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A low cost adsorbent prepared from material of biological origin Setaria verticillata (Grasses) has been utilized as an adsorbent for the removal of Reactive Yellow 15 (RY15) dye from an aqueous solution. The combined effect of the initial pH, adsorbent dose, and initial dye concentration was investigated using Response Surface Methodology (RSM). The most influential adsorption factor on each adsorption experimental design response was identified from the Analysis Of Variance (ANOVA). The experimental values of percentage removal were found to be in good agreement with the predicted values. pH value of 2, initial RY15 concentration of 50 mg L 21 and adsorbent dose of 50 mg are found to be the optimum conditions, for adsorption of RY15 from an aqueous solution. Thermodynamic parameters such as change in standard free energy change, enthalpy and entropy DG o , DH o , and DS o have been evaluated, and it has been found that the adsorption process is feasible, exothermic and spontaneous in nature. The experimental data were analyzed by the Langmuir, Freundlich, Sips and Temkin adsorption isotherms. Maximum monolayer adsorption capacity of the RY15 dye is found to be 138.6 mg g 21. The experimental data fitted well with the pseudo-second order kinetic model.

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Aromatic polyamides and polythioamides with pendent chlorobenzylidine rings were synthesized through direct polycondenzation of 2-(p-chlorobenzalimino) terephthalic acid with the diamines 4,4 0 -oxidianiline (1a), 4,4 0 -methylenediamide (1b), 4,4 0 -diaminodiphenyl sulfone (1c), and thioamines 4,4 0 -(bisthiourea) diphenyl ether (3a), 4,4 0 -(bisthiourea) diphenyl methane (3b), 4,4 0 -(bisthiourea) diphenyl sulfone (3c), respectively, in DMF using P(OPh) 3 /pyridine. The polymers were precipitated using water as nonsolvent. FTIR and 1 H-NMR spectroscopic analysis was used to characterize the monomers and polymers. Representative polyamides and polythioamides were used for the removal of heavy metal ions such as Pb(II), Cd(II), Cu(II), and Cr(III) from aqueous solutions. The effects of pH, contact time, and initial concentration on the uptake of metal ions have been investigated. The adsorption capacities under competitive conditions were in the order Pb (II) > Cu (II) > Cr (III) > Cd (II). The adsorbed ions were eluted by treatment with 2N HCl, and the activities of the polymers are retained after fourth regeneration.