Surface Of Granular Activated Carbon Research Articles

Granular activated carbon assisted biocathode for effective electrotrophic denitrification in microbial fuel cells

Granular activated carbon (GAC) has been widely used at the anode of a microbial fuel cell (MFC) to enhance anode performance due to its outstanding capacitance property. To the best of our knowledge, there haven't been any studies on GAC in the cathode for biofilm development and nitrate reduction in MFC. In this study, by adding GAC to biocathode, we investigated the impact of different GAC amounts and stirring speeds on power generation and nitrate reduction rate in MFC. The denitrification rate was found to be nearly two-times higher in MFCs with GAC (0.046 ± 0.0016 kg m−3 d−1) compared to that deprived of GAC (0.024 ± 0.0012 kg m−3 d−1). The electrotrophic denitrification has produced a maximum power density of 37.6 ± 4.8 mW m−2, which was further increased to 79.2 ± 7.4 mW m−2 with the amount of GAC in the biocathode. A comparative study performed with chemical catalyst (Pt carbon with air sparging) cathode and GAC biocathode showed that power densities produced with GAC biocathode were close to that with Pt cathode. Cyclic voltammetry analysis conducted at 10 mV s−1 between −0.9 V and +0.3 V (vs. Ag/AgCl) showed consistent reduction peaks at −0.6V (Ag/AgCl) confirming the reduction reaction in the biocathode. This demonstrates that the GAC biocathode used in this research is effective at producing power density and denitrification in MFC. Our belief that the nitrate reduction was caused by the GAC biocathode in MFC was further strengthened when SEM analysis showing bacterial aggregation and biofilm formation on the surface of GAC. The GAC biocathode system described in this research may be an excellent substitute for MFC's dual functions of current generation and nitrate reduction.

Highly efficient removal of amoxicillin from water by three-dimensional electrode system within granular activated carbon as particle electrode

Amoxicillin (AMX) is a widely used broad-spectrum antibiotic. In this study, a three-dimensional electrode system (3DES) was constructed with granular activated carbon (GAC) packed between the anode and cathode electrodes to degrade AMX. Under optimal conditions of 3DES (current density of 5 mA/cm2, 17 mM NaCl as the electrolyte, an initial pH of 5.56, and a GAC-quartz sand volume ratio of 9:1), the removal efficiency of AMX reached 98.98 % after 2 h of treatment. It was also shown that the total organic carbon (TOC) removal efficiency (R) and reaction rate constant (k) of 3DES were 47.6 % and 0.22 h−1, respectively, much higher than the sum of the two-dimensional electrode system (2DES) and adsorption process (30.7 % and 0.12 h−1). Thus, there existed the synergy between electrolysis and adsorption in 3DES, which enhanced the TOC removal efficiency and removal rate by up to 35.5 % and 46.8 %, respectively. Electrochemical characterization was explored using an electrochemical workstation. It demonstrated that GAC played an important role in reducing the mass transfer resistance, and the mass transfer rate of 3DES was 2.24 times that of the 2DES. It was also deduced that AMX adsorbed on the surface of GAC directly participated in the electrochemical oxidation to achieve the in-situ regeneration of activated carbon. The results of Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and Brunauer-Emmett-Teller (BET) of GAC verified it again. In summary, 3DES has good electrochemical performance, and it is an efficient, cost-effective, and environmentally friendly system for AMX degradation.

Anammox bacteria enrichment and denitrification in moving bed biofilm reactors packed with different buoyant carriers: Performances and mechanisms

Anaerobic ammonium oxidation (anammox) is recognized as the most cost-effective process for nitrogen removal from wastewater. In this study, effects of polyethylene plastics, nonwoven fabric, granular activated carbon (GAC) and polyurethane sponge as buoyant carriers were evaluated in lab-scale moving bed biofilm reactors (MBBRs). The overall performance of MBBRs with four types of carriers from priority to inferiority was noticed as, GAC, nonwoven fabrics, polyurethane sponge and polyethylene plastics under the same packing ratio of 20 v% and an average carrier size of 4 × 4 × 4 mm. The hydrophobic surface of GAC could selectively adsorb hydrophobic protein and favor anammox bacteria attachment, which contributed to achieving a total nitrogen removal rate of 0.40 kg-N/(m3·d) in 60 days. In conclusion, our results provide compelling evidence for achieving effective anammox process in an MBBR with GAC carriers and would benefit towards accomplishing a stable partial nitritation-anammox process in the future.

