous study reported for unmodified ACPKS only 1.005 mol/kg AC.

Production and characterization of activated carbon from pyrolysis biochar of cellulosic cotton-based textile wastes

The increased in the production of textile wastes has been associated to the to the excessive formation of solid wastes resulting to detrimental threat to both human and the environment. Therefore, the upcycling of these wastes materials is in utmost importance. In this study, cotton textile wastes (CTW) undergone slow pyrolysis in a static bed reactor at different temperatures (350 °C − 550 °C), to produce biochar as a precursor for the production of activated carbon (AC). The biochar were then chemically activated using H3PO4 at different impregnation ratios and then heat-treated to obtain the (AC). The produced biochar and AC were characterized using scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy. Results showed that highest char yield (27.64 wt%) was obtained at 450 °C, with a microporosity structure increased as the temperature increases. On the other hand, the micropore volume of AC increases as the impregnation ratio increases. Finally, the AC exhibit an acidic surface with an abundance of oxygen surface groups, making it promising candidates for different applications.

Optimization of process variables to prepare activated carbon from Noug (Guizotia abyssinica cass.) stalk using response surface methodology

Even though adsorption is considered the simple, effective, and efficient method for the treatment of wastewater, accessibility of low-cost and locally available activated carbon remains the challenge. In response to this, recently significant amounts of agricultural byproducts have been investigated to prepare low-cost porous carbon, but there is still a problem related to cost and availability. So, Noug stalk, chosen because of its abundance and low cost as an agricultural byproduct in Ethiopia, was chemically activated with phosphoric acid to produce a low-cost porous carbon. The production of Noug stalk activated carbon (NSAC) is optimized using response surface methodology. A central composite design was used to investigate the effect of three process parameters, namely carbonization temperature (450–650 °C), activation time (90–150 min), and impregnation ratio (w/w) (1–3), on the BET surface area and yield of porous carbon. The analysis of variance (ANOVA) result shows that all three process parameters showed a significant effect on the surface area of porous carbon, while only carbonization temperature showed a significant effect on the yield of porous carbon. The best conditions for NSAC preparation were a carbonization temperature of 537.50 °C, an activation time of 127 min, and an impregnation ratio of 1.95, resulting in a BET surface area and yield of 473.45 m2 g−1 and 53.78%, respectively. The expected and observed values of the model for the outcome variable were highly comparable. Several analytical techniques, including proximal analysis, Fourier transform infrared spectroscopy, and N2 adsorption-desorption, were used to characterize the NSAC. The results demonstrated that the prepared NSAC has a highly porous structure comparable to porous carbon obtained from other biomass feedstocks. This implies it would be used as a potential low-cost alternative for wastewater treatment using the adsorption process.

Malachite green dye adsorption by jackfruit based activated carbon: Optimization, mass transfer simulation and surface area prediction

The exposure of basic dye towards human and environment can caused severe adverse effects. Hence, this study aimed (i) to optimize the adsorption of malachite green (MG) dye onto jackfruit peel based activated carbon (JPAC) by using response surface methodology (RSM) and (ii) to simulate the mass transfer process using Polymath mass transfer (PMT) model. The RSM revealed that the optimum activation temperature, activation time and potassium hydroxide (KOH) impregnation ratio, IR to be 782 °C, 1 h and 2.96 g/g which translated into 66.80 mg/g of MG adsorption and 34.52 % of JPAC's yield. The Freundlich isotherm model described the adsorption process the best while the Langmuir monolayer adsorption capacity was computed to be 376.33 mg/g. The kinetic data obeyed the PMT model the best where the rate constant, KPMT decreased from 1.20 to 0.41 h−1 as the MG concentration increased from 25 to 300 mg/L. Also, the PMT model was succeeded in predicting the surface area, aPMT of JPAC to be 807.77 m2/g and this value is comparable with the actual JPAC's mesopores surface area of 714.25 m2/g (error 11.58 %). The adsorption of MG onto JPAC was aided by several functional groups such as primary or secondary alcohol, non-bonded hydroxy group and methoxy through ion-dipole force and dipole-dipole force. Based on thermodynamic parameters, MG-JPAC adsorption system was endothermic in nature (∆H° = 37.12 kJ/mol), had an increment of randomness at solid-liquid interface (∆S° = 0.19 kJ/mol·K), spontaneous in nature (−20.11 kJ/mol) and physisorptionally governed (Ea = 9.46 kJ/mol).

