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Martins R.J.E.,University of Applied science of Braganca | Martins R.J.E.,University of Porto | Vilar V.J.P.,University of Porto | Boaventura R.A.R.,University of Porto
Desalination and Water Treatment | Year: 2010

Aquatic bryophytes are frequently used as biomonitors for trace metals in aquatic ecosystems. Nevertheless, their special characteristics also allow using them as biosorbents to clean industrial wastewaters. As biosorption is a low-cost and effective method for treating metal-bearing wastewaters, understanding the process kinetics is relevant for design purposes. In this study, the ability of the aquatic bryophyte Fontinalis antipyretica to remove lead from simulated wastewaters was evaluated. Previously, the effect on biosorption of parameters such as the initial solution pH, contact time and initial metal ion concentration was investigated. The biosorption process is highly pH-dependent, and the favorable pH for maximum Pb2+ adsorption on the aquatic moss was found to have an optimum value in the range 4.0-6.0. The equilibrium sorption capacity of lead by Fontinalis antipyretica increased with the initial metal concentration. For an initial metal concentration of 10 mg L-1, the uptake capacity at equilibrium was 4.8 mg g-1. Nevertheless, when the initial concentration increased up to 100 mg L-1, the uptake of lead was 10 times higher. Maximum adsorption rates were achieved almost in the first 10-20 min of contact, and a further increase in the contact time had a negligible effect on the Pb2+ sorption. Three kinetic models (pseudo-first order, pseudo-second order and Elovich) were fitted to the experimental data and compared by the F-test. The pseudo-second order biosorption kinetic model provided the better correlation with the experimental data (R2 = 1.00). Probably the chemisorption is the rate-limiting step and the biosorption mechanism follows a pseudo-second order reaction model. The applicability of the Langmuir and Freundlich adsorption isotherms to the present system was also assessed. The equilibrium experimental data of lead sorption was very well described by the Langmuir model with R2 values exceeding 0.993. The maximum lead sorption capacity by Fontinalis antipyretica attained a value of 68 mg of lead ions per gram of aquatic moss. © 2010 Desalination Publications. Source


Martins R.J.E.,University of Applied science of Braganca | Martins R.J.E.,University of Porto | Vilar V.J.P.,University of Porto | Boaventura R.A.R.,University of Porto
Brazilian Journal of Chemical Engineering | Year: 2014

Because biosorption is a low cost and effective method for treating metal-bearing wastewaters, understanding the process kinetics is relevant for design purposes. In the present study, the performance of the aquatic moss Fontinalis antipyretica for removing cadmium and lead from simulated wastewaters has been evaluated. Five kinetic models (first-order, pseudo-first-order, Elovich, modified Ritchie second-order and pseudo-second-order) were fitted to the experimental data and compared. Previously, the effect of parameters such as the initial solution pH, contact time, and initial metal ion concentration on biosorption was investigated. The initial pH of the solution was found to have an optimum value in the range of 4.0-6.0. The equilibrium sorption capacity of cadmium and lead by Fontinalis antipyretica increased with the initial metal concentration. For an initial metal concentration of 10 mg L-1, the uptake capacity of the moss, at equilibrium, is the same for both metals (4.8 mg g-1). Nevertheless, when the initial concentration increases up to 100 mg L-1, the uptake of Pb(II) was higher than 78%. The pseudo-second order biosorption kinetics provided the better correlation with the experimental data (R2 ≥ 0.999). Source


Martins R.J.E.,University of Applied science of Braganca | Boaventura R.A.R.,University of Porto
Water Science and Technology | Year: 2011

