Synergistic chemo-enzymatic hydrolysis of poly(ethylene terephthalate) from textile waste

Due to the rising global environment protection awareness, recycling strategies that comply with the circular economy principles are needed. Polyesters are among the most used materials in the textile industry, therefore achieving a complete poly(ethylene terephthalate) (PET) hydrolysis in an environmentally-friendly way is a current challenge. In this work a chemo-enzymatic treatment was developed in order to recover the PET building blocks, namely terephthalic acid (TA) and ethylene glycol. To monitor the monomer and oligomer content in solid samples, a Fourier-Transformed Raman method was successfully developed. A shift of the free carboxylic groups (1,632 cm-1) of TA into the deprotonated state (1,604 and 1,398 cm-1) was observed and bands at 1,728 and 1,398 cm-1 were used to assess purity of TA after the chemo-enzymatic PET hydrolysis. The chemical treatment, performed under neutral conditions (T=250 °C, P=40 bar) led to conversion of PET into 85% TA and small oligomers. The latter were hydrolysed in a second step by using the Humicola insolens cutinase (HiC) yielding 97% pure TA, therefore comparable with the commercial synthesis grade TA (98%)

Synergistic chemo-enzymatic hydrolysis of poly(ethylene terephthalate) from textile waste

Due to the rising global environment protection awareness, recycling strategies that comply with the circular economy principles are needed. Polyesters are among the most used materials in the textile industry, therefore achieving a complete poly(ethylene terephthalate) (PET) hydrolysis in an environmentally-friendly way is a current challenge. In this work a chemo-enzymatic treatment was developed in order to recover the PET building blocks, namely terephthalic acid (TA) and ethylene glycol. To monitor the monomer and oligomer content in solid samples, a Fourier-Transformed Raman method was successfully developed. A shift of the free carboxylic groups (1,632 cm-1) of TA into the deprotonated state (1,604 and 1,398 cm-1) was observed and bands at 1,728 and 1,398 cm-1 were used to assess purity of TA after the chemo-enzymatic PET hydrolysis. The chemical treatment, performed under neutral conditions (T=250 °C, P=40 bar) led to conversion of PET into 85% TA and small oligomers. The latter were hydrolysed in a second step by using the Humicola insolens cutinase (HiC) yielding 97% pure TA, therefore comparable with the commercial synthesis grade TA (98%)

Soil Awareness and Education : Developing a pan European Approach

This paper describes the activities of the Working Group (WG) on Soil Awareness and Education established in 2008 under the banner of the European Soil Bureau Network (ESBN), sponsored by the Joint Research Centre (JRC) of the European Commission (EC). In their individual countries members of the group have been involved in a range of activities reaching out to the education sector and policy and public stakeholder groups. This group plans to build on these activities, share best practice and develop initiatives to take forward at the European level

Interrogation of optical pH sensor based on sol-gel doped new luminescent europium chelate with compact photon counting system

