Activated Carbon Particles Research Articles

Effects of Constant Electric Field on Biodegradation of Phenol by Free and Immobilized Cells of Bradyrhizobium japonicum 273

It is shown that bacteria Bradyrhizobium japonicum 273 were capable of degrading phenol at moderate concentrations either in a free cell culture or by immobilized cells on granulated activated carbon particles. The amount of degraded phenol was greater in an immobilized cell preparation than in a free culture. The application of a constant electric field during cultivation led to enhanced phenol biodegradation in a free culture and in immobilized cells on granulated activated carbon. The highest phenol removal efficiency was observed for an anode potential of 1.0 V/S.H.E. The effect was better pronounced in a free culture. The enzyme activities of free cells for phenol oxidation and benzene ring cleavage were very sensitive to the anode potential in the first two steps of the metabolic pathway of phenol biodegradation catalyzed by phenol hydroxylase—catechol-1,2-dioxygenase and catechol-2,3-dioxygenase. It was observed that at an anode potential of 0.8 V/S.H.E., the meta-pathway of cleavage of the benzene ring catalyzed by catechol-2,3-dioxygenase became competitive with the ortho-pathway, catalyzed by catechol-1,2-dioxygenase. The obtained results showed that the positive effect of constant electric field on phenol biodegradation was rather due to electric stimulation of enzyme activity than electrochemical anode oxidation.

A Three-Dimensional Activated Carbon Electrode with Carbon Fiber Felt Framework and Ordered Macropores for Enhanced Capacitive Deionization Performance

Capacitive deionization (CDI) is a promising energy-efficient electrochemical water treatment technology and a scalable electrode having high mass loading is an essential imperative to the success of this technology. A thick CDI electrode was constructed by loading activated carbon particles as the electroactive material into a three-dimensional framework fabricated from a mixture felt of conductive carbon fiber serving as an electron transfer channel and removable yak hair functioning to provide an ion transport pathway. The carbon fiber reduces the electrode electrical resistance and the ultimately removed yak hair creates an ordered macropore array that provides an ion reservoir as well as a conduction channel for reducing ion transport distance inside the electrode. The resulting composite electrode with an optimal carbon fiber and yak hair content shows a specific capacitance of 219.27 F g-1 at 0.1 A g-1 and reaches salt adsorption capacity of 15.75 mg g-1 and average salt adsorption rate of 17.10 mg g-1 h-1 with more than 50% retention after 200 cycles. The designed three-dimensional composite exhibits enhanced deionization and long-term stability that is believed to be a low-cost and simple assembly solution for achieving a high mass loading and scalable electrode for the industrial CDI applications.

The degradation of sulfamilamide wastewater by three-dimensional electrocatalytic oxidation system composed of activated carbon bimetallic particle electrode

Antibiotics remaining in wastewater can lead to serious environmental problems, such as bacterial drug resistance and biological toxicity. Electrocatalytic oxidation is becoming an effective method to degrade antibiotics. In this study, we simply synthesized bimetallic oxide activated carbon particle electrode (GAC-Co-Mn) by impregnation method and designed a bench-scale electrocatalytic reaction tank for the first time. Then, a three-dimensional electrocatalytic oxidation system composed of GAC-Co-Mn particle electrode and electrocatalytic reaction tank was used to degrade sulfanilamide antibiotic wastewater. The removal efficiency and mechanism of sulfanilamide (SA) were studied by UV spectrophotometry and ultra-performance liquid chromatography/triple quadrupole mass spectrometry. TOC-L analyzer was used to determine the contents of total organic carbon (TOC) and total nitrogen (TN) of SA wastewater before and after degradation. Electron paramagnetic resonance spectroscopy was used to confirm the production of hydroxyl radicals (•OH). The electrocatalytic activity of the materials was investigated by electrochemical workstation. In addition, we found that this three-dimensional electrocatalytic oxidation system not only has good degradation efficiency for SA, but also has good degradation efficiency for 2,4-dinitrophenol, p-nitroaniline and p-aminobenzenesulfonic acid. Moreover, GAC-Co-Mn still has good degradation efficiency after 6 cycles, indicating that GAC-Co-Mn has good structural stability. Therefore, we believe that the method has good application potential in the field of water treatment.

