Activated Carbon Dosage Research Articles

Treatment of hypersaline industrial wastewater from salicylaldehyde production by heterogeneous catalytic wet peroxide oxidation on commercial activated carbon

Abstract In this work, a heterogeneous catalytic wet peroxide oxidation process combined activated carbon (AC) and hydrogen peroxide (H 2 O 2 ) was applied for the removal of organic matter from the salicylaldehyde industry wastewater with high organics content, strong acid and ultrahigh salinity. The effects of different crucial factors such as temperature, initial pH, H 2 O 2 concentration and AC dose on the removal efficiency were investigated. It was found that the degradation of organic matter was inhibited by the high salinity at room temperature. Excess AC was unfavorable to the removal of organic matter. The TOC removal efficiency was significantly dependent on the pH, which could be explained in terms of the electrostatic forces among AC, H 2 O 2 , and organics in the solution. The optimal operating conditions established through the experiments were as follows: reaction temperature 60 °C, initial pH of 3, H 2 O 2 concentration of 21.7 g/L, AC dose of 15 g/L and reaction time of 1 h. Under such operation conditions, the removal efficiency of TOC, COD, phenol and formaldehyde were 91.21%, 88.52%, 99.54% and 97.18%, respectively. Furthermore, the catalytic stability of AC was evaluated through the continuous reuse experiments, and the structure and chemical features of AC were analyzed by using ASPS 2020 and SEM/EDS before and after using.

Multi-Objective Optimization of Indigo Carmine Removal by an Electrocoagulation/GAC Coupling Process in a Batch Reactor

A coupling process between Electrocoagulation (EC) and GAC was employed to separate dyes from aqueous solutions. The removal of an indigoid dye, namely C.I. Acid Blue 74, was tested. A novel approach for optimizing EC-based techniques is presented. In addition to maximizing removal efficiency, minimizing consumptions of energy and electrode materials were also targeted by means of multi-objective optimization in order to reduce the specific costs. A very good cost-efficiency feature of EC/GAC coupling process operated under optimal conditions to treat wastewater from dyestuff has been revealed. The independent variables considered were the current density, influent pH, contact time, granular activated carbon dose, and initial dye concentration. Simple maximization of color removal efficiency and multi-objective optimization were compared. Two different constraints were considered for each type of optimization. The determined costs outline the cheapness feature of the EC/GAC system as a potential dye wastewater treatment technology.

Decolorization of Low Molecular Compounds of Seaweed by Using Activated Carbon

Commercially available carrageenan powder which is extracted from seaweed possesses yellowish color and off-odor that deter their usage in human food, pharmaceutical and cosmetic industries. The objective of this study was to investigate of decolorization of low molecular compounds of seaweed using activated carbon (AC). The effects of changes on AC dosage, temperature and contact time were investigated. The effect of color concentration was analysed using Hunter Laboratories ColorFlex® Colorimeter. Colors were measured in reflectance mode using the Hunter L a b system, with D65 as the illuminant and a 10 o standard observer angle. It was observed that an increase in activated carbon dosage decreases color. UV VIS Spectrophotometer was used to investigate whether adsorbed sample gives an effect to the molecular compounds before and after AC addition. In conclusion, the treatment using AC gives complete decolorization of carrageenan solution. This study also confirms contact time not really affected on bleaching process.

Study of Chromium Adsorption onto Activated Carbon

The results of a comparative study of chromium removal from model systems and wastewater by activated carbon AG-5 are reported. The process of chromium adsorption from laboratory solution was studied at different activated carbon dosages. The results obtained by neutron activation analysis (NAA) and atomic absorption spectrometry (AAS) showed that about 85 % of chromium was removed from model systems and only 4 % from wastewater. The NAA data point to an increase of Fe, Ni, and Cu content in activated carbon after wastewater treatment, which is indicative of competitive adsorption.

