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The excess of mango peels is considered manufacturing waste in the sugar and juice industry. There is an increasing interest in looking for alternative ways to employ this waste to address this overload. Here, we show the efficient use of mango peels as a noncost carbon source for the synthesis of graphene. We demonstrate for the first time the synthesis of graphene on Cu substrates from mango peels, a biomass rich in pectin. It is observed that plasma presence is essential for the growth of graphene from mango peels. At 15 and 30 min of plasma exposure, we observed the presence of multilayered graphene, at longer plasma exposure, i.e., 60 min, there is the formation of monolayer graphene, attributed to the etching of multiple layers formed at short times due to long plasma exposure time. When employing this technique, precautions must be taken due to the etching effect of plasma, such as reducing either the plasma exposure time or the plasma power. Finally, we present a graphene growth pathway under plasma environment on the basis of our experimental observations.

No abstract

This proposal evaluates the energy potential of agricultural residues of Zea mays from an indigenous community in Mexico. The study consists of four stages: (a) evaluation of residue production in all community farming areas (b) morphological and physicochemical characterization, using scanning electron microscopy (SEM), as well as infrared spectroscopy (FTIR) and Raman (c) the proximal and functional evaluation of the residues, through fiber analysis, determination of fixed carbon, humidity, estimation of calorific value, ash microanalysis and elemental analysis, and (d) evaluation of energy potential and multicriteria analysis. The results show that Z. mays residues have initial moisture values of less than 10%, ash content below 20%, fixed carbon around 14% and a calorific value of 17.6 MJ/kg associated with polymeric compounds and carbohydrates, as well as a percentage of extractable compounds of the order of 40%. The production of these residues on the 249 hectares (ha) of cultivation used would generate 23 TJ/year, whereas if the total number of hectares available were cultivated, the total energy generation would be 330 TJ/year, which is enough to satisfy the wood fuel demand of approximately seven communities with the characteristics of the study community. Due to this potential, as well as the results of the characterization, the agricultural mentioned residues are an energy alternative to meet the energy demand in communities in Michoacán, Mexico.

A 23 factorial design was used to evaluate the influence of temperature, catalyst and time and esterification degree (DE) of pectin obtained from mango, orange and tangerine peels as well as tamarind seeds by using the acid hydrolysis method. The study showed that a high temperature positively influenced the percentage of pectin yield for the four second generation biomasses. Nevertheless, the temperature showed a greater influence in the solubility and diffusion of the acid solvent in the tamarind seed matrix, resulting a pectin recovery 32.9%. Concerning the %DE, the most statistically significant value observed was dependent on the type of biomass studied. The %DE and the nature of the pectin are determining factors in the pectin’s final use, in the present work the pectin extracted was used to produce furfural, a precursor of high value chemicals. The furfural production was achieved through alkaline hydrolysis and enhanced using the Maillard reaction, reaching a maximum concentration of 71.8 g/L which represents a 42.1% increase from the alkaline hydrolysis.