Pyrolysis of sewage sludge for sustainable biofuels and value-added biochar production

The study deals with the pyrolysis of sewage sludge to produce eco-friendly and sustainable fuels along with value-added biochar products. The experiments were conducted in a fixed-bed cylindrical glass reactor in the temperature range of 250-700 °C and achieved the product yield of 22.4 wt% bio-oil, 18.9 wt % pyrolysis gases, and 58.7 wt% biochar at 500 °C optimum temperature. The chemical composition of bio-oil was investigated by gas chromatograph-mass spectroscopy and fourier transformation infrared techniques. The ASTM standard procedures were used to assess the fuel qualities of bio-oil, and they were found to be satisfactory. Bio-oil has a greater H/C ratio (3.49) and a lower O/C ratio (1.10), indicating that it is suitable for engine use. The gas chromatographic analysis of pyrolysis gases confirmed the presence of 41.16 wt % combustible gases, making it suitable for use in spark-ignition engines. X-ray fluorescence analysis of biochar showed that it had a good amount of carbon, nitrogen, phosphorus, and potassium along with some micro-and macro-nutrient which proves its potential to utilize as organic manure in the agriculture sector. In addition, the data obtained from the TGA analysis during the pyrolysis of sewage sludge was applied to calculate kinetic parameters via the Coats-Redfern method.

Effectiveness of pectoralis major myocutaneous flap in the surgical management of oral cancer: A retrospective study

INTRODUCTION

Over 80,000 oral cancer cases get diagnosed each year in India, majority undergoing extensive resections owing to their late presentation. Pectoralis major myocutaneous (PMMC) flap is a pedicled axial pattern flap which is based on thoracoacromical artery. It is readily available as a viable alternative to free flap reconstruction, especially for the economically poor and malnourished patients. Its proximity to head and neck structures gives added advantage to reconstruct complex and large volume oral and maxillofacial defects. It provides a relatively good possibility of functional and aesthetic restoration providing both mucosal lining and skin cover.

MATERIALS AND METHODS

This was a prospective observational study of 29 PMMC flap reconstructions, conducted between 2013-2016. The reconstruction outcomes assessed in this study were divided into two categories namely "success" and "failure" based on certain functional parameters observed during follow-up of 1 year. The complications were broadly classified as major/minor and flap related/non-flap related. We assessed the feasibility of using a PMMC flap for reconstructing various subsites of oral cavity cancer. Further, the association of patient variables with complication rates and outcome of reconstruction were analysed.

RESULTS

Out of 29 patients overall complications were noted in 15 (51.7%) cases with a female preponderance. Flap-related complications were noted in 9 whereas non-flap-related complications were seen in 6 patients. Major and minor complications were noted in 2 (both flap related) and 13 cases respectively. Complete full thickness flap necrosis was not encountered in any patient. Patients with flap skin paddle size ≤ 36 cm² (n = 12) had significantly increased overall complication rates. Despite complications a high success rate (93.1%, n = 27) was achieved with this mode of reconstruction.

CONCLUSION

The PMMC flap reconstruction is a versatile, reliable and an affordable single staged procedure with a high success rate in terms of achieving treatment goals. Although it has moderately high complication rates, but PMMC flap proved to be a workhorse in locally advanced cases of head and neck cancer at the end of 1 year follow-up.

Pattern of hexa-valent chromium in air borne respirable dust generated at various workplaces in opencast chromite mines

The paper presents a study into air borne respirable dust (ARD) concentration at various workplaces in two open cast chromite mines of Sukinda chromite belt, India. One of these mines is mechanised and the other one is semi-mechanised. The study has been conducted in three phases and ARD concentration has been measured at various workplaces in both the mines. Apart from the determination of ARD concentration, the dust samples collected on filter papers were analysed for hexa-valent chromium by colorimetric method and Cr(VI) direct absorption measurement. In addition, the particle size ranges in ARD have been determined by using cascade impactor fitted onto high volume samplers and laser guided particle size analyser. The paper finally presents a comparison between ARD concentration vis-à-vis the presence of hexa-valent chromium concentration in collected samples of both mechanised and semi-mechanised mines.

Biodegradation of poly(epsilon-caprolactone)/starch blends and composites in composting and culture environments: the effect of compatibilization on the inherent biodegradability of the host polymer

The biodegradability of poly(epsilon-caprolactone) (PCL) was studied in blends and composites of modified and granular starch. Four types of PCL-starch compositions were prepared: (i) PCL-granular starch blends; (ii) hydrophobic coating of starch particles by n-butylisocyanate (C(4) starch) and octadecyltrichlorosilane (C(18) starch), followed by melt blending with PCL; (iii) PCL-starch blends compatibilized by PCL-g-dextran grafted copolymer (PGD); and (iv) PCL-grafted starch particles (PGS) as obtained by in situ ring-opening polymerization of caprolactone (CL) initiated directly from hydroxyl functions at the granular starch surface. Biodegradability of these materials was measured by monitoring the percentage of weight loss in composting and the rate of fungal colonization when samples were used as a sole carbon source for fungus (A. niger). Intrinsic viscosity [eta] of host PCL chains was measured after extraction of composted samples in boiled chloroform. SEM was used to study the surface morphology after compost incubation of the samples. The inherent biodegradability of host polymer was enhanced with surface compatibilization during composting for longer incubation. It was observed that the weight loss during composting increased with the decrease in interfacial tension between filler and polymer. In general, it was concluded that inherent biodegradability does not depend very significantly on the concentration of starch in the polyester matrix, but on the compatibilization efficiency. The effect of the PCL fraction in the graft copolymer, when used as compatibilizer, was also studied on the biodegradability of the host polymer.

UV-irradiated biodegradability of ethylene--propylene copolymers, LDPE, and I-PP in composting and culture environments

The biodegradability of UV-irradiated films of ethylene--propylene copolymers (E--P copolymer), isotactic polypropylene (i-PP), and low-density polyethylene (LDPE), was measured in composting and culture environments by monitoring the variations in intrinsic viscosity [eta], weight loss per surface area, surface changes by SEM, colonization of fungus, chain scission, and evolution of hydroxyl and carbonyl groups by FT-IR spectroscopy. Photooxidation was used as a pretreatment for biodegradation of polymers. A systematic decrease in intrinsic viscosity [eta] and increase in carbonyl/hydroxyl regions in FT-IR spectra was found from 0 to 100-h irradiated samples. The degradation rate was strongly dependent on the composition of copolymers and markedly increased with decrease in ethylene content. Important surface erosion was detected after composting by SEM for longer UV-irradiated samples. It was estimated that chain-scission was directly related to photoirradiation.