Performance of wasteland biomass Calotropis gigantea derived activated carbon as Lithium-ion battery anode

In the present study, activated carbon produced from wasteland biomass of Calotropis gigantea stem has been used as a potential anode for lithium-ion batteries (LIBs). Activated carbon was derived from Calotropis gigantea by chemical activation using CaOCl2 and biomass at 0.5:1 and 1:1 ratio along with thermal treatment at 400 °C, 600 °C, and 900 °C, respectively, under normal atmospheric conditions. The electrochemical performance of the biomass-derived anode was analysed in CR2032 type coin-cell by cyclic voltammetry (CV), galvanostatic charge-discharge, rate capability, and electrochemical impedance spectroscopy (EIS). From the above studies, it was found that the chemical activation parameter(s) has a pronounced effect on the electrochemical performance. Electrode prepared from the activated carbon produced by chemical impregnation ratio of 0.5:1 with thermal treatment of 600 °C demonstrated the highest specific capacity of ~446 mAhg−1 owing to suitable hierarchical porous structure able to (de)intercalate Li-ions at ease. To summarize, it can be postulated that the wasteland biomass-derived activated carbon is a promising, cost-effective, eco-friendly material that can be utilized to synthesize LIBs anode, potentially replacing graphite in the future.

Adsorptive Elimination of Methyl Orange Dye over the Activated Carbon Derived from Bitter Almond Shells. An Isothermal, Thermodynamic, and Kinetic Study

Abstract: Bitter almond shells (BAS) were inspected as a low-cost precursor in producing activated carbon (AC) through the optimized ZnCl2 activation route. The raw BAS were impregnated with ZnCl2 at multiple ratios (1:1 - 3:1 ZnCl2:BAS), followed by carbonization at various temperatures (400 – 800 °C) for different durations (30 – 120 minutes) in a tubular reactor. The typical AC sample was prepared using a 1:1 ZnCl2:BAS impregnation ratio and activated at 500 °C for 60 minutes. The AC yield under those conditions was 23.46%. The BET surface area (SABET), Boehm titration method, point of zero charge (pHPZC), Field Emission-Scanning Electron Microscopy (FE-SEM), X-ray diffraction (XRD), Fourier Transform Infra-Red spectroscopy (FTIR), and Energy Dispersive X-ray (EDX) of the optimal AC sample were determined. The identification outcomes disclosed that this AC sample is mesoporous with SABET, iodine number, total pore volume, and average pore width of 1221.60 m2/g, 1444.23 mg/g,1.50 cm3/g, and 4.98 nm, respectively. The adsorptive removal of methyl orange (MO) dye from its aqueous phase by this AC was accomplished at various solution pH (2–10), different amounts of the AC (0.05-0.4 g), multiple initial concentrations (50–400 mg/L), variable temperature (10-50 °C) and varied contact time (0–420 min) in a batch- mode operation. The maximum monolayer adsorption capacity of 224.71 mg/g was obtained at 323 K, pH= 2.0, initial (MO) concentration of 400 mg/L, 0.25 g AC dose, and 420 minutes contact time. The kinetic outcomes best fitted to the pseudo-2nd -order kinetics model, while the MO equilibrium capacity obeyed the Langmuir model rather than other models. Thermodynamic studies of the MO adsorption by the BAS-derived AC disclosed that the adsorption was spontaneous and endothermic. The adsorption mechanism of MO by the declared AC mostly involved electrostatic attractions and hydrogen bonding interaction. This work demonstrates that BAS is an advantageous raw material for producing low-cost and effectual mesoporous AC carbon with substantive surface area.

