(201z) Evaluation of Operational Variables in the Degradation of Orange II Using Iron Nanoparticles Supported on Fique Fibers

EVALUATION OF OPERATIONAL VARIABLES IN THE DEGRADTION EF ORANGE II USING IRON NANOPARTICLES SUPPORTED ON FIQUE FIBERS

Please leave this line blank

Karen G. Bastidas G^1(*), Cesar A. Sierra A², Hugo R. Zea R³

^{1, 3} Department of Chemical and Environmental Engineering., Universidad Nacional de Colombia, Bogotá (Col)

² Chemistry department. Universidad Nacional de Colombia, Bogotá (Col)

 ^(*)Email: kgbastidasg@unal.edu.co

Please leave these two lines blank

Please leave these two lines blank

ABSTRACT

Degradation and mineralization of the dye Orange II (OII) was performed with nanoparticles supported on natural fiber Fique (Furcraea andina spp) as catalysts in reactions conditions that promotes the heterogeneous Fenton reaction. A Box-Behnken experimental design was used to evaluate the effect of: pH (2.5 - 3.5), initial OII concentration: 𝐶𝑂𝐼𝐼₀ (2𝑥10^-5 - 2𝑥10^-4M), initial hydrogen peroxide concentration 𝐶𝐻₂𝑂₂ (1𝑥10^-4- 10𝑥10^-3M) and load of iron in the catalyst (10.9,14.9 𝑎𝑛𝑑 13.2) wt.% in the degradation of OII. 93.23% of degradation was obtained after 4 hours of catalytic activity under following conditions: pH: 2.5, 𝐶𝑂𝐼𝐼0: 1.1𝑥10^-4M, 𝐶𝐻₂𝑂₂: 5.05𝑥10^-3M and 10.9 𝐹𝑒 %𝑤𝑡. pH was determinate to be the most influential variable in the degradation process, reporting to have better degradation at lower pH. A simplified pseudo-first-order kinetic model was proposed and described 16 of the degradation conditions with a R² above 0.9; a very remarkable result for such a simple model. The effect of Cl^-  ion in the OII degradation was determinate to be damaging in term of degradation rates for concentration as low as 0.05M and damaging both.The influence of temperature on the degradation process, reaches for 30, 50 and 70°C after 60 minutes of reaction 67, 89 and 94% of degradation. About catalyst stability reported a deactivation then 28 hrs of reaction (only 45% of degradation) and in terms of Fe lixiviated from the catalyst to the reaction solution,by FAAS was determinated the average value of the amount of iron in solution for each run, corresponds to 0.822ppm.

INTRODUCTION

The availability of natural water resources has declined over time, becoming one of the biggest problems today. Oxidation processes with iron nanoparticles (NPs) applied to dyes from the textile industry is one of modern technologies that look for remediation technologies in water sources. This work shows how the combination of natural cellulosic fibers [1] and iron oxide nanoparticles [2] could provide exceptional materials for the treatment of organic dyes in wastewater. Likewise, this approach allows an easy separation catalyst treated water process, turning the catalyst in a highly recyclable and reusable material.

The catalytic oxidation reaction was performed in a jacketed glass batch reactor (500 mL), kept under constant agitation (240 rpm). Each run lasted 240 minutes; used 800 mg of catalyst contained in paper bags (with pore size: 0.45μm, dimensions: 450x500x0.8mm, permeability: 1500 L/m².s, material: thermosetting filter paper for tea bags [3]) in contact with 250 mL of an OII solution (C16H11N2NaO4S, Sigma -Aldrich®), experiments were performed at 20°C. Values of the experimental pH (2.5 - 3.5), initial OII concentration: 𝐶𝑂𝐼𝐼0 (2𝑥10^-5- 2𝑥10^-4M), initial hydrogen peroxide concentration 𝐶𝐻₂𝑂₂ (1𝑥10^-4- 10𝑥10^-3M) and load of iron in the catalyst (10.9,14.9 𝑎𝑛𝑑 13.2) wt.%, were set according within the limits of the ranges reported for others authors [4-5].

The reaction advance was continuously monitored using an UV-vis spectrophotometry to track the absorbance the OII molecule in a quartz cell; OII concentrations were assessed through a calibration curve obtained at a wavelength of 486nm. The DOE conditions that provided one of the highest OII degradation were used to perform two new sets of experiment, the first once investigates the effect of temperature in the degradation reaction, in this case, degradation experiment were done at 30, 50 and 70oC. The second set of experiments comprised continues cycles of reaction at 20oC (up to 7 cycles), in which the very same catalyst was reuse.