Adsorption of Cd(II), Hg(II) and Zn(II) from aqueous solution using mesoporous activated carbon produced from Bambusa vulgaris striata

Mesoporous activated carbon (surface area of 608m2/g) has achieved high efficiency in removal of cadmium, mercury and zinc ions from water solution. The proposed low-cost adsorbent was physically activated with water steam from the bamboo species Bambusa vulgaris striata. The batch studies suggested an activated carbon dose of 0.6g/L, solution pH of 9 and an equilibrium time of 16h in static conditions. The pseudo-second order equations represented the adsorption kinetics with high correlation. Fitting of the experimental results to the Langmuir, Freundlich, Redlich–Peterson and Toth isotherm models showed an almost homogeneous surface coverage and presence of physical adsorption. The highest adsorption capacities, calculated from the Langmuir model, are 239.45, 248.05 and 254.39mg/g of cadmium, mercury and zinc, respectively.

Application of response surface methodology (RSM) for optimization of color removal from POME by granular activated carbon

Color is one of the major remaining contaminants in the palm oil mill effluent (POME) following the conventional treatment of POME. The removal of color from POME using adsorption on activated carbon was investigated. The adsorption experimental design was performed using the standard response surface method (RSM) design that is central composite design to determine the optimum process variables for color removal by using the Design-Expert software (version 7.0. Stat-Ease, trial version). Besides obtaining optimum values, RSM also has the advantage of studying the interaction between various experimental parameters compared to one-factor-at-a-time. The equilibrium experimental data were analyzed by Langmuir and Freundlich isotherms. The statistical analysis showed that the quadratic model as well as the model terms was significant. The model had very low probability value (0.0003). The R 2 for the model was 0.9184 and the adjusted R 2 was 0.8380. The validation of the model showed experimental value and predicted value of 0.124 and 0.106, respectively. The optimum conditions suggested by the model for the process variable were 87.9 min, 4.05 and 7.86 g, for time, pH and granular activated carbon dose, respectively. The maximum removal obtained at these conditions was 89.95 %. The adsorption isotherm data were fitted well to the Langmuir isotherm compared to Freundlich isotherm with R 2 value of 0.850 for the former and 0.273 for the later.

In Situ Sequestration of Hydrophobic Organic Contaminants in Sediments under Stagnant Contact with Activated Carbon. 1. Column Studies

The effectiveness of activated carbon (AC) treatment to sequester hydrophobic organic contaminants in sediments under stagnant contact was comprehensively studied for the first time. Two years of column experiments were conducted to simulate field conditions with two study sediments contaminated with petroleum and polychlorinated biphenyls, respectively, and variations in AC-sediment contact times, initial AC mixing regimes and distribution, AC particle sizes, and pore-water flow. The benefit of AC treatment was gradually enhanced with time toward the end point of the treatment, where sorption equilibrium is established between sediment and AC. After two years of stagnant contact, the contaminant uptake in polyethylene passive samplers embedded in the columns was reduced by 95-99% for polycyclic aromatic hydrocarbons and 93-97% for polychlorinated biphenyls with 5 and 4 wt % AC dose, respectively, when AC was initially applied by mechanical mixing. These results verify that AC treatment can effectively control the availability of hydrophobic organic contaminants under stagnant conditions within a reasonable time frame following an initial distribution of AC into the sediment. The effectiveness of AC treatment was strongly dependent on AC particle size and AC distribution, while the effect of AC initial mixing regimes and pore-water flow was not pronounced.

Membrane fouling mitigation by activated carbon addition in activated sludge filtration

Activated carbon (AC) was added into the activated sludge to alleviate membrane fouling during sludge microfiltration. The fouling mitigation profiles were evaluated at different AC sizes and doses by a single-fibre microfiltration system. It was found that the granular AC added in the sludge suspension can absorb the organic substances in the sludge in a certain level, including biopolymer clusters (BPC). There are three impacts from AC addition, including the positive effect by mechanically scouring the membrane surface, the positive effect by adsorb organic substances, and the negative impact of breaking up sludge flocs to release the organic matter. The whole effect of AC addition on membrane fouling has to depend on the relative intensity of these three effects. The suitable AC should have a smaller mean size below 200 μm, by which the membrane fouling mitigation efficiency was positively correlated with AC doses.

