Tecia Vieira Carvalho

Removal of phenol and conventional pollutants from aqueous effluent by chitosan and chitin

The present study deals with phenol adsorption on chitin and chitosan and removal of contaminants from wastewater of a petroleum refinery. The adsorption kinetic data were best fitted to first- and second-order models for chitosan and chitin, respectively. The results of adsorption isotherms showed Langmuir model more appropriately described than a Freundlich model for both adsorbents. The adsorption capacity was 1.96 and 1.26 mg/g for chitin and chitosan, respectively. Maximum removal of phenol was about 7080% (flow rate: 1.5 mL/min, bed height: 18.5 cm, and 30 mg/L of phenol. Wastewater treatment with chitin in a fixed-bed system showed reductions of about 52 and 92% for COD and oil and greases, and for chitosan 65 and 67%, respectively. The results show improvement of the effluent quality after treatment with chitin and chitosan.

Determination of Insecticide Residues in Vegetal Fruits

Pesticides compounds represent an important class of pollutants for food, soil and surface water resources. Thus, a simplified method using gas chromatography was used for determining five insecticide residues in fruit samples produced in Ceara State (Brazil). The insecticides were simultaneously extracted from the fruit samples with a mixture of water-methanol (1 : 1% v/v) from lipid-containing crops and then reextracted with ethyl acetate. Cleanup by silica gel column chromatography was not necessary. The extracts were analyzed by GC-ECD. Analytical parameters, such as limit of detection (LOD), limit of quantification (LOQ), linearity, precision, and recovery were considered for the orange fruit. A sufficient recovery of 52.1, 57.0, 49.5, and 108.5% for parathion methyl, malathion, chlorpyrifos, and 2,4-dichlorophenol was found. The compounds 2,4-dichlorophenol, malathion, parathion methyl, and chlorpyrifos were found in all the fruit samples analyzed.

Recent Development of Chitosan Nanocomposites with Multiple Potential Uses

This chapter reviews an actual relevant literature about the most important methods used in the processing of chitosan nanocomposites, which are based on most extensively used biodegradable polymer matrices. A particular attention has been focused on the biodegradable polymer chitosan because of their widespread use in the bionanocomposite films field. Thus, the processing procedures and the results obtained of various applications from chitosan nanocomposite films have been compiled. The current research trends in chitosan-based material films for applications, including biodegradable composites and the use of chitosan are presented. This chapter will increase the interest of researchers in chitosan-based chitosan nanocomposites and the development of new ideas in this field.