Effect of Manufacturing Process and Xanthan Gum Addition on the Properties of Cassava Starch Films

The objective of this work was to manufacture biodegradable films by two different processes (casting and extrusion), from different combinations of cassava starch and xanthan gum. These films were produced by casting and by extrusion from six different starch-xanthan gum combinations (0, 2, 4, 6, 8 and 10% w/w), containing glycerol as plasticizer (20% w/w) and were also characterized according to their microstructure, optical, mechanical, and barrier properties. Scanning electron microscopy of the starch-xanthan gum extruded films showed reticulated surface and smooth interior, suggesting that xanthan was driven to the surface and gelatinized starch to the interior of the films during extrusion. Films manufactured by casting were entirely homogeneous. In general, casted films presented lower opacity and water vapor permeability and higher stress at break than films manufactured by extrusion. Xanthan gum addition affected mechanical properties of starch films, improving their stress and strain at break, especially for extruded samples, but these properties did not show stability at different RH conditions.     

Agricultural solid waste for sorption of metal ions,part II: competitive assessment in multielemental solution and lake water

Sugarcane bagasse and hydroponic lettuce roots were used as biosorbents for the removal of Cu(II), Fe(II), Mn(II), and Zn(II) from multielemental solutions and lake water, in batch processes. These biomasses were studied in natura (lettuce roots, NLR, and sugarcane bagasse, NSB) and chemically modified with HNO₃ (lettuce roots, MLR, and sugarcane bagasse, MSB). The results showed higher adsorption efficiency for MSB and either NLR or MLR. The maximum adsorption capacities (q_max) in multielemental solution for Cu(II), Fe(II), Mn(II), and Zn(II) were 35.86, 31.42, 3.33, and 24.07 mg/g for NLR; 25.36, 27.95, 14.06, and 6.43 mg/g for MLR; 0.92, 3.94, 0.03, and 0.18 mg/g for NSB; and 54.11, 6.52, 16.7, and 1.26 mg/g for MSB, respectively. The kinetic studies with chemically modified biomasses indicated that sorption was achieved in the first 5 min and reached equilibrium around 30 min. Sorption of Cu(II), Fe(II), Mn(II), and Zn(II) in lake water by chemically modified biomasses was 24.31, 14.50, 8.03, and 8.21 mg/g by MLR, and 13.15, 10.50, 6.10, and 5.14 mg/g by MSB, respectively. These biosorbents are promising and low costs agricultural residues, and as for lettuce roots, these showed great potential even with no chemical modification.     

Management of invasive populations of the freshwater crayfish <Emphasis Type="Italic">Procambarus clarkii</Emphasis> (Decapoda,Cambaridae): test of a population-control method and proposal of a standard monitoring approach

Invasive species are one of the main threats to biodiversity. When an alien species is introduced into a new environment, fast identification and definition of management strategies may avoid or minimize impacts. When an invasive species is already established, the most adopted approaches are population control and monitoring. In order to perform such strategies, assessment of characteristics of the invasive population is imperative. This study tested a new method of population size estimation and monitoring in an invasive population of crayfish Procambarus clarkii in a conservation area in the Atlantic Rain Forest (Southeastern Brazil). The population dynamics was studied for 1 year to examine the efficacy of the selected method and to evaluate if the population is stable. Later, the effect of periodical removal of animals on the population size was tested. The method of population estimation used in this study proved to be very effective. We recommend using it to monitor invasive populations of P. clarkii. The population size varied discretely over the year with variable but low growth rate, indicating that the population is already established which introduce a notable threat to native species. The continuous removal of specimens proved to be inefficient since the growth rate was higher after the removal. One intensive removal event might be more effective than a continuous moderate removal as the one applied in this study.     

Assessment comparison of commercial TiO2 and TiO2 sol-gel on the degradation of caffeine using artificial radiation

Environmental Science and Pollution Research - The presence of endocrine disrupting compounds in water receptor bodies, such as drugs, currently has in scientific field a great focus of studies...     

