Remoção de chumbo(II) em sistemas descontínuos por carvões ativados com ácido fosfórico e com vapor

Adsorption of heavy metal cations by activated carbon is dependent on the capacity of the material in promoting adsorption and the time needed to reach equilibrium. Carbon samples were previously activated either by phosphoric acid treatment at 400 ºC or by steam at 800 ºC. The results of Pb(II) adsorption by these activated carbons have shown that equilibrium was typically reached within the first 5 min of contact between carbon and metal solution, with a maximum adsorption capacity higher than 69 mg g-1 for the vapor-activated sample. Temperature influences the sorption capacity, which corresponds to an endothermic process. Lead(II) retention is more pronounced at high temperature and low pH.

Remoção de chumbo(II) em sistemas contínuos por carvão ativado com vapor

Fixed-bed column studies were undertaken to evaluate the performance of a commercial Brazilian activated carbon in removing Pb(II) from aqueous environment. Breakthrough points were found out for the metal adsorption by varying different operating parameters like feed concentrations (10 and 20 mg L-1) and bed heights (0.5, 1.5 and 2.8 cm). A good agreement was observed between the experimental data and the values predicted by the bed depth service time (BDST) model. Regeneration of the exhausted columns was possible with HCl, and the adsorption capacity was maintained after three adsorption-desorption cycles.

Validação de metodologia analítica para determinação de mercúrio total em amostras de urina por espectrometria de absorção atômica com geração de vapor frio (CV-AAS): estudo de caso

Mercury is a toxic metal used in a variety of substances over the course history. One of its more dubious uses is in dental amalgam restorations. It is possible to measure very small concentrations of this metal in the urine of exposed subjects by the cold vapor atomic absorption technique. The present work features the validation as an essential tool to confirm the suitability of the analytical method chosen to accomplish such determination. An initial analysis will be carried out in order to evaluate the environmental and occupational levels of exposure to mercury in 39 members of the auxiliary dental staff at public consulting rooms in the city of Araguaína (TO).

Sistema RTP: uma técnica poderosa para o monitoramento da formação de nanotubos de carbono durante o processo por deposição de vapor químico

In this work, a TPR (Temperature Programmed Reduction) system is used as a powerful tool to monitor carbon nanotubes production during CVD (Chemical Vapour Deposition), The experiments were carried out using catalyst precursors based on Fe-Mo supported on Al2O3 and methane as carbon source. As methane reacts on the Fe metal surface, carbon is deposited and H2 is produced. TPR is very sensitive to the presence of H2 and affords information on the temperature where catalyst is active to form different forms of carbon, the reaction kinetics, the catalyst deactivation and carbon yields.

Reator de UV-Ozônio com lâmpada a vapor de mercúrio a alta pressão modificada para tratamento superficial de óxidos transparentes condutivos utilizados em dispositivos poliméricos eletroluminescentes

An UV-Ozone reactor was developed with an ignition tube extracted into HID mercury lamp used to irradiation on zinc oxide (ZnO) and fluorinated tin oxide (FTO) films for PLEDs devices. Different exposures times were used. In contact angle measurements revealed better results for ZnO and FTO by 15 and 5 min, respectively. In Diffuse Reflectance Infra-red Fourier Transformed (DRIFT) spectroscopy allowed the observation of water, hydrocarbon and carbon dioxide adsorbed on the untreated TCO surfaces. After the UV-Ozone treatment the contaminants were significantly reduced or eliminated and the PLEDs devices decreased threshold voltages in comparison with respectively untreated TCOs.

Production Cycle Optimization: Defining the Market Potential for a New Planning Tool

An optimization tool has been developed to help companies to optimize their production cycles and thus improve their overall supply chain management processes. The application combines the functionality that traditional APS (Advanced Planning System) and ARP (Automatic Replenishment Program) systems provide into one optimization run. A qualitative study was organized to investigate opportunities to expand the product’s market base. Twelve personal interviews were conducted and the results were collected in industry specific production planning analyses. Five process industries were analyzed to identify the product’s suitability to each industry sector and the most important product development areas. Based on the research the paper and the plastic film industries remain the most potential industry sectors at this point. To be successful in other industry sectors some product enhancements would be required, including capabilities to optimize multiple sequential and parallel production cycles, handle sequencing of complex finishing operations and to include master planning capabilities to support overall supply chain optimization. In product sales and marketing processes the key to success is to find and reach the people who are involved directly with the problems that the optimization tool can help to solve.