Summary: This paper presents recent measurements of novel Eu3+-complex doped sol gel layers (ref 1) which are intended for use as pH indicators, with interrogation by monitoring their fluorescent decay with a compact photon-counting receiver (ref 2). The basic chemistry is outlined and the instrumental arrangement and experimental results are described.Requirements and basic concept of indicator chemistry. Luminescent lanthanide chelates have many applications, being useful alternatives to standard fluorescent dyes especially when there is significant autofluorescence. They are also useful donors for use in energy transfer experiments to determine static inter-molecular distances. These applications arise because of the chelates' excellent solubility and unusual spectral characteristics, including narrow (&lt;10 nm) spectral emission, large Stokes shifts (&gt;150 nm), potentially high quantum yields. Selvin et al. have synthesized several lanthanide chelates but all show inconvenient excitation maxima around 340 nm. In contrast, our novel long-wave luminescent dye, based on europium luminescence initiated by a covalently-bonded antenna fluorophor, shows excitation maxima at 370 nm where low cost LEDs are now available. To design sensors of high stability and long lifetime, the sensor matrix and sensor technology are of prime interest. Sol-gel technology enables the production of proton-permeable glassy layers at room temperature and offers simple methods for manipulation of the basic composition, molecular structure, and hence the chemical characteristics of organic matrices. Time-resolved fluorometry is preferable to conventional fluorometry, since there are no intensity related problems due to turbid samples, self-filter effect, and cuvette geometry. Also, the fluorescence decay time is usually independent of the concentration of the indicator, even when it has been partially modified by leaching out, by decomposition, or by photo bleaching. In the current work, the Eu3+-complex has been successfully entrapped into tetramethoxysilane (TMOS)-based sol-gel matrices. It was initially found that a Eu3+-complex, which showed useful pH sensitivity in aqueous solution, lost this sensitivity when immobilized in sol-gel matrices. In order to recover this property, the pH indicator bromothymol blue (BTB) was added to the starting sol-gel components and it was found that the useful pH response that was present in water was not only restored, but was actually improved upon. Instrumentation and experiment for interrogation of Eu3+-complex-doped sol-gel coated layer. The arrangement shown in fig 1 was used for rapid interrogation of fluorescence lifetime. The arrangement improves signal to noise because the sol-gel coating is illuminated directly with a filtered UV LED source, rather than via an optical fibre probe. This increases illumination intensity by removing optical power loss in the launch optics, illuminates a large coating area, and reduces the background auto-fluorescence signal generated from combined launch and return optics. The main excitation peak occurs at 370 nm, which falls in the absorption band of the pH-sensing layer. It should be noted that this arrangement, which was used to improve signal to noise and reduce self-fluorescence in our measurement, was considered to be only an interim step on the way to developing an all-fibre system for illumination and collection of light. Clearly similar gains in signal can be achieved by using larger input and output fibres or fibre bundles, and self-fluorescence can be reduced by use of separate fibre cables for incident and fluorescent light.<br/

Comparison of Surface and Spectral Properties of Optical Sensor Layers Prepared by Spin/Spray Coating and Printing Techniques

This study investigated the surface properties of optical sensor layers prepared using sol-gel technology and their response to dissolved NH3. A glass substrate was used to fabricate the optical sensor layers. The sol-gel solution was applied to the glass substrate using three different techniques: spin coating (SC), inkjet printing (IP), and spray coating (SP). In this work, we have attempted to investigate the effects of the different techniques for producing the sensor layers and to determine their response in the presence of ammonia. The surface properties (surface free energy—SFE and surface chemical composition—XPS) and spectral properties (response to ammonia and real-time response) of the prepared optical sensor layers were characterised. The results show that the sensor layers prepared by different techniques have similar SFE and XPS values, but different responses to dissolved NH3 solution and different responses in real-time measurements (exposure to fresh fish). Sensor layers prepared with a spray coating (SP) are the most responsive, the most sensitive, and have a higher response over time and the biggest colour change compared to SC and IP sensor layers

Single application of sewage sludge - impact on the quality of an alluvial agricultural soil.

The effects of sewage sludge on soil quality with regard to its nutrient and heavy metal content, microbial community structure and ability to maintain specific soil function (degradation of herbicide glyphosate) were investigated in a three months study using an alluvial soil (Eutric Fluvisol). Dehydrated sewage sludge significantly increased soil organic matter (up to 20.6% of initial content), total and available forms of N (up to 33% and 220% of initial amount, respectively), as well as total and plant available forms of P (up to 11% and 170% of initial amount, respectively) and K (up to 70% and 47% of initial amount, respectively) in the upper 2cm soil layer. The increase of organic matter was most prominent 3d after the application of sewage sludge, after 3months it was no longer significant. Contents of nutrients kept to be significantly higher in the sewage sludge treated soil till the end of experiment. Contents of some heavy metals (Zn, Cu, Pb) increased as well. The highest increase was found for Zn (up to 53% of initial amount), however it was strongly bound to soil particles and its total content was kept below the maximum permissible limit for agricultural soil. Based on molecular fingerprinting of bacterial 16S rRNA gene and fungal ITS fragment on 3rd day and 3rd month after sewage sludge amendment, significant short term effects on bacterial and fungal communities were shown due to the sewage sludge. The effects were more pronounced and more long-term for bacterial than fungal communities. The mineralization of (14)C-glyphosate in the sewage sludge soil was 55.6% higher than in the control which can be linked to (i) a higher glyphosate bioavailability in sewage sludge soil, which was triggered by the pre-sorption of phosphate originating from the sewage sludge and/or (ii) beneficial alterations of the sewage sludge to the physical-chemical characteristics of the soil

