Methylene blue and iodine adsorption onto an activated desert plant.

Although frequently less toxic than many colorless effluents, colored effluents are generally considered by the public as an indicator of pollution. The present investigation aimed at identifying the effectiveness of a local desert plant characteristic of Southwest Algeria and known as Salsolavermiculata, which was pyrolyzed and treated chemically with a 50% zinc chloride solution, to remove methylene blue and iodine. The natural plant adsorption capacities were respectively 23mg/g and 272mg/g for methylene blue and iodine. Corresponding results for the pyrolyzed plant uptakes were 53mg/g and 951mg/g, while those for the pyrolyzed plant, chemically treated and activated at 650 degrees C, were 130mg/g and 1178mg/g, respectively. In comparison, the standard Merck activated carbon capacities were 200mg/g for methylene blue and 950mg/g for iodine. Consequently, this low-cost local plant may also prove useful for the removal of large organic molecules as well as potential inorganic contaminants.

Plasmachemical degradation of azo dyes by humid air plasma: Yellow Supranol 4 GL, Scarlet Red Nylosan F3 GL and industrial waste.

A recent non-thermal plasma technique (i.e., a gliding arc discharge which generates reactive species at atmospheric pressure) is tested for pollution abatement of dyes dispersed in synthetic solutions and industrial effluents. Yellow Supranol 4 GL (YS) and Scarlet Red Nylosan F3 GL (SRN) are toxic synthetic dyes widely used in the Algerian textile industry and frequently present in liquid wastes of manufacture plants. Classical removal treatment processes are not efficient enough, so that the presence of dyes in liquid effluents may cause serious environmental problems, in connection with reusing waste waters for irrigation. The degradation processes achieved by the oxidising species formed in the plasma are followed by UV/VIS spectroscopy and by chemical oxygen demand measurements. They are almost complete (i.e., 92.5% for YS and 90% for dilute SRN) and rapidly follow pseudo-first-order laws, with overall estimated rate constants 3 x 10(-4) and 4 x 10(-4)s-1 for YS and SRN, respectively. The degradation rate constant for the industrial mixture (i.e., k = 1.45 x 10(-3)s-1) is a mean value for two consecutive steps (210(-3) and 6 x 10(-5)s-1) measured at the absorption peaks of the major constituent dyes, YS and SRN.