Preparation of zinc oxide catalyst with activated carbon support for ozone decomposition

Investigation of catalyst for ozone decomposition was carried out by using zinc oxide (ZnO) catalyst and granular activated carbon (GAC) support. Ozone needs to be decomposed because it is harmful to human and can lead to death. Before GAC was used as a support, GAC was pre-treated using chloride acid (HCl) and sodium hydroxide (NaOH) to remove impurities. ZnO was impregnated onto the surface of GAC by using zinc carbonate (ZnCO3) solution as precursor and then calcined at 300 °C to decompose carbon dioxide (CO2). Size of GAC and loading percentage of ZnO were varied to get the highest catalytic activity. Size of GAC was varied between 18 – 100 mesh and loading percentage was between 0 – 2%-w. The morphology, composition, and crystal phase were characterized by BET, SEM-EDX, and XRD method. From XRD method, crystal phase of catalyst was changed from ZnCO3 structure to ZnO when calcined with exact temperature. Ozone decomposition was performed at room temperature and atmospheric pressure using fixed bed reactor. ZnO/GAC with smallest size (60 – 100 mesh) and highest loading percentage (2%-w) showed the highest activity which the conversion reached 100% for 30 minutes. ZnO/GAC with smallest size and highest loading percentage had the largest surface area and the most active sites to decompose ozone.

Preparation and characterization of copper oxide catalyst with activated carbon support for ozone decomposition in industrial environment

In this research, ozone decomposition has been synthesized based on copper oxide (CuOx) with granular activated carbon (GAC) as a support catalyst, being used as ozone decomposer in effluent gas emissions of industries that use ozone. Therefore, catalysts were made as a mask filter to decompose ozone. CuOx was impregnated to the surface of GAC by using copper carbonate (CuCO3) as precursor and then calcined to release carbon dioxide with temperature of 300 °C for 1 hour. Size of activated carbon and loading percentage of copper oxide to the support were varied to get the optimum value. The quality of a catalyst such as pore diameter and surface area are characterized by BET, the cross-sectional surface of the catalyst and the catalyst elements composition are analyzed by X-ray spectroscopy (SEM-EDX) and X-Ray Fluorescence (XRF), while CuOx composition and crystal phase are analysed by XRD. Mask filter, which contained catalysts for ozone decomposition, was tested using a fixed bed reactor at room temperature and atmospheric pressure. Results of the catalytic conversion were tested using iodometric method. Activated carbon with smallest diameter (60 - 100 mesh) and highest loading percentage (2 %-wt) showed the highest activity which the ozone conversion to oxygen reached 100%. Amount of CuOx on the support also determine the efficiency of catalyst due to appropriate amount of CuOx probably maintain the morphology and crystal phase of the catalyst.

Residual organic fluorinated compounds from thermal treatment of PFOA, PFHxA and PFOS adsorbed onto granular activated carbon (GAC)

Perfluorooctanoic acid (PFOA), perfluorohexanoic acid (PFHxA) and perfluorooctane sulfonate (PFOS) adsorbed onto granular activated carbon (GAC) were thermally treated in N2 gas stream. The purpose was to assess the fate of perfluoroalkyl and polyfluoroalkyl substances (PFASs) during thermal regeneration of GAC, which had been used for water treatment. Mineralized F, residual PFASs including short-chained species, and volatile organic fluorine (VOF) were determined. In a temperature condition of 700 °C, VOF were 13.2, 4.8, and 5.9 % as for PFOA, PFHxA, and PFOS. However, the VOF decreased to 0.1 %, if the GAC and off-gas were kept at 1000 °C. No PFASs remained in GAC at 700–1000 °C; at the same time, short-chained PFASs were slightly detected in the aqueous trapping of off-gas at 800 and 900 °C conditions. The destruction of PFASs on GAC could be perfect if the temperature is higher than 700 °C; however, the process is competitive against volatile escape from GAC. Destruction in gaseous phase needs a temperature as high as 1000 °C. Destruction of PFASs on the surface of GAC, volatile escape from the site, and thermolysis in gas phase should be considered, as to thermal regeneration of GAC.

