Valorization of underutilized waste biomass from invasive species to produce biochar for energy and other value-added applications.

Biochar production from invasive species biomass discarded as waste was studied in a fixed bed reactor pyrolysis system under different temperature conditions for value-added applications. Prior to pyrolysis, the biomass feedstock was characterized by proximate, ultimate, and heating value analyses, while the biomass decomposition behavior was examined by thermogravimetric analysis. The heating values of the feedstock biomass ranged from 18.65 to 20.65 MJ/kg, whereas the volatile matter, fixed carbon, and ash content were 61.54-72.04 wt %, 19.27-26.61 wt % and 1.51-1.86 wt %, respectively. The elemental composition of carbon, hydrogen, and oxygen in the samples was reported to be in the range of 47.41-48.47 wt %, 5.50-5.88 wt % and 46.10-45.18 wt %, respectively, while the nitrogen and sulphur content in the biomass samples were at very low concentrations, making it more useful for valorization from environmental aspects. The biochar yields were reported in the range of 45.36-58.35 wt %, 28.63-44.38 wt % and 22.68-29.42 wt % at a pyrolysis temperature of 400 °C, 500 °C, and 600 °C, respectively. The biochars were characterized from ultimate analysis, heating value, energy densification ratio, energy yield, pH, Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy and energy dispersive X-ray spectrometry (SEM and EDX), to evaluate their potential for value-added applications. The carbon content, heating value, energy densification ratio, and the porosity of the biochars improved with the increase in pyrolysis temperature, while the energy yield, hydrogen, oxygen, and nitrogen content of the biochars decreased. This study revealed the potential of the valorization of underutilized discarded biomass of invasive species via a pyrolysis process to produce biochar for value-added applications.

Effect of cultivar on the content of selected phytochemicals in avocado peels.

The peels of ripe fruit of 'Hass' and 'Hass' type (HT) avocado cultivars were evaluated for phytochemical composition and other attributes. Peels represented from 8.78 to 14.11% of fruit weight. Their color ranged from homogeneous black to black with very small greenish spots. The oil content in the peels was low. Twelve fatty acids were identified in peel oil and the ratio of unsaturated to saturated fatty acids suggested that peel oil might contribute to human health. The phytochemical composition varied significantly with cultivar. However, many HT peels were superior than 'Hass' peel in their content of α-tocopherol, ß-sitosterol, perseitol, and cyanidin-3-glucoside, which was up to 211.67, 45.92, 337.17, and 519.27% higher in HT peels, respectively. The content of some phenolic compounds, especially procyanidin B2 and epicatechin, was significantly lower in 'Hass' than in many HT peels. Few HT peels showed a higher content of carotenoids and chlorophyll than 'Hass' peels. Lutein was the most abundant carotenoid. Chlorophyll a and b were also abundant in peels and low concentrations of chlorophyll derivatives were observed. Avocado peels are an important source of bioactive compounds, including some carotenoids, acids, sterols, and volemitol, which were observed for the first time.