Sub-ppb detection of formaldehyde with cantilever enhanced photoacoustic spectroscopy using quantum cascade laser source

Abstract A novel cantilever enhanced photoacoustic spectrometer with mid-infrared quantum cascade laser was applied for selective and sensitive formaldehyde (CH 2 O) gas measurement. The spectrum of formaldehyde was measured from 1,772 to 1,777 cm -1 by tuning the laser with a spectral resolution of 0.018 cm -1 . The band at 1,773.959 cm -1 was selected for data analysis, at which position the laser emitted 47 mW. In univariate measurement, the detection limit (3r, 0.951 s) and the normalized noise equivalent absorption coefficient (3r) for amplitude modulation (AM) were 1.6 ppbv and 7.32 9 10 -10 W cm -1 (Hz) -1/2 and for wavelength modulation (WM) 1.3 ppbv and 6.04 9 10 -10 W cm -1 (Hz) -1/2 . In multivariate measurement, the detection limit (3r) can be as low as 901 pptv (1,773.833-1,774.085 cm -1 , 15 spectral points each 0.951 s) for AM and 623 pptv (1,773.743-1,774.265 cm -1 , 30 spectral points each 0.951 s) for WM. Because measurement time increases in multivariate measurement, its application is justified only when interferents need to be resolved. Potential improvements of the system are discussed

Remoción de plomo presente en soluciones acuosas utilizando biocarbón producido a base de coronta de maíz

Se produjo biocarbón a partir de residuos de coronta de maíz (Zea mays) para remover plomo de soluciones acuosas. La carbonización del residuo se realizó a 600 °C por 2 h a 1 atmosfera de nitrógeno controlada. Se realizaron análisis texturales, morfológicos y estructurales para caracterizar el material. De los datos de la isoterma de adsorción de N2, el material mostró una estructura microporosa de 144,13 m2/g de área superficial. Se realizaron experimentos de adsorción de Pb2+ en equilibrio y cinética, donde los datos de equilibrio se ajustan mejor al modelo de Dubinin-Radushkevich (R2 ≥ 0,990) con capacidad de adsorción máxima de 12,16 mg/g con. Asimismo, para los datos de cinética, el modelo con mejor ajuste fue el de Elovich (R2 ≥ 0,994). Sin embargo, la cinética de adsorción también se ajustó a los modelos de Pseudo-Primer orden (R2 ≥ 0,990) y Pseudo- Segundo orden (R2 ≥ 0,992), con valores de adsorción de 10,54 mg/g y 15,59 mg/g respectivamente. El análisis de la espectrometría de energía dispersiva (EDS), después de las pruebas de adsorción detectaron la presencia de Pb2+ en la estructura del biocarbón. La coronta de maíz tiene un potencial uso para la producción de biocarbón y la remoción de Pb2+, demostrando ser eficiente

Investigation of Sulfonated Graphene Oxide as the Base Material for Novel Proton Exchange Membranes

This work deals with the development of graphene oxide (GO)-based self-assembling membranes as possible innovative proton conductors to be used in polymer electrolyte membrane fuel cells (PEMFCs). Nowadays, the most adopted electrolyte is Chemours’ Nafion; however, it reveals significant deficiencies such as strong dehydration at high temperature and low humidity, which drastically reduces its proton conductivity. The presence of oxygenated moieties in the GO framework makes it suitable for functionalization, which is required to enhance the promising, but insufficient, proton-carrying features of GO. In this study, sulfonic acid groups (–SO3H) that should favor proton transport were introduced in the membrane structure via a reaction between GO and concentrated sulfuric acid. Six acid-to-GO molar ratios were adopted in the synthesis procedure, giving rise to final products with different sulfonation degrees. All the prepared samples were characterized by means of TGA, ATR-FTIR and Raman spectroscopy, temperature-dependent XRD, SEM and EDX, which pointed out morphological and microstructural changes resulting from the functionalization stage, confirming its effectiveness. Regarding functional features, electrochemical impedance spectroscopy (EIS) as well as measurements of ion exchange capacity (IEC) were carried out to describe the behavior of the various samples, with pristine GO and commercial Nafion® 212 used as reference. EIS tests were performed at five different temperatures (20, 40, 60, 80 and 100 °C) under high (95%) and medium (42%) relative humidity conditions. Compared to both GO and Nafion® 212, the sulfonated specimens demonstrate an increase in the number of ion-carrying groups, as proved by both IEC and EIS tests, which reveal the enhanced proton conductivity of these novel membranes. Specifically, an acid-to-GO molar ratio of 10 produces a six-fold improvement of IEC (4.23 meq g-1) with respect to pure GO (0.76 meq g-1), while a maximum eight-fold improvement (5.72 meq g-1) is achieved in SGO-15

