Management strategy of an invasive woody plant species through conversion into adsorbents for remediation of polluted water

G. V. NUNELL; P.R. BONELLI; A. L. CUKIERMAN

Invasive Species: Ecology, Management Strategies and Conservation

Nova Science Publishers, Inc

Lugar: Hauppauge; Año: 2016; p. 55 - 80

A strategy for managing invasive woody plant species, which constitute a major threat to biodiversity worldwide, is to identify value-added uses. In this direction, wood from invasive species may result an attractive option as abundant, renewable feedstock for the sustainable manufacture of adsorbents for environmental applications, contributing to control their spread. Among worldwide invasive species, Parkinsonia aculeata, belonging to the Fabaceae family, is in the league of the most noxious woody plants. It can form dense, and often impenetrable thorny thickets along watercourses impeding access to drinking water supplies, excluding native vegetation, and causing soil erosion. Although different routes have been proposed for its management, control is still difficult. Within this scenario, the present chapter explores the feasibility of using Parkinsonea aculeata wood as a feedstock for the sustainable development of adsorbents targeted at pollutants removal from wastewater. For this purpose, the chemical activation process employing different chemical reagents is comparatively explored. Solutions of phosphoric acid, ammonium chloride, and potassium carbonate, involving different preparation conditions, are used. Characterization of chemical and textural-morphological features of the resulting adsorbents is conducted by a set of complementary techniques. Their performance in the removal of oxo-anions and organic compounds from model dilute solutions, using nitrate ion and phenol as representative species of these kinds of water contaminants, is also investigated at equilibrium pre-established conditions. The activating agent strongly affects yield, the elemental composition, surface chemistry, porous structures development, and adsorptive performance of the adsorbents. Activation with phosphoric acid and potassium carbonate solutions leads to adsorbents with typical features characterizing activated carbons, as evidenced in pronounced developments of their porous structures with BET surfaces areas of 968 m2 g-1 and 777 m2 g-1, respectively. Conversely, the sample obtained with the ammonium salt presents a slight porosity development but a noticeably high N content. It shows the best behavior in nitrate uptake, leading to the highest removal level among the developed samples. Instead, only the adsorbents with well-developed porous structures enable to attain high levels of phenol adsorption, pointing to a major role of the textural characteristics. Present results demonstrate that adsorbents adequate for the removal of different kinds of pollutant species from wastewater may be developed by chemical activation of invasive P.aculeata wood. Their characteristics and, consequently, adsorptive behavior may be conveniently tuned according to the nature of the contaminant by a proper selection of the chemical reagent employed.