Treatment of pyridine-bearing wastewater by Nano Zero-valent iron supported on activated carbon derived from agricultural waste

Nano zero-valent iron particles (nZVI) supported on granular activated carbon (GAC) (nZVI/GAC) were synthesized and its feasibility was explored for the treatment of pyridine-bearing wastewater. nZVI/GAC was synthesized by the borohydride reduction method under ethanol atmosphere. The synthesized nZVI/GAC was characterized by scanning electron microscopy (SEM), X-ray diffraction, Fourier transform infrared spectroscopy, and N2 adsorption–desorption study. Results indicated that the nZVI was well dispersed on the surface of GAC. The presence of support material apparently decreased the extent of aggregation and size of the nZVI and thus, facilitated in increasing the pyridine removal efficiency. Batch studies were carried out in order to evaluate the effect of operating parameters such as pH (2 ≤ pH ≤ 9), dose (m) (5 ≤ m ≤ 15 g/l), initial concentration (Co) (50 ≤ Co ≤ 1000 mg/l), and temperature (T) (288 ≤ T ≤ 318 K). At optimum condition, maximum removal of pyridine was found to be ~86% at m = 15 g/l, pH = 6, Co = 100 mg/l, and T = 303 K. The degradation kinetics has been investigated, and pseudo-first-order kinetic model was found to be suitable fit for the experimental data kinetic model. The apparent activation energy (Ea) of this process was found to be ~22.46 (kJ/mol). The nZVI/GAC showed stable performance for the degradation of pyridine-bearing wastewater until five consecutive cycles.

Impact of ozonation pre-treatment of oil sands process-affected water on the operational performance of a GAC-fluidized bed biofilm reactor.

Treatment of oil sands process-affected water (OSPW) using biodegradation has the potential to be an environmentally sound approach for tailings water reclamation. This process is both economical and efficient, however, the recalcitrance of some OSPW constituents, such as naphthenic acids (NAs), require the pre-treatment of raw OSPW to improve its biodegradability. This study evaluated the treatment of OSPW using ozonation followed by fluidized bed biofilm reactor (FBBR) using granular activated carbon (GAC). Different organic and hydraulic loading rates were applied to investigate the performance of the bioreactor over 120 days. It was shown that ozonation improved the adsorption capacity of GAC for OSPW and improved biodegradation by reducing NAs cyclicity. Bioreactor treatment efficiencies were dependent on the organic loading rate (OLR), and to a lesser degree, the hydraulic loading rate (HLR). The combined ozonation, GAC adsorption, and biodegradation process removed 62 % of chemical oxygen demand (COD), 88 % of acid-extractable fraction (AEF) and 99.9 % of NAs under optimized operational conditions. Compared with a planktonic bacterial community in raw and ozonated OSPW, more diverse microbial communities were found in biofilms colonized on the surface of GAC after 120 days, with various carbon degraders found in the bioreactor including Burkholderia multivorans, Polaromonas jejuensis and Roseomonas sp.

Comparison Between Dielectric Barrier Discharge Plasma and Ozone Regenerations of Activated Carbon Exhausted with Pentachlorophenol

In this study, two regeneration methods (dielectric barrier discharge (DBD) plasma and ozone (O3) regeneration) of saturated granular activated carbon (GAC) with pentachlorophenol (PCP) were compared. The results show that the two regeneration methods can eliminate contaminants from GAC and recover its adsorption properties to some extent. Comparing the DBD plasma with O3 regeneration, the adsorption rate and the capacity of the GAC samples after DBD plasma regeneration are greater than those after O3 regeneration. O3 regeneration decreases the specific surface area of GAC and increases the acidic surface oxygen groups on the surface of GAC, which causes a decrease in PCP on GAC uptake. With increasing regeneration cycles, the regeneration efficiencies of the two methods decrease, but the decrease in the regeneration efficiencies of GAC after O3 regeneration is very obvious compared with that after DBD plasma regeneration. Furthermore, the equilibrium data were fitted by the Freundlich and Langmuir models using the non-linear regression technique, and all the adsorption equilibrium isotherms fit the Langmuir model fairly well, which demonstrates that the DBD plasma and ozone regeneration processes do not appear to modify the adsorption process, but to shift the equilibrium towards lower adsorption concentrations. Analyses of the weight loss of GAC show that O3 regeneration has a lower weight loss than DBD plasma regeneration.