Organic and total mercury determination in sediments by cold vapor atomic absorption spectrometry: methodology validation and uncertainty measurements

The purpose of the present study was to validate a method for organic Hg determination in sediment. The procedure for organic Hg was adapted from literature, where the organomercurial compounds were extracted with dichloromethane in acid medium and subsequent destruction of organic compounds by bromine chloride. Total Hg was performed according to 3051A USEPA methodology. Mercury quantification for both methodologies was then performed by CVAAS. Methodology validation was verified by analyzing certified reference materials for total Hg and methylmercury. The uncertainties for both methodologies were calculated. The quantification limit of 3.3 µg kg-1 was found for organic Hg by CVAAS.

Efeito da adição de lantânio em catalisadores de Ni/ZrO2 aplicados na reação de reforma a vapor de etanol

The catalytic performance of Ni/ZrO2 catalysts loaded with different lanthanum content for steam reforming of ethanol was investigated. Catalysts were characterized by BET surface area, X-ray diffraction, UV-vis spectroscopy, temperature programmed reduction, and X-ray absorption fine structure techniques. Results showed that lanthanum addition led to an increase in the degree of reduction of both NiO and nickel surface species interacting with the support, due to the higher dispersion effect. The best catalytic performance at 450 ºC was found for the Ni/12LZ catalyst, which exhibited an effluent gaseous mixture with the highest H2 yield.

Efeito do teor de umidade sobre o pré-tratamento a vapor e a hidrólise enzimática do bagaço de cana-de-açúcar

The effect of moisture content in the steam treatment and enzymatic hydrolysis of sugarcane bagasse was evaluated. Steam treatment was perfomed at 195-210 ºC for 4-8 min using cane bagasse with moisture contents in the range 16-100 wt% (dry basis). Increased moisture contents not only had a positive influence in recovery of main cane biomass components but also resulted in better substrates for enzymatic hydrolysis. As a result, drying is not required for optimal pretreatment and enzymatic hydrolysis of sugarcane bagasse, which can be processed into second generation ethanol immediately after crushing and hot water washing.

Cristalización de zeolita beta mediante conversión asistida por vapor: influencia de los parámetros de síntesis

In the present work, beta zeolites were prepared by an alternative route called steam-assisted conversion (SAC). Several zeolites were synthesized using amorphous dry gels with a low SDA concentration (0.09 mol, TEAOH). Temperature and crystallization time were the main parameters studied. X-ray diffraction (XRD), infrared spectroscopy (IR) and scanning electron microscopy (SEM) were the characterization techniques employed. The zeolites prepared showed mixed phases such as beta, MTW and ZSM-5 while only one sample treated at 150ºC with 24 h of crystallization time showed a pure ZSM-5 phase (SAC-5). These preliminary results serve as a starting point for optimizing the synthesis of a specific type of zeolite using the SAC method.

Role of oxidation-reduction cycle of iron in direct leaching of zinc concentrate

Direct leaching is an alternative to conventional roast-leach-electrowin (RLE) zinc production method. The basic reaction of direct leach method is the oxidation of sphalerite concentrate in acidic liquid by ferric iron. The reaction mechanism and kinetics, mass transfer and current modifications of zinc concentrate direct leaching process are considered. Particular attention is paid to the oxidation-reduction cycle of iron and its role in direct leaching of zinc concentrate, since it can be one of the limiting factors of the leaching process under certain conditions. The oxidation-reduction cycle of iron was experimentally studied with goal of gaining new knowledge for developing the direct leaching of zinc concentrate. In order to obtain this aim, ferrous iron oxidation experiments were carried out. Affect of such parameters as temperature, pressure, sulfuric acid concentration, ferrous iron and copper concentrations was studied. Based on the experimental results, mathematical model of the ferrous iron oxidation rate was developed. According to results obtained during the study, the reaction rate orders for ferrous iron concentration, oxygen concentration and copper concentration are 0.777, 0.652 and 0.0951 respectively. Values predicted by model were in good concordance with the experimental results. The reliability of estimated parameters was evaluated by MCMC analysis which showed good parameters reliability.