Improved degradation of diuron herbicide and pesticide wastewater treatment in a three-dimensional electrochemical reactor equipped with PbO2 anodes and granular activated carbon particle electrodes

The electrocatalytic performance of porous carbon felt/PbO2 and planar titanium/PbO2 anodes in a three-dimensional electrochemical reactor (3DER) equipped with granular activated carbon (GAC) particle has been studied for synergistic degradation of diuron herbicide (DIU) and treatment of pesticide wastewater. The results showed that porous carbon felt/PbO2 anode in addition to high stability can provide around three times more surface area than titanium/PbO2 for degradation reactions. Optimization of DIU degradation in 3DER system with carbon felt/PbO2 anode was performed by a five-level rotatable central composite design. The TOC mineralization rate under optimal conditions (pH = 4.7, current density = 13.5 mA cm−2, Na2SO4 concentration = 0.04 M and DIU concentration = 40 mg L−1) for the 3ٍِDER system with carbon felt/PbO2 and titanium/PbO2 anodes after 50 min were 100% and 63.8%, respectively. However, the electrocatalytic efficiency of carbon felt/PbO2 and titanium/PbO2 anodes in the absence of GAC particles to remove TOC was 85.5 and 42.7%, respectively. The energy consumed in the 3DER system equipped with carbon felt/PbO2 anode was 2.28 times less than the 3DER system with titanium/PbO2. The contribution of direct and indirect oxidation of DIU in 3DER degradation systems was determined by radical scavenging technique. The safety of the anodes was evaluated for Pb2+ leakage. The DIU degradation pathway was proposed based on the intermediates identified by LC-MS. The performance of optimized 3DER systems was evaluated for treatment of real pesticide wastewater. The chemical oxygen demand (COD) removal efficiency after 300 min of reaction in the 3DER system with carbon felt/PbO2 and titanium/PbO2 electrodes was 95% and 62.5%, respectively.

An insight on effects of activated carbon and a co-promoter on carbon dioxide hydrate formation and dissociation

The influence of activated carbon (AC) particle size on the formation and dissociation of CO2 hydrates was investigated. ACs with different particle sizes (250–420 µm; 420–841 µm; larger than 841 µm) were employed in the hydrate formation experiment at 276.2 K and 3.6 MPa in the quiescent condition. The result showed that the large AC particle size was more effective on promoting CO2 hydrate formation with shorter induction time, higher gas uptake, and higher formation rate. The study continued to investigate the effects of AC saturated with the solution of sodium dodecyl sulfate (SDS) on the CO2 hydrate formation. It was observed that the addition of 2 mM and 4 mM SDS increased the gas uptake compared with that of AC, while the addition of 6 mM SDS did not. The synergistic effect of SDS and AC was discussed. Moreover, the observed morphology during the hydrate formation and dissociation was provided.

Predicting acoustic performance of high surface area particle stacks with a poro-elastic model

Because of the high sound absorption they offer at low frequencies, there is a growing interest in high surface area particles and how they might be applied in noise control. Therefore, a model that can accurately predict the acoustic behavior of this type of materials will be useful in relevant applications. A poro-elastic model based on a combination of Biot theory and an existing rigid model of granular activated carbon (GAC) is introduced in the current work. The input parameters for this model consist of a certain number of properties that are known by measurement, and a set of values obtained by matching the model prediction with acoustic measurements. Measured absorption coefficients and surface impedance of stacks of several types of different activated carbon particles are shown in this paper. A fitting procedure that determines the unknown parameters is also described. It is shown that the model is able to predict the acoustic behavior of the particle stacks, and especially to capture the frame resonances at low frequencies, thus, validating the proposed model. Beyond the activated carbon used in the present tests, it is reasonable to generalize this model to stacks of other high surface area particles.