Critical analysis of the waste management performance of two uranium production units in Brazil--part I: Poços de Caldas production centre

Waste management strategies in mining projects will depend to a large extent on the characteristics of the operational process, the type of ore and prevailing socio-environmental conditions, amongst other issues. The expenditures required by the management scheme and the implementation of remediation programs will be determined by the extent that the above issues were considered in the planning phase of the project. Several works have been published in the literature concerning the analysis of waste management programs and environmental impacts associated with uranium projects around the world. However, the vast majority do not report a comprehensive assessment integrating the various relationships among operational process, environmental impact, remediation strategy and costs. This study, divided into two papers, presents a detailed critical analysis of the waste management strategies adopted in two uranium production centres in Brazil, i.e., the Poços de Caldas Project (Part I) and the Caetité Project (Part II). The operational processes are described and the environmental impacts of the generated wastes as well as the adopted management strategies and costs are examined. Also, in Part II, a comparison between both production centres is made emphasizing the impacts of environmental and social-economical issues on the overall assessment.     

Contamination Levels and Preliminary Assessment of the Technical Feasibility of Employing Natural Attenuation in 5 Priority Areas of Presidente Bernardes Refinery in Cubatão, São Paulo, Brazil

Five priority areas of potential impact by contaminants (API) were investigated at the Presidente Bernardes Refinery in Cubatão, São Paulo, Brazil with the following aims: (i) to identify both organic and inorganic contaminants present in soil and groundwater; (ii) to define the environmental conditions relevant for microbial activity at the site and (iii) to evaluate the feasibility of employing natural attenuation for treatment of the hydrocarbon contamination. One area (API 1) was an uncontrolled landfill, where waste materials from the refinery were deposited between 1954 and 1986, and four areas (API 4, 5, 7 and 11) were located in the operational section of the refinery. Soil contamination by regulated BTEX compounds (benzene, toluene, total xylenes) was restricted to two samples from API 1. Nonregulated ethylbenzene was detected in one soil sample from API 4, one from API 5 and two from API 1. No soil contained regulated PAH above threshold levels. Several nonregulated PAHs were found in 6 soil samples from API 1, 3 soil samples from API 4 and 1 soil sample from API 5. Site soils contained very high aluminium concentrations, but metal contamination was restricted to one soil sample from API 1, which contained nickel above threshold limits. BTEX contamination of groundwater was due mostly to benzene. Of the 17 PAH molecules tested, only naphthalene and 2-methylnaphthalene occurred in groundwater. The sum of total BTEX and total PAH exceeded 200 μg/L in only a few monitoring wells in API 4, 5 and 11 and was always below 2.640 μg/L. Be, Cd, Cr, Cu, Hg, Ni, Se, Ag, Tl and Zn were not detected in groundwater, which was contaminated in a few locations by aluminium (mostly below 1 mg/L), lead (<0.066 mg/L) and arsenic (<0.056 mg/L). S, K, Ca, Mg and Fe were present in groundwater in excess of physiological requirements for microbial growth, but low concentrations of N and P could become growth limiting. However, BTEX were efficiently degraded in saturated and unsaturated zone microcosms and nutrient amendments did not stimulate biodegradation rates measurably. The inorganic carbon pool in groundwater was up to one order of magnitude larger than the organic carbon pool. Total inorganic carbon (TIC) in API groundwater exceeded TIC of clean groundwater by factors of 2 (API 4), 6 (API 5, 7 and 11) or 10 (API 1). Most of the inorganic carbon incorporated into groundwater beneath the refinery originated from biodegradation in the unsaturated soil, which contained a microbiota (10⁶ cells/g on average) capable of growth with most of the pure (benzene, toluene, ethylbenzene and xylene) and mixed hydrocarbons tested (diesel oil, gasoline, naphtha, condensate, aromatic residue and fuel oil). A viscous hydrocarbon paste uncovered in API 1 was insoluble in water but dissolved in dichloromethane. Many organic components of this paste were biodegradable as evidenced by weight reduction of the hydrocarbon paste and by the growth of suspended and attached biomass in saturated zone microcosms, where the paste was the only carbon source. This study indicates that monitored natural attenuation may be a technically feasible and efficient means for plume control in API 1, 4 and 5, provided the plumes in API 4 and 5 are not expanding. This technique is not suitable for contaminant reduction in API 11.     