Preparation and Properties of Porous poly(vinyl alcohol)/Powdered Activated Carbon Composite

Using poly (vinyl alcohol) (PVA) crosslinked with formaldehyde as matrix, starch or calcium hydrogen carbonate as the foaming agent and powdered activated carbon (AC) as the adsorptive constituent, porous PVA/AC composite was prepared by means of chemical crosslinking method. The adsorption behavior of simulated wastewater containing methyl orange dye on porous PVA/AC composite was studied. The experiment indicates that the optimal dosage of AC, sulphuric acid and formaldehyde (37% solution) are 5.0 g, 18 wt. % and 10 ml respectively at the condition of 10.0 g dosage of poly (vinyl alcohol), 95 ml distilled water and 10.0 g starch. It was found that starch was preferably incorporated into the PVA matrix in the form of an aqueous dispersion. In addition, the key factors of influence on water-absorbency including the amount of activated carbon and formaldehyde as well as the concentration of sulphuric acid have been discussed.

Activated Carbon and Clay Minerals for the Sorptive Removal of Denatonium Ions from Denatonium Benzoate Solutions

This study assessed the feasibility of utilizing activated carbon and clay minerals for treating water impacted with the bittering agent denatonium benzoate (DB). Our specific study objectives were to 1) evaluate denatonium ion sorption to smectite clay minerals (bentonite and hectorite) and activated carbon (powdered and granular) at constant pH and ionic strength and 2) examine the impact of pH on denatonium ion sorption to each solid material. The experimental results indicated that high doses (33,000 mg/L) of as-received granular activated carbon and as-received clay minerals completely removed denatonium from aqueous solutions containing 100 - 1000 mg/L denatonium benzoate. Powdered activated carbon at doses of 5 - 100 mg/L exhibited favorable monolayer sorption of denatonium ions from a pH 6.95, 70 mg/L aqueous denatonium benzoate solution with a Langmuir separation factor (r) of 0.481, a maximum sorption capacity (Sm) of 74 mg/g, and a Langmuir constant of 15.3 L/g. A maximum removal of 23% of denatonium was achieved at the highest powdered activated carbon dosage employed. Denatonium ion removal with peroxide treated bentonite and peroxide treated hectorite did not result in complete removal of the ion and exhibited favorable sorption as evidenced by Freundlich 1/n values ranging from 0.803 to 1.194; Freundlich constants (Kf) ranged from 8 ng/L to 575 ng/L. Denatonium ion sorption to peroxide treated bentonite appeared to depend on pH while hectorite sorption of denatonium ions was independent of hydrogen ion concentrations. For powdered activated carbon adsorption, as pH increased denatonium ion sorption decreased. Overall, the work demonstrates that denatonium can be effectively removed from water via activated carbon or clay mineral sorption.

Removal of Yellow 2G dye from aqueous solutions using activated carbon prepared from mosambi and cotton an agricultural waste

Adsorption of Yellow 2G from aqueous solution on the surface of Activated carbon of mosambi peel (ACMP) and stem of cotton (ACCS) was accomplished under the optimize conditions of pH, adsorbent dose, initial concentration of dye and contact time. Spectrometric technique was used for the measurements of concentration of dye before and after adsorption. Colour was effectively been removed at all selected pH, and the increase in activated carbon dose showed an increase in the removal’s percentage. The result shows that the removal efficiency increases with adsorbents dose increases and at neutral pH. The equilibrium data fit well with both Langmuir and Freundlich models of adsorption. The value of separation factor RL for ACMP and ACCS was found to be 0.135 and 0.080 respectively suggesting that the isotherm to be favorable at the concentration studied. The results of findings are discussed to reflect the removal efficiency of adsorbent.

The Performance of Coconut Shell-based Activated Carbon (CSAC) in Treating Drinking Water

The demand and market growth of activated carbon (AC) in drinking water treatment have been increasing over the recent years. This is because of the better properties and relatively lower cost of AC compared to inorganic adsorbents like ceramics. However, there have been limited studies on the effects of AC preparation including type of cleansing agent on the adsorption of metal and the turbidity of treated tap water. Therefore, this research investigated the effect of types of cleansing agent and sorbent dosage on turbidity reduction and metal removal in drinking water treatment. The analysis showed that 200 g dosage of AC that has been cleansed with FeCl3 has the turbidity and metal removal improved the most. For aesthetic value of drinking water though, filtration by using AC cleansed with KOH gave better taste and increasing the sorbent dosage up to 300 g increased this performance.