Study of simultaneous electro-Fenton and adsorption processes in a reactor containing porous carbon electrodes and particulate activated carbon

• Novel electro-Fenton reactor with porous carbon electrodes and activated carbon (AC). • • OH electrochemical generation was observed in the absence of Fe(II). • Increased electrical conductivity and • OH production at high levels of AC packing. • The effect for simultaneous adsorption and electro-Fenton process was studied. • Promising process for potabilization or wastewater treatment at circumneutral pH. Although electro-Fenton wastewater treatment processes are particularly attractive for their high oxidation power, they are seriously limited by the low pH values that are required for the process, the subsequent neutralization of acid and the addition and removal of iron chemicals. In this work, a study on the design, characterization and performance of a novel electro-Fenton reactor, shows that there is a simultaneous effect that can overcome these limitations when combining activated carbon (AC) adsorption and electro-Fenton effects, while working at same time under neutral pH conditions. The reactor arrangement proposed, involves a cation exchange resin that continuously supplies Fe(II) ions to a chamber containing an AC adsorption bed that is positioned between two concentric porous carbon electrodes. Preliminary experiments assessing the 2e - electrochemical reduction of dissolved oxygen to produce H 2 O 2 in the reactor in the absence of AC, showed that while the concentrations of electro-generated peroxide are, as expected, proportional to the current density, they are inversely related to the current efficiency values. A fluorescence study of hydroxyl radical ( • OH) production on the other hand, showed that in the absence and in the presence of iron ions, the corresponding concentration of • OH is 0.800 and 1.057 µM, respectively. Experiments with the reactor using varying amounts of AC, resulted not only in coupled adsorption effects characterized by a removal capacity that increases with the amount of AC, but also in increased electrical conductivity and higher electro-Fenton activity that is probably related to an improved electrical contact between the AC particles and the polarized carbonaceous electrode surface. The performance of the electro-Fenton reactor proposed in this work, was finally evaluated in terms of the removal of a model pollutant dye in both synthetic and real secondary effluents using different AC packed levels. Consistent with previous experiments, the fully compacted AC presented the higher removal rates due to the simultaneous effect of the adsorption of the pollutant and the coupled electro-Fenton degradation process.

Improved electrochemical performance of symmetric polyaniline/activated carbon hybrid for high supercapacitance: Comparison with indirect capacitance

AbstractPolyaniline (PANI) chains doped with very small amount of Activated Carbon (AC) as an electrode material in aqueous H2SO4 electrolyte was successfully employed in this work to enhance the electrochemical capacitive properties of PANI. The aim of this research is to improve overall specific capacitance of PANI by incorporating only minute amount of AC as a PANI dopant. There are many reports available on PANI/AC but the use of such a minute amount of AC in H2SO4 electrolyte which enhances the overall specific capacity of the composite has not been reported elsewhere. An improvement in the specific capacitance from 763.44 to 897.50 F g−1 in aqueous 0.1 M H2SO4 electrolyte solution is observed by adding mere 0.04 g of AC. It is envisaged that AC enhances SO4−2 ion transportation, forwards a stable and fast surface redox reactions, hence collectively improving the overall capacitive performance of supercapacitor electrode. The charge/discharge measurements shows that AC particles stops the PANI chains degradation during charge/discharge cycle. Also, the retention rate (54%) of PANI1.0/AC0.04 indicates approximately 11% more stability than pure PANI (43%) electrode alone. It was further observed that the electrochemical impedance parameters viz., that charge transfer resistance (Rct) (0.79 Ω), response frequency (0.26 Hz), response time (3.84 s) and knee frequency (9.16 Hz) of PANI1.0/AC0.04 electrode material shows excellent performance of the PANI doped AC. Considering its high specific capacitance, low‐cost and ease of synthesis, PANI1.0/AC0.04 seems to be a promising electrode material for next generation symmetric supercapacitors.

