Nature Environment and Pollution Technology

Lingfeng Zhu ¹, Weiyong Zhu ¹, Xiaoqi Chai ¹, Yingying Li ¹, Guoting Li ¹

Affiliations
1 Department of Environmental and Municipal Engineering, North China University of Water Resources and Electric Power, Zhengzhou 450011, CN

Abstract

As one of the major oxidation intermediates generated in advanced oxidation processes, 1,4-benzoquinone is proved to be highly toxic. Adsorptive removal of 1,4-benzoquinone by sugarcane bagasse, a low-cost agricultural waste, was systematically investigated. It was observed that most of the adsorption occurred within the initial 30 min. The results showed that Elovich kinetic model could better describe the kinetic data under all the solution pH conditions examined by non-linear regressive method. Pseudo-second-order kinetic model apparently fitted the experimental data better than pseudo-first-order kinetic model when using linear simulation method. The adsorption process was highly pH dependent, with the greatest adsorption occurring under neutral pH condition, and the highest uptake of 4.5 mg/g was achieved at pH 8.0. Ionic strength test indicated that 1,4-benzoquinone adsorption might form outer-sphere surface complexes with sugarcane bagasse. Natural organic matter (humic acid) significantly inhibited the uptake of 1,4-benzoquinone onto sugarcane bagasse. The study showed that sugarcane bagasse has a great potential application for the adsorptive removal of toxic 1,4-benzoquinone.

Keywords

Sugarcane Bagasse, 1,4-Benzoquinone, Biosorption, Kinetics, Water Purification.

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Guoting Li ¹, Yanmin Feng ¹, Xiaoqi Chai ¹, Xiaoshuang He ¹

Affiliations
1 Department of Environmental and Municipal Engineering, North China University of Water Resources and Electric Power, Zhengzhou 450011, CN

Abstract

Fly ash, an industrial waste from thermal power plants, was used for the adsorptive removal of 1,4-benzoquinone, one of the oxidation intermediates generated in AOPs. Effect of fly ash dosage and solution pH was investigated. The highest 1,4-benzoquinone uptake occurred at pH 7.0. Neutral and alkaline conditions were more favourable for the adsorptive removal of 1,4-benzoquinone. Isotherm data at 288, 298 and 308 K were simulated by Langmuir, Freundlich, Temkin, Redlich-Peterson, Koble-Corrigan and Dubinin- Radushkevich isotherm models. Both the Koble-Corrigan and Dubinin-Radushkevich isotherms can predict equilibrium adsorption behaviour better at different reaction temperatures. The reaction enthalpy was 29.42 kJ/mol and the entropy achieved 164.52 J/mol·K. The change of Gibbs free energy achieved -19.48 kJ/mol at 298 K. The above indicates that the sorption process was spontaneous and endothermic. This also reveals that, fly ash has the potential for the adsorptive removal of 1,4-benzoquinone.

Keywords

Adsorption, 1,4-Benzoquinone, Fly Ash, Kinetic Model, Isotherm Model.

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Lingfeng Zhu ¹, Yixue He ¹, Yujie Guo ¹, Xi Chen ¹, Guoting Li ¹

Affiliations
1 Department of Environmental and Municipal Engineering, North China University of Water Resources and Electric Power, Zhengzhou 450011, CN

Abstract

In order to enhance the adsorption performance of TiO₂, CeO₂ was tentatively introduced into the matrix of TiO₂ by sol-gel method. The prepared adsorbent CeO₂-TiO₂ was used for the efficient adsorptive removal of antibiotics tetracycline (TC). It was observed that the introduction of CeO₂ into TiO₂ matrix has improved the removal efficiency of TC by 57.6% compared to pure TiO₂. The uptake of TC was highly dependent on the solution pH conditions and the highest uptake of TC occurred under alkaline condition. Linear simulation method failed to discern which kinetic model was better to describe the kinetic data between pseudo-first-order and pseudo-second-order models. By nonlinear simulation, Elovich kinetic model was found to be the best model to describe the TC adsorption onto CeO₂-TiO₂, indicating that the pronounced diffusion-control process was the rate-determining step. The maximal adsorption capacity of the prepared sorbent was 59.3 mg/g using Langmuir isotherm model at 298 K. The uptake of TC increased with an increase in the reaction temperature, which demonstrates that the adsorption of TC was endothermic.

