Método de quantificação do residual de ácido naftênico em água produzida sintética após adsorção com fibra têxtil / Method for quantification of naphthenic acid residual in synthetic produced water after adsorption with textile fiber

A água produzida (AP) na extração de petróleo representa um potencial impacto ambiental devido ao seu descarte, muitas vezes sem tratamentos adequados para a remoção de contaminantes. O objetivo deste trabalho é propor um método de quantificação de ácido naftênico (AN) em AP sintética. O método desenvolvido baseou-se na extração do AN em meio orgânico seguido de leituras em FTIR. O método proposto demonstrou reprodutibilidade com curva de calibração com coeficiente de correlação acima de 0,99

Insights into nanofiltration of textile wastewaters for water reuse

Textile industry constitutes nowadays one the largest consumers of water, and consequently the wastewater reuse can be a profitable operation. In this study, the decontamination of pure dyes solutions (Remazol Turquoise Blue G, Remazol Yellow GR and Lanaset Blue 2R) and synthetic textile wastewaters was evaluated in a nanofiltration (NF) cross-flow cell, using polyamide NF membranes, NF90 and DK, with molecular weight cut-off between 200-400 Da and 150-300 Da, respectively. Permeate flux and the color reduction were evaluated for the different dye solutions under different temperature and pH conditions and, NaCl, wetting and dispersant concentrations. DK membrane showed the best results in terms of permeate flux for all the dye solutions tested. The highest permeate flux was achieved for higher temperatures under acidic to neutral pHs values, resulting in almost 100 % color removal for all situations

Modeling of trivalent chromium speciation in binding sites of marine macroalgae Sargassum Cymosum

In this study, the marine macroalgae Sargassum cymosum was used for the purification of waters contaminated with trivalent chromium. FTIR analysis revealed a high heterogeneity of the biosorbent surface, as indicated by the different absorption peaks. Biomass titration revealed two main functional groups, carboxylic and hydroxyl. The pK(1,H) value and the number of carboxylic groups were estimated as 3.05 +/- A 0.01 and 1.90 +/- A 0.01 mmol g(-1), respectively. An equilibrium model considering the metal speciation in aqueous solution was able to predict the experimental data at different pH values. Adsorption of chromium increases significantly with an increase of the solution pH. Furthermore, the speciation of the binding sites as a function of the solution pH was predicted, showing that Cr(OH)(2+) has a higher affinity than Cr3+ to the binding sites. A mass transfer model considering an intraparticle diffusion resistance was able to predict the kinetic data, showing that Cr3+ diffuses faster that CrOH2+

Adding value to marine macro-algae Laminaria digitata through its use in the separation and recovery of trivalent chromium ions from aqueous solution

In this study, Laminaria seaweed was used in its protonated form as an effective biosorbent for chromium(III) removal from aqueous solutions. The effect of different operating conditions (pH, initial metal concentration and temperature) on the efficiency of the biosorption process was assessed. Biosorption was strongly dependent on the solution pH and less dependent on the temperature. The Cr(III) adsorption capacity of the seaweed increased with the pH. The maximum uptake capacity for Cr(III) was 42 mg g(-1) at pH 4, considering a maximum initial chromium concentration of 250 mg g(-1), at 25 degrees C. Langmuir and Freundlich models were able to fit well the experimental equilibrium data. The Langmuir equilibrium model parameters at pH = 4 and T = 25 degrees C are q(max) = 41 +/- 1 mg g(-1) and K-L = 0.31 +/- 0.04 L mg(-1). The adsorptive behavior of biosorbent particles was modeled using a batch reactor mass transfer kinetic model, which successfully predicts Cr(III) concentration profiles, with an average homogeneous diffusivity, D-h, of 0.13 x 10(-8) +/- 0.08 cm(2) s(-1). The biosorbent was characterized in terms of apparent density, real density, porosity, particle size and pore size distribution. The chemical characterization of the biosorbent was based on the determination of the main chemical constituents present in the structure of the biomass, and in the identification of active sites on the surface, by the Fourier Transform Infrared Spectroscopy (FTIR) technique. FTIR analysis of Laminaria digitata revealed the complex nature of the biomass, with different binding groups, such as carboxyl and sulfonic, which are responsible for the binding of the metals