Use of biosurfactants from urban wastes compost in textile dyeing and soil remediation

A compost isolated humic acid-like (cHAL) material was pointed out in previous work for its potential as auxiliary in chemical technology. Its potential is based on its relatively low 0.4 g L −1 critical micellar concentration (cmc) in water, which enables cHAL to enhance the water solubility of hyd...

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Veröffentlicht in:Waste management (Elmsford) 2009, Vol.29 (1), p.383-389
Hauptverfasser: Montoneri, Enzo, Boffa, Vittorio, Savarino, Piero, Tambone, Fulvia, Adani, Fabrizio, Micheletti, Luca, Gianotti, Carlo, Chiono, Roberto
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Sprache:eng
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Zusammenfassung:A compost isolated humic acid-like (cHAL) material was pointed out in previous work for its potential as auxiliary in chemical technology. Its potential is based on its relatively low 0.4 g L −1 critical micellar concentration (cmc) in water, which enables cHAL to enhance the water solubility of hydrophobic substances, like phenanthrene, when used at higher concentrations than 0.4 g L −1. This material could be obtained from a 1:1 v/v mixture of municipal solid and lignocellulosic wastes composted for 15 days. The compost, containing 69.3% volatile solids, 39.6% total organic C and 21 C/N ratio, was extracted for 24 h at 65 °C under N 2 with aqueous 0.1 mol L −1 NaOH and 0.1 mol L −1 Na 4P 2O 7, and the solution was acidified to separate the precipitated cHAL in 12% yield from soluble carbohydrates and other humic and non-humic substances. In this work two typical applications of surfactants, i.e., textile dyeing (TD) and soil remediation by washing (SW), were chosen as grounds for testing the performance of the cHAL biosurfactant against the one of sodium dodecylsulfate (SDS), which is a well established commercial synthetic surfactant. The TD trials were carried out with nylon 6 microfiber and a water insoluble dye, while the SW tests were performed with two soils contaminated by polycyclic aromatic hydrocarbons (PAH) for several decades. Performances were rated in the TD experiments based on the fabric colour intensity (Δ E) and uniformity ( σΔ E), and in the SW experiments based on the total hydrocarbons concentration (CW PAH) and on the residual surfactant ( C re) concentrations in the washing solution equilibrated with the contaminated soils. The results show that both cHAL and SDS exhibit enhanced performance when applied above their cmc values. However, while in the TD case a significant performance effect was observed at the surfactants cmc value, in the SW case the required surfactants concentration values were equivalent to 25–125 × cmc for cHAL and to 4–22 × cmc for SDS. The vis-a-vis comparison of the two surfactants gave the following results: in the TD case the cHAL biosurfactant at 0.4 g L −1 yields good colour intensity and equal colour uniformity as SDS at 5 g L −1, in the SW case cHAL was found to enhance CW PAH by a factor of 2–4 relative to SDS with one soil, whereas with the other soil the two surfactants behaved similarly. The C re data, however, showed that both soils absorbed by far more SDS (68–95%) than cHAL (12–54%). The results
ISSN:0956-053X
1879-2456
DOI:10.1016/j.wasman.2008.01.011