No abstract

The cupuassu shell (Theobroma grandiflorum) which is a food residue was used in its natural form as biosorbent for the removal of C.I. Reactive Red 194 and C.I. Direct Blue 53 dyes from aqueous solutions. This biosorbent was characterized by infrared spectroscopy, scanning electron microscopy, and nitrogen adsorption/desorption curves. The effects of pH, biosorbent dosage and shaking time on biosorption capacities were studied. In acidic pH region (pH 2.0) the biosorption of the dyes were favorable. The contact time required to obtain the equilibrium was 8 and 18 h at 298 K, for Reactive Red 194 and Direct Blue 53, respectively. The Avrami fractionary-order kinetic model provided the best fit to experimental data compared with pseudo-first-order, pseudo-second-order and chemisorption kinetic adsorption models. The equilibrium data were fitted to Langmuir, Freundlich, Sips and Radke-Prausnitz isotherm models. For both dyes the equilibrium data were best fitted to the Sips isotherm model.

The aqai palm stalk (Euterpe oleracea) is a food residue used in its natural form (AS) and also protonated (AAS) as biosorbents for the removal of the textile dyes C.I. Reactive Black 5 and C.I. Reactive Orange 16 from aqueous solutions. This biosorbent was characterized by infrared spectroscopy, scanning electron microscopy, and nitrogen adsorption/desorption curves. The effects of pH, biosorbent dosage, and shaking time on the biosorption capacities were studied. In the acidic pH region (pH 2.0), the biosorption of the dyes was favorable. The contact time to obtain the equilibrium at 298 K was fixed at (10 and 4) h for the AS and AAS biosorbents, respectively, using both dyes. The Avrami fractionary-order kinetic model provided the best fit to the experimental data compared with the pseudofirst-order and pseudosecond-order kinetic adsorption models. The equilibrium data were fitted to the Langmuir, Freundlich, and Sips isotherm models. For both dyes the equilibrium data were best fitted to the Sips isotherm model.

Personal exposure and possible cancer risk to formaldehyde and acetaldehyde were appraised in 8 work places at a university in Brazil. Levels of formaldehyde measured ranged from 22.5 to 161.5 μg·m−3 and from 18.3 to 91.2 μg·m−3 for acetalde-hyde. The personal exposure, expressed as the potential dose in indoor air, was calculated to range from 129.8 to 930.4 μg·day−1 (low exposure) and 183.9 to 1318.1 μg·day−1 (medium exposure) for formaldehyde and 105.5 to 525.3 μg·day−1 (low exposure) and 149.5 to 744.2 μg·day−1 (medium exposure) for acetaldehyde. The indoor/outdoor ratio showed the existence of indoor sources of the compounds which were mainly in practical classes and research laboratories. The highest formaldehyde and acetaldehyde levels were found where chemical reagents were manipulated. Relating the levels found to the permissible limit given by the US OSHA showed there was no particular risk although some formaldehyde levels did exceed the lower exposure limit of the US agency NIOSH. Any cancer risk would be highest for female technicians and teaching researchers.

No abstract