Biomassa vegetal em processos de remediação de contaminação ambiental por metais

Abstract

The use of plant biomass in environmental remediation processes constitutes a promising field for technologies that mitigate the impacts of trace metals in the environment. This study evaluated the potential of different plant species for remediation processes in environments with the presence of trace metals silver (Ag), cadmium (Cd), lead (Pb) and mercury (Hg). Chapter I addressed the use of processed biomass of the aquatic macrophyte Salvinia biloba Raddi (Salviniaceae) for biosorption of silver nanoparticles (Ag⁰NPs) and silver ions (Ag⁺), analyzing the efficiency of removing adsorbates from water and determining them and kinetic models and adsorption isotherm parameters. The equilibrium time was 1 hr for both adsorbates and the adsorption efficiency was up to 62% for Ag⁰NPs. The kinetic model indicated a predominantly superficial adsorption process for both adsorbates. The correlation (R²) indicated an adjustment to the Freundlich isotherm for Ag⁰NPs and Sips for Ag⁺ and the affinity parameter of the isotherms indicated a favorable type of adsorption for both adsorbates. The results demonstrated that the S. biloba biosorbent is promising for the removal of Ag⁰NPs and Ag⁺ from aqueous solutions, and its potential for the remediation of contaminated waters can be emphasized. Chapter II addressed the phytoremediation potential of plant species in the prospection of Hg from the environment. Twenty-five species of plants sampled in the southern region of the Amazon were evaluated, quantifying Hg, both in the biomass of plants and in the associated soil, as well as the process of compartmentalization of Hg in plant tissues using phytoremediation coefficients. The results showed significant differences in the accumulation of Hg in the soil between the sampling points, between the plant species evaluated and between the parts (leaf and root) of each plant. The study highlighted seven species with efficient translocation, bioconcentration and bioaccumulation, emphasizing the potential of these species for prospecting Hg from terrestrial environments. Chapter III addressed the use of S. biloba for the remediation of aqueous solutions contaminated with Cd⁺² and Pb⁺². The efficiency of removing metals from water (remediation) was evaluated in addition to toxicological testing using a nematode model to evaluate the potential for water detoxification by the plant. The remedial effect of the plant was evidenced through the results of the kinetic and isotherm models in addition to the detoxification effect observed with the significant reduction in the mortality rate of nematodes subjected to phytoremediated solutions by S. biloba plants. In general, the study highlighted different species of promising plants for use in remediation techniques for trace metals considered dangerous to the environment, highlighting the potential of plant biomass for this purpose.