LDF based parametric optimization to model fluidized bed adsorption of trichloroethylene on activated carbon particles

Trichloroethylene (TCE) is largely used in industries as a cleaning and degreasing solvent. TCE is a potential carcinogen and is known to cause organ damage when exposed to prolonged higher concentrations. Numerical simulation of fixed and fluidized bed adsorption of TCE can help in the development of efficient adsorption processes to prevent industrial workers in the vicinity from acute TCE exposure. In the present work, a parametric optimization based numerical experimentation algorithm is implemented by open-source computational solvers to model fixed and fluidized bed adsorption of trichloroethylene vapors on activated carbon. The algorithm optimizes four parameters pertaining to linear driving force (LDF) formulation of surface barrier and microporous diffusion. The optimized parameters were utilized to evaluate ζ¯, a dimensionless number defined as the temporal and spatial average ratio of surface barrier diffusion resistance to microporous diffusion resistance. The average value of ζ¯ is 0.139 for fixed bed operation (u/umf=0.7), 1.130 for fluidized bed operation (u/umf=1), 4.436 for fluidized bed operation (u/umf=1.5) and 6.317 for fluidized bed operation (u/umf=2). Therefore, the dimensionless number ζ¯ may serve to predict the extent of change in amount adsorbed per unit adsorbent mass with change in fluidization velocity.

Molecular Engineering of Hydrogels for Rapid Water Disinfection and Sustainable Solar Vapor Generation.

Consumption of unsafe water is a major cause of morbidity and mortality in developing regions. Pasteurizing or boiling water to remove pathogens is energy-intensive and often impractical to off-grid communities. Therefore, low capital cost, rapid and energy-efficient water disinfection methods are urgently required to address global challenges of safe water access. Here, anti-bacterial hydrogels (ABHs) with catechol-enabled molecular-level hydrogen peroxide generators and quinone-anchored activated carbon particles are designed for effective water treatment. The bactericidal effect is attributed to the synergy of hydrogen peroxide and quinone groups to attack essential cell components and disturb bacterial metabolism. ABHs can be directly used as tablets to achieve >99.999% water disinfection efficiency within 60min without energy input. No harmful byproducts are formed during the treatment process, after which the ABH tablets can be easily removed without residues. Taking advantage of their excellent photothermal and biofouling-resistant properties, ABHs can also be applied as solar evaporators to achieve stable water purification under sunlight (≤1kW m-2 ) after months of storage and operation in bacteria-containing river water. The ABH platform offers reduced energy and chemical demands for point-of-use water treatment technologies in remote areas and emergency rescue applications.

Role of sodium oleate in the in-situ pore wetting of porous active carbon by 1H LF-NMR: Implications for porous mineral flotation

The filling of pores by flotation-reagent-contained water plays an important role in porous mineral flotation. This paper studied the role of sodium oleate (NaOL, a commonly used flotation reagent) solution in the in-situ wetting process of pores of porous active carbon using 1H LF-NMR, FTIR as well as contact angle measurements. The floatability of active carbon particles wetted by NaOL solutions was evaluated by particles-bubble attachment measurements. The pore wetting percentage decreased as the NaOL concentration increased. The variation trend in pore wetting percentage by NaOL solutions was from fast to slow. Increasing the NaOL concentration contributed to achieve a lower pore wetting percentage as well as rate. The NaOL solution with a high concentration significantly improved the hydrophobicity of the sample, which further prevents the pore wetting process.

A comprehensive mathematical model for analyzing synergistic effect of oxidation and mass transfer enhancement during UV-Fenton removal of VOCs

Volatile organic compounds (VOCs) emissions are regarded as a worth concerned threat to human health. The UV-Fenton coupled with mass transfer enhanced process shows promising effects on VOCs treatment. However, the detailed mechanism and mathematical model for this method have not been established. This work focuses on the hypothesis and validation of a mathematical model for UV-Fenton removal of VOCs using activated carbon particles to enhance mass transfer efficiency. Based on the mathematical model of reaction-diffusion-mass transfer, a mathematical model is established by using a series of important parameters such as ub, Dg, Dl, Kial, Kla and hydroxyl radical lifetime. The proposed model in this study introduces the key parameter of synergistic factor, which greatly improves the consistency between the model predicted results and the experimental data (the determination coefficient R2 distribution range changed from 0.71–0.98 to 0.95–0.98). Moreover, it can also explain reasonably the steady trend of outlet VOC concentration after 30 min of reaction. The mathematical model confirms that the addition of activated carbon during the UV-Fenton reaction ensures mass transfer efficiency and considerably improves (growth from 2% to 54%) the VOCs removal efficiency due to the synergy between UV-Fenton oxidation and mass transfer enhancement. Meanwhile, it provides insight into fruitful utilization of the oxidation capacity in the oxidation reaction,and achieves the purpose of predicting the efficiency of VOC removal in the Fenton process.