Sensitized photooxygenation of mononitrophenols in micellar media

The singlet molecular oxygen‐mediated photooxidation of simple nitrophenols was studied in micellar (CTAB) alkaline solutions.

A different behaviour for the values of the overall rate constant (K_t ) and the reactive rate constant (K_t ) in the interaction nitrophenol‐singlet molecular oxygen was observed as a function of surfactant concentration. The former decreases as [CTAB] increases, from values of 1–3 × 10⁹ M^–1 s^–1 in the absence of surfactant to values at least one order of magnitude lower at [CTAB] ～0.1 M. Parallel, k_t remains practically unaffected, in values of the order of 10⁶ — 10⁷ M^–l s^–1, depending on the particular nitrophenol, within the same [CTAB] range. The quantum yield of nitrophenols photooxidation reaches a maximum at [CTAB] ～0.1 M.

The results are discussed in terms of a combination of causes, the polarity of the nitrophenolic microenvironment being the driving effect. The implication of the results on environmental decontamination are also analyzed.     

Measurement of sustainability performance in Brazilian organizations

In recent years, sustainability issues are gaining greater prominence among organizations and their stakeholders around the world. This paper aims to verify the sustainability performance of Brazilian organizations in performance measures and to propose sustainable guidelines with the intention of directing future efforts to the transition to sustainable development. The research utilized a triangulated approach by collecting qualitative and quantitative data acquired through multiple collection methods of a theoretical literature review, documentary analysis of corporate reports, questionnaire survey and semi-structured interviews with industry professionals and academic researchers. The results show that internal organizational factors are the main inductors of the sustainable environment in organizations, and sustainability must be tied to strategic planning, starting from upper management to lower levels. It is essential to use sustainable performance measurement systems in order to respond to external and internal levers and serve as benchmarking for future corporate operations and strategies. In addition, it is the responsibility of organizations to focus their efforts on environmental protection, reduction of energy, corporate reputation, quality management, customer satisfaction and investor relations, as they are considered to be more important and have a relationship of dependence on organizational sustainability. The findings will be of value to professionals and academics who want to start measuring and for continuously improving the sustainability performance of their organizations according to the technical, economic, environmental, social and governance dimensions. This research work also helps to understand the perceptions and expectations of stakeholders.     

Evaluation of hexavalent chromium removal in a continuous biological filter with the use of central composite design (CCD)

Hexavalent chromium is frequently found in industrial effluents as a result of the industrial applications of this compound and its anti-corrosive features. However, hexavalent chromium is extremely toxic, and its discharge in water is regulated, with a maximum limit of 0.1 mg/L in accordance with legislation established by CONAMA-Brazil (no. 397, April 3, 2008). To achieve lower discharge values, it is necessary to reduce from Cr(VI) to Cr(III), which is less toxic, and an economic alternative involves biological removal of this compound. Residence time distributions (RTDs) were measured to evaluate the behavior of actual biofilter operation conditions in a biofilter flow. The medium residence time distributions used were 8 and 24 h (recommended by the legislation). To optimize this process, a central composite design was used, considering the initial chromium concentration and pH as the independent variables and the removal of hexavalent chromium as the response. The boundary curves and surface response showed optimal behavior at 3.94 mg/L [Cr(0)] and a pH of 6.2. The removal process of hexavalent chromium is mathematically described by the Michaelis-Menten kinetic model. This model appropriately represents the variation of chromium concentration along the bioreactor.