Resumo O uso de coagulantes à base de plantas (coagulante natural) em tratamentos de efluentes tem potencial contra coagulantes inorgânicos utilizados comercialmente. Este trabalho teve como objetivo avaliar os coagulantes orgânicos hemiceluloses catiônicas (CH) - sintetizadas a partir da casca de amendoim - associadas ao tanino catiônico (TSG) - comercial - para coagulação/floculação como tratamento primário, seguido de separação sólido-líquido via sedimentação/flotação por ar (DAF). O ensaio foi realizado em jar test em efluente de uma indústria multinacional do setor de beneficiamento de grãos, localizada na cidade de Uberlândia-MG. Os diagramas de coagulação foram determinados pelo método de interpolação espacial de dados do modelo de regressão de Kringing e o teste de Tukey foi utilizado para avaliar a diferença nos resultados obtidos. Os pontos ótimos de eficiência de remoção de turbidez (TRE), superiores a 98%, foram alcançados para a associação TSG/CH com 200 mg L-1 (pH 10,72), 350 mg L-1 (pH 9,72), 500 mg L-1 (pH 9,56) na sedimentação. Para a separação por DAF, a associação de TSG/CH resultou em valores de TRE superiores a 95% nas dosagens de 350 mg L-1 (pH 9,59) e 500 mg L-1 (pH 7,92). Além disso, os resultados obtidos indicam que o uso associado de TSG/CH como auxiliar de coagulação, favoreceu o acoplamento bolha-partícula, resultando em menor volume de lodo, além disso, o CH expandiu a ação do TSG para a região básica.

Abstract The use of plant-based coagulants (natural coagulants) in wastewater treatments has potential advantages over the inorganic coagulants used commercially. This study evaluated organic coagulants cationic hemicelluloses (CH) synthesized from peanut shell and associated with commercial cationic tannin (TSG) for use as the primary coagulation/flocculation treatment, followed by solid-liquid separation via sedimentation/flotation by dissolved air (DAF). The assay was carried out in a jar test on effluent from a multinational industry in the grain processing sector, located in the city of Uberlândia-MG. Coagulation diagrams were determined using the data spatial interpolation method of the Kringing regression model and the Tukey test was used to assess the difference in the results obtained. The optimum removal points of turbidity removal efficiency (TRE), greater than 98%, were achieved for the TSG/CH association with 200 mg L-1 (pH 10.72), 350 mg L-1 (pH 9.72), 500 mg L-1 (pH 9.56) in sedimentation. For the separation by DAF, the association of TSG/CH resulted in TRE values greater than 95% at dosages of 350 mg L-1 (pH 9.59) and 500 mg L-1 (pH 7.92). Furthermore, the results indicate that the associated use of TSG/CH, a coagulation aid, favored the coupling of the DAF bubble-particle, resulting in a smaller volume of sludge. In addition, CH expanded the action of TSG to the basic region.

The composite LiFePO4/polyaniline was prepared by chemical synthesis to promote the intensification of the electrochemical properties for use as cathodes in lithium ion batteries. The X-ray diffraction (XRD) of LiFePO4 synthesized by solvothermal method were indexed to the orthorhombic structure, according to the JCPDS 40-1499. The spectra Raman and FTIR showed a high degree of ordering of LiFePO4 with interaction between LiFePO4 surface with structure conjugate of conducting polymers. The cyclic voltammogram of the composite synthesized chemically showed a significant reduction in the value of ΔE p (ΔE p = 0.20 V) when compared to LiFePO4 (ΔE p = 0.41 V), with lower charge transfer resistance values, indicating favoring electron transfer rate in the composite. Thus, the alternative synthesis route of the LiFePO4 / PAni composite was easy to handle and allowed an increase in the electrochemical properties of the LiFePO4, compared to the traditional methods that require additional thermal treatments.

The synthesis of cationic derivatives of hemicelluloses from corn husk was carried out by the reaction of hemicelluloses with 2,3-epoxypropyltrimethylammonium chloride (ETA) in aqueous sodium hydroxide. The characterization of the cationic derivatives was carried out by elemental analysis, Fourier Transformed Infrared Spectroscopy (FTIR) and Thermogravimetric Analysis (TG/DTA). An important characteristic was the solubility in water of the produced derivatives. This characteristic was used to apply derivatives as auxiliary coagulation with tannin in wastewater treatment for industrial laundries. The results showed that the association of tannin and cationic hemicelluloses (3,200 mg L-1) is important because the turbidity removal was greater than 95% in all range of pH, including alkaline regions. Then it is unnecessary to adjust the pH before the coagulation step.

Doped Li1.05M0.02Mn1.98O4 (M = Ga3+ or Al3+) were prepared by Pechini synthesis using lithium and manganese acetates, citric acid, ethylene glycol, and the respective oxide or acetate of the doping ions in molar ratios of 2.00 (Mn1.98 + M0.02) to 1.05 Li. The TGA/DTA of the precursor gels showed weight loss/energy relative to crystallization below 450 ºC. From the XRD, a single cubic phase (Fd3m) was identified for the all-doped or undoped oxides after only 2 h calcination. The unit cell parameters a for both aluminum- and gallium-doped oxides calcined at 750 °C for 2 h (8.212 Å and 8.210 Å, respectively) were higher than that for the undoped oxide (8.199 Å). The crystallite sizes ranged from ~ 20 nm to 70 nm, conferring nanometric character. The specific capacities decreased in order: Cdischarge (Li1.05Mn2O4) >Cdischarge (Li1.05Ga0.02Mn1.98O4) >Cdischarge (Li1.05Al0.02Mn1.98O4), but with increasing capacity retention for the doped samples.

The aim of this paper was the recovering of the cathodic material from discarded lithium ion batteries for obtainment of the lamellar double hydroxides (LDHs) by the co-precipitation method at variable pH in HCl and H2O2 1:1 (v/v) acid solution containing Co and Al (extracted from cathodic material composed of LiCoO2 and aluminum foil). These metals were precipitated in LiOH at pH 9 or 11, or NH4OH at pH 9 and submitted to the hydrothermal treatment (HT) to improve the structural organization of the LDHs lamellae. After precipitation, the resulting solids were structurally characterized by XRD for phase identification and calculation of the unit cell parameter, thermally by TGA for the identification of the mass loss and morphologically by SEM. The sample obtained by precipitation with LiOH at pH 11 / hydrothermal treatment showed diffraction peaks similar to hydrotalcite, morphological and thermal characteristics similar to the pattern Co-Al-Cl LDH obtained by co-precipitation at constant pH 8.