Lihui Huang

Preparation of activated carbon derived from cotton linter fibers by fused NaOH activation and its application for oxytetracycline (OTC) adsorption

The objective of this research is to produce high surface area-activated carbon derived from cotton linter fibers by fused NaOH activation and to examine the feasibility of removing oxytetracycline (OTC) from aqueous solution. The cotton linter fibers activated carbon (CLAC) was characterized by N(2) adsorption/desorption isotherms, Fourier transform infrared spectroscopy (FTIR), and scanning electron microscope (SEM). The results showed that CLAC had a predominantly microporous structure with a large surface area of 2143 m(2)/g. The adsorption system followed pseudo-second-order kinetic model, and equilibrium was achieved within 24h. The equilibrium data were described well by Langmuir isotherm. Thermodynamic study showed that the adsorption was exothermic reaction at low concentration and became endothermic nature with the concentration increasing. Competitive adsorption took place in the weakly acidic to neutral conditions. Under the strong acidity or strong alkaline condition, the adsorption of the oxytetracycline was hindered by electrostatic repulsion. The adsorption mechanism depended on the pH of the solutions as well as the pK(a) of the oxytetracycline.

Enhanced adsorption of chromium onto activated carbon by microwave-assisted H3PO4 mixed with Fe/Al/Mn activation

FeCl3, AlCl3 and MnCl2 were used as the assisted activation agent in activated carbon preparation by H3PO4 activation using microwave heating method. The physico-chemical properties of activated carbons were investigated by scanning electron microscope (SEM), N2 adsorption/desorption, Boehms titration, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). To investigate the adsorption performances of chromium onto these newly developed activated carbons, a batch of experiments were performed under different adsorption conditions: solution pH, initial Cr(VI) ion concentration, contact time and co-existing ions. The results suggested that carbon with MnCl2 as assisted activation agent displayed the highest BET surface area (1332m(2)/g) and the highest pore volume (1.060cm(3)/g). FeCl3, AlCl3 and MnCl2 had successfully improved Cr(VI) adsorption and activated carbon with FeCl3 as assisted activation agent exhibited the best uptake capacity. To study the transformation of Cr(VI) in adsorption process, total chromium in the aqueous solution was also recorded. The ratio of the amount of Cr(VI) to Cr(III) on each adsorbent was explained by XPS analysis results. Both the co-existing salts (Na2SO4 and NaNO3) demonstrated promoted effects on Cr(VI) removal by four carbons. The pseudo-second-order model and Freundlich equation displayed a good correlation with adsorption data.

Influences of two antibiotic contaminants on the production, release and toxicity of microcystins

The influences of spiramycin and amoxicillin on the algal growth, production and release of target microcystins (MCs), MC-LR, MC-RR and MC-YR, in Microcystis aeruginosa were investigated through the seven-day exposure test. Spiramycin were more toxic to M. aeruginosa than amoxicillin according to their 50 percent effective concentrations (EC(50)) in algal growth, which were 1.15 and 8.03 μg/l, respectively. At environmentally relevant concentrations of 100 ng/l-1 μg/l, spiramycin reduced the total MC content per algal cell and inhibited the algal growth, while exposure to amoxicillin led to increases in the total MC content per algal cell and the percentage of extracellular MCs, without affecting the algal growth. Toxicity of MCs in combination with each antibiotic was assessed in the luminescent bacteria test using the toxic unit (TU) approach. The 50 percent effective concentrations for the mixtures (EC(50mix)) were 0.56 TU and 0.48 TU for MCs in combination with spiramycin and amoxicillin, respectively, indicating a synergistic interaction between MCs and each antibiotic (EC(50mix)<1TU). After seven-day exposure to 100 ng/l-1 μg/l of antibiotics, spiramycin-treated algal media and amoxicillin-treated algal media showed significantly lower (p<0.05) and higher (p<0.05) inhibition on the luminescence of Photobacterium phosphoreum, respectively, compared with the untreated algal medium. These results indicated that the toxicity of MCs were alleviated by spiramycin and enhanced by amoxicillin, and the latter effect would increase threats to the aquatic environment.

