Preparation Of Nano-metal Handling Of Typical Organic Contaminants

Chlorophenols can be found in various chemical waste waters and can exist in various media of the environment with relatively high concentration. They are easy to accumulate in the surroundings and endangered human as well as ecological environment over a long period of time. Azo dyes, which contain one or more azo bonds (-N=N-), have many different types and full range of chromatography, are a major class of synthetic, colored organic compounds. During the dyeing production process, about 15% of them end up in wastewaters. Most azo dyes are highly carcinogenic and toxic. Therefore, the degradation research of chlorophenols and azo dyes has important practical significance. Recent years, for the unique property advantages, nano-metals have been used to remedy groundwater and soil pollutants, and show a good prospect.Dispersed nanoparticles Fe0 was obtained through chemical reduction, and using cation exchange resin as carrier, through chemical reduction we obtained loaded nanoparticles Fe,Ni,Fe-Ni,Fe-Pd. The degradation of 2,4,6-trichlorophenol (TCP) by hydrogen peroxide catalyzed by dispered nano-iron and the degradation of azo dyes in aqueous solutions by loaded nanoscale Fe,Ni, and Fe-Ni,Fe-Pd bimetallic nanoparticles were investigated. Scanning electron microscopy (SEM) of as-synthesized nanoparticles showed the presence of spherical particles having a size of 10-200 nm.The influences of pH, temperature, the concentration of H2O2, ionic strength, the amount of nanoparticles Fe,Ni,Fe-Ni,Fe-Pd and Ni (or Pd) loading in the bimetallic metals on the degradation of TCP and azo dyes were investigated. Batch experiments showed that:1. Under optimal conditions of the experiment: 50 mL of the reaction system (containing 10mL 1.10mmol/L of the TCP, 10mL of 50 mmol/L HClO4, 1.0 mL 80 mmol/L of H2O2, 0.4 mL 7mmol/L nano-iron), over 95% of TCP can be degraded in 20min. In acidic condition the degradation of TCP showed high degradation activity. Reaction temperature had a great impact on the occurrence homolysis of H2O2, as the temperature rised, the chlorophenol degradation efficiency increased.2. Zero-valent metal particles Fe, Ni, Fe-Ni, Fe-Pd could well degraded azo dyes. Under acidic conditions using Fe, in addition to Orange I, Acid Yellow G, Acid Yellow 17 which degradation rate were 96.1%, 53.3%, 39.3%, the degradation rate of other dyes was complete 100% within 60min. Especially using Fe-Ni, Fe-Pd had even better degradation efficiency. The bimetallic Fe-Ni,Fe-Pd nanoparticles demonstrated an enhanced degradation rate compared to Fe,Ni nanoparticles.3. The results showed that the solution pH, the addition of Fe(or Ni, Fe-Ni, Fe-Pd), and the Ni (or Pd) loading in Fe-Ni (or Fe-Pd) nanoparticles were the main factors that influenced the degradation rate of azo dyes. With increasing acidity, temperature, nanoparticles addition, the Ni (or Pd) loading, the degradation rate increased rapidly. The existence of Na2SO4 could inhibit the decolorization of azo dyes in some extent.4. In this study, cation exchange resin as a carrier loaded zero-valent nano-metal particles, but it was not just a carrier, but also collectors of the reaction product Fe2+, which could significantly prevent Fe2+ releasing into the solution, to avoid its adverse impact to the environment. More importantly, after the activation of renewable, these nanoparticles showed a significantly long life span with sustained reactivity.