Biosorption optimal pH and kinetics of lead (II) on Ascophyllum nodosum seaweed at 20°Cwere studied. In order to improve structural stability of alginate and avoid leaching, thebiomass was pre-treated with CaCl2. Biosorption kinetics experimental data showed gratercoefficients of correlation (R2) on pseudo second order mathematic model. Physical chemistryparameters: particle size influence (75 μm - 180 μm and 0 μm - 75 μm) and biosorbent andmetal concentrations in solution were evaluated in the biosorption kinetics. Pseudo secondorder constant, k2 = 1.0x10-4 g.mg-1min-1, of biosorbent with particle size 75-180 μm increasedin 20% as particle size decreased to 0-75 μm, meanwhile, q2e increased from 67,7 to 94,5mg/g at the same conditions. Lead (II) residual concentrations in solution were determinedby atomic absorption spectroscopy. For data processing and statistic treatment of non...

Lead (II) biosorption on Ascophyllum nodosum seaweed at 20°C and initial pH 4-5 wasstudied, by using models of Langmuir and Freundlich isotherms. In order to establishseaweed, CaCl2 was used. The granulometry used in the biosorbent was 0-75 μm. In Fourier transform infrared spectroscopy, FT-IR, a shift in the signal of carbonyl group of crosslinkedsample before metal biosorption and after (1600.92 cm-1 to 1573.91 cm-1) and 1400 cm-1 (thatwas from 1415.75 cm-1 to 1409.96 cm-1) was observed, suggesting a chelating (bidentate)character of the metal biosorption onto carboxylic groups that belongs to the units of alginatemonomeric. The bands at 3305.99 cm-1 allowed the recognition of hydroxyl groups in thebiosorbent. The scanning electronic microscopy, SEM, verified heterogeneity of biosorbentparticles. In the energy-dispersive X-ray spectroscopy, EDAX, a very strong signal in thecarbon and...

Biosorption kinetics of cadmium (II) on cross-linked pectin extracted from orange peels at 20°C was studied, obtaining an equilibrium sorption capacity, q , of 99.56 mg/g in pH range e 4.5-5.5. Pectic material was extracted through acid hydrolysis (pH: 1.5, temperature: 90°C, time: 30 min) and crosslinked with formaldehyde acidic solution in order to diminish hydration capacity and swelling, as well as polysaccharide leaching when found in aqueous environment. Biosorption kinetics experimental data showed greater coefficients of correlation (R ) on pseudo second order mathematic model. Physical chemistry parameters: particle size influence (125 µm - 500 µm and 0 µm - 125 µm) and biosorbent and metal concentrations in solution were evaluated in the biosorption kinetics. Pseudo second order -4 -1 -1 constant, k = 8.0x10 g.mg min , of biosorbent with particle size 125-500 µm increase...

The objective of the present work was to determine the optimal conditions for the coagulation of suspended particles of silver iodide of negative charge by the action of solutions of chitosan, aluminum sulfate and the mixed action of both coagulants. The suspension of colloidal particles of AgI was obtained by mixing diluted solutions of KI and AgNO3 in excess of KI. In all the experiments the volume of the colloidal system was 600 mL and pH= 6. The optimal parameters for the coagulation process were determined based on the Jar Test method. For the chitosan solution the optimal parameters were: concentration 0.01%, pH = 4.5 and a volume of 25 mL; for aluminum sulfate: concentration 30 ppm, pH = 4.0 and volume 25 mL. In the case of the mixed action of both coagulants, the optimal parameters were 5 mL of a 30 ppm solution of aluminum sulfate at pH 4.0 and 20 mL of a 0.01% chitosan solution...