Aquatic bryophytes are frequently used as biomonitors for trace metals in aquatic ecosystems. Nevertheless, their special characteristics also allow using them as biosorbents to clean industrial wastewaters. As biosorption is a low cost and effective method for treating metal-bearing wastewaters, understanding the process kinetics is relevant for design purposes. In this study, the ability of the aquatic bryophyte Fontinalis antipyretica to remove lead from simulated wastewaters was evaluated. Three kinetic models (pseudo-first order, pseudo-second order and Elovich) were fitted to the experimental data and compared by the F-test. Previously, the effect on biosorption of parameters such as the initial solution pH, contact time and initial metal ion concentration was investigated. The initial pH of the solution was found to have an optimum value is in the range 4.0-6.0. The equilibrium sorption capacity of lead by Fontinalis antipyretica increased with the initial metal concentration. For an initial metal concentration of 10mgL -1, the uptake capacity at equilibrium was 4.8mgg -1. Nevertheless, when the initial concentration increased up to 100mgL -1, the uptake of lead was 10 times higher. The pseudo-second order biosorption kinetic model provided the better correlation with the experimental data (R 2=1.00). The applicability of the Langmuir and Freundlich adsorption isotherms to the present system was also assessed. The maximum lead sorption capacity by Fontinalis antipyretica was 68mgg -1. © IWA Publishing 2010. Source


Gouveia E.,University of Applied science of Braganca | Coelho V.,University of Applied science of Braganca | Monteiro L.,University of Applied science of Braganca
Acta Horticulturae | Year: 2010

Cryphonectria parasitica, introduced in the NE of Portugal since 1989, is now an important and widespread pathogen of chestnut (Castanea sativa Mill.) which causes losses in chestnut fruit production and led to decline and death of many chestnut trees. Hypovirulence, a virus mediated attenuation of fungal pathogenesis, has not been frequent until now in Portugal but recently some cases of healing cankers were reported by chestnut growers. We assessed these sites and one of them, where healing cankers were clustered, was intensively surveyed. From all the trees with healing cankers, white and orange phenotypes of C. parasitica were isolated, which are both of the same vc type (EU-11). White isolates of C. parasitica showed reduced pigmentation in colony colour which was not completely stable, suppressed conidiation, reduction of phenol oxidase but no significant differences in lesion length and sporulation on chestnut twigs on dormant chestnut trees. Hypovirulent strains have dsRNA virus in the cytoplasm which is the typical element that reduces virulence in C. parasitica. Bands of dsRNA were identified in all of the white isolates and some variation in band dimension and number of bands was detected. The L-dsRNA (12 kbp), which is the diagnostic fragment of C. parasitica infection, was detected. The presence of white phenotypes of infected C. parasitica (CHV) and the fact that spreads occur in natural conditions is promising for its development as a biological control agent of chestnut blight. Source


Gouveia E.,University of Applied science of Braganca | Coelho V.,University of Applied science of Braganca | Fonseca F.,University of Applied science of Braganca | Nunes L.,University of Applied science of Braganca | Monteiro L.,University of Applied science of Braganca
Acta Horticulturae | Year: 2010

Chestnut ink disease represents a great risk for chestnut (Castanea sativa Mill.) in all regions of chestnut production of Europe and North America. Induced by soil borne oomycetes, Phytophthora cinnamomi and P. cambivora, both parasites infect the root system and cause root and collar rot resulting in dieback, decline and finally, the death of infected trees. There are no single control measures for root rot pathogens and control with systemic and selective oomycetes biochemical substances can be important as part of the integrated disease management of these soil borne parasites. In this work we studied the effect of potassium phosphonate to protect roots from P. cinnamomi. Chestnut seedlings were planted in potting mix previously inoculated with P. cinnamomi (Pr 120). One group of five pots, with three seedlings each were submitted to potassium phosphonate foliar spraying (3 ml L-1Atlante ®) and another group of five pots were water foliar sprayed. Seedlings had been grown in a nursery for 120 days. At the end of the experiment, visual symptoms of the crown and root system were assessed. Parameters related with roots: root length, root rot length, root number, root rot number, crown diameter, height and biomass were evaluated. Statistic significant differences between treatments were obtained in all root studied variables. Potassium phosphonate by foliar spraying prevented P. cinnamomi infections of roots of chestnut and can be a key factor in the management of ink disease of chestnut. Source

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