Production of soybean husks activated carbon for basic dye adsorption: characterization, kinetics, equilibrium, and thermodynamic studies

ABSTRACT Soybean husks were used as a precursor to prepare activated carbon (SHAC) by chemical activation with ZnCl2 under different experimental conditions. The best operational conditions for SHAC production were determined using a 23 factorial design and variance analysis (ANOVA). The best results were achieved with an impregnation ratio of 1 g ZnCl2/g soybean husks, a residence time of (180 min), and a temperature of (650ºC), resulting in SHAC with a high surface area (1150 m2/g) and pore volume (0.5933 cm3/g). The selected SHAC was used to adsorb malachite green (MG) from aqueous solutions. The MG adsorption process followed pseudo-second-order kinetics and Langmuir isotherms, with maximum adsorption capacities of 152.53 mg/g, 153.29 mg/g, and 166.83 mg/g at 30°C, 40°C, and 50°C, respectively. Furthermore, the pH of the point of zero charge of the selected SHAC was close to neutral, making it suitable for adsorbing cationic species in basic pH solutions.

CO2 Adsorption Performance of Activated Coke Prepared from Biomass and Coal

CO2 adsorption is one of the promising CCS technologies, and activated coke is a solid adsorbent with excellent adsorption properties. In this study, activated coke was prepared by using bituminous coal and coconut shells activated with KOH or CaCl2 in a physically activated atmosphere and modified with ammonia. The effect of the active agent impregnation ratio on the physicochemical properties of activated coke was investigated by N2 adsorption isotherms, scanning electron microscopy (SEM) and Fourier transform infrared spectrometry (FTIR). The CO2 adsorption performance of activated coke was tested, and the effect of nitrogen-containing functional groups on CO2 adsorption was investigated by experiments and simulations. The results showed that the specific surface area of activated coke reached 629.81 m2/g at a KOH impregnation ratio of 0.5 and 610.66 m2/g at a CaCl2 impregnation ratio of 1. The maximum CO2 adsorption capacity of activated coke reached 71.70 mg/g and 90.99 mg/g for conventional power plant flue gas and oxy–fuel combustion flue gas, respectively. After ammonia modification, the CO2 adsorption capacity of activated coke was further increased. Simulations showed that pyrrole and pyrrole functional groups changed the polarity of graphene and established weak interactions with CO2.

Study of synthesis and characterization of raw bagasse, its char and activated carbon prepared using chemical additive

This paper reports the use of naturally available raw material as sugarcane bagasse (SB) to prepare cost-effective activated carbon. Activated carbon preparation from SB by using ZnCl2 was carried out by chemical activation method. The raw bagasse, its char and activated carbon were characterized on the basis of iodine number, carbon, hydrogen, nitrogen analysis, Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and Brunauer-Emmett-Teller (BET) surface area to check their effectiveness. During activated carbon synthesis, the impregnation ratio of SB and ZnCl2 was maintained at 1:1-1:3 and activation temperature was in the range of 600-900 °C for 1 h. From the characterization study, the highest iodine adsorption of activated carbon was found to be 1140.69 mg/g with a 1:2 ratio at 900 °C whereas char gives an iodine number of 529.63 mg/g at the same temperature. The BET surface area of raw bagasse, its char and activated carbon (SB-Zn2-900) obtained was 4.30, 514.27 and 1386.58 m2/g, respectively, which shows charrification and chemical activation improves surface area. The optimum ratio of impregnation and activation temperature was found to be 1:2 at 900 °C. In this work, activated carbon was successfully prepared and obtained product has better characteristics than previously reported studies.

Groundnut shell chemically treated with KOH to prepare inexpensive activated carbon: Methylene blue adsorption and equilibrium isotherm studies

Groundnut shell activated carbon (GNSAC) is made from groundnut shells using potassium hydroxide (KOH) at 600 °C in a nitrogen atmosphere. The properties of the products were examined using FT-IR, XRD, SEM with EDS, and BET analysis. The activating temperature of 600 °C and the impregnation ratio of 1:1 were observed as optimum for achieving the highest surface area (412 m2/g). The adsorption efficiency of optimized GNSAC (1:1) was evaluated using a methylene blue (MB) dye solution. The effects of contact time, pH, adsorbent dose, and beginning dye concentration on the removal efficiency of MB were investigated among the GNS/KOH ratios of a 1:1 sample used as the adsorbent. Additionally, the Langmuir and Freundlich adsorption models were used to support the adsorption isotherms. According to the adsorption data at these ideal conditions, GNSAC is capable of absorbing 83.33 mg/g of dye at equilibrium as demonstrated by the Langmuir isotherm. This result demonstrates that GNSAC is a potentially useful material for wastewater treatment.

