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Rare earth elements such as neodymium (Nd) are important elements used mainly in developing new technologies. Although they are found in low concentrations in nature, they can be obtained by extracting solid samples such as phosphogypsum. Among the techniques, adsorption has been used successfully with several adsorbent materials. In this work, two strains of Spirulina platensis (LEB-18 and LEB-52) were employed as biosorbents for efficiently removing the Nd element from the aqueous media. Biosorption tests were carried out in a batch system, and the results of the biosorption kinetics showed that for both materials, the biosorption of Nd was better described by the Avrami model. Moreover, it could be considered that 80 min would be necessary to attain the equilibrium of Nd(III) using both biosorbents. The result of the biosorption isotherms showed that for both strains, the best-fitted model was the Liu model, having a maximum biosorption capacity of 72.5 mg g(-1) for LEB-18 and 48.2 mg g(-1) for LEB-52 at a temperature of 298 K. Thermodynamics of adsorption showed that for both LEB-18 and LEB-52 the process was favorable ( increment G degrees < 0) and exothermic ( increment H degrees -23.2 for LEB-18 and increment H degrees -19.9 for LEB-52). Finally, both strains were suitable to uptake Nd, and the better result of LEB-18 could be attributed to the high amount of P and S groups in this biomass. Based on the results, a mechanism of electrostatic attraction of Nd3+ and phosphate and sulfate groups of both strains of Spirulina platensis was proposed.

In this work, a high porous activated carbon from Jacaranda mimosifolia was developed and employed for ketoprofen adsorption. After the pyrolysis process at 973.15 K, the material presented cavities with different sizes allocated on the particle surface. The material presented a pH at the point of zero charge of 4.1 with the best adsorption at pH 2. The best adsorbent dosage was 0.72 g L-1, corresponding to a removal of 96%. The system reached the adsorption equilibrium after 120 min and was described by the linear driving force model. The isotherms revealed that the adsorption capacity decreased with the temperature and followed the Langmuir model, with a maximum adsorption capacity of 303.9 mg g-1. This high capacity can be associated with the high surface area (928 m2 g-1) and pore volume (0.521 cm3 g-1) values. The thermodynamic values indicated that the adsorption system is spontaneous and exothermic. The enthalpy value indicates that the interactions between the adsorbent and adsorbate are physical. Regeneration tests showed a decreasing percentage of removal of 7.86% after 5 cycles. Finally, the adsorbent showed efficiency when treating a simulated effluent containing drugs and inorganic salts, showing the removal of 71.43%.

The present work consisted of preparing and characterizing composite carbon materials (WRCC) from raw winery residues (WR) activated with zinc chloride to produce a carbon adsorbent. The WRCC was used for the adsorption of emerging contaminants in aqueous media. The WRCC presented a morphology with favorable characteristics for the adsorption process, giving an abundant porous structure with pores of different sizes. The results show the WRCC's effectiveness, presenting surface area values (227 m2 g-1) and total pore volume (0.175 cm3 g-1). The general order kinetic model predicted the experimental curves sufficiently. The Sips model better described the two adsorbates' equilibrium data, with maximum adsorption capacities of 376.0 and 119.6 mg g-1 for 2-nitrophenol and ketoprofen, respectively. The WRCC carbon material was also highly efficient, with maximum removal of 81.4% and 94% in 1000 mg L-1 of the compounds 2-nitrophenol and ketoprofen. Finally, the prepared material has essential characteristics that make it an efficient adsorbent in treating effluents with emerging contaminants.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES In this work the synthesis of a magnetic geopolymer from silica, metakaolin, iron zero-valent, soybean oil, sodium hydroxide and hydrogen peroxide was proposed. The magnetic geopolymer was characterized by X-ray diffraction, Fourier transform infrared spectrometry, surface area, mean pore diameter and pore volume by BET and BJH methods, scanning electron microscopy and vibrating sample magnetometer. The synthesized material was tested as an adsorbent of the anionic dye Acid Red 97 (AR97). The results showed that the magnetic geopolymer is mesoporous, has sufficient magnetization to be removed by action of a magnetic field of the aqueous solution, removes more than 94% of dye in only 20 minutes, and has a high adsorptive capacity of 1814.27 mg g-1 of AR97 at a temperature of 318 K. The magnetic geopolymer presented adsorption capacity very close to the initial one for up to five cycles of use. This adsorbent was synthesized from low cost materials with extremely high adsorption capacity and could be easily separated from the treated liquid effluent. Neste trabalho foi proposto a síntese de um geopolímero magnético a partir de sílica, metacaulim, ferro zero valente, óleo de soja, hidróxido de sódio e peróxido de hidrogênio. O geopolímero magnético foi caracterizado por difração de raios-X, espectrometria de infravermelho com transformada de Fourier, área superficial, diâmetro médio de poro e volume de poro pelos métodos BET e BJH, microscopia eletrônica de varredura e magnetômetro de amostra vibrante. O material sintetizado foi testado como adsorvente do corante aniônico Acid Red 97 (AR97). Os resultados mostraram que o geopolímero magnético é mesoporoso, possui magnetização suficiente para ser removido por ação de um campo magnético da solução aquosa, remove mais de 94% de corante em apenas 20 minutos, e possui alta capacidade adsortiva, de 1814,27 mg g-1 de AR97 na temperatura de 318 K. O geopolímero magnético apresentou capacidade de adsorção muito próxima da inicial por até cinco ciclos de utilização. Este adsorvente foi sintetizado a partir de materiais de baixo custo, apresentando capacidade de adsorção extremamente alta, podendo ser facilmente separado do efluente líquido tratado.