A physicochemical study of Al(+3) interactions with edible seaweed biomass in acidic waters.

UNLABELLED: In this article, a study of the Al(+3) interactions in acidic waters with biomass of different edible seaweeds: brown (Fucus vesiculosus, Saccorhiza polyschides), red (Mastocarpus stellatus, Gelidium sesquipedale, Chondrus crispus), and green (Ulva rigida, Codium tomentosum), has been performed. The influence of both, the initial concentration of metal and the solution pH, on the Al-uptake capacity of the biomass has been analyzed. From preliminary tests, species Fucus vesiculosus and Gelidium sesquipedale have been selected for a more exhaustive analysis. Sorption kinetic studies demonstrated that 60 min are enough to reach equilibrium. The intraparticle diffusion model has been used to describe kinetic data. Equilibrium studies have been carried out at pH values of 1, 2.5, and 4. Langmuir isotherms showed that the best uptake values, obtained at pH 4, were 33 mg/g for F. vesiculosus and 9.2 mg/g for G. sesquipedale. These edible seaweeds have been found particularly effective in binding aluminum metal ions for most of the conditions tested. Physicochemical data reported at these low pH values could be of interest, not only in modeling aluminum-containing antacids-food pharmacokinetic processes produced in the stomach (pH values 1 to 3) but in remediation studies in acidic waters. PRACTICAL APPLICATION: Aluminum is thought to be linked to neurological disruptions such as Alzheimer's disease. In this article, the adsorption ability of different types of edible seaweeds toward aluminum has been studied. The choice of low pH values is due to the fact that stomach region is acidic with a pH value between 1 and 3 as a consequence of hydrochloric secretion; so physicochemical data reported in this study could be of interest in modeling drug-food interactions, in particular those referring to aluminum-containing antacids-food pharmacokinetic processes produced in the gastrointestinal tract.

Aluminium removal from wastewater by refused beach cast seaweed. Equilibrium and dynamic studies.

Aluminium removal has been investigated in synthetic and real wastewaters provided by an aluminium surface treatment plant. Marine algae, obtained as beach cast seaweed (a refuse substance) were used as adsorption material. The influence of pH, metal concentration and time for aluminium elimination was studied by use of synthetic solutions. The optimum pH value was 4.0, which provided a maximum adsorption capacity of 22.5 mg g(-1). The adsorption percentage surpassed 80% in less than 30 min of contact time. Real solutions from the industrial unit were fully characterized and tested in two different fixed-bed columns. One column was filled with 27.5 g of dried beach cast seaweed. Three cycles of adsorption and two of desorption were carried out. The first cycle (12 mg g(-1) maximum sorption capacity) was enough to reach the maximum adsorption capacity at 15 mL min(-1) flow rate. The second column was packed with 1100 g of seaweed and its behaviour was compared to another column filled with activated charcoal, following both the same experimental procedure. Maximum sorption capacity was 14 mg g(-1) for seaweed, whereas the activated charcoal only reached 1.6 mg g(-1) (flow rate of 250 mL min(-1)).