Acoustic emission detection in composites is complicated in comparison with metallic structures due to the complex nature of acoustic emission wavelet transform in anisotropic materials. In this study, the adhesively bonded single-lap joints with zero-degree orientation are used to trigger different failure mechanisms when subjected to tensile test with acoustic emission monitoring. Acoustic emission signals which are studied for damage characterization are obtained during tensile tests. The range of peak frequency with time, pertaining to the failure mode in adhesively bonded single-lap joints has been identified using wavelet transform. Signals and their characteristics representing different failure modes are identified and validated using wavelet transform analysis. Continuous wavelet transform is then applied to identify the frequency range and time history for failure modes in each signal. The fractured surface area of the bonded single-lap joint specimen was examined directly using a scanning electron microscope and also identified the failure mechanism of bonded single-lap joints. The results obtained from acoustic emission technique are compared with scanning electron microscope results, to find the evidence of predicted damage. This study of the frequency content of each test using continuous wavelet transform is then performed and the classification of several failure modes is identified.

Coagulation is an important step in the physicochemical treatment of wastewater. Due to the disadvantage associated with the commonly used inorganic metal salts and other synthetic polymers, in recent years, research on the use of natural organic polymers as coagulant is gaining importance. In this study, the coagulation potential of alginate extracted from brown algae, Sargassum sp. for the removal of Congo red dye from aqueous solution has been identified. The yield of alginate extraction was found to be 40.8%. The extracted alginate was characterized by Fourier transform infrared spectroscopy and Scanning electron microscopy techniques. The effect of initial pH (4-6), alginate dose (10-60 mg/L), calcium dose (1-6 g/L), and initial dye concentration (50-250 mg/L) on dye removal have been investigated. It is inferred from the study that the maximum removal of dye (96%) was achieved with increasing alginate and calcium dose for increasing dye concentration, at pH 4. The obtained results were compared with the literature on Congo red dye removal using various adsorbents and coagulants.

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This study deals with the coagulation potential of alginate extracted from marine algae Sargassum sp. for the removal of sulphur black dye from its aqueous solution. The alginate extraction was found to be efficient (44.8%) and the extracted alginate was characterized by Fourier transform infrared spectroscopy and Scanning electron microscopy techniques. Batch experiments (coagulation test) were performed to investigate the effect of alginate dose (10‐60 mg/L), calcium dose (1‐6 g/L) and initial dye concentration (50‐250 mg/L) on dye removal. The maximum dye removal (98.2%) was achieved under the optimal conditions of the initial dye concentration 200 mg/L, Calcium dose 6 g/L, and alginate dose 30 mg/L. The kinetics study for the coagulation process was carried out and found that it suitably fits in second‐order kinetics model. The literature on application of algal alginate for various wastewater treatment methods were compared with the present study and the results obtained revealed that the alginate from Sargassum sp. can be used as an efficient coagulant for the removal of sulphur black dye. © 2015 American Institute of Chemical Engineers Environ Prog, 34: 1427–1434, 2015

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