Considering that OII degradation monitored by UV-vis spectrophotometry does not enable to determine if there was complete oxidation of the dye molecule, also was quantified TOC and TN; finally, HPLC was used to identify the possible intermediate compounds generated during the reaction of Orange II degradation. RESULTS AND CONCLUSIONS

The effects of the reaction conditions on the degradation of OII on iron supported on modified fique fiber catalysts was studied. A Box-Behnken design of experiments allowed to determine the individual and the combined interaction of the main factor studied (pH, 𝐶𝑂𝐼𝐼0, 𝐶𝐻₂𝑂₂₀ and 𝐹𝑒 𝑤𝑡.%). A maximum OII degradation of 95.61% was obtained operating at pH: 2.5, 𝐶𝑂𝐼𝐼₀:1.1𝑥10^-4M, 𝐶𝐻2𝑂20: 1.1𝑥10−2𝑀 and 13.2 %𝐹𝑒 𝑤𝑡., the second highest degradation value (93.23%) was obtained working at the same pH, 𝐶𝑂𝐼𝐼0 but at lower 𝐶𝐻2𝑂20 and %𝐹𝑒 𝑤𝑡; the second operating conditions generated a slighter lower degradation but using half of the H2O2 and with a catalyst of only 10.9% of iron, making it an interesting option from the engineering point of view. The presence of inhibitory chloride ions had a not so significant negative effect (reduction only 10% compared to the maximum degradation reached), temperature show to have a positive effect on the degradation process. However TOC and TN experiment showed that not complete mineralization was achieved in any of the experimental conditions tested. Compounds of benzene and naphthalene were identified after dye degradation by HPLC chromatography.

Contour plots allowed to have a better understanding of the combined effects of 𝐶𝑂𝐼𝐼0, 𝐶𝐻2𝑂20 and 𝐹𝑒 𝑤𝑡.% as a function of pH, which was statically determinate to be the variable whit the highest impact in the process. Low pH level (2.5) was found to be the most favorable condition for Orange II degradation, being this some of the lowest pH values found in literature for heterogeneous Fenton reactions, converting the novel iron/modified fique fiber catalyst into a very attractive alternative for specific applications at low pH.

 A simplified pseudo-first-order kinetic model was proposed and was able to describe 16 of the degradation conditions with a R2 above 0.9; a very remarkable result for such a simple model. The effect of the presence of chloride ions in the reaction solution were evaluated, results show that concentrations as low as 0.005 M reduces the rate of OII degradation but after 4 hrs of reaction reaches the same OII degradation that the chloride ions free experiment. On the contrary, the 0.01 M of chloride ions OII degradation test underperforms in the whole extension of the experiment.

Catalyst stability was outstanding up to the initial 4 reaction cycles, but strongly decreased after subsequent cycles; Fe lixiviation from the catalyst to the reaction solution was in the order of 5.38% of the impregnated iron and may explain the loss of catalytic activity after several reaction cycles.

REFERENCES

[1] J. E. Peinado, L. F. Ospina, L. Rodríguez, J. Miller, C. Carvajal,R. Negrete, "Guía ambiental del subsector fiquero" Cadena Productiva Nacional del Fique-Cadefique, Bogotá DC., vol. 21. 2006.

[2] F. M. Duarte, F. J. Maldonado-Hódar, L. M. Madeira, “Influence of the iron precursor in the preparation of heterogeneous Fe/activated carbon Fenton-like catalysts” Appl. Catal. Gen., vol. 458, pp. 39–47, 2013.

[3] LCIMAN, “Diámetro 450mm-500mm filtro de papel para bolsas de té heatseal” [Online], China, 2016. Disponible: https://spanish.alibaba.com/p-detail/diameter-450mm-500mm-heatseal-filter-paper-for-tea-bags-60531187249.html.

[4] J. H. Ramirez, C. A. Costa, L. M. Madeira, “Experimental design to optimize the degradation of the synthetic dye Orange II using Fenton’s reagent” Catal. Today, vol. 107–108, pp. 68–76, 2005.

[5] R. Yuan, S. N. Ramjaun, Z. Wang, J. Liu, “Effects of chloride ion on degradation of Acid Orange 7 by sulfate radical-based advanced oxidation process: Implications for formation of chlorinated aromatic compounds” J. Hazard. Mater., vol. 196, pp. 173–179, 2011.