Activated Carbon Dosage Research Articles

Impurity removal technology of Tongan injection in liquid preparation process

In order to effectively remove the invalid impurities in Tongan injection, optimize the optimal parameters of the impurity removal technology of liquid mixing process, in this paper, taking Tongan injection as the research object, with the contents of celandine alkali, and sinomenine, solids reduction efficiency, and related substances inspection as the evaluation indexes, the removal of impurities and related substances by the combined process of refrigeration, coction and activated carbon adsorption were investigated, the feasibility of the impurity removal method was definited and the process parameters were optimized. The optimized process parameters were as follows: refrigerated for 36 h, boiled for 15 min, activated carbon dosage of 0.3%, temperature 100 degrees C, adsorption time 10 min. It can effectively remove the tannin, and other impurities, thus ensure the quality and safety of products.

Experimental design and response surface modeling for optimization of humic substances removal by activated carbon: A kinetic and isotherm study

The presence of humic acid (HA) in water treatment processes is very harmful and the cause of undesirable color, taste, and smell. Drinking water containing high concentrations of humic substances can be the cause of many health problems. Therefore, the removal of these compounds from water resources is a very important topic. In this research, response surface methodology (RSM) has been used to optimize the effect of main operational variables responsible for higher HA removal by activated carbon (AC). A three-level Box–Behnken factorial design (BBD) was used to optimize initial concentration of HA, time, pH, and AC dose for humic substances removal. The characterization of AC was carried out using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD) analysis. A coefficient of determination (R 2 ) value of 0.98, model F-value of 82.32 and its low P-value (F < 0.0001), and low value of coefficient of variation (9.94%) indicated the fitness of the response surface quadratic model during the present study. At initial optimum concentration (5.25 mg HA/L), pH (5.85), contact time (36.01 minutes), and dose (1.38 g AC/L), the model predicted 1.90 mg HA/L. Equilibrium adsorption of HA onto AC had best fitness with the Freundlich isotherm and pseudo-second-order kinetic model.

Preparation of sludge-derived KOH-activated carbon for crude glycerol purification

Activated carbon (AC) was prepared from wastewater treatment sludge by KOH activation and then used for the adsorptive purification of crude glycerol (CG). The effect of different KOH: char (w/w) ratios (1–6), KOH soaking times (5–25 h), and activation temperatures (500–900 °C) on the surface properties of the obtained sludge-derived ACs and their adsorption capacity for impurities in H3PO4 pretreated CG was explored. The preparation conditions affected the textural properties and surface chemistry of the sludge-derived AC and its efficiency in the adsorptive purification of CG. Oxygen-containing surface functional groups, particularly carbonyl groups, as well as the textural properties, played a more important role in the adsorptive purification of CG. Among the sludge-derived ACs, the one impregnated at a KOH: char (w/w) ratio of 5.0 for 25 h and then activated at 800 °C exhibited the most suitable surface properties for the purification of pretreated CG, attaining a 93.0 % (w/w) glycerol level at an AC dose of 67 g/L for 2 h with agitation at 250 rpm. The AC adsorption of impurities from the pretreated CG followed the Langmuir isotherm. However, the reusability of the used AC by hexane or diethyl ether extraction was not suitable.

A novel hybrid approach of activated carbon and ultrasound cavitation for the intensification of palm oil mill effluent (POME) polishing

This investigation focuses on activated carbon (AC) adsorption and ultrasound (US) cavitation for polishing the palm oil mill effluent (POME). Both AC adsorption and US cavitation were investigated individually, in series and operating them in a combined way. The efficiency of above processes has been evaluated in terms of removal of chemical oxygen demand (COD) and total suspended solids (TSS). For the individual operation, the optimisation studies were carried out by using the following conditions: AC dosage (50–200 g/L); contact time (2, 4, 6 h); US power amplitude (50% and 80%) and US cavitation time (30–180 min). The optimisation studies utilising US power amplitude (50%) and cavitation time (15 min) followed by AC adsorption using minimum AC dosage (50 g/L) and contact time (30 min) resulted in ∼100% COD and 83.33% TSS removals which meets the discharge limits set by the Department of Environment (DoE), Malaysia. The hybrid operation was also studied by simultaneously employing AC adsorption and US cavitation and it was observed that an adsorption dosage of 50 g/L resulted into achieving 73.08% COD and 98.33% TSS removals within 15 min of US irradiation. With the possibility of continuous and feasible sonochemical reactors, this hybrid approach of US cavitation followed by AC adsorption could be an alternative processing technique for POME polishing.