Combined Effect of Activated Carbon Particles and Non-Adsorptive Spherical Beads as Fluidized Media on Fouling, Organic Removal and Microbial Communities in Anaerobic Membrane Bioreactor.

The combined effect of acrylonitrile butadiene styrene (ABS) spherical beads and granular activated carbon (GAC) particles as fluidized media on the performance of anaerobic fluidized bed membrane bioreactor (AFMBR) was investigated. GAC particles and ABS beads were fluidized together in a single AFMBR to investigate membrane fouling and organic removal efficiency as well as energy consumption. The density difference between these two similarly sized media caused the stratified bed layer where ABS beads are fluidized above the GAC along the membrane. Membrane relaxation was effective to reduce the fouling and trans-membrane pressure (TMP) below 0.25 bar could be achieved at 6 h of hydraulic retention time (HRT). More than 90% of soluble chemical oxygen demand (SCOD) was removed after 80 d operation. Biogas consisting of 65% of methane was produced by AFMBR, suggesting that combined use of GAC and ABS beads did not have any adverse effect on methane production during the operational period. Scanning Electron Microscope (SEM) examinations showed the adherence of microbes to both media. However, 16S rRNA results revealed that fewer microbes attached to ABS beads than GAC. There were also compositional differences between the ABS and GAC microbial communities. The abundance of the syntrophs and exoelectrogens population on ABS beads was relatively low compared to that of GAC. Our result implied that syntrophic synergy and possible occurrence of direct interspecies electron transfer (DIET) might be facilitated in AFMBR by GAC, while traditional methanogenic pathways were dominant in ABS beads. The electrical energy required was 0.02 kWh/m3, and it was only about 13% of that produced by AFMBR.

Rebound behaviors of hydrophilic particle on gas bubble: effect of particle size and liquid properties

AbstractBACKGROUNDThe interaction between particles and bubbles commonly occurs in catalysis, flotation and medical processes. Compared with the overwhelming amount of research dedicated to particle adhesion on gas bubbles, there is less on the rebound behaviors of hydrophilic particles on bubbles. Carrying out studies in order to understand the effect of particle size and liquid properties on rebound behaviors becomes an essential task.RESULTSThe rebound velocity and angle of a particle are small when a collision takes place near the top surface of a bubble. At the bubble top, gravity counteracts the upward rebound. Smaller rebound velocity is found for small particles due to inertia. The contact time between particle and bubble increases with an increase in particle size. The surface tension almost has no effect on the rebound velocity and angle of particles. By increasing liquid viscosity, the rebound velocity of the particles decreases and the contact time increases.CONCLUSIONSA hydrophilic particle cannot adhere on a gas bubble in pure water. However, at very large viscosity, adhesion takes places. In processes where longer contact time between hydrophilic particle and gas bubble is desirable, increasing liquid viscosity and particle size should be the choice, while efforts to change the surface tension are found to be unnecessary. Hydrophilic activated carbon particles have better dispersion in water and shorter contact time on bubble surfaces than hydrophobic N‐doped carbon particles. © 2021 Society of Chemical Industry (SCI).

Electrochemical capacitive behaviors of carbon/titania composite prepared by Tween 80-assisted sol-gel process for capacitive deionization

Hybridization of carbon with metal compounds has gained substantial attention in the development of robust electrodes for capacitive deionization (CDI). A composite of activated carbon (AC) with titania (TiO2) was concocted via Tween 80-assisted sol-gel process. The effects of Tween 80 on AC particles interaction with titanium tetraisopropoxide (TTIP) and properties of the composite were systematically scrutinized by multiple analytical techniques including scanning electron microscopy (SEM), laser diffraction (LD), contact angle (CA) measurement, X-ray diffraction (XRD), nitrogen sorption isotherms and X-ray photoelectron spectroscopy (XPS). Electrochemical characterization was conducted by cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), and electrochemical impedance spectroscopy (EIS). The results show the essential role of Tween 80 for homogeneous bonding of titania and altering characteristics of AC-T80/TiO2 composite. As such, the composite exhibited enhanced specific capacitance, and efficiency owing to the modulated benchmark properties (wettability, homogeneity, structure, and conductivity). Subsequently, the composite delivered the salt adsorption capacity (SAC) of 17.1 mg g−1 (26% higher than surfactant-free composite) at 1.4 V, with outstanding capacity retention (87%) over 150 cycles in oxygen saturated saline water (10 mM). This work discloses a novel strategic approach for carbon-metal compound composites synthesis with fundamental aspects for CDI application.