Effect of iron impregnation ratio on the properties and adsorption of KOH activated biochar for removal of tetracycline and heavy metals

The effect of iron impregnation ratio on magnetic biochars (MBCs) prepared by biomass pyrolysis accompanied by KOH activation has been less reported. In this study, MBCs were produced by one-step pyrolysis/KOH-activation of walnut shell, rice husk and cornstalk with different impregnation ratios (0.3–0.6). The properties, adsorption capacity and cycling performance for Pb(II), Cd(II) and tetracycline of MBCs were determined. MBCs prepared with low impregnation ratio (0.3) showed stronger adsorption capacity on tetracycline. The adsorption capacity of WS-0.3 toward tetracycline was up to 405.01 mg g−1, while that of WS-0.6 was only 213.81 mg g−1. It is noteworthy that rice husk and cornstalk biochar with an impregnation ratio of 0.6 were more effective in removing Pb(II) and Cd(II), and the content of Fe0 crystals on surface strengthened the ion exchange and chemical precipitation. This work highlights that the impregnation ratio should be changed according to the actual application scenarios of MBC.

Adsorption Behavior of Multi-Component BTEX on the Synthesized Green Adsorbents Derived from Abelmoschus esculentus L. Waste Residue.

Benzene, toluene, ethylbenzene, and xylene (BTEX) removal is one of the most common difficulties in air pollution control. They are emitted from several processes, prejudicial to the environment and humans. BTEX leads to various environmental risks, and there is a significant need for a creating process for the complete removal of BTEX from air streams. This study's objective is the multi-component adsorption of BTEX pollutants from an air stream, by synthesizing activated carbons (ACs) under several operations. A lignocellulosic waste biomass, Abelmoschus esculentus L. (AE), was utilized as the precursor for synthesizing activated carbons (AE-ACs), and their surface chemical characteristics were investigated. Optimization processes were examined, and the change in the surface area of AE-ACs was investigated as change of some variables resultslike activation agent, impregnation ratio, temperature, and activation time. The maximum surface area of 968 m2/g and total pore volume of 0.51 cm3/g were attained at 1:2 impregnation ratio, activation time of 110 min, and activation temperature of 800 °C, under N2 atmosphere. A mixture of BTEX pollutants was employed to consider the effect of humidity (0.5, 1, 1.5, and 2 wt%) and initial concentrations (from 5 to 300 mg/m3), using a contact time of 120 min at the temperature of 25 °C. Under the studied conditions, the multi-component and single-component BTEX adsorption capacities by HCl-activated carbon, AE-ACH, were specifically achieved to 6.86-51.36 mg/g and 22-93.62 mg/g, respectively. Overall, Abelmoschus esculentus L. was exploited for the synthesis of AE-ACH which was successfully utilized for efficient BTEX capture from a polluted air stream.

Vacuum impregnation of liquid into carrot assisted by high hydrostatic pressure

ABSTRACT Carrot was impregnated with pigment solution by vacuum heat sealing (VS) and/or high hydrostatic pressure treatment (HHP; 100–600 MPa, 25°C, 5 min). Impregnation efficacy was evaluated as impregnation ratio (%) by image analysis, while damages of cell membrane and texture were quantified by electrical impedance spectroscopy and texture analysis, respectively. Combinations of VS and HHP exclusively achieved 100% impregnation. Meanwhile, the damages were comparable between the samples after VS and VS + 100 MPa treatment and aggravated by elevated levels of HHP. As for the texture, breaking stress (hardness) decreased after VS and VS + HHP (100–600 MPa) comparably. Meanwhile, breaking strain (deformability) significantly increased after VS + HHP (200–600 MPa), indicating further damage of strain texture as compared with that after VS and VS + 100 MPa treatments. It was indicated that impregnation of carrot was fully achieved by a combination of VS and 100 MPa treatment, while minimizing the cell membrane and texture damages. Difference in the impregnation efficacy between carrot and apple was discussed based on their image data.