Adsorptive Isotherms and Removal of Microbial Inhibitors in a Bio-Based Hydrolysate for Xylitol Production

Adsorption isotherms and thermodynamics of microbial inhibitors generated by the acid-catalyzed hydrolysis of hemicellulose were investigated using activated carbon as the adsorbent. Parameters of temperature (25–65°C) and pH (1.0–10.0) were employed to study the adsorption isotherms of phenol, acetic acid, and furfural. The results based on the Langmuir model indicated that a higher efficiency of adsorption could be achieved at a lower pH and lower temperature for phenol and acetic acid. Furfural removal from the aqueous solution was only dependent on temperature, with a higher performance at 25°C. Negative values obtained for the heat of adsorption (ΔH), entropy (ΔS), and free energy (ΔG) indicated that the adsorption of all three components is exothermic (physisorption) in nature, with a mechanism based on the affinity of the solute toward the adsorbent and non-spontaneous. The adsorptive removal of the main inhibitors (8.7 g/L phenols and 4.2 g/L acetic acid) from the concentrated hydrolysate of oat hull hemicellulose was dependent on the activated carbon dosage, temperature, and pH. Under operational conditions of pH 1.0 and 25°C with an incremental carbon dosage of 1.25–5% in the hydrolysate, the removal of phenols was 64–95.4% and that of acetic acid was 6–13.2%, respectively. The xylitol fermentation process indicated that oat hull hemicellulosic hydrolysate is low in toxicity to Candida guilliermondii. Meanwhile, a mild adsorptive detoxification using activated carbon resulted in over 10% increase in xylitol yield (≈ 0.8 g/g) and productivity (0.5 g/L/h).

Anaerobic stabilized landfill leachate treatment using chemically activated sugarcane bagasse activated carbon: kinetic and equilibrium study

Adsorption via activated carbon (AC) is one of the best methods to treat stabilized landfill leachate. However, this technique has been justified due to expensive and limited resource of AC precursor. Thus, in this study, sugarcane bagasse, a cheap and abundant biomass from agricultural waste, was used to prepare AC. The prepared sugarcane bagasse activated carbon (SCAC) was tested for color, chemical oxygen demand (COD), and ammoniacal nitrogen (NH3-N) removals from anaerobic stabilized landfill leachate. SCAC was prepared using physical and chemical activation. SCAC was characterized for its surface area, surface morphology, and functional groups. The performance of the adsorbent was examined in a batch mode study by varying the shaking speed, contact time, adsorbent dosage, and pH. The experimental results indicated that SCAC could adsorb and remove the pollutants from anaerobic municipal stabilized landfill. Removal of color, COD, and NH3-N were favorably described by Langmuir isotherm model, with a maximum monolayer adsorption capacity of 555.56 Pt/Co, 126.58 and 14.62 mg/g, respectively. Pseudo-second-order model fits well with the experimental results and indicates that the adsorption was controlled by chemisorptions. The experimental results revealed that the optimum experimental conditions (e.g. 200 rpm shaking speed, 180 min contact time, 7 g AC dosage, and pH 7) resulted in 94.74, 83.61, and 46.65% removal of color, COD, and NH3-N, respectively.

Characterization of P-nitrophenol adsorption kinetic properties in batch and fixed bed adsorbers

P-nitrophenol (PNP) adsorption in batch and fixed bed adsorbers was studied. The homogeneous surface diffusion model (HSDM) based on external mass transfer and intraparticle surface diffusion was used to describe the adsorption kinetics for PNP in stirred batch adsorber at various initial concentrations and activated carbon dosages. The fixed bed model considering both external and internal mass transfer resistances as well as axial dispersion with non-linear isotherm was utilized to predict the fixed bed breakthrough curves for PNP adsorption under the conditions of different flow rates and inlet concentrations. The equilibrium parameters and surface diffusivity (D s ) were obtained from separate experiments in batch adsorber. The obtained value of D s is 4.187×1012 m2/s. The external film mass transfer coefficient (k f ) and axial dispersion coefficient (D L ) were estimated by the correlations of Goeuret and Wike-Chang. The Biot number determined by HSDM indicated that the adsorption rate of PNP onto activated carbon in stirred batch was controlled by intraparticle diffusion and film mass transfer. A sensitivity analysis was carried out and showed that the fixed bed model calculations were sensitive to D s and k f , but insensitive to D L . The sensitivity analysis and Biot number both confirm that intraparticle diffusion and film mass transfer are the controlling mass transfer mechanism in fixed bed adsorption system.

