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In this study,a novel nanoscale zero-valent iron (nZVⅥ) composite materialwas successfully synthesized using a low-cost natural clay,Hangjin 2# clay (HJ clay) as the support and tested for the decolorization of the azo dye Methyl Orange (MO) in aqueous solution by nZVI partclcles.According to the characterization and MO decolorization experiments,the sample with 5∶1 HJ clay-supported nZVI (HJ/nZVI) mass ratio (HJ-nZVI5) showed the best dispersion and reactivity and the highest MO decolorization efficiency.With the same equivalent Fe0 dosage,the HJ-nZVI1 and HJ-nZVI5 samples demonstrated a synergetic effect for the decolorization of MO:their decolorization efficiencies were much higher than that achieved by physical mixing of HJ clay and nZVIs,or the sum of HJ clay and nZVIs alone.The synergetic effect was primarily due to the improved dispersion and more effective utilization of the nZVI particles on/in the composite materials.Higher decolorization efficiency of MO was obtained at larger HJ-nZVI dosage,higher temperature and under N2 atmosphere,while the MO initial concentration and pH were negatively correlated to the efficiency.HJ clay not only works as a carrier for nZVI nanoparticles,but also contributes to the decolorization through an adsorption-enhanced reduction mechanism.The high efficiency of HJ-nZVI for decontamination gives it great potential for use in a variety of remediation applications.