An unified cosmological evolution driven by a mass dimension one fermionic field

An unified cosmological model for an Universe filled with a mass dimension one (MDO) fermionic field plus the standard matter fields is considered. After a primordial quantum fluctuation the field slowly rolls down to the bottom of a symmetry breaking potential, driving the Universe to an inflationary regime that increases the scale factor for about 71 e-folds. After the end of inflation, the field starts to oscillate and can transfer its energy to the standard model particles through a reheating mechanism. Such a process is briefly discussed in terms of the admissible couplings of the MDO field with the electromagnetic and Higgs fields. We show that even if the field loses all its kinetic energy during reheating, it can evolve as dark matter due a gravitational coupling (of spinorial origin) with baryonic matter. Since the field acquires a constant value at the bottom of the potential, a non-null, although tiny, mass term acts as a dark energy component nowadays. Therefore, we conclude that MDO fermionic field is a good candidate to drive the whole evolution of the Universe, in such a way that the inflationary field, dark matter and dark energy are described by different manifestations of a single field.Comment: 22 pages, 5 figure

Strategies for the bioremediation of azo dyes containing wastewaters

Publicado em "Book of abstracts of the 2nd Meeting of the Institute for Biotechnololgy and Bioengineering"Azo dyes are an important class of wastewater pollutants resulted especially from textile industry. Biological treatment based on the anaerobic azo bound reductive cleavage, followed by a second step for the transformation of the resulted aromatic amines, seems promising. In our studies, the surface chemistry of a commercial activated carbon (AC) was selectively modified by chemical oxidation and thermal treatments and tested as a natural redox mediator on chemical and biological anaerobic azo dye reduction [1]. Batch experiments with 0.1 g L−1AC demonstrated an increase of the first-order rates, up to 9-fold, as compared with assays without AC. Thermal treated samples gave better results due to their positively charged surface, favouring electrostatic attraction between the carbon and the anionic dyes tested. The low amount of AC used and the positive results demonstrated, constitutes a significant breakthrough in the field of redox mediated processes which will certainly open new perspectives for wastewater treatment processes. In order to investigate the fate of aromatic amines, two UASB reactors were operated under denitrifying conditions: R1 contained nitrate and R2 a nitrate and nitrite mixture as terminal electron acceptors [2]. The R1 results demonstrated that aniline could be degraded under denitrifying conditions while sulfanilic acid remains. The presence of nitrite in the influent of R2, caused a chemical reaction that led to immediate disappearance of both aromatic amines and the formation of an intense yellow solution. Based on the HPLC-MS analysis, the structures of possible products were proposed. Denitrification activity tests suggest some detoxification

Carbon nanotubes as novel redox mediators for dyed wastewaters biodegradation

Due to their large-scale production and extensive application, dyes have turned serious pollutants as when improperly handled and disposed, they may create serious public health and environmental problems. One of the problems that textile industry is facing is related with the incomplete exhaustion of dyes onto textile fibre from an aqueous dyeing process and the need to implement innovative and sustainable effluent treatment methods to remove colour. Biological treatment systems were shown to be promising technologies. The main limiting factor of the reductive transformations by anaerobic sludge is the electron transfer, a slow process. This limitation can be overcome by making use of redox mediators, compounds that accelerate the electron transfer from a primary electron donor to a terminal electron acceptor, to speed up the process. Activated carbon (AC) has been shown as a feasible redox mediator. Samples of microporous thermal treated AC (ACH2) and mesoporous carbons: Xerogels (XA, XB) and Carbon nanotubes (CNT) were tested on azo dye and textile wastewater biodegradation. ~80 % Mordant Yellow 10 (MY10) and 70 % of Reactive Red 120 (RR120) colour removal was obtained with all the carbon materials. Acid Orange 10 (AO10) is not biodegraded in the absence of Carbon Materials, but with XB a 98 % of colour removal at 4.48 ± 0.74 d-1 of reduction rate was achieved. For MY10 and RR120, rates increased in the order: control < ACH2 < XA < XB < CNT. HPLC analysis confirmed the reduction of dyes with the corresponding aromatic amines formation. Biological treatments of real wastewater lead to 65 % of colour removal with rate improvement in the presence of CNT

