The removal of humic substances by nano zero-valent iron supported on activated carbon and implementation of response surface methodology

2019 ◽  
Vol 166 ◽  
pp. 230-236 ◽  
Author(s):  
Kubra Ulucan-Altuntas
2017 ◽  
Vol 19 (1) ◽  
pp. 104-112 ◽  
Author(s):  
Mehdi Ahmadi ◽  
Kurosh Rahmani ◽  
Ayat Rahmani ◽  
Hasan Rahmani

Abstract In this paper, the removal of benzotriazole (BTA) was investigated by a Photo-Fenton process using nano zero valent iron (NZVI) and optimization by response surface methodology based on Box-Behnken method. Effect of operating parameters affecting removal efficiency such as H2O2, NZVI, and BTA concentrations as well as pH was studied. All the experiments were performed in the presence of ultraviolet radiation. Predicted levels and BTA removal were found to be in good agreement with the experimental levels (R2 = 0. 9500). The optimal parameters were determined at 60 min reaction time, 15 mg L-1 BTA, 0.10 g L-1 NZVI, and 1.5 mmol L-1 H2O2 for Photo-Fenton-like reaction. NZVI was characterized using X-ray diffraction (XRD), transmission electron microscope (TEM) images, and scanning electron microscope (SEM) analysis.


Catalysts ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 412 ◽  
Author(s):  
Yajun Li ◽  
Yongxiang Zhang ◽  
Qi Jing ◽  
Yuhui Lin

Nano zero-valent iron (NZVI) is widely used for reducing chlorinated organic pollutants in water. However, the stability of the particles will affect the removal rate of the contaminant. In order to enhance the stability of nano zero-valent iron (NZVI), the particles were modified with F-127 as an environmentally friendly organic stabilizer. The study investigated the effect of the F-127 mass ratio on the colloidal stability of NZVI. Results show that the sedimentation behavior of F-NZVI varied at different mass ratios. A biphasic model was used to describe the two time-dependent settling processes (rapid sedimentation followed by slower settling), and the settling rates were calculated. The surface morphology of the synthesized F-NZVI was observed with a scanning electron microscope (SEM), and the functional groups of the samples were analyzed with Fourier Transform Infrared Spectroscopy (FTIR). Results show that the F-127 was successfully coated on the surface of the NZVI, and that significantly improved the stability of NZVI. Finally, in order to optimize the removal rate of 2,4-dichlorophenol (2,4-DCP) by F-NZVI, three variables were tested: the initial concentration 2,4-DCP, the pH, and the F-NZVI dosage. These were evaluated with a Box-Behnken Design (BBD) of response surface methodology (RSM). The experiments were designed by Design Expert software, and the regression model of fitting quadratic model was established. The following optimum removal conditions were determined: pH = 5, 3.5 g·L−1 F-NZVI for 22.5 mg·L−1 of 2,4-DCP.


2016 ◽  
Vol 74 (2) ◽  
pp. 343-352 ◽  
Author(s):  
Morteza Khosravi ◽  
Simin Arabi

In this study, iron zero-valent nanoparticles were synthesized, characterized and studied for removal of methylene blue dye in water solution. The reactions were mathematically described as the function of parameters such as nano zero-valent iron (NZVI) dose, pH, contact time and initial dye concentration, and were modeled by the use of response surface methodology. These experiments were carried out as a central composite design consisting of 30 experiments determined by the 24 full factorial designs with eight axial points and six center points. The results revealed that the optimal conditions for dye removal were NZVI dose 0.1–0.9 g/L, pH 3–11, contact time 20–100 s, and initial dye concentration 10–50 mg/L, respectively. Under these optimal values of process parameters, the dye removal efficiency of 92.87% was observed, which very close to the experimental value (92.21%) in batch experiment. In the optimization, R2 and R2adj correlation coefficients for the model were evaluated as 0.96 and 0.93, respectively.


2017 ◽  
Vol 8 (2) ◽  
pp. 35-45 ◽  
Author(s):  
Vesna Kecić ◽  
◽  
Đurđa Kerkez ◽  
Miljana Prica ◽  
Sanja Rapajić ◽  
...  

2017 ◽  
Vol 20 (1) ◽  
pp. 57-68

Response surface methodology has been used to design experiments and to optimize the effect of independent variables responsible for higher adsorption of humic substances by activated carbon supported nanoscale zero-valent iron from aqueous solutions. The variables of initial concentration, time, pH, adsorbent dose was examined. The characterization of NZVI/AC was carried out by SEM-EDS and XRD analysis. The adsorption isotherms and kinetics of humic substances on AC and NZVI/AC were studied. The findings showed that the particle size of synthesis NZVI were in the range 20-50nm. The experimental data followed the Langmuir isotherm and pseudo-second kinetic model. For AC, optimum conditions of initial concentration, pH, contact time, and adsorbent dose were 5 mg L-1, 4.43, 46.28 min, and 1.5 g L-1, respectively. For NZVI/AC, optimum conditions of initial concentration, pH, contact time, and adsorbent dose were 5.48 mg L-1, 5.44, 44.7 min, 0.65 g L-1, respectively. Predicted removal efficiency by Box-Benken models for activated carbon and NZVI were 60 and 100 percent, respectively.


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