Microwave-assisted modification of activated carbon with ammonia for efficient pyrene adsorption

Xinyu Ge,Zhansheng Wu,Zhilin Wu,Yujun Yan,Giancarlo Cravotto,Bang-Ce Ye 한국공업화학회 2016 Journal of Industrial and Engineering Chemistry Vol.39 No.-

With the aim to enhance the adsorption properties of polycyclic aromatic hydrocarbons (PAHs) fromaqueous solutions, coal-based activated carbon (CAC) was modified with three different protocols: (i)ammonia treatment (A-CAC), (ii) microwave radiation (M-CAC) (iii) and combined microwave radiationin the presence of ammonia (MA-CAC). The original CAC and all the modified samples were characterizedby SEM, nitrogen adsorption–desorption, Boehm method, point of zero charge, FTIR and XPS. The surfacearea increased from 764.96 to 1293.78 m2/g for CAC and MA-CAC, whereas the total oxygen-containinggroups decreased from 1.57 to 0.25 mmol/g. The pyrene adsorption capacity of all the modified sampleswas higher than CAC and the adsorption process for pyrene to the equilibrium needed only 40 min. Adsorption of pyrene on CAC and MA-CAC varies from the monolayer to multilayer process. The filmdiffusion could control the adsorption rate of pyrene onto carbons. The adsorption capacity of the CACand modified samples had a good positive correlation with surface area, carboxyl groups, and lactonesgroups. The modified samples, especially MA-CAC, showed an enhanced adsorption of pyrene openingthe way to a more general application as efficient adsorbent for PAHs contaminant.

Photodegradation of formaldehyde by activated carbon loading TiO2 synthesized via microwave irradiation

Fei Tian,Zhansheng Wu,Yujun Yan,Xinyu Ge,Yanbin Tong 한국화학공학회 2015 Korean Journal of Chemical Engineering Vol.32 No.7

A microwave-assisted synthetic method to form a series of AC/TiO2 for application as photocatalytic degradation of formaldehyde (HCHO) is presented. The influence of prepared conditions such as microwave power, microwave time, and the ratio of activated carbon and titanium dioxide sol (AC/TiO2-sel) on the degradation of HCHO was investigated. HCHO conversion of 58.68% was achieved by AC/TiO2 at microwave power of 700W for 15 min with AC/TiO2-sel ratio of 1 : 2, which maintained multiple properties including high content of anatase and TiO2 largely distributed on AC without reunion, and possessed abundant functional groups for degradation. The influence of operation parameters on the degradation was also investigated: increasing dosage of catalyst and decreasing the initial concentration of HCHO could increase the conversion of HCHO. Acidic conditions can promote degradation effect. Stronger intensity of UV irradiating could improve efficiency of photocatalytic conversion of HCHO.

Microwave-assisted modification of activated carbon with cationic surfactants for enhancement of naphthalene adsorption

Zhonghai Sun,Zhansheng Wu,Dandan Liu,Xiufang He 한국화학공학회 2018 Korean Journal of Chemical Engineering Vol.35 No.2

Polycyclic aromatic hydrocarbons (PAHs) are toxic pollutants harmful to humans. To improve the adsorption capacity of PAHs on activated carbon (AC) from the aqueous system, AC was modified with cationic surfactants through microwave heating. Naphthalene is a typical PAH used as a model pollutant to test the adsorption properties of sample; the sample with the best adsorption performance was named SAC. The SAC was characterized by SEM, FTIR and BET in detail compared with AC. The specific surface area and the average pore size of SAC increased by nearly 100m2 g−1 and 0.14 nm more than the original AC, respectively. The adsorption experiment was carried out by batch technique with variables such as contact time, adsorbent amount, pH and temperature. Results showed that naphthalene was adsorbed rapidly during the first 20min, and thereafter reached adsorption equilibrium in 40 min. The adsorption kinetics of naphthalene on SAC can be well described by the pseudo-second-order model and the Freundlich isotherm model better fitted the adsorption isotherms of naphthalene on SAC. Naphthalene adsorption process on SAC was spontaneous and temperature was found to negatively affect the adsorption capacity. Furthermore, film diffusion was confirmed the rate limiting step. The π-π stacking electron donor acceptor interaction, hydrophobic interaction and hydrogen bonding may play more key roles in naphthalene adsorption on SAC than AC. Thus, microwave- assisted surfactants modification was proven to be an effective method to enhance the adsorption of naphthalene onto SAC from aqueous solution.