Acid Light Yellow Removal from Wastewater Using Peanut Shell-Based Activated Carbon

Peanut shell-based activated carbon was prepared by 60% zinc chloride activation. The activation temperature was 923K and activation time was 90min. The activated carbon was applied on the removal of acid light yellow from wastewater. The effects of the amount of adsorbent, the initial dye concentration and pH value of solution were investigated. The results showed that the optimum conditions for dye removal: activated carbon dosage of 2.5g/L, initial dye concentration of 50mg/L, pH value of 3. The color removal efficiency attained above 95%. It is concluded that activated carbon developed from peanut shell could be effective and practical for utilizing in dye wastewater treatment.

Adsorption of Direct Blend Yellow D-3RNL onto bamboo-base activated carbon: optimization, kinetics, and isotherm

Adsorption of Direct Blend Yellow D-3RNL in aqueous solution by activated carbons prepared from Moso timber bamboo stem residues was optimized by using central composite design matrix and response surface methodology. A maximum dye removal from the experimental validation reached 92.1% under the optimum conditions (initial dye concentration 20 mg L-1, pH 2, bamboo-based activated carbon dosage 20 g L-1, temperature 50°C, and time of adsorption 20 h) with the relative standard deviation 5.37%. The high R2 value (0.9487) for the second-order model obtained from the analysis of variance (ANOVA) indicated that the experimental data fitted well with the predicted data. The adsorption followed the nonlinear model of pseudo-second-order reaction and agreed well with Freundlich judged by the levels of Akaike Information Criterion and Akaike weight. Furthermore, the thermodynamics analysis indicated that the adsorption was a spontaneous, endothermic, entropy-increasing, and chemisorption process.

Phenol Removal from Aqueous Solution by Microwave Combined with Granular Active Carbon

The removal of phenol from aqueous solution was evaluated by using microwave technique assisted with active carbon. The effective factors such as the concentration of phenol , active carbon dosage, microwave power and irradiation time on the removal rate were investigated. When the concentration of phenol was 150 mg/l, active carbon dosage was 6 g/l, microwave power was 500 W, and irradiation time was 8 min, the removal ratio of phenol reached 95. 03%. The research on kinetics suggested that the process of treatment accords to the first-order reaction.

Adsorption of fluoranthene in surfactant solution on activated carbon: equilibrium, thermodynamic, kinetic studies

Adsorption of fluoranthene (FLA) in surfactant solution on activated carbon (AC) was investigated. Isotherm, thermodynamic, and kinetic attributes of FLA adsorption in the presence of the surfactant on AC were studied. Effects of AC dosage, initial concentration of TX100, initial concentration of FLA, and addition of fulvic acid on adsorption were studied. The experimental data of both TX100 and FLA fitted the Langmuir isotherm model and the pseudo-second-order kinetic model well. Positive enthalpy showed that adsorption of FLA on AC was endothermic. The efficiency of selective FLA removal generally increased with increasing initial surfactant concentration and decreasing fulvic acid concentration. The surface chemistry of AC may determine the removal of polycyclic aromatic hydrocarbons. The adsorption process may be controlled by the hydrophobic interaction between AC and the adsorbate. The microwave irradiation of AC may be a feasible method to reduce the cost of AC through its regeneration.

Enhancement of removal of trace organic contaminants by powdered activated carbon dosing into membrane bioreactors

This study compared the removal efficiency of 22 widespread trace organic contaminants by a laboratory-scale membrane bioreactor (MBR) with and without direct addition of powdered activated carbon (PAC) into the activated sludge reactor over a period of 312 days. The removal of hydrophilic and biologically persistent trace organic contaminants was immediately improved to above 95% after the addition of PAC into MBR. However, a compound-specific gradual decrease in removal underscored the requirement for the addition of fresh PAC. Adsorption onto PAC-added sludge appeared to play a significant role in the relatively more effective aqueous phase removal of a few resistant compounds such as carbamazepine in this study. A slower reduction in removal efficiency of compounds showing extraordinary persistence such as fenoprop and diclofenac was observed after raising the PAC concentration in the MBR from 0.1 to 0.5g/L. Nevertheless, comparison of extent of removal in terms of PAC usage indicated the suitability of more frequent dosing of smaller amounts of PAC.