Keywords

CeO₂-TiO₂, Tetracycline, Adsorption, Kinetics, Isotherm.

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Xiao Mi ¹, Yujie Guo ¹, Chunyu Zhang ¹, Li Wang ¹, Shen Zhang ¹, Bobo Zou ¹, Zejie Wang ¹, Guoting Li ¹

Affiliations
1 Department of Environmental and Municipal Engineering, North China University of Water Resources and Electric Power, Zhengzhou 450011, CN

Abstract

Sugarcane bagasse, an agricultural waste biomass was used to prepare biochar by pyrolyzing the biomass under oxygen-limited conditions. The prepared biochar was used for the adsorptive removal of a cationic dye methylene blue (MB) under a magnetic field. It was found that the existence of the external magnetic field had significantly enhanced the uptake of MB onto the bagasse biochar. The increased biochar dosage actually declined the uptake of MB while the effect of the magnetic field was still significant. The adsorption kinetics was investigated under different solution pH conditions. The experimental data were simulated using non-linear pseudo-first-order, pseudo-second-order and Elovich kinetic models. The Elovich kinetic model was found to be more suitable to describe the adsorption kinetics. This indicates that the adsorption of MB onto BC400 is a chemisorption process in which the rate-determining step is diffusion in nature. The uptake of MB is mainly attributed to the π-π electron-donor-acceptor interaction and electrostatic attraction.

Keywords

Biochar, Methylene Blue, Adsorption Kinetics, Bagasse, Magnetic Field.

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Gangfu Song ¹, Mingzhao Shen ¹, Kaiyang Zhu ¹, Guoting Li ¹

Affiliations
1 Department of Environmental and Municipal Engineering, North China University of Water Resources and Electric Power, Zhengzhou 450011, CN

Abstract

Adsorbent Mn-modified tourmaline was creatively prepared by wet impregnation in a MnSO4 solution and subsequent calcination procedure. The prepared Mn-modified tourmaline was used for the adsorptive removal of a cationic dye methylene blue (MB). The experimental data under different solution pH conditions were simulated using both linear and non-linear kinetic models. Linear pseudo-secondorder model and non-linear Elovich kinetic model were found to be more suitable to describe the adsorption kinetics. This indicates that the adsorption of MB onto the Mn-modified tourmaline is possibly a chemisorption process in which the rate-determining step is diffusion in nature. The adsorption isotherms were also investigated and the experimental data were fitted by both Langmuir and Freundlich models. Usinxg Langmuir model, the calculated maximal adsorption capacities for MB achieved 158.5 mg/g at 298 K. Thermodynamic analysis indicates that the changes of enthalpy and entropy of the adsorption processes are 55.6 KJ mol-1 and 199.0 J mol-1 k-1, respectively. The negative value of Gibbs free energy change and the positive value of enthalpy also indicates that the adsorption process is spontaneous and endothermic.

Keywords

Mn-Modified Tourmaline, Methylene Blue, Adsorption Kinetics, Isotherm.

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Ruqin Gao ¹, Yiming Gu ¹, Guoting Li ¹, Qian Sun ¹

Affiliations
1 School of Environmental and Municipal Engineering, North China University of Water Resources and Electric Power, Zhengzhou 450045, CN

Abstract

Using diatomite as the main material, diatomite-based porous ceramsite was prepared by wet grinding, molding by rolling and high-temperature calcinations. The structure and properties were characterized by X-ray diffraction, Scanning Electron Microscope, Mercury Injection Apparatus and so on. The ultraviolet-visible spectrophotometer was used to analyse the adsorption properties of diatomite-based porous ceramsite on Cu²⁺. The results show that the pore size distribution of materials is 300~3500 nm, the specific surface area is 6.14 m²/g, and the pore porosity is 47.8%. Plenty of unsaturated bonds, such as -OH, Si-O-Si and O-Si-O, cluster on the surface of ceramsite. The removal rate of Cu²⁺ reaches 92.5%.

Keywords

Diatomite-Based Porous, Ceramsite, Adsorption, Copper.

