The impact of acid hydrolysis conditions on carbohydrate determination in lignocellulosic materials: a case study with Eucalyptus globulus bark

Lignocellulosic biomass represents a suitable feedstock for production of biofuels and bioproducts. Its chemical composition depends on many aspects (e.g. plant source, pre-processing) and it has impact on productivity of industrial bioprocesses. Numerous methodologies can be applied for biomass characterisation, with acid hydrolysis being a particularly relevant step. This study intended to assess the most suitable procedures for acid hydrolysis, taking Eucalyptus globulus bark as a case study. For that purpose, variation of temperature (90–120 °C) was evaluated over time (0–5 h), through monosaccharides and oligosaccharides contents and degradation. For glucose, the optimal conditions were 100 °C for 2.5 h, reaching a content of 48.6 wt.%. For xylose, the highest content (15.2 wt.%) was achieved at 90 °C for 2 h, or 120 °C for 0.5 h. Maximum concentrations of mannose and galactose (1.0 and 1.7 wt.%, respectively) were achieved at 90 and 100 °C (2–3.5 h) or at 120 °C (0.5–1 h). These results revealed that different hydrolysis conditions should be applied for different sugars. Using this approach, total sugar quantification in eucalyptus bark was increased by 4.3%, which would represent a 5% increase in the ethanol volume produced, considering a hypothetical bioethanol production yield. This reflects the importance of feedstock characterization on determination of economic viability of industrial processes.

Eucalyptus Bark as Source of Bio-oil or Phenolic Compounds

Background: Eucalyptus bark and scraps are generated in the production of medium density fiberboard (MDF). An approach aiming to add value to such wastes was studied, following the concepts of circular economy and biomass cascade strategy. Bio-oil and phenolic resin were produced by pyrolysis from two types of biomass, Eucalyptus bark and MDF waste. As is well known, conventional phenolic resins are normally obtained from fossil resources. These products were obtained from the pyrolysis of two types of biomass to reduce environmental waste and dependence on petroleum-based products. Objective: The main objective of the present study was to produce phenolic resin from Eucalyptus wastes, aiming to reduce the fossil dependence on conventional resins used in the production line of MDF. Materials and Methods: Fast pyrolysis and slow pyrolysis were employed for bio-oil and phenolic resin production. The bio-oil and resins were characterized with standard lab analyses for their physicochemical properties, while their thermal properties were studied via thermogravimetric analysis (TGA). Results: The shear strength of the lap internal bonding of the phenolic resin binders with 19.8% of bio-oil were 2.09, 1.34, and 1.63 MPa under dry, boiler, and soaked conditions, respectively, which were acceptable for panel fabrication, which can represent a significant saving in terms of fossil resins and cost reduction. Discussion: By the results, 1 g medium fraction of bio-oils was equivalent to 1.35 g of conventional phenols, indicating those bio-oils as phenolic structures that could be used as binders. The bio-oil yields for bark and MDF were 40.9 and 25.1, respectively, which indicate a potential for replacing the conventional fossil-based phenolic resin. Conclusion: The results revealed the possibility of replacing conventional fossil-based chemicals with phenolic resin from renewable resources with similar overall properties, replacing about 1/3 of the conventional resin.

Removal of Cu (II) ion from Ezana (Meli) Gold Mining Wastewater Using Eucalyptus Bark as Adsorbent

This study investigated the potential use of Eucalyptus Bark (EB) powder as an adsorbent in batch mode experiments for removal of Cu2+ from Ezana (Meli) wastewater. The discharge of untreated gold mining wastewater contaminated by Cu (II), which is threatening ecosystems and carcinogenic to the human. Since the removal by using adsorption method is cost effective and environmentally friendly, it has been widely studied by many researchers. Characterizations of Eucalyptus Bark were analyzed using proximate analysis, Fourier transform infrared (FTIR) and X-ray diffractometer (XRD). Various characterization techniques showed that the effluent discharged from the factory contains: total