REMOÇÃO DE COMPOSTOS FARMACÊUTICOS PRESENTES EM ÁGUAS RESIDUAIS POR ADSORSÃO EM CARBONIZADOS E CARVÕES ACTIVADOS OBTIDOS A PARTIR DE DESPERDÍCIOS DE BIOMASSA

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Activated carbons from the co-pyrolysis of rice wastes for Cr(III) removal

Publication . Dias, Diogo; Bernardo, Maria; Lapa, Nuno; Pinto, Filomena; Matos, Inês; Fonseca, Isabel Maria

ABSTRACT: Rice husk and polyethylene were mixed (50 % w/w each) and submitted to a pyrolysis assay. Four physical activations with CO2 were performed on the resulting co-pyrolysis char (PC). The activation at 800 °C, for 4h, generated the activated carbon (PAC3) with the best textural properties. PC, PAC3 and a commercial activated carbon (CAC) were characterized and submitted to Cr(III) removal assays. PC had a high percentage of volatile matter that was removed after the physical activation, resulting in more available pores in the final material (PAC). In the Cr(III) removal assays, two S/L ratios were tested: 5 and 10 g L-1. PC did not remove any Cr(III) from the solutions, but PAC presented similar results to CAC. At the S/L of 5 g L-1, Cr(III) removal was of 58.5 % for PAC and 62.5 % for CAC, both by adsorption mechanism; at the S/L of 10 g L-1, Cr(III) removal was almost complete due to precipitation caused by pH increase. The highest uptake capacities were of 7.92 mg g-1 for PAC and 8.71 mg g-1 for CAC, at the S/L of 5 g L-1. The results indicated that PAC3 may be a viable alternative to CAC on Cr(III) removal from aqueous media.

2018Journal article

Open access

Cr(III) removal from synthetic and industrial wastewaters by using co-gasification chars of rice waste streams

Publication . Dias, Diogo; Lapa, Nuno; Bernardo, Maria; Ribeiro, W.; Matos, Inês; Fonseca, Isabel Maria; Pinto, Filomena

ABSTRACT: Blends of rice waste streams were submitted to co-gasification assays. The resulting chars (G1C and G2C) were characterized and used in Cr(III) removal assays from a synthetic solution. A Commercial Activated Carbon (CAC) was used for comparison purposes. The chars were non-porous materials mainly composed by ashes (68.3-92.6% w/w). The influences of adsorbent loading (solid/liquid ratio - S/L) and initial pH in Cr(III) removal were tested. G2C at a S/L of 5 mg L-1 and an initial pH of 4.50 presented an uptake capacity significantly higher than CAC (7.29 and 2.59 mg g(-1), respectively). G2C was used in Cr(III) removal assays from an industrial wastewater with Cr(III) concentrations of 50, 100 and 200 mg L-1. Cr(III) removal by precipitation (uptake capacity ranging from 11.1 to 14.9mg g(-1)) was more effective in G2C, while adsorption (uptake capacity of 16.1 mg g(-1)) was the main removal mechanism in CAC.

2018Journal article

Open access