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Guoting Li ¹, Mingju Wang ¹, Xi Chen ¹, Xinbao Li ¹

Affiliations
1 Department of Environmental and Municipal Engineering, North China University of Water Resources and Electric Power, Zhengzhou 450011, CN

Abstract

Sugarcane bagasse, an agricultural waste biomass was innovatively used to prepare ammonium acetate modified sugarcane bagasse via a simple wet impregnation method. The prepared adsorbent was used for the adsorptive removal of copper from aqueous solution. It was found that an increase in adsorbent dosage significantly increased the removal efficiency for copper. Compared to the raw bagasse, the adsorption capacity of the modified bagasse was dramatically enhanced by 116.2%. At pH 5.0, 7.0 and 9.0, the reaction kinetic data were simulated and compared using pseudo-first-order, pseudo-second-order and Elovich kinetic models. Results indicate that both pseudo-second-order and Elovich kinetic models could better describe the adsorption kinetics. This demonstrates that the adsorption of copper onto the modified bagasse was a chemisorption process in which the ratedetermining step is diffusion in nature. Thermodynamic analysis demonstrated the enthalpy and entropy of the adsorption process as 643.6 KJ mol^-1 and 250.5 J mol^-1 k^-1, respectively. The positive value of the reaction enthalpy implies that the uptake of copper increases with a rise in the reaction temperature. The adsorption of copper was spontaneous and endothermic in nature.

Keywords

Sugarcane Bagasse, Ammonium Acetate, Copper, Adsorption Kinetics.

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Ruqin Gao ¹, Yue Geng ², Guoting Li ¹, Yiming Gu ¹, Sun Qian ¹

Affiliations
1 School of Environmental and Municipal Engineering, North China University of Water Resources and Electric Power, Zhengzhou 450045, CN
2 School of Environmental and Municipal Engineering, North China University of Water Resources and Electric Power, Zhengzhou 450045, IN

Abstract

Taking diatomite as the main material, the DPC was obtained by solid-phase sintering and low-temperature calcination craft. The study focused on the content of tourmaline to influence of materials’ microstructure, pore size distribution and the decolourization ability for malachite green aqueous solution. Samples in different tourmaline content were characterized by scanning electron microscopy, Hg porosimetry and so on. The results indicate that sample with 12% tourmaline has the smallest average aperture of 177.5 nm and biggest specific surface area of 6.83 m2/g; tourmaline content is enhanced from 0% to 16%, the materials’ porosity decreased from 49.3% to 36.5% and materials’ decolourization ability to malachite green solution’s strengthens gradually. When tourmaline content is 16%, malachite-green aqueous solution is completely decolourized in 6h and the absorption peaks disappear at 412 nm and 618 nm.

Keywords

DPC, Tourmaline, Pore Structure, Malachite Green.

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Gangfu Song ¹, Wei Li ¹, Jingrong Zhai ¹, Shulei Sun ¹, Yalin Li ¹, Guoting Li ¹

Affiliations
1 Department of Environmental and Municipal Engineering, North China University of Water Resources and Electric Power, Zhengzhou 450011, CN

Abstract

Zr-Mn binary oxide was prepared by a simple co-precipitation method, in which Mn(II) was tentatively used to prepare a precursor solution. Then the prepared Zr-Mn binary oxide was used for the adsorptive removal of tetracycline (TC). Effect of molar ratio of Zr/Mn, adsorbent dose and solution pH was investigated. The Zr-Mn binary oxide with a presumed molar ratio of Zr/Mn at 2:1 had a better adsorption performance. The removal efficiency of TC (15 mg/L) at a dose of 10 mg achieved as much as 97.4%, which demonstrated an excellent adsorption capability of Zr-Mn binary oxide. Acidic and near-neutral solution pH conditions were favourable for the uptake of TC. Freundlich model described the adsorption isotherm better than Langmuir model, indicating a heterogeneous surface of the prepared adsorbent. Using Langmuir model, the calculated maximal adsorption capacities for TC achieved 129.5 mg/g at 298 K. Thermodynamic analysis indicated that the changes of enthalpy and entropy of the adsorption processes were 206.32 KJ mol^-1 and 752.0 J mol^-1 k^-1, respectively. The negative value of Gibbs free energy change and the positive value of enthalpy also indicated that the adsorption process is spontaneous and endothermic.

Keywords

Zr-Mn Binary Oxide, Tetracycline, Adsorption, Isotherm.

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