The Process of Greening Cycle as Method of Operative Environmental

The structural change of society from product-based business to service- and further to need-based business has caused the fact that work for environmental issues has spread from conventional factories and environmentally harmful production to concern services and offices as well. Almost every company has an office, so a relatively small environmental burden caused by an individual office grows remarkable already at the state level and globally even more. Motivation to work for environmental issues in an individual office could be challenging even without the fact that wasted environmental impacts bound also wasted costs. Besides cost savings, a concretely greener image of a company has its value in the B2Cas well as in the B2B-field. Consumers and clients are more and more conscious of environmental issues and demand concrete actions instead of speeches, good thoughts and meaningless certifications. Internal work for environmental issues at a strategy level is not sufficient, so operational environmental management is needed for changing old practices. This research is about the effects of operative environmental management on the greening process of an office-based business. The research is outlined to concern the operative work in the office including field sales. Target was to concretely lower the environmental impacts of Lyreco Finland and to find cost savings directly by changing the operative practices in the office and also indirectly by affecting the level of environmental knowledge of the personnel. During the greening process, the aim was also to create concrete arguments for marketing as well. The circle of greening process, which was especially created for this diploma work, was used as a method. The circle divides a year to themes and sections separated by factors of environmental impacts. Separation is based on Brett Wills’ thoughts of seven green wastes (Wills, Brett. The Green Intensions. 2009) and follows it uneasily. The circle aimed at ensuring evolutionary growth of knowledge instead of being revolutionary in the changing process. Committing personnel to the process from its start by asking ideas from them and giving them clear directions was an important part of the research of operative management. Because of working from distance, communication with personnel was operated by frequent training days and weekly greening notes via emails and intranet. Also availability for communication was an important task because of the telecommuting. Research results of this work show that operative environmental management in an officebased business today is mostly management of change. When the strategic environmental friendliness is taken into a concrete level, the most important individual factor is motivating the operating personnel. Research shows that evolutionary change is found being an efficient way to make a change. Also understanding one´s own impact on the environmental burden and on the whole greening process clearly motivates the personnel. Results show that in the operative realization of the greening process, clear directions of new working practices, being as concrete as possible, and committing personnel to follow them make the process more effective. The operative environmental management and the cycle of the greening process decrease the environmental burden and save costs. The concrete results could be used as believable arguments in marketing and therefore exploited in communication with interest groups. Commitment of the management is also one of the key factors of success in the greening process. In this research, changes in the business field by a company trade took the focus of the management away from the greening process and made the process more inefficient by decreasing the amount of training days. The circle of greening process will be used as a tool in the future, as well, and therefore it will help observe environmental impacts of a company and increase sustainable development. Commitment of management to the evolutionary environmental work helps the operating personnel lower environmental impacts, decrease costs and build a concretely greener image.

Customer relationship management through life cycle analysis, case professional service firm in B2B market

The objective of this master’s thesis was to study how customer relationships should be assessed and categorized in order to support customer relationship management (CRM) in the context of business-to-business (B2B) and professional services. This sophisticated and complex market is utilizing possibilities of CRM only rarely and even then the focus is often on technology. The theoretical part considered first CRM from the value chain point of view and then discussed the cyclical nature of relationships. The case study focused on B2B professional service firm. The data was collected from company databases and included the sample of 90 customers. The research was conducted in three phases first studying the age, then the service type of relationships and finally executing the cluster analysis. The data was analysed by statistical analysis program SAS Enterprise Guide. The results indicate that there are great differences between developments of customer relationships. While some relationships are dynamically growing and changing, most of customers are remaining constant. This implies expectations and requirements of customers are similarly divergent and relationships should be managed accordingly.