Biological Responses to Activated Carbon Amendments in Sediment Remediation

Sorbent amendment with activated carbon (AC) is a novel in situ management strategy for addressing human and ecological health risks posed by hydrophobic organic chemicals (HOCs) in sediments and soils. A large body of literature shows that AC amendments can reduce bioavailability of sediment-associated HOCs by more than 60-90%. Empirically derived biodynamic models can predict bioaccumulation in benthic invertebrates within a factor of 2, allowing for future scenarios under AC amendment to be estimated. Higher AC dose and smaller AC particle size further reduce bioaccumulation of HOCs but may induce stress in some organisms. Adverse ecotoxicity response to AC exposure was observed in one-fifth of 82 tests, including changes in growth, lipid content, behavior, and survival. Negative effects on individual species and benthic communities appear to depend on the characteristics of the sedimentary environment and the AC amendment strategy (e.g., dose and particle size). More research is needed to evaluate reproductive end points, bacterial communities, and plants, and to link species- and community-level responses to amendment. In general, the ability of AC to effectively limit the mobility of HOCs in aquatic environments may outshine potential negative secondary effects, and these outcomes must be held in comparison to traditional remediation approaches.

Degradation of dyes using combined photo-Fenton/activated carbon: synergistic effect

In this paper, the effect of activated carbon (AC) on the photocatalytic degradation of dyes using photo-Fenton process was investigated. Reactive Red 198 (RR198) and Reactive Red 120 (RR120) were used as model dyes. The surface characteristics of AC were investigated using Fourier transform infrared. Photocatalytic dye degradation was studied using UV–Vis spectrophotometer and ion chromatography. The effects of AC dosage, initial dye concentration, pH, and salt on dye degradation were investigated. Formate, acetate, and oxalate anions were detected as dominant aliphatic intermediates, where they were further oxidized slowly to CO2. Nitrate, chloride, and sulfate anions were detected as the photocatalytic mineralization products of dyes. The results indicated that the AC/Fe could be used as an eco-friendly material to remove dyes. In addition, AC has synergistic effect when degrading dyes from colored wastewater using photo-Fenton process.

Polychlorinated biphenyl sorption to activated carbon and the attenuation caused by sediment

Activated carbon (AC) is currently being used to treat polychlorinated biphenyl (PCB) contaminated field sediment. In the presence of sediment, the sorption capacity of AC for PCBs can be reduced. In this study, sorption attenuation of AC is investigated using previously published data from 5 sampling sites where reductions in aqueous concentrations caused by AC amendment have been reported. AC-water partitioning coefficients (KAC_clean_water) were determined at a relevant PCB concentration in clean water using polyoxymethylene (POM) passive samplers. Logarithmic ACwater partitioning coefficient values ranged from 7.39 to 9.59 for trichlorinated to pentachlorinated congeners. These AC-water partitioning coefficients were used in a numerical model to predict expected reductions in aqueous concentrations. Results reveal an overprediction of actual reductions by a median factor ranging from 2.5 to 5.6. To obtain an estimate of AC sorption attenuation, an AC-water partitioning coefficient more representative of sediment conditions (KAC_apparent) was fitted via the model based on the observed reductions in aqueous concentrations. On average, median KAC_apparent values of individual PCB congeners were smaller than KAC_clean_water values by 1.08 log units, or a factor of 12, with corrections ranging from 0.1 to 2.3 log units. The main controls on the reduction in sorption of PCBs to AC are PCB physico-chemical properties and AC amendment variables. Generally AC sorption attenuation increased with PCB hydrophobicity and decreased with increasing AC-sediment contact time and AC dose.