Adsorption of tetracycline and ciprofloxacin on activated carbon prepared from lignin with H3PO4 activation

AbstractAdsorption of tetracycline (TC) and ciprofloxacin (CPX) onto activated carbon prepared from lignin by H3PO4 impregnated was investigated. Lignin-activated carbon (LGAC) was carbonized at 450°C in a muffle furnace for 1 h. Scanning electron microscope, N2 adsorption–desorption isotherms, X-ray diffraction, pH at the point of zero charge and Boehm titration analysis need to characterize the properties of LGAC. Batched adsorption experiments were performed to study the adsorption properties and interaction mechanisms between TC/CPX and LGAC. The prepared activated carbon was found to have a porous structure with surface area of 931.53 m2/g and many functional groups (acidic groups, basic groups). The adsorption kinetics for the two adsorbates both well fitted the pseudo-second-order model (R2 > 0.99). Compared with Temkin isotherm and Freundlich isotherm, the adsorption equilibrium data were very well represented by the Langmuir isotherm. The maximum adsorption capacities for the TC and CPX calculate...

Preparation of activated carbons from Iris tectorum employing ferric nitrate as dopant for removal of tetracycline from aqueous solutions

Ferric nitrate was employed to modify activated carbon prepared from Iris tectorum during H₃PO₄ activation and ability of prepared activated carbon for removal of tetracycline (TC) was investigated. The properties of the activated carbon samples with or without ferric nitrate, ITAC-Fe and ITAC, were measured by scanning electron microscopy (SEM), N₂ adsorption/desorption isotherms, Fourier transform infrared spectroscopy (FTIR) and Boehms titration. The results showed that mixing with iron increased the BET surface area, total pore volume and the adsorption capacity as compared to the original carbon. FTIR and Boehms titration suggested that ITAC-Fe was characteristic of more acidic functional groups than ITAC. Adsorption of TC on both samples exhibited a strong pH-dependent behavior and adsorption capacity reduced rapidly with the increasing solution pH. The adsorption kinetics agreed well with the pseudo-second-order model and the adsorption isotherms data were well described by Langmuir model with the maximum adsorption capacity of 625.022 mg/g for ITAC and 769.231 mg/g for ITAC-Fe. The present work suggested that ITAC-Fe could be used to remove tetracycline effectively from aqueous solutions.

Characterization of Activated Carbon Fiber by Microwave Heating and the Adsorption of Tetracycline Antibiotics

In this research, activated carbon fiber heated by microwave (WACF) under nitrogen (N2) atmosphere adsorption of tetracycline antibiotics (TCs) was analyzed. WACF was obtained under the microwave radiation temperature of 600°C and the radiation time of 15 min. The properties of WACF were characterized by a scanning electron microscope (SEM), N2 adsorption/desorption isotherms, and X-ray diffraction (XRD) compared with activated carbon fibers (ACF) without any treatment. WACF had lower surface area (1008 m2/g) but higher external surface area (429 m2/g) than ACF (surface area: 1153 m2/g; external surface area: 308 m2/g). Meanwhile, the adsorption efficiencies of TCs (including tetracycline hydrochloride (TC) and oxytetracycline hydrochloride (OTC)) on WACF were both increased by about 4 times. These results indicated that mesoporosity amplification of WACF played a crucial role in the adsorption capacity of the two TCs. The kinetics and equilibrium data were agreed well with the pseudo-second-order kinetics model (R 2 > 0.99) and Langmuir isotherm model (R 2 > 0.98), respectively. It suggested that the adsorption process was dominated by chemisorption. Batch experiments showed the maximum adsorption capacities for both adsorbates were 339 and 331 mg/g respectively at pH 2.

Adsorption of Cd(II) on lotus stalks-derived activated carbon: batch and column studies

Abstract This paper reports a study of adsorption of Cd(II) from aqueous solutions using activated carbon made from lotus stalks (LSAC). The properties of LSAC were characterized by scanning electron microscopy and BET surface area. Zeta potential was also determined. The batch Cd(II) adsorption on LSAC was performed to study the different sorption parameters (time, pH, temperature and ionic strength) that influence the adsorption of Cd(II) onto LSAC and to explore the adsorption mechanisms. Bench-scale column tests were also carried out to determine breakthrough curves with varying flow rates and fixed-bed heights. In general, the theoretical q e calculated using the pseudo-second-order kinetic model agreed better with the experimental data than the first-order one. Among the three widely-used isotherms (Langmuir, Freundlich, and Temkin models), the Langmuir model appeared to describe the experimental results best. The Adam–Bohart equation was appropriate for relative concentration ranging from 0.01 up t...

