Abstract: The purity, specific surface area and adsorption properties of palygorskite were improved through wet purification and acid modification. The modified palygorskite was used as a carrier and KBH₄ as a reducing agent to prepare palygorskite/nano-iron composite material using ion exchange method under the protection of argon gas. Hence, the stability of nano-iron could be enhanced, iron-nano particles were prevented from condensing into groups, and the effective area of the nano-iron reacting with pollutants could be increased. Compared with nano-iron, palygorskite/nano-iron composite is more stable and easier to store. Furthermore, with nitrate as target contaminant in groundwater for example, the usage of palygorskite/nano-iron composite in permeable reactive barrier technology, extraction processing technology and injection processing technology in removing nitrate was discussed. Treated by these techniques, the nitrate concentration in groundwater can be effectively degraded.

Key words: palygorskite, wet purification, acid processing, nano-iron, nitrates, groundwater