Mesoporous titania thin films as efficient enzyme carriers for paraoxon determination/detoxification: effects of enzyme binding and pore hierarchy in biocatalyst activity and reusability

The aims of this work were to efficiently immobilize organophosphate degrading enzyme, His6-OPH, on hierarchical mesoporoustitania thin films and further, to use this biocatalyst films as efficient tools in the detection/detoxofication of pesticides, paraoxon in our case. His6-OPH was immobilized on mesoporous thin films with uniform (9nm) and bimodal (13-38nm) pore size distribution, through covalent attachment and physical adsorption. The biocatalyst films show good activity, and enhanced stability with respect to the free enzyme at extreme conditions of pH and temperature, especially around neutral pH and room temperature. In addition, they can be easily separated from the reaction media and reused multiple times without significant loss in activity.Fil: Francica, Cynthia. University of Maribor. Faculty of Mechanical Engineering. Centre of Sensor Technology; EsloveniaFil: Bellino, Martin Gonzalo. Comisión Nacional de Energía Atómica. Gerencia del Área de Seguridad Nuclear y Ambiente. Gerencia de Química (CAC); Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Soler Illia, Galo Juan de Avila Arturo. Comisión Nacional de Energía Atómica. Gerencia del Área de Seguridad Nuclear y Ambiente. Gerencia de Química (CAC); Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Lobnik, A.. University of Maribor. Faculty of Mechanical Engineering. Centre of Sensor Technology; Esloveni

Removal of Pb2+, CrT, and Hg2+ Ions from Aqueous Solutions Using Amino-Functionalized Magnetic Nanoparticles

In this paper, a circular economy approach with the adsorption and desorption of heavy metal (HM) ions&mdash;i.e., lead (Pb2+), chromium (CrT), and mercury (Hg2+)&mdash;from aqueous solutions was studied. Specific and selective binding of HM ions was performed on stabilized and amino-functionalized iron oxide magnetic nanoparticles (&gamma;-Fe2O3@NH2 NPs) from an aqueous solution at pH 4 and 7. For this purpose, &gamma;-Fe2O3@NH2 NPs were characterized by thermogravimetric analysis (TGA), Fourier-transform infrared spectroscopy (FTIR), specific surface area (BET), transmission electron microscopy (TEM), EDXS, and zeta potential measurements (&zeta;). The effects of different adsorbent amounts (mads = 20/45/90 mg) and the type of anions (NO3&minus;, Cl&minus;, SO42&minus;) on adsorption efficiency were also tested. The desorption was performed with 0.1 M HNO3. The results showed improvement of adsorption efficiency for CrT, Pb2+, and Hg2+ ions at pH 7 by 45 mg of g-Fe2O3@NH2 NPs, and the sequence was as follows: CrT &gt; Hg2+ &gt; Pb2+, with adsorption capacities of 90.4 mg/g, 85.6 mg/g, and 83.6 mg/g, respectively. The desorption results showed the possibility for the reuse of &gamma;-Fe2O3@NH2 NPs with HNO3, as the desorption efficiency was 100% for Hg2+ ions, 96.7% for CrT, and 91.3% for Pb2+