Cellulose Modification And Dispersion Of Nano Zero-valent Iron (NZVI) For Discoloration Of Dyes

Nano zero-valent iron (NZVI) cause its high reactivity, huge specific surface area and environmental friendly always been used to remove several contaminants (including chlorinated organic compounds, heavy metals, antibiotics, dyes and so on) in groundwater or soil. Meanwhile, its advantage was a limit factor in application. The NZVI particles were easy to aggregate and oxidize due to its magnetism and high reactivity. For further application, researchers try to immobilize or modify NZVI particles to overcome the aggregation and oxidation. The environmental friendly dispersant was popular to use in NZVI modified due to the low price and simple operation. In this study, NZVI was innovatively and successfully by using hydroxyethyl Cellulose (HEC) and hydroxypropylmethyl cellulose (HPMC) as dispersants.The unmodified NZVI and modified NZVI have been character with XRD, SEM, TEM, BET, FT-IR and XPS. The systematic characterization observations illustrate that compared with bare nano zero-valent iron particles (BNZVI), the particle sizes of HEC modified (ENZVI) and HPMC modified (PNZVI) were decreased, while the dispersity and antioxidizability of ENZVI and PNZVI particles were increased. The BET of BNZVI, ENZVI and PNZVI was 33.7 m2/g、38.2 m2/g and 37.5 m2/g, separately. That indicate the specific surface area of modified NZVI was increased because of the HEC and HPMC coating disperse the iron particles. At last, the FT-IR found the signals of -CH2 and -OH in 1450 cm-1 and 3207 cm-1, XPS found the signals of C-C and C-O, that indicated the HEC and HPMC sure presence on NZVI surface.The discoloration efficiencies of ENZVI, PNZVI, and BNZVI were compared by using dyes (including orange Ⅱ, methyl orange, methyl blue, and methylene blue) as target pollutant. Experiments found the property of modified NZVI particles were best while dispersant content was 1.24% wt. The results show that both the discoloration efficiency and reaction rate of ENZVI and PNZVI are higher than that of BNZVI. In addition, effects of dispersant content, dye type, pH value, initial dye concentration, iron dosage, and reaction temperature on discoloration efficiencies were studied. The results show that discoloration efficiency was decreased by increasing initial pH value and dye concentration, and it was increased with the increase of the iron dosage and reaction temperature. Under optimized NZVI addition of 0.7 g/L, the discoloration efficiencies of ENZVI and PNZVI were increased to 96.33% and 98.62%, respectively.And the possible discoloration pathway and dispersant modification mechanism of NZVI were discussed. Dynamics calculation demonstrates the discoloration reaction well fit the pseudo first order reaction kinetics principle. This study suggests HEC and HPMC dispersed NZVI can be utilized as a promising modified nano-material for degradation of dye wastewater.