CHARACTERIZATION AND USE OF IN NATURA AND CALCINED RICE HUSKS FOR BIOSORPTION OF HEAVY METALS IONS FROM AQUEOUS EFFLUENTS

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Heavy metal removal by adsorption using rice husks as a bioadsorbent was evaluated as an alternative for wastewater treatment. Batch equilibrium experiments and kinetic sorption studies were performed using monocoinponent solutions of Ni(II), Cd(II), Zn(II), Pb(II) and Cu(I I) in surface samples of in natura (RH) and calcined rice husks (RHA). RHA showed higher potential for removing lead and copper. Experimental data for adsorption isotherms of lead and copper were adjusted by Langmuir, Freundlich and Dubinin-Radushkevick (D-R) models, being better represented by the Langmuir model. The calcination of RI-I increased its surface area, improving its adsorption properties. From a morphological analysis obtained by SEM and diffraction patterns (XRD), a longitudinal fibrous and amorphous structure was observed for RI-I. TGA results indicated a total mass loss of around 60% for RH and 24.5% for RNA.293619633Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP

First report on dung beetles in intra-Amazonian savannahs in Roraima, Brazil

This is the first study to address the dung beetle (Coleoptera: Scarabaeidae: Scarabaeinae) diversity in intra-Amazonian savannahs in the state of Roraima, Brazil. Our aim was to survey the dung beetle fauna associated with these savannahs (regionally called 'lavrado'), since little is known about the dung beetles from this environment. We conducted three field samples using pitfall traps baited with human dung in savannah areas near the city of Boa Vista during the rainy seasons of 1996, 1997, and 2008. We collected 383 individuals from ten species, wherein six have no previous record in intra-Amazonian savannahs. The most abundant species were Ontherus appendiculatus (Mannerheim, 1829), Canthidium aff. humerale (Germar, 1813), Dichotomius nisus (Olivier, 1789), and Pseudocanthon aff. xanthurus (Blanchard, 1846). We believe that knowing the dung beetles diversity associated with the intra-Amazonian savannahs is ideal for understanding the occurrence and distribution of these organisms in a highly threatened environment, it thus being the first step towards conservation strategy development

Influence of the liquid saturation degree on the fluid dynamics of a spouted-bed coater

The influence of the liquid saturation degree on the fluid dynamics of the conventional spouted bed coating process is investigated using inert particles such as ABS(R), placebo tablet and glass beads. An aqueous polymeric suspension was used as the coating liquid. The suspension was characterized by its surface tension, density, theology and contact angle between the suspension and the solid surface. The maximum suspension flow rate supported by the bed was determined for these three particles, at operating conditions established by preliminary tests. The solids velocity inside the spouted bed was also measured in order to correlate this circulation rate with the saturation degree of the bed. The fluid dynamics behavior of the bed was analyzed and correlated to the liquid saturation degree as well as particle and suspension characteristics. (C) 2004 Elsevier B.V. All rights reserved.43101275128

Drying conditions influence on physical properties of recycled paper

In this work, recycled cellulose pulp was dried in a convective dryer and at natural environment conditions. Physical properties of the paper (moisture content, grammage, thickness, apparent and absolute densities, porosity, stretch, tension and burst resistances, dimensional stability and water absorption) were determined and the influence of the drying air temperature and velocity on the final quality of the dried paper, concerning these properties, was analyzed and compared to the paper dried at natural environment conditions. Optical and scanning electronic microscopy was employed to analyze structural changes on the paper surface after drying. The increase of both variables (temperature and air velocity) enhances the drying rates, but is harmful to the quality of the paper, leading to a final product with less uniformity and over-dried surface. (c) 2007 Elsevier B.V. All rights reserved.461095596

Energy efficiency and drying kinetics of recycled paper pulp

In this work, the influences of the air temperature and velocity on the drying kinetics of recycled paper pulp were analyzed. The increase of both variables positively influences the process, concerning the final moisture content and the drying time. However, optical microscopy and visual observation showed worse quality of the paper for drying conditions of high air temperature and velocity, presenting less uniformity and overdried surfaces. The dryer energy efficiency was evaluated by performance parameters and the results were compared with the ones obtained for other types of industrial paper dryers, presenting good agreement.25101639164

Biosorption of chromium(VI) using a Sargassum sp packed-bed column

Chromium(VI) is present in several industrial wastewaters and it can cause health and environmental hazards above certain concentrations. Equilibrium studies have shown the feasibility of using Sargassum sp. algae for chromium removal from aqueous solutions by biosorption. However, for the design and operation of chromium biosorption processes, dynamic flow studies are required. The objective of the study was to examine chromium(VI) removal from an aqueous solution using a packed-bed column with Sargassum sp. algae as a biosorbent. The dynamic behavior of the biosorption column was investigated through experiments and the influence of operating conditions, such as initial chromium concentration, flow rate and amount of biosorbent, on the column removal capacity have been analyzed using the factorial design methodology. The capacity of removal obtained at optimum conditions was 19.06 mg of metal/g biosorbent. (c) 2007 Elsevier Ltd. All rights reserved.9983094309