Bioremediation of naphthalene in water by Sphingomonas paucimobilis using new biodegradable surfactants based on poly (ɛ-caprolactone)

Abstract

a b s t r a c t New amphiphilic block surfactants ABA based on a central segment of polycaprolactone with different molecular composition were evaluated in the bioremediation of naphthalene in water by Sphingomonas paucimobilis and compared with sodium dodecyl sulphate as reference surfactant (SDS). Also the biodegradation of the new surfactants by bacteria, S. paucimobilis and a mixture of bacteria (Pseudomonas aureginosa, Bacillus subtilis, Bacillus amyloliquefaciens and Bacillus megaterium) was studied by indirect impedance technique and carbon dioxide determination. All the bacteria biodegraded in solution and micellar phase the central segment of PCL with mineralization rates in the range of 0.024-0.036 mg of CO 2 per day. S. paucimobilis biodegraded naphthalene in the presence of the new surfactants and GC analysis demonstrated that conversion to products started immediately after inoculum. In all the experiments, except for SDS, at 140 h of incubation time, the remaining naphthalene concentration was about 10% of the initial concentration. In contrast, the production of CO 2 was delayed 4-7 days and values around 75%of naphthalene mineralization degree were achieved in three weeks. The addition of PCL-surfactants, in solution and in micellar phase, not interfered in the naphthalene mineralization. These results have shown promising potential of these biodegradable PCL-surfactants in surfactant-enhanced remediation (SER) technology for removing residual organics from contaminated groundwater and soils.

Hierarchically organized micellization of thermoresponsive rod‐coil copolymers based on poly[oligo(ethylene glycol) methacrylate] and poly(ε‐caprolactone)

“…These copolymers showed a LCST and their aqueous solutions started to become cloudy around 91 C for POEGMA Co (21), thus, the transmittance rapidly dropped to 0%. In the other hand, the LCST decreased with increasing molecular weight of the copolymer and thus, the LCST value for POEGMA Co (29) was 80 C. The LCST was concentration dependent and its value for POEGMA Co (29) decreased from 89 to 80 C as the concentration increases from 0.5 to 1 g/L.…”

“…The transmittance of aqueous polymer solutions was monitored at 550 nm at a heating rate of 1 C/min for samples POEGMA Co (29) and POEGMA Co (21) in presence and absence of NaCl. These copolymers showed a LCST and their aqueous solutions started to become cloudy around 91 C for POEGMA Co (21), thus, the transmittance rapidly dropped to 0%.…”

“…47 The addition of sodium chloride to POEGMA Co (29) aqueous solution led to a decrease of the LCST from 80 C (in its absence) to 76 C for 1 M NaCl.…”

“…The white solid product was eluted through a basic alumina column with dichloromethane (yield ¼ 70%). (29) and 75:1 for POEGMA Co (39).…”

“…Lately, with an increase in environmental awareness, amphiphilic biodegradable copolymers offer interesting properties for biotechnological applications. 29 These amphiphilic block copolymer brushes should exhibit interesting phase behavior. Thus, fluorescence spectroscopy, dynamic light scattering (DLS), TEM, and MTDSC studies were carried out to have a detailed knowledge of their selforganization behavior, including critical micelle concentration and temperature (cmc and cmt), micellar size, and aggregate morphology.…”