Comparison study of naphthalene adsorption on activated carbons prepared from different raws

Pengyun Liu,Zhansheng Wu,Zhonghai Sun,Jun Ye 한국화학공학회 2018 Korean Journal of Chemical Engineering Vol.35 No.10

Five activated carbons (ACs) from apricot shells (ACAS), mixture of lignin and cellulose (ACLC), wood (ACW), walnut shells (ACWS), and coal (CAC) were prepared and used as adsorbents to study the adsorption behavior of naphthalene. All ACs were characterized by scanning electron microscopy, N2 adsorption-desorption method, Xray photoelectron spectroscopy, and elemental analysis. The effects of initial concentration, contact time, ionic strength, pH, and temperature on the adsorption of ACs for naphthalene were examined. Results show that CAC exhibit higher micropore specific surface area and contain more C-O bond than other ACs. Except for ACW, CAC is the least polar or the most hydrophobic adsorbent among ACs. This finding may be helpful in the formation of hydrogen bonding between CAC and naphthalene. The adsorption quantity of CAC was 227.03mg g1 at 303K, which was considerably higher compared with that of other ACs. The kinetics process of naphthalene on all ACs was controlled by pseudo-second-order kinetic model. The adsorption equilibrium of naphthalene on ACs was reached at 40min. The adsorption isotherms of naphthalene to ACs were consistent with the Freundlich isotherm model. The result of thermodynamic analysis shows that the adsorption occurs spontaneously. Moreover, the higher starting naphthalene concentration and lower adsorption temperature significantly can enhance the adsorption capacity of CAC. The maximum adsorption value of naphthalene on ACs was also observed at pH 4 under the same conditions. Moreover, the increase in ionic strength slightly promotes the adsorption of naphthalene on ACs. The microporous structure, element content and surface functional group of ACs affect its adsorption capacity.

Adsorption behavior of phenanthrene onto coal-based activated carbon prepared by microwave activation

Xuemin Xiao,Fei Tian,Yujun Yan,Zhilin Wu,Zhansheng Wu,Giancarlo Cravotto 한국화학공학회 2015 Korean Journal of Chemical Engineering Vol.32 No.6

Coal-based activated carbon (CAC) was prepared from coal produced in Xinjiang of China by microwave activation. CAC was characterized and used as an adsorbent for phenanthrene adsorption. The effects of temperature, adsorption time, CAC amount, initial concentration and pH value of solution on phenanthrene adsorption were studied. The adsorption rate of phenanthrene onto CAC was obtained nearly 100% with initial concentration of 100 mg/L and CAC dosage of 0.3 g at 25 oC. Phenanthrene adsorption was well described with the Langmuir isotherm. The pseudosecond- order model was found to more effectively explain the adsorption kinetics of phenanthrene. The lower temperature was favorable to the adsorption rate and equilibrium adsorption capacity of phenanthrene onto CAC. The thermodynamic parameters ΔHθ, ΔSθ and ΔGθ computed for phenanthrene adsorption onto CAC demonstrate the process was spontaneous, radiative, and entropically driven. Thus, CAC prepared by microwave activation could be effective for removing phenanthrene.

Structure and magnetic properties of CrN thin films on La0.67Sr0.33MnO3

Zhongpo Zhou,Dingbo Zhang,Haiying Wang,Tianxing Wang,Zhansheng Lu,Zongxian Yang,Zhiwei Ai,Hao Wu,Chang Liu 한국물리학회 2018 Current Applied Physics Vol.18 No.11

High crystalline quality CrN thin films have been grown on La0.67Sr0.33MnO3 (LSMO) templates by molecular beam epitaxy. The structure and magnetic properties of CrN/LSMO heterojunctions are investigated combining with the experiments and the first-principles simulation. The Nėel temperature of the CrN/LSMO samples is found to be 281 K and the saturation magnetization of CrN/LSMO increases compared to that of LSMO templates. The magnetic property of CrN/LSMO heterostructures mainly comes from Cr atoms of (001) CrN and Mn atoms of (001) LSMO. The (001) LSMO induces and couples the spin of the CrN sublattice at CrN/LSMO interface.

Enhanced carrier transport and visible light response in CA-β-CD/g-C3N4/Ag2O 2D/0D heterostructures functionalized with cyclodextrin for effective organic degradation

Xue Li,Tingting Liu,Fei Tian,Xiyang Tao,Zhansheng Wu 한국화학공학회 2022 Korean Journal of Chemical Engineering Vol.39 No.11

The high cost and low carrier separation efficiency of g-C3N4/Ag2O photocatalysts affect its application in the degradation of organic pollutants. In this study, the CA-βCD/g-C3N4/Ag2O 2D/0D heterojunction photocatalysts were successfully prepared to enhance the visible light response and inhibit the electron-hole recombination simultaneously during pollutant degradation. The 10:1:1 CA-βCD/g-C3N4/Ag2O showed the outstanding photochemical catalysis performance for the degradation of organic pollutants. The degradation efficiency of methyl orange, reactive black and norfloxacin was 2.53, 1.92 and 1.14 times than that of 1:1 g-C3N4/Ag2O. In addition, 10:1:1 CA-β-CD/g-C3N4/Ag2O also showed excellent photocatalytic stability. The free radical scavenging experiment and electron spin resonance proved that ·O − 2 was the chief active specie in the degradation process. The mechanism research results showed that the formation of heterojunction improved the utilization rate of sunlight and promoted the separation efficiency of photo-generated electrons and holes, which significantly advanced the photocatalytic activity of the composite catalyst. The preparation of CA-βCD/g-C3N4/Ag2O provided ideas for modification of photocatalyst by macromolecular organic matter.