Electronic waste recovery in Finland:consumers’ perceptions towards recycling and re-use of mobile phones

Abstract This paper examines consumers’ awareness and perceptions towards mobile phone recycling and re-use. The results are based on a survey conducted in the city of Oulu, Finland, and analysed in the theoretical framework based on the theories of planned behaviour (TPB) and value-belief-norm (VBN). The findings indicate that consumers’ awareness of the importance and existence of waste recovery system is high; however, awareness has not translated to recycling behaviour. The survey reveals that 55% of respondents have two or more unused mobile phones at homes. The more phones stored at homes, the more often reasons ‘I don’t know where to return’ and/or ‘have not got to do it yet’ were mentioned. This indicates that proximity and the convenience of current waste management system are inadequate in promoting the return of small waste electrical and electronic equipment (WEEE). To facilitate re-use, and the highest level of recovery, consumers will need to be committed to return end-of-use electronics to WEEE collection centres without delays. Further, the supply and demand of refurbished mobile phones do not meet at this moment in Finland due to consumer’s storing habits versus expectations of recent features under guarantee and unrealistic low prizes. The study also points out that, in order to change current storing habits of consumers, there is an explicit need for more information and awareness on mobile phone collection in Finland, especially on regarding retailers’ take-back

Combined Partial Oxidation of Methane to Synthesis Gas and Production of Hydrogen or Carbon Monoxide in a Fluidized Bed using Lattice Oxygen

ISSN:2194-4296ISSN:2194-428

Substitution potential of rare earth catalysts in ethanol steam reforming

Abstract This study suggests the possibility of substituting rare earths containing catalysts in ethanol steam reforming by means of sustainability assessment. Four Ni-catalysts are assessed; two of the Ni-catalysts are rare earths containing catalysts Ni/Al₂O₃-CeO₂and Ni/La₂O₃ while the other two are non-rare earths containing catalysts Ni/Al₂O₃ and Ni/ZnO. The sustainability assessment tool used covers environmental, health and safety and economic indicators in conjunction with a linear scale transformation (Max) normalization technique and an analytical hierarchy method to evaluate the sustainability performance of the catalysts. The sustainability assessment results obtained demonstrated that Ni/Al₂O₃ is the best performing catalysts in terms of the overall sustainability of the ethanol steam reforming reaction. The rare earths containing catalyst supports, i.e. cerium and lanthanum oxides can be successfully substituted with aluminum oxide catalyst support whilst still maintaining the overall sustainability performance of the reaction

End-of-use vs. end-of-life:when do consumer electronics become waste?

Abstract This study focuses on the lifespan of consumer electronics. The article reviews end-of-life terminology in scientific literature and suggests distinguishing end-of-use and end-of-life stages. The question, when electronics become waste, is approached using the concept of a system called PSSP language, which classifies artefacts based on their attributes of purpose, structure, state and performance. It is highlighted that waste as a concept is dynamic; the same thing can be waste or non-waste at different times and places and for different people. Further, the article reviews the impact of storage behavior on the realization of the waste hierarchy, using mobile phones as a case study. Evidence suggests that over half of customers use their mobile phones for only two years, and there is little incentive to keep them in use longer. Surveys also indicate that over half of the customers do not return their phones for reuse or recycling but keep them at home. The article suggests that the three key factors, promoting the storing of an old phone, are the shortness of usage time, perceived residual value of replaced equipment and concerns of personal information security. It is also indicated that memories and the personal attachment to the device contribute to consumers’ storage decision. It is concluded that, to prolong the use of mobile phones, there is a demand for changing consumers attitudes towards the return of electronics for reuse and repair to be more positive

Concentration of meat processing industry wastewater by reverse osmosis and anaerobic digestion of the concentrate

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