Aplicação de espectroscopias raman e infravermelho na identificação e quantificação de plastificantes em filmes comerciais de PVC esticável

This paper reports the use of Raman and infrared techniques for the qualitative and quantitative analysis of plasticizers in polyvinylchloride (PVC) commercial films. FT-Raman marker bands were indentified for di-2-ethyl-hexyl adipate (DEHA) and di-2-ethyl-hexyl phthalate (DEHP), allowing for the rapid identification of these species in the commercial film. Quantitative analysis by FT-IR resulted in plasticizers concentrations ranging from 11 to 27% (w/w). Considering the little sample preparation and the low cost of the techniques, FT-IR and FT-Raman are viable techniques for a first assessment of plasticizers in commercial samples.

Anaerobic co-digestion of crude glycerin and starch industry effluent

The Brazil's Biodiesel Production and Use Program introduces biodiesel in the Brazilian energy matrix, bringing along the perspective of a growth of the glycerin offer, co-product generated in the proportion of 10 kg for each 100 L of biodiesel. The aim of this study was to evaluate the addition of crude glycerin in the anaerobic digestion of cassava starch industry effluent (cassava wastewater), in a horizontal semi-continuous flow reactor of one phase in laboratory scale. It was used a reactor with a 8.77 L of useful volume, a medium support for corrugated conduit of polyvinyl chloride (PVC), temperature of 261 ºC, fed with cassava wastewater and glycerin, with hydraulic detention times of 4 and 5 days and increasing volumetric organic load of 3.05; 9.32; 14.83 and 13.59 g COD L-1 d-1, obtained with the addition of glycerin at 0; 2; 3 and 2% (v/v), respectively. The average removal efficiencies of TS and TVS were decreasing from the addition of glycerin to the cassava wastewater, averaging 81.19 to 55.58% for TS and 90.21 to 61.45% for TVS. The addition of glycerin at 2% increased the biogas production compared to the control treatment, reaching 1.979 L L-1 d-1. The biogas production as a function of the consumed COD was higher for the control treatment than for the treatments with addition of glycerin, which indicates lower conversion of organic matter into biogas.

Construction and calibration of TDR probes for volumetric water content estimation in a Distroferric Red Latosol

The determination of volumetric water content of soils is an important factor in irrigation management. Among the indirect methods for estimating, the time-domain reflectometry (TDR) technique has received a significant attention. Like any other technique, it has advantages and disadvantages, but its greatest disadvantage is the need of calibration and high cost of acquisition. The main goal of this study was to establish a calibration model for the TDR equipment, Trase System Model 6050X1, to estimate the volumetric water content in a Distroferric Red Latosol. The calibration was carried out in a laboratory with disturbed soil samples under study, packed in PVC columns of a volume of 0.0078m³. The TDR probes were handcrafted with three rods and 0.20m long. They were vertically installed in soil columns, with a total of five probes per column and sixteen columns. The weightings were carried out in a digital scale, while daily readings of dielectric constant were obtained in TDR equipment. The linear model θν = 0.0103 Ka + 0.1900 to estimate the studied volumetric water content showed an excellent coefficient of determination (0.93), enabling the use of probes in indirect estimation of soil moisture.

Poultry carcass decomposition and physicochemical analysis of compounds in different Composter types

This study aimed to assess five composter types in poultry carcasses decomposition and to perform a physicochemical analysis of the compounds obtained. Composter types used were six-hole brick, wood, screen, windrow with three PVC pipes with six holes and windrow with three PVC pipes with 10 holes. Composting was followed by four periods using wood shaving like substrate with one bird carcass placed in each composter. Pile turning was performed every 10 days and temperature in each layer was measured on 1st, 7th, 14th, 19th and 29th day, at 3 p.m., as well as room temperature. Temperature during pile turning was also measured at five points per layer and carcass weighing performed to calculate decomposition percentage. Physicochemical parameters evaluated in substrates were moisture, ash, phosphorus, potassium, nitrogen, pH, organic carbon and C/N ratio, up to 30 days. Data were analyzed by repeated measures model, using MIXED method of SAS software. All values of final physicochemical composition of substrates were found according to values of IN-25, except nitrogen. The composter types were efficient in decomposition of poultry carcasses.

Buckling analysis of PVC sheets with RIB

This study has a technical and applied character. A PVC structured wall pipe can be produced by spirally winding a ribbed sheet having a male-female lock, chemically welded by an adhesive. These pipes are "flexible" and are used mainly in underground installations, to convey fluids in free duct regime. Initial studies have indicated that the buckling resistance of the ribs from the sheet coiling to the tube manufacturing is the critical design parameter. This study presents the theoretical analytical development in order to obtain the critical buckling moment of these sheets. This analysis uses concepts initially developed to calculate buckling resistance in monosymmetrical profiles that are very used in the metallic structure industry. Since the material used was PVC, that has different mechanical properties than steel and aluminum, it was necessary to consider the differences in the analytical treatment. It is important to emphasize that the results obtained are product of the co-operative work of engineers from industry and university.

Identification of fatty foods with contamination possibilities by plasticizers when stored in PVC film packaging

Poly-(vinyl chloride) (PVC) requires the addition of plasticizers - additives that give flexibility and malleability for its processing into flexible film. The most used ones are: di-(2-ethylhexyl) adipate (DEHA) and di-(2-ethylhexyl) phthalate (DEHP). Toxic effects of DEHP have been observed by several authors. Phthalates are being replaced by alternative substances in PVC flexible products, because of their possible toxicological effects. DEHA is a substitute for phthalates widely used as a plasticizer in PVC materials for involving food. Some authors have shown that the exposure to DEHA also induces toxicity. A cross-sectional study was performed to identify which fatty foods carry the possibility of contamination by DEHP and DEHA. Eighteen different foods with at least 3% (m/m) fat and the possibility of being wrapped in plastic film were determined. This study suggested that all foods were subject to contamination by DEHP and DEHA in those conditions - in decreasing consumption order of 96 to 22% in the convenience sample. New guidelines on the limits of DEHA and DEHP established by the Brazilian legislation, as additives in PVC film for packaging fatty food, are still relevant to ensure human health.

Physicochemical and microbiological characteristics of minimally processed 'Champagne' oranges (Citrus reticulata × Citrus sinensis) in different packgings

The objective of this study was to investigate the influence of the level of minimal processing and modified atmosphere on the quality of 'Champagne' orange stored under refrigeration. The fruits were subjected to the following processing: a) whole fruit without flavedo; b) whole fruit without flavedo and albedo; and c) segmented into wedges and packed as follows: uncoated packaging (control); polyethylene film; PVC film; gelatin-based edible films (3%); and polyesthyrene translucent plastic container with a lid. The minimally processed oranges were stored at 5 ± 1°C for 8 days and were subjected to physicochemical and microbiological analyses every two days. Greater weight loss occurred in fruits without flavedo and segmented, uncoated, and coated with the edible gelatin film During storage, there was a slight increase in Total Soluble Solids (TSS) for the treatments with greater weight loss and reduction in acidity and ascorbic acid, regardless of the packaging type. The microbial counts did not exceed the acceptable limits in the treatments; however, higher counts were observed at the end of storage. The minimally processed fruit packed in lidded polystyrene containers and polyethylene and PVC films kept their overall fresh visual appearance with a few physicochemical and microbiological changes up to the 8th day of storage.