On the Adsorption Capability of Powder Activated Carbon for Phenol

Using solid phase extraction and high performance liquid chromatography (HPLC), this paper studies the adsorption capability of activated carbon to phenol. The phenol wastewater is simulated with raw water and pure water, respectively. In detail, we examine impact factors including adsorption time, activated carbon dosage, equilibrium concentration of phenol. Using the adsorption principles from the aspect of kinetics, our study shows that adsorption of powder activated carbon to phenol conforms to the Fran Delhi Freundrich adsorption model.

Adsorption of nitrate from aqueous solution using activated carbon-supported Fe0, Fe2(SO4)3, and FeSO4

In this laboratory scale study, impregnated almond shell activated carbon was used as adsorbent to investigate its feasibility for nitrate adsorption from aqueous medium. The effects of activated carbon dosage and contact time have been examined in batch experiments. Experimental data show that impregnated activated carbons by Fe 0 , Fe 2 (SO 4 ) 3 , and FeSO 4 were more effective than virgin almond activated carbon in nitrate removal. The maximum nitrate removal was 70% and 10-15% for modified activated carbons and virgin activated carbon, respectively. These experiments were conducted at pH 6.2, 20 oC, and initial concentrations of 20 mg/l nitrate-N. The increase in modified activated carbon dosages increased the removal of nitrate. The equilibrium time was found to be 30 min for modified activated carbons

Experimental Study on the Preparation of Nutshell Activated Carbon and the Disposal of Catering Wastewater

The study used self-made nutshell activated carbon and took catering wastewater as research object. After pretreatment, the catering wastewater was adsorbed by nutshell activated carbon.Throught investigating the adsorption value of methylene blue and iodine,the effect of Peach pit shell activated carbon is higher than others.The optimal conditions are determined: proper time of reaction 4 h, Peach shell activated carbon dosage 30 mg/L, pH 6.0, reaction temperature 30°C. Under this optimum, the removal rate of CODcr as well as grease can be as high as 92.75% and 87.05%, respectively.

Removal of Bisphenol A from Aqueous Solution by Activated Carbon Derived from Oil Palm Empty Fruit Bunch

The potential of the activated carbon prepared from the empty fruit bunch of oil palm wastes to remove bisphenol A (BPA) from aqueous media was investigated. The experiments were performed by varying the contact time, activated carbon dose, initial BPA concentration, and pH of the solution. The Langmuir, Freundlich, and Temkin isotherm models were employed to discuss the adsorption behavior. The equilibrium data were perfectly represented by the Langmuir isotherm with R 2 of 0.9985. The maximum monolayer adsorption capacity of the activated carbon was found to be 41.98 mg/g. Kinetic studies indicated that the adsorption process followed the pseudo-second-order kinetic with a rate constant of 0.3 × 10−3/min. The activated carbon was characterized by means of Fourier transform infrared spectrometry, Brunauer–Emmett–Teller, and field emission scanning electron microscopy analyses. The results of the present study indicate that the activated carbon prepared from the empty fruit bunch is a promising candidate as a low-cost bio-adsorbent for the removal of BPA from aqueous solution.

Treatment of oilfield produced water using Fe/C micro-electrolysis assisted by zero-valent copper and zero-valent aluminium

In this study, the Fe/Cu/C and Fe/Al/C inner micro-electrolysis systems were used to treat actual oilfield produced water to evaluate the feasibility of the technology. Effects of reaction time, pH value, the dosage of metals and activated carbon, and Fe:C mass ratio on the treatment efficiency of wastewater were studied. The results showed that the optimum conditions were reaction time 120 min, initial solution pH 4.0, Fe dosage 13.3 g/L, activated carbon dosage 6.7 g/L, Cu dosage 2.0 g/L or Al dosage 1.0 g/L. Under the optimum conditions, the removal efficiencies of chemical oxygen demand (COD) were 39.3%, 49.7% and 52.6% in the Fe/C, Fe/Cu/C and Fe/Al/C processes, respectively. Meanwhile, the ratio of five-day biochemical oxygen demand to COD was raised from 0.18 to above 0.35, which created favourable conditions for the subsequent biological treatment. All these led to an easy maintenance and low operational cost.