Anaerobic biotransformation of nitroanilines enhanced by the presence of low amounts of carbon materials

Three microporous activated carbons -original (AC0), chemical oxidized with HNO3 (ACHNO3) and thermal treated (ACH2)-, and three mesoporous carbons - xerogels (CXA and CXB) and nanotubes (CNT)-, were tested on the biological reduction of o-, m- and p-nitroaniline (NoA) at a concentration above the half maximal inhibitory concentration (IC50) for a methanogenic consortium degrading a mixture of volatile fatty acids (VFA) containing acetate, propionate and butyrate. NoAs were only partially reduced in the absence of carbon materials (CM). Rates were dependent on the nitro group position, increasing in the order metha>para>ortho. CM lead to NoAs almost total reduction and at higher rates. With AC0 and ACH2, rates increased 3-fold, 4-fold and 8 fold for o-, m- and p-NoA, respectively

Improvement of the upflow anaerobic sludge blanket reactor performance for azo dye reduction by the presence of low amounts of activated carbon

Activated carbon (AC) was investigated as redox mediator of the azo dye Acid Orange 10 (AO10) anaerobic biodegradation in a laboratory scale Upflow Anaerobic Sludge Blanket (UASB). During reactor operation, the effect of AC concentration and the hydraulic retention time (HRT) were investigated and better results were obtained with 0.15 g of AC per g of Volatile Suspended Solids (VSS) and 10 h, respectively. In the mediated reactor, with an HRT of 10 h, high colour and COD removal was obtained, ~70% and ~85%, respectively. In the control, thought similar COD removal, AO10 decolourisation was only 20%, evidencing the ability of AC to accelerate the reduction reactions in continuous reactors

Dyes-environmental impact and remediation

Dyes are an important class of synthetic organic compounds used in many industries, especially textiles. Consequently, they have become common industrial environmental pollutants during their synthesis and later during fibre dyeing. Textile industries are facing a challenge in the field of quality and productivity due to the globalization of the world market. As the highly competitive atmosphere and the ecological parameters become more stringent, the prime concern of the textile processors is to be aware of the quality of their products and also the environmental friendliness of the manufacturing processes. This in turn makes it essential for innovations and changes in these processes, and investigations of appropriate and environmentally friendly treatment technologies or their residues. The large-scale production and extensive application of synthetic dyes can cause considerable environmental pollution, making it a serious public concern. Legislation on the limits of colour discharge has become increasingly rigid. There is a considerable urgent need to develop treatment methods that are effective in eliminating dyes from their waste. Physicochemical and biological methods have been studied and applied, although each has its advantages and disadvantages, with the choice being based on the wastewater characteristics, available technology and economic factors. Some industrial-scale wastewater treatment systems are now available; however, these are neither fully effective for complete colour removal nor do they address water recycling. This chapter outlines the background of dye chemistry, the application areas and the impact of dyeing effluents in the environment. The processes/techniques being implemented and developed for wastewaters remediation are revisited

UV/Tio2 photocatalytic reactor for real textile wastewaters treatment

Textile dye wastewaters are characterized by strong colour, salts and other additives, high pH, temperature, chemical oxygen demand (COD) and biodegradable materials. Being aesthetically and environmentally unacceptable, these wastewaters need to be treated before their discharge. Anaerobic bioprocesses have been proposed as being environmentally friendly and relatively cheap; however, when applied to real effluent with a complex composition, they can fail. In this study, a photoreactor combining UV light and TiO2, immobilized in cellulosic fabric, was applied for the treatment of two industrial textile wastewaters. High colour and COD removal, and detoxification, were achieved for both wastewaters, at controlled pH of 5.5. Effluents showed very poor biodegradability due to their complex composition; thus, the proposed process is an efficient alternative