Bio-hydrogen production based on catalytic reforming of volatiles generated by cellulose pyrolysis: an integrated process for ZnO reduction and zinc nanostructures fabrication

The paper presents a process of cellulose thermal degradation with bio-hydrogen generation and zinc nanostructures synthesis. Production of zinc nanowires and zinc nanoflowers was performed by a novel processes based on cellulose pyrolysis, volatiles reforming and direct reduction of ZnO. The bio-hydrogen generated in situ promoted the ZnO reduction with Zn nanostructures formation by vapor–solid (VS) route. The cellulose and cellulose/ZnO samples were characterized by thermal analyses (TG/DTG/DTA) and the gases evolved were analyzed by FTIR spectroscopy (TG/FTIR). The hydrogen was detected by TPR (Temperature Programmed Reaction) tests. The results showed that in the presence of ZnO the cellulose thermal degradation produced larger amounts of H2 when compared to pure cellulose. The process was also carried out in a tubular furnace with N2 atmosphere, at temperatures up to 900 °C, and different heating rates. The nanostructures growth was catalyst-free, without pressure reduction, at temperatures lower than those required in the carbothermal reduction of ZnO with fossil carbon. The nanostructures were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS) and transmission electron microscopy (TEM). The optical properties were investigated by photoluminescence (PL). One mechanism was presented in an attempt to explain the synthesis of zinc nanostructures that are crystalline, were obtained without significant re-oxidation and whose morphologies are dependent on the heating rates of the process. This route presents a potential use as an industrial process taking into account the simple operational conditions, the low costs of cellulose and the importance of bio-hydrogen and nanostructured zinc.

Can hydrogen peroxide and quercetin improve production of Eucalyptus grandis x Eucalyptus urophylla?

Vegetative propagation is considered the best choice for the rapid multiplication of plant species, however, rooting may still present difficulties. Substances, such as auxins, phenolic compounds and hydrogen peroxide, are recognized as able to improve this process. The aim of the present work was to determine if hydrogen peroxide in combination with quercetin or indole butyric acid, can modify some characteristics related to rooting and development in cuttings of Eucalyptus grandis x Eucalyptus urophylla. Cuttings were periodically evaluated at 30, 60 and 90 days according to the following criteria: height, diameter and survival percentage. After planting (90 days), a destructive evaluation was performed to determine rooting percentage, average size and number of roots. Polyamines content and polyamine oxidase activity, as biochemical markers of plant development, were determined. No statistically significant differences in height, diameter, survival and rooting percentage, root length and number of roots per cuttings were found. Treatments induced a decrease in putrescine levels and polyamine oxidase activity in roots. For absence of positive responses, the use of these substances as a treatment to improve cutting production is economically unviable.

Dormancy breaking of the fig tree with hydrogen cyanamide and garlic extrate

The supply of cold hours needed to the dormancy breaking of shoots is the limiting factor for the cultivation of temperate climate fruit trees in warmer regions. In subtropical conditions, it is necessary to use chemical products to promote uniform sprouting. This research aimed at evaluating the effect of garlic extract and hydrogen cyanamide in sprouting, growth, production and production cycle of the fig tree. The experiment was conducted during the production cycles of 2011/12 and 2012/13. We used plants from the cultivar Roxo de Valinhos. Production pruning was made in the months of July/2011 and July/2012, and the following treatments were applied immediately after it: 2% hydrogen cyanamide and garlic extract in 4%, 8% and 12% doses, and a control treatment. Split plots were used as the experimental design, with five repetitions in blocks; each plot consisted of five treatments with hydrogen cyanamide, garlic extract and control; the subplots consisted of two production cycles. The use of hydrogen cyanamide promoted an anticipation of sprouting and the use of hydrogen cyanamide and garlic extract promoted a concentration of the productive period, when compared to the control. The estimated garlic extract dose that promoted the highest production per plant was 3%.