English

In this study, the efficiency of activated carbon produced from Henna wood was studied to remove herbicide from aqueous solutions by adsorption. The parameters that affect the adsorption such as contact time, activated carbon dosage, initial concentration of adsorbate, stirring rate, temperature, and pH on bentazon adsorption were studied. The use of Henna wood as a raw material to produce activated carbon by physical activation was investigated. The activated carbons produced were characterized by nitrogen adsorption isotherms and point of zero charge properties. Brunauer, Emmett and Teller (BET) surface area of the activated carbon was determined. The removal of herbicide from aqueous solutions by adsorption on activated carbon produced was studied. The results of the present investigation showed that activated carbons prepared from Henna wood have good adsorption capacity for the removal of bentazon from aqueous solution. The Langmuir model provides the best correlation of the experimental equilibrium data. Adsorption isotherm according to BET classification was of Type I. The adsorption isotherms of bentazon revealed that adsorption increased as the concentration increases up to a saturation point. Enthalpy, entropy and free enthalpy adsorption have a negative value indicating that the adsorption of bentazon on the Henna wood activated was feasible, spontaneous and exothermic at 20 to 40°C. Keywords: Activated carbon, adsorption, thermodynamic parameters, Henna wood, Bentazon. African Journal of Biotechnology , Vol 13(31) 3597-3606

Activated carbon enhanced ozonation of oxalate attributed to HO[rad] oxidation in bulk solution and surface oxidation: Effect of activated carbon dosage and pH

Ozonation of oxalate in aqueous phase was performed with a commercial activated carbon (AC) in this work. The effect of AC dosage and solution pH on the contribution of hydroxyl radicals (HO) in bulk solution and oxidation on the AC surface to the removal of oxalate was studied. We found that the removal of oxalate was reduced by tert-butyl alcohol (tBA) with low dosages of AC, while it was hardly affected by tBA when the AC dosage was greater than 0.3g/L. tBA also inhibited ozone decomposition when the AC dosage was no more than 0.05g/L, but it did not work when the AC dosage was no less than 0.1g/L. These observations indicate that HO in bulk solution and oxidation on the AC surface both contribute to the removal of oxalate. HO oxidation in bulk solution is significant when the dosage of AC is low, whereas surface oxidation is dominant when the dosage of AC is high. The oxalate removal decreased with increasing pH of the solution with an AC dosage of 0.5g/L. The degradation of oxalate occurs mainly through surface oxidation in acid and neutral solution, but through HO oxidation in basic bulk solution. A mechanism involving both HO oxidation in bulk solution and surface oxidation was proposed for AC enhanced ozonation of oxalate.

Defluoridation of wastewater using powdered activated carbon developed from Eichhornia crassipes stem: optimization by response surface methodology

The present investigation describes the removal of fluoride from synthetically fluoridated water using powdered activated carbon (PAC) developed through steam activation of carbonized Eichhornia crassipes stem by series of batch sorption experiments. Process is optimized by response surface methodology and experimental matrix is developed by central composite rotatable design. Influence of five different parameters viz. pH, adsorbent dose, temperature, contact time, and revolutions per minute (RPM) were studied in the range of 2–12, 2–12 g/L, 20–60°C, 20–180 min, and 100–300, respectively. Prepared PAC was characterized to obtain physical properties and instrumentally analyzed to observe surface texture of raw PAC and spent PAC with fluoride using methods viz. SEM, EDAX, and XRD. Physical properties, such as surface area and total pore volume, obtained equal to 97.68 m2/g and 0.5185 cm3/g, respectively. From the performed experiments for fixed initial concentration of 10 mg/L, maximum fluoride removal (70%) was obtained at a pH of 5 and it took 133 min to attain this state with activated carbon dose, temperature, and RPM of 9 g/L, 48°C, and 240, respectively. Second regression model equation was derived to study analysis of variance showing significance of the process parameters. Results of the performed study reveals that the adsorption of fluoride over AC prepared from E. crassipes stem can be cost-effective and prominent for the treatment of fluoridated waste water.

Response surface methodology approach for methyl orange dye removal using optimized Acacia mangium wood activated carbon

The existing approach of response surface methodology was extended to study the adsorption of methyl orange dye on optimized Acacia mangium wood-based activated carbon with a Brunauer, Emmett and Teller surface area of 1,767 m2/g. The experiments were carried out in a batch system, and the optimal condition was determined by means of the face-centered central composite design of response surface methodology. The effect of activated carbon dose, temperature and contact time on the adsorption capacity and percentage removal of methyl orange dye molecules were optimized. The experimental results indicated that the optimal conditions for the maximum adsorption capacity were 0.515 g/L, 55.0 °C and 24 h for adsorbent dose, temperature and contact time, respectively. Under these conditions, the maximum adsorption capacity and percentage removal were found to be 181 mg/g and 90.5 %, respectively. At optimized conditions of methyl orange dye removal, studies of the kinetic and thermodynamic behavior of adsorption revealed that it followed the pseudo-second-order rate model and was spontaneously endothermic in nature.