Effect of granular activated carbon particle sizes and depths in slow sand filter on water purification

Most rural dwellers in Nigeria depend on contaminated water from ponds, streams and wells for drinking water. Every household needs simple water purification device like Slow Sand Filter (SSF) to prevent water-borne diseases. This study was conducted to determine the effect of Granular Activated Carbon (GAC) particle sizes and depths in SSF on the purification of water. Two sets of SSF were fabricated using 6 inches (15.24cm) diameter PVC pipe, fine sand (0.25 mm grain size) with 35 cm depth. GAC for the first set SSFs (particle sizes 10 mm, 14 mm with 15 cm depth) and GAC for the second set of the SSFs has 15 and 25 cm depths with particle size 10 mm. The SSF has 50 litres storage tank from which raw water flows into the filter chamber (15.25 diameter and 110 cm long PVC). The filter was kept moist for 21 days for schmutzdecke to fully develop which is effective in trapping bacteria. Raw water was poured into the SSF, water samples were collected and analyzed using standard methods. The SSF has a capacity of producing 35 litres/h clean water. Percentage reduction of Lead, Manganese, Copper, Iron, Turbidity and Total Coliform Counts of the filtered water compared with the control were 91.35-99.88%, 90.00-98.33%, 42.00-100.00%, 46.67-100.00%, 13.04-99.15% and 16.67-57.69%, respectively. The SSF increased pH and Calcium by 7.14-27.71% and 83.65-98.21%, respectively. SSF with 10 mm and 25 cm depths GAC reduced the pollutants than the other two filters and it is recommended for purifying pond water.

Application of a fluidized three-dimensional electrochemical reactor with Ti/SnO2–Sb/β-PbO2 anode and granular activated carbon particles for degradation and mineralization of 2,4-dichlorophenol: Process optimization and degradation pathway

A three-dimensional electrochemical reactor with Ti/SnO2–Sb/β-PbO2 anode and granular activated carbon (3DER-GAC) particle electrodes were used for degradation of 2,4-dichlorophenol (2,4-DCP). Process modeling and optimization were performed using an orthogonal central composite design (OCCD) and genetic algorithm (GA), respectively. Ti/SnO2–Sb/β-PbO2 anode was prepared by electrochemical deposition method and then its properties were studied by FESEM, EDX, XRD, Linear sweep voltammetry and accelerated lifetime test techniques. The results showed that lead oxide was precipitated as highly compact pyramidal clusters in the form of β-PbO2 on the electrode surface. In addition, the prepared anode had high stability (170 h) and oxygen evolution potential (2.32 V). A robust quadratic model (p-value < 0.0001 and R2 > 0.99) was developed to predict the 2,4-DCP removal efficiency in the 3DER-GAC system. Under optimal conditions (pH = 4.98, Na2SO4 concentration = 0.07 M, current density = 35 mA cm−2, GAC amount = 25 g and reaction time = 50 min), the removal efficiency of 2,4-DCP in the 3DER-GAC system and the separate electrochemical degradation process (without GAC particle electrode) were 99.8 and 71%, respectively. At a reaction time of 80 min, the TOC removal efficiencies in the 3DER-GAC and the separate electrochemical degradation system were 100 and 57.5%, respectively. Accordingly, the energy consumed in these two systems was calculated to be 0.81 and 1.57 kWh g−1 TOC, respectively. Based on the results of LC-MS analysis, possible degradation pathways of 2,4-DCP were proposed. Trimerization and ring opening reactions were the two dominant mechanisms in 2,4-DCP degradation.

Efficient Removal of Dye from Wastewater without Selectivity Using Activated Carbon-Juncus effusus Porous Fibril Composites.