Microbial community structure and operational performance of a fluidized bed biofilm reactor treating oil sands process-affected water

This study evaluated the treatment of oil sands process-affected water (OSPW) using a fluidized bed biofilm reactor (FBBR) with granular activated carbon (GAC) as support media. The bioreactor was operated for 120 days at different organic and hydraulic loading rates. The combined GAC adsorption and biodegradation process removed 51% of chemical oxygen demand (COD), 56% of acid-extractable fraction (AEF) and 96% of classical naphthenic acids (NAs) under optimized operational conditions. Bioreactor treatment efficiencies were dependent on the organic loading rate (OLR), and to a lower degree, on the hydraulic loading rate (HLR). Further ultra performance liquid chromatography/high resolution mass spectroscopy (UPLC/HRMS) analysis showed that the removal of classical NAs increased as the carbon number increased. Compared with planktonic bacterial community in OSPW, more diverse microbial structures were found in biofilms colonized on the surface of GAC after 120-day treatment, with various carbon degraders namely Polaromonas jejuensis, Algoriphagus sp., Chelatococcus sp. and Methylobacterium fujisawaense in the GAC-biofilm reactor. The results of this study, therefore, showed that the GAC-biofilm seems to be a promising biological treatment method for OSPW remediation.

Sorptive Uptake Studies of an Aryl-Arsenical with Iron Oxide Composites on an Activated Carbon Support.

Sorption uptake kinetics and equilibrium studies for 4-hydroxy-3-nitrobenzene arsonic acid (roxarsone) was evaluated with synthetic magnetite (Mag-P), commercial magnetite (Mag-C), magnetite 10%, 19%, and 32% composite material (CM-10, -19, -32) that contains granular activated carbon (GAC), and synthetic goethite at pH 7.00 in water at 21 °C for 24 h. GAC showed the highest sorptive removal of roxarsone and the relative uptake for each sorbent material with roxarsone are listed in descending order as follows: GAC (471 mg/g) > goethite (418 mg/g) > CM-10 (377 mg/g) CM-19 (254 mg/g) > CM-32 (227 mg/g) > Mag-P (132 mg/g) > Mag-C (29.5 mg/g). The As (V) moiety of roxarsone is adsorbed onto the surface of the iron oxide/oxyhydrate and is inferred as inner-sphere surface complexes; monodentate-mononuclear, bidentate-mononuclear, and bidentate-binuclear depending on the protolytic speciation of roxarsone. The phenyl ring of roxarsone provides the primary driving force for the sorptive interaction with the graphene surface of GAC and its composites. Thus, magnetite composites are proposed as multi-purpose adsorbents for the co-removal of inorganic and organic arsenicals due to the presence of graphenic and iron oxide active adsorption sites.

Kinetics of hydrophobic organic contaminant extraction from sediment by granular activated carbon

Ex situ solid phase extraction with granular activated carbon (GAC) is a promising technique to remediate contaminated sediments. The methods' efficiency depends on the rate by which contaminants are transferred from the sediment to the surface of GAC. Here, we derive kinetic parameters for extraction of polycyclic aromatic hydrocarbons (PAH) from sediment by GAC, using a first-order multi-compartment kinetic model. The parameters were obtained by modeling sediment-GAC exchange kinetic data following a tiered model calibration approach. First, parameters for PAH desorption from sediment were calibrated using data from systems with 50% (by weight) GAC acting as an infinite sink. Second, the estimated parameters were used as fixed input to obtain GAC uptake kinetic parameters in sediment slurries with 4% GAC, representing the ex situ remediation scenario. PAH uptake rate constants (kGAC) by GAC ranged from 0.44 to 0.0005 d−1, whereas GAC sorption coefficients (KGAC) ranged from 105.57 to 108.57 L kg−1. These values are the first provided for GAC in the presence of sediment and show that ex situ extraction with GAC is sufficiently fast and effective to reduce the risks of the most available PAHs among those studied, such as fluorene, phenanthrene and anthracene.