Adsorptive Removal of Reactive Yellow 145 Dye from Textile Industry Effluent Using Teff Straw Activated Carbon: Optimization Using Central Composite Design

This study aimed to optimize the preparation condition of activated carbon using Teff straw as a precursor material via evaluating its potential in terms of maximizing the adsorptive removal of Reactive Yellow 145 dye (RY 145) from aqueous solutions. Selective factors, such as activation time, activation temperature, and impregnation ratio on the preparation of Teff Straw-based Activated Carbon (TSAC) were optimized using response surface methodology (RSM). A quadratic regression model with estimated coefficients was developed by RSM and it was observed that model predictions were matched with experimental value with an acceptable R2 value (0.98). Further, the TSAC prepared at optimal condition was characterized using Fourier-transform infrared (FTIR), Scanning electron microscopy (SEM), and X-ray diffraction (XRD) techniques. The TSAC prepared at optimal condition showed anionic nature with a BET surface area of 627.7 m2/g. In addition, important adsorptive parameters (contact time, solution pH, adsorbent dose, and dye concentration) were evaluated through batch experiments. In such a way, it was determined that 2 h for activation time, 539 °C for activation temperature, and impregnation ratio of 5 g of phosphoric acid per 1 g of TSAC were optimal for efficient adsorption with maximum removal of 98.53% for RY 145 dye. In addition, the TSAC was subjected to test in order to determine its adsorptive performance by treating real textile industry effluent for examining its Chemical Oxygen Demand (COD) removal potential. The results showed that 76% COD was removed from the real textile effluent, which met Ethiopian Environmental Protection Authority (EPA) standard. The finding of this paper asserts that this material is a good and low-cost bio-sorbent that can be used for the removal of pollutants from textile wastewater. Nevertheless, additional investigations of the adsorbents including regeneration options are advisable to draw explicit conclusions.

Design of experiments as a tool to guide the preparation of tailor-made activated carbons

Activated carbon produced from biomass exhibits a high specific surface area due to the natural hierarchical porous structure of the precursor material. To reduce production costs of activated carbon, bio-waste materials receive more and more attention, which has led to a steep increase in the number of publications over the past decade. However, the characteristics of activated carbon are highly dependent on the properties of the precursor material used, making it difficult to draw assumptions about activation conditions for new precursor materials based on published work. Here, we introduce a Design of Experiment methodology with a Central Composite Design to better predict the properties of activated carbons from biomass. As a model precursor, we employ well-defined regenerated cellulose-based fibers which contain 25 wt.% chitosan as intrinsic dehydration catalyst and nitrogen donor. The use of the DoE methodology opens up the possibility to better identify the crucial dependencies between activation temperature and impregnation ratio on the yield, surface morphology, porosity and chemical composition of the activated carbon, independent of the used biomass. The use of DoE yields contour plots, which allows for more facile analysis on correlations between activation conditions and activated carbon properties, thus enabling its tailor-made manufacturing.

Mass transfer simulation on remazol brilliant blue R dye adsorption by optimized teak wood Based activated carbon

The reactive dye of remazol brilliant blue R (RBBR) can be toxic to aquatic ecosystems and humans. Hence, the objectives of this study were to optimize teak wood-based activated carbon (TWAC) via response surface methodology (RSM) to adsorb RBBR and to simulate the mass transfer process using Polymath software. The optimum conditions in preparing TWAC were discovered to be 470 Watt of radiation power, 6.40 min of radiation time, and 1.48 g/g of impregnation ratio (IR), resulting in RBBR uptakes of 83.97 mg/g and TWAC’s yield of 30.60%. Isotherm study revealed that the adsorption of RBBR onto TWAC was best described by the Langmuir model with maximum monolayer adsorption capacity, Qm of 337.55 mg/g. The kinetic data were best described by the Polymath Mass Transfer (PMT) model where the rate constant, kPTM was found to increase from 4.84 to 5.22 h−1 when RBBR initial concentration increased from 25 to 300 mg/L. The PMT model predicted the adsorption surface area, am to be 940.79 m2/g, which is highly accurate with the actual mesopores surface area of 983.25 m2/g. The RBBR molecules formed an attraction force with TWAC’s surface functional groups through hydrogen bond (cyclohexane), dipole–dipole force (polysulfides and terminal/medial alkyne), and ion–dipole force (phenol and hydroxy group). Thermodynamic parameters of ΔH°, ΔS°, ΔG°, and Ea were computed to be −3.55 kJ/mol (exothermic), 0.07 kJ/mol.K, −24.37 kJ/mol (spontaneous) and 21.23 kJ/mol (physisorption), respectively.