Adsorption techniques have been successfully applied in water purification because of their flexibility, simplicity of design, and effectiveness. Activated carbon is an effective absorbent using for dye adsorption; however, the powder structure is not conducive for practical applications and cannot be used to filter dye solutions which are challenges that still need to be addressed. Herein, a natural cellulose-based absorbent, activated carbon-Juncus effusus fiber (AC-JE fiber), demonstrates the removal of all kinds of dyes without selectivity and humic substances and humic-like organics from wastewater. The combined macroporous structures of JE fibers and the microporous and mesoporous structures of activated carbon particles enhance their adsorption properties. These composite absorbents have excellent adsorption and continuous filtration effect. The rejection rate is approximately 100% not only on acidic and anionic dyes but also on basic and cationic dyes. Moreover, the dye solution adsorbed by AC-JE fibers exhibits an ideal freshwater quality (almost no bacteria), similar to that of the deionized water. The AC-JE fibers prove their potential for dye removal, in both adsorption and filtration. Their sterilization ability substantiates their potential in the field of water purification as they can be used as ideal absorbents based on cellulose for removing dyes and purifying wastewater.

A novel ball-milled aluminum-carbon composite for enhanced adsorption and degradation of hexabromocyclododecane

Hexabromocyclododecane (HBCD) is one of the priority persistent organic pollutants (POPs), yet a cost-effective technology has been lacking for the removal and degradation of HBCD. Zero-valent aluminum (ZVAl) is an excellent electron donor. However, the inert and hydrophilic surface oxide layer impedes the release of the electrons from the core metallic Al, resulting in poor reactivity towards HBCD. In this research, a new type of modified mZVAl particles (AC@mZVAlbm/NaCl) were prepared through ball milling mZVAl in the presence of activated carbon (AC) and NaCl, and tested for adsorption and reductive degradation of HBCD in water. AC@mZVAlbm/NaCl was characterized with a metallic Al core with newly created reactive surface coated with a thin layer of crushed carbon nanoparticles. AC@mZVAlbm/NaCl was able to rapidly (within 1 h) adsorb HBCD (C0 = 2 mg L−1) and thus effectively enriched HBCD on the carbon surface of AC@mZVAlbm/NaCl. The pre-enriched HBCD was subsequently degraded by the electrons from the core Al, and ∼63.44% of the pre-sorbed HBCD was completely debrominated after 62 h of the contact. A notable time lag (∼12 h) from the onset of the adsorption to the debromination was observed, signifying the importance of the solid-phase mass transfer from the initially adsorbed AC particles to the reactive Al-AC interface. Overall, AC@mZVAlbm/NaCl synergizes the adsorptive properties of AC and the high reactivity of metallic Al, and enables a novel two-step adsorption and reductive degradation process for treating HBCD or likely other POPs.

Biological activated carbon process for biotransformation of azo dye Carmoisine by Klebsiella spp.

ABSTRACT The feasibility of employing the biological activated carbon (BAC) process to debilitate azo dye Carmoisine by Klebsiella spp. was investigated. Plate assay revealed the capability of Klebsiella spp. for removal of Carmoisine via degradation. Kinetic parameters were measured for Carmoisine debilitation by Klebsiella spp. using the suspended anaerobic process. Two types of granular and rod-shaped activated carbon were used to form the biological beds in order to study the Carmoisine debilitation in batch processes. Scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM) were used to indicate the colonization and biofilm formation of bacteria grown on activated carbon particles (ACPs). Thin-layer chromatography (TLC), liquid chromatography–mass spectrometry (LC–MS), high-pressure liquid chromatography (HPLC) and biosorption studies demonstrated biotransformation of Carmoisine into its constituent aromatic amines during the Carmoisine debilitation in suspended anaerobic and BAC processes. The porosity of activated carbons, inoculation size and age of biological beds were the important factors affecting the viability of bacterial cells grown on ACPs and, consequently, the rate and efficiency of the Carmoisine debilitation process determined through spectrophotometry. The reusability of biological beds was demonstrated by conducting sequential batch experiments. In conclusion, the BAC process proved to be an efficient method for anaerobic dye degradation.