Effects of Dielectric Barrier Discharge Plasma Treatment on Pentachlorophenol Removal of Granular Activated Carbon

The pentachlorophenol (PCP) adsorbed granular activated carbon (GAC) was treated by dielectric barrier discharge (DBD) plasma. The effects of DBD plasma on the structure of GAC and PCP decomposition were analyzed by N2 adsorption, thermogravimetric, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and gas chromatography mass spectrometry (GC-MS). The experimental data of adsorption kinetics and thermodynamics of PCP on GAC were fitted with different kinetics and isotherm models, respectively. The results indicate that the types of N2 adsorption isotherm of GAC are not changed by DBD plasma, while the specific surface area and pore volume increase after DBD plasma treatment. It is found that the weight loss of the saturated GAC is the highest, on the contrary, the weight loss of DBD treated GAC is the least because of reduced PCP residue on the GAC. The XPS spectra and SEM image suggest that some PCP on the GAC is removed by DBD plasma, and the surface of GAC treated by DBD plasma presents irregular and heterogeneous morphology. The GC-MS identification of by-products shows that two main dechlorination intermediate products, tetrachlorophenol and trichlorophenol, are distinguished. The fitting results of experimental data of adsorption kinetics and thermodynamics indicate that the pseudo-first-order and pseudo-second order models can be used for the prediction of the kinetics of virgin GAC and DBD treated GAC for PCP adsorption, and the Langmuir isotherm model fits better with the data of adsorption isotherm than the Freundlich isotherm in the adsorption of PCP on virgin GAC and DBD treated GAC.

Surface modification of a granular activated carbon by dielectric barrier discharge plasma and its effects on pentachlorophenol adsorption

Abstract The surface properties of a granular activated carbon (GAC) were modified by dielectric barrier discharge (DBD) plasma to enhance its adsorption capacity to pentachlorophenol (PCP). Surface characteristics and adsorption capacity of GAC before and after DBD plasma modification were investigated. Results showed that the surface of GAC after plasma modification, especially N 2 plasma, became smoother and the particulates on virgin GAC's surface were eliminated due to deposit effect of plasma. The N 2 plasma modification reduced the specific surface area and surface oxygen-containing functional groups of GAC. In contrast, O 2 plasma modification increased the specific surface area and introduced oxygen-containing groups.

Preparation of Nano-Sized TiO<sub>2</sub> Supported on Granular Activated Carbon and the Photocatalytic Degradation of Methylene Blue

nanosized TiO2 were prepared using TiOSO4 as the precursor by hydrolysis-precipitation and hydrothermal method. Through dipping granular activated carbon (GAC) into the TiO2 hydrosols, The nanosized TiO2/GACs composite was obtained. The surface morphology, microstructure and element distribution of the composite were characterized by TEM, SEM, XRD, EDS respectively. The results show that the synthesized nanosized TiO2 is anatase phase with average size of 150-200 nm and can be dispersed uniformly on the surface of GACs. Photocatalytic experimental shows that when the load amount is 1.5%, the nanosized TiO2/GACs composite have the best effect of removal methylene blue,the rate up to 97.0 % in 180 min.

Modeling and simulations of the removal of formaldehyde using silver nano-particles attached to granular activated carbon

A combined reaction, consisting of granular activated carbon (GAC) adsorption and catalytic oxidation, has been proposed to improve the removal efficiencies of formaldehyde, one of the major indoor air pollutants. In this study, silver nano-particles attached onto the surface of GAC (Ag-GAC) using the sputtering method were evaluated for the simultaneous catalytic oxidation and adsorption of formaldehyde. The evolution of CO 2 from the silver nano-particles indicated that formaldehyde was catalytically oxidized to its final product, with the oxidation kinetics expressed as pseudo-first order. In addition, a packed column test showed that the mass of formaldehyde removed by the Ag-GAC was 2.4 times higher than that by the virgin GAC at a gas retention time of 0.5 s. However, a BET analysis showed that the available surface area and micro-pore volume of the Ag-GAC were substantially decreased due to the deposition of the silver nano-particles. To simulate the performance of the Ag-GAC, the homogeneous surface diffusion model (HSDM), developed for the prediction of the GAC column adsorption, was modified to incorporate the catalytic oxidation taking place on the Ag-GAC surface. The modified HSDM demonstrated that numerical simulations were consistent with the experimental data collected from the Ag-GAC column tests. The model predictions implied that the silver nano-particles deposited on the GAC reduced the adsorptive capacity due to decreasing the available surface for the diffusion of formaldehyde into the GAC, but the overall mass of formaldehyde removed by the Ag-GAC was increased due to catalytic oxidation as a function of the ratio of the surface coverage by the nano-particles.