Preparation of Enteromorpha prolifera-based cetyl trimethyl ammonium bromide-doped activated carbon and its application for nickel(II) removal.

Activated carbon was prepared from Enteromorpha prolifera (EP) by H3PO4 activation in the presence of doped cetyl trimethyl ammonium bromide (CTAB), producing EPAC-CTAB. The thermal decomposition process of the activated carbon substrate was identified by thermo-gravimetric analysis. Scanning electron microscope (SEM), N2 adsorption/desorption, Fourier transform infrared spectroscopy (FTIR), Boehm titration, and X-ray Photoelectron Spectroscopy (XPS) were employed to characterize the physicochemical properties of native EPAC and EPAC-CTAB. EPAC-CTAB exhibited smaller surface area (689.0m(2)/g) and lower total pore volume (0.361cm(3)/g) than those of EPAC (1045.8m(2)/g and 1.048cm(3)/g), while the number of acidic groups, oxygen and nitrogen groups on the surface of EPAC-CTAB increased through CTAB doping. The batch kinetics and isotherm adsorption studies of nickel(II) onto the adsorbents were examined and agreed well with the pseudo-second-order model and the Langmuir model. The maximum adsorption capacity determined from the Langmuir model was 16.9mg/g for EPAC and 49.8mg/g for EPAC-CTAB. Under acidic condition, the adsorption of nickel(II) onto EPAC and EPAC-CTAB was hindered due to ion competition and electrostatic repulsion. The results indicated that using CTAB as a dopant for EPAC modification could markedly enhance the nickel(II) removal.

Preparation of activated carbon derived from leather waste by H3PO4 activation and its application for basic fuchsin adsorption

AbstractLeather activated carbon (LAC) was prepared from the leather waste by H3PO4 impregnated at 105°C for 3 h and activated at 450°C for 1 h in a muffle furnace. Based on LAC, Mn-modified leather activated carbon (LAC-Mn) was also studied. The two adsorbents were characterized by scanning electron microscopy, pore distribution, N2 adsorption/desorption isotherms, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. Several factors, such as contact time, dosage, and pH were studied, which indicated that cation exchange, hydrophobicity, and π-electron-donor–acceptor interaction were likely the adsorption mechanisms for basic fuchsin adsorption. Meanwhile, adsorbent effects of LAC and LAC-Mn were highly pH dependent, which reached maximum under alkaline conditions. The adsorption kinetic followed the pseudo-second-order kinetic model with high correlation coefficients (R2 > 0.99), which means intra-particle diffusion process was not the only mechanism involved. Thermodynamics sho...

Study of ciprofloxacin adsorption and regeneration of activated carbon prepared from Enteromorpha prolifera impregnated with H3PO4 and sodium benzenesulfonate.

Activated carbons were derived from Enteromorpha prolifera immersed in H3PO4 solution or the H3PO4 solution mixed with sodium benzenesulfonate (SBS), producing AC and AC-SBS. NaOH solution was employed in regeneration of ciprofloxacin (CIP)-loaded AC and AC-SBS to obtain RAC and RAC-SBS. The properties of the original and regenerated activated carbons were characterized by thermo-gravimetric analysis (TGA), scanning electron microscopy (SEM), N2 adsorption/desorption isotherms and Fourier transform infrared spectroscopy (FTIR). Batched adsorption studies were carried out to compare CIP adsorption behaviors of the four carbons. The results suggested that the four samples exhibited higher proportions of mesopores and similar functional groups. Although AC displayed much higher specific surface area (SBET) (1045.79m2/g) than AC-SBS (738.03m2/g), its CIP adsorption capacity was much less than AC-SBS. The maximum adsorption capacity for AC, AC-SBS, RAC and RAC-SBS were found to be 250mg/g, 286mg/g, 233mg/g and 256mg/g, respectively, with the isotherms adhering to Langmuir isotherm model. The electrostatic attraction and cation exchange between CIP and the four carbons were the dominant adsorption mechanisms. Moreover, the thermodynamic parameters represented that the adsorption process had been confirmed to be a spontaneous and endothermic reaction.