ABSTRACT
In the present research, the presence of water hyacinth (Eichhornia crassipes) on the surface of the San Jose Dam located in the city of San Luis Potosi, S.L.P, Mexico, was monitored and mapped. The monitoring was conducted for 2 years (2018-2020) with remote sensing data from OLI Landsat 8 sensors, based on the normalized difference vegetation index (NDVI). The results demonstrated the capability and accuracy of this method, where it was observed that the aboveground cover area, proliferation, and distribution of water hyacinth are influenced by climatic and anthropogenic factors during the four seasons of the year. As part of a sustainable environmental control of this invasive species, the use of water hyacinth (WH) root (RO), stem (ST), and leaf (LE) components as adsorbent material for Pb(II) present in aqueous solution was proposed. The maximum adsorption capacity was observed at pH 5 and 25 °C and was 107.3, 136.8, and 120.8 mg g-1 for RO, ST, and LE, respectively. The physicochemical characterization of WH consisted of scanning electron microscopy (SEM), N2 physisorption, infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), charge distribution, and zero charge point (pHPZC). Due to the chemical nature of WH, several Pb(II) adsorption mechanisms were proposed such as electrostatic attractions, ion exchange, microprecipitation, and π-cation.
ABSTRACT
Sargassum algae has become a major environmental issue due to its abundance in the Pacific Ocean with hundreds of tons reaching the beaches of the Mexican Caribbean every year. This generates large quantities of decomposing organic matter that have a negative impact on the region's economy and ecosystems. Sargassum valorization has turned out to be a fundamental aspect to mitigate its environmental impact. This study proposes the use and application of untreated Sargassum biomass for the decontamination of waters polluted with lead (Pb) and cadmium (Cd) through single and binary adsorption tests. Physicochemical and textural properties examined by SEM, XRD, and FT-IR elucidated that Sargassum biomass is viable to be used as a potential environmental benign adsorbent, exhibiting Cd(II) and Pb(II) adsorption capacities as high as 240 mg g-1 and 350 mg g-1, respectively, outperforming conventionally used adsorbents. This is attributed to its morphology, favorable surface charge distribution, and the presence of -OH and -COH groups. A strong affinity between the biomass and metal pollutants was evidenced by a thermodynamics study, showing a spontaneous and endothermic process. This work sets a practical route for the utilization of the Sargassum biomass, demonstrating its applicability as a potential material for heavy-metal-polluted water remediation, making a substantial contribution to a circular economy system.