The fate and transport of the SiO 2 nanoparticles in a granular activated carbon bed and their impact on the removal of VOCs

Adsorption isotherm, adsorption kinetics and column breakthrough experiments evaluating trichloroethylene (TCE) adsorption onto granular activated carbon (GAC) were conducted in the presence and absence of silica nanoparticles (SiO 2 NPs). Zeta potentials of the SiO 2 NPs and the GAC were measured. Particle size distribution (PSD) of SiO 2 NPs dispersions was analyzed with time to evaluate the extent of aggregation. TEM analysis was conducted. The specific surface area and the pore size distribution of the virgin and the spent GAC were obtained. The fate and transport of the SiO 2 NPs in the GAC fixed bed and their impact on TCE adsorption were found to be a function of their zeta potential, concentration and PSD. The interaction of the SiO 2 NPs and the GAC is of an electrokinetic nature. A weak electrostatic attraction was observed between the SiO 2 NPs and the GAC. This attraction favors SiO 2 NPs attachment on the surface of GAC. SiO 2 NPs attachment onto GAC is manifested by a reduction in the amount of TCE adsorbed during the column breakthrough experiments suggesting a preloading pore blockage phenomenon. However, no effect of SiO 2 NPs was observed on the isotherm and the kinetic studies, this is mainly due to the fast kinetics of TCE adsorption.

Consequence of chitosan treating on the adsorption of humic acid by granular activated carbon

In this work, equilibrium and kinetic adsorption of humic acid (HA) onto chitosan treated granular activated carbon (MGAC) has been investigated and compared to the granular activated carbon (GAC). The adsorption equilibrium data showed that adsorption behaviour of HA could be described reasonably well by Langmuir adsorption isotherm for GAC and Freundlich adsorption isotherm for MGAC. It was shown that pre-adsorption of chitosan onto the surface of GAC improved the adsorption capacity of HA changing the predominant adsorption mechanism. Monolayer capacities for the adsorption of HA onto GAC and MGAC were calculated 55.8 mg/g and 71.4 mg/g, respectively. Kinetic studies showed that film diffusion and intra-particle diffusion were simultaneously operating during the adsorption process for MGAC.

Activated carbon catalyzed persulfate oxidation of Azo dye acid orange 7 at ambient temperature

Persulfate (PS) oxidative degradation of azo dye acid orange 7 (AO7) in an aqueous solution was studied in the presence of suspended granular activated carbon (GAC) at ambient temperature (e.g., 25°C). It was observed that there existed a remarkable synergistic effect in the GAC/PS combined system. Higher PS concentration and GAC dosage resulted in higher AO7 degrading rates. Near-neutral was the optimal initial pH. Adsorption had an adverse effect on AO7 degradation. AO7 had not only a good decolorization, but a good mineralization. The decomposition of PS followed a first-order kinetics behavior both in the presence and in the absence of AO7. Radical mechanism was studied and three radical scavengers (methanol (MA), tert-butanol (TBA), phenol) were used to determine the kind of major active species taking part in the degradation of AO7 and the location of degradation reaction. It was assumed that the degradation of AO7 did not occur in the liquid phase, but in the porous bulk and boundary layer on the external surface of GAC. SO4− or HO, generated on or near the surface of GAC, played a major role in the AO7 degradation. Finally, the recovery performance of GAC was studied through the GAC reuse experiments.

Preparation and photocatalytic activity of TiO2-coated granular activated carbon composites by a molecular adsorption-deposition method

TiO2 nanoparticle-coated granular activated carbon (GAC) composite photocatalysts (CPs) were successfully prepared by a molecular adsorption-deposition (MAD) method. The CPs were detected by scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS), BET surface area and UV-Vis adsorption spectroscopy, and their photoactivity was evaluated by methyl orange (MO) photodegradation. The results show that small-sized TiO2 nanoparticles were dispersed well, deposited on the surface of GAC, and showed slight blue shift in comparison with pure TiO2. With the increase in TiO2 content, the CPs showed band gaps in lower energy, smaller surface areas and the higher content of Ti3+ ions. Compared with pure TiO2 and others CPs samples, CPs-382 sample showed the highest photoactivity due to the optimum TiO2 content and surface area besides the synergic effect of photocatalytic degradation of TiO2 and adsorptive property of GAC. In addition, the CPs could be very easily reclaimed, recycled and reused for methyl orange removal while high photoactivity is preserved.