López Morales, José L.

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    Removal of triclosan, tricloroethylene and perchloroethylene contaminants from aqueous solutions by adsorption with tire crumb rubber
    (2014) López Morales, José L.; Román Velázquez, Félix R.; College of Arts and Sciencies - Sciences; Morell Cruz, Luis A.; Meléndez Martínez, Enrique; Perales Pérez, Oscar; Department of Chemistry; Molina Bas, Omar I.
    There is a growing need for the development of low cost adsorbent materials to remove contaminants from environmental waters and avoid them reaching our natural resources, which include our drinking water supplies. Based on this need, we have placed, considerable effort in the evaluation of tire crumb rubber (TCR) as a low cost sorbent material for the removal of contaminants such as volatile organic compounds (VOCs), poly-aromatic hydrocarbons (PAHs), antibiotics of veterinary origin, heavy metals and antimicrobials. The use of TCR as sorbent material is important due to the immense environmental concerns associated with the disposal/recycling of waste tires. In this work, the effectiveness of TCR for the removal of the antimicrobial triclosan (TCS) and the organic compounds trichloroethylene (TCE) and perchloroethylene (PCE) from aqueous solutions was evaluated through controlled batch experiments. Carbon black (CB) and styrene-butadiene polymer (SBP), which are the main components in TCR, were evaluated as well to assess their contribution in the sorption process. In addition, TCR was entrapped with calcium-alginate beads and was evaluated for TCS removal. The adsorption isotherms were fitted with the Langmuir and Freundlich isotherm models. The Freundlich isotherm model better described the adsorption of TCS onto TCR, CB and SBP, while for TCE and PCE it was the Langmuir isotherm model who better described their sorption onto the above mentioned materials. In addition, desorption of TCS, TCE and PCE from TCR was evaluated as well. The maximum removal of TCS onto TCR, CB and SBP were 89, 95 and 92% respectively at pH 3, however did not changed significantly until above pH 7. Results indicate that removal of TCS with SBP proceeds via an absorption process. Maximum desorption of TCS from TCR was ~89% using methanol as extracting solution. Likewise, TCE removal with TCR was over 80% for all concentrations evaluated suggesting that is independent on concentration. In the experiments using CB and SBP, TCE removal decreased as concentration increased, implying that TCE sorption onto CB and SBP is favored at lower concentrations. Similarly, PCE removal with TCR was approximately 95% for all concentrations evaluated suggesting that removal does not depend on concentration. In the experiments using CB and SBP, PCE removal increased as concentration increased, implying that PCE sorption onto CB and SBP is favored at higher concentrations. Moreover, a series of sorption/desorption experiments were performed for 5 cycles to evaluate the potential reuse of TCR to remove the selected contaminants from aqueous media. Approximately, 94% of the 86% of TCS previously adsorbed by TCR was desorbed. Similarly, for TCE 93% of the 83% adsorbed by TCR was desorbed; while for PCE 86% of the 94% adsorbed was successfully desorbed. These results demonstrate the feasibility of TCR as a low-cost, green alternative to remove these contaminants from water systems.
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    Determination of Arsenic (As), Cadmium (Cd), Chromium (Cr), Cobalt (co) and Lead (Pb) in "𝘚𝘮𝘰𝘰𝘵𝘩 𝘤𝘢𝘺𝘦𝘯𝘯𝘦" pineapple fruit, leaves tissue and soil using inductively coupled Plasma-Optical Emission Spectrometry (ICP-OES).
    (2005) López Morales, José L.; Román Velázquez, Félix R.; College of Arts and Sciencies - Sciences; Romañach Suárez, Rodolfo; Cortés Figueroa, José E.; Department of Chemistry; Rodríguez, Gustavo Martínez
    The island of Vieques is currently surrounded by controversy since it was used for military purposes for an extended period of time. There have been several scientific reports stating that all the land used by the United States Navy for military activities is contaminated with explosives (Cruz, 1988) and heavy metals (García 𝘦𝘵 𝘢𝘭., 2000), affecting the island’s flora (Massol and Díaz, 2000) and fauna (Massol and Díaz, 1999). Other reports stated that the contamination extended not only to the firing range zone, but to the civilian zones as well (Massol and Díaz, 2001). Inductively coupled plasma with optical emission spectrometry (ICP-OES) was employed to determine the total concentration of Arsenic, Cadmium, Chromium, Cobalt and Lead in 𝘚𝘮𝘰𝘰𝘵𝘩 𝘤𝘢𝘺𝘦𝘯𝘯𝘦 fruits, leave tissues and soil samples from a pineapple plantation. 𝘚𝘮𝘰𝘰𝘵𝘩 𝘤𝘢𝘺𝘦𝘯𝘯𝘦 is a pineapple variety that currently is been cultivated in Vieques as an experimental crop. This plantation is located in “El Sector Luján”, inside the civilian zone and far from the firing range zone. Another plantation of the same variety in Barceloneta was selected as control in order to compare results of the metals mentioned above that could have resulted as a consequence of the Navy’s military activities. A microwave assisted acid digestion procedure was employed for sample preparation prior to the analysis. No contamination was observed in the “𝘚𝘮𝘰𝘰𝘵𝘩 𝘤𝘢𝘺𝘦𝘯𝘯𝘦” and its leaves tissues samples from Vieques when compared with the control plantation in Barceloneta. Values for As were observed below the quantitation limits. Soil samples from the control plantation in Barceloneta exhibited higher levels of As, Cr, Cd, Co and Pb than the Vieques’ plantation. Values as high as 331, 77, 6, 13 and 76 mg/Kg were found for these metals respectively. Some values for these metals were below the estimated limit of quantitation (LOQ).