Effect of solution pH and activated carbon dosage on the decolourization ability, nitrogen components and antioxidant activity of peanut meal hydrolysate

SummaryActivated carbon was used to remove the colour of peanut meal hydrolysate. Effects of solution pH and activated carbon dosages on the decolourization efficiency, nitrogen components and antioxidant activity of the hydrolysate were investigated. The results showed that the colour and the undigested protein or large peptides could be removed efficiently under acidic condition (pH 2.0–4.0), while less small peptides were adsorbed under this condition. Among these total amino acids (AAs), the loss of aromatic AA (Tyr and Phe) was the largest regardless of the solution pH. Greater loss of acidic AA (Glu and Asp) was observed under acidic condition, while the loss of basic AA (His, Lys and Arg) followed the opposite trend. The antioxidant activity of the hydrolysate was also reduced after decolourization, which was likely due to the loss of total phenolics and peptides containing aromatic and/or acidic AA.

Salt stress in a membrane bioreactor: Dynamics of sludge properties, membrane fouling and remediation through powdered activated carbon dosing

Membrane bioreactors are a well-established technology for wastewater treatment. However, their efficiency is adversely impacted by membrane fouling, primarily inciting very conservative operations of installations that makes them less appealing from an economic perspective. This fouling propensity of the activated sludge is closely related to system disturbances. Therefore, improved insight into the impact of fouling is crucial towards increased membrane performance. In this work, the disturbance of a salt shock was investigated with respect to sludge composition and filterability in two parallel lab-scale membrane bioreactors. Several key sludge parameters (soluble microbial products, sludge-bound extracellular polymeric substances, supramicron particle size distributions (PSD), submicron particle concentrations) were intensively monitored prior to, during, and after a disturbance to investigate its impact as well as the potential governing mechanism. Upon salt addition, the supramicron PSD immediately shifted to smaller floc sizes, and the total fouling rate increased. Following a certain delay, an increase in submicron particles, supernatant proteins, and polysaccharides was observed as well as an increase in the irreversible membrane fouling rate. Recovery from the disturbance was evidenced with a simultaneous decrease in the above mentioned quantities. A similar experiment introducing powdered activated carbon (PAC) addition used for remediation resulted in either no or less significant changes in the above mentioned quantities, signifying its potential as a mitigation strategy.

A novel cleaning process for industrial production of xylose in pilot scale from corncob by using screw-steam-explosive extruder.

Steam explosion is the most promising technology to replace conventional acid hydrolysis of lignocellulose for biomass pretreatment. In this paper, a new screw-steam-explosive extruder was designed and explored for xylose production and lignocellulose biorefinery at the pilot scale. We investigated the effect of different chemicals on xylose yield in the screw-steam-explosive extrusion process, and the xylose production process was optimized as followings: After pre-impregnation with sulfuric acid at 80°C for 3h, corncob was treated at 1.55MPa with 9mg sulfuric acid/g dry corncob (DC) for 5.5min, followed by countercurrent extraction (3 recycles), decoloration (activated carbon dosage 0.07g/g sugar, 75°C for 40min), and ion exchange (2 batches). Using this process, 3.575kg of crystal xylose was produced from 22kg corncob, almost 90% of hemicellulose was released as monomeric sugar, and only a small amount of by-products was released (formic acid, acetic acid, fural, 5-hydroxymethylfurfural, and phenolic compounds were 0.17, 1.14, 0.53, 0.19, and 1.75g/100g DC, respectively). All results indicated that the screw-steam-explosive extrusion provides a more effective way to convert hemicellulose into xylose and could be an alternative method to traditional sulfuric acid hydrolysis process for lignocellulose biorefinery.

Removal of Heavy Metals from Contaminated Soils by Washing with Citric Acid and Subsequent Treatment of Soil-Washing Solutions

Soil washing experiments were carried out with citric acid as washing reagent for the remediation of soils highly contaminated with heavy metals, then activated carbon was used in absorption processing for leaching solution. In this study, the effects of the main operating variables for removal of metals from soils were first discussed. The results showed that 36.% Pb, 47.74% Cu and 61.88% Cd were removed from the contaminated soils by optimizing the washing parameters at citric acid concentration 0.2 mol/l, mixing time 2 h, liquid-soil ratio 20 and solution pH=4, respectively. In the adsorption experiments of leachates, the optimum conditions were found as follows: solution pH=7, mixing time of 2 h, standing time of 60 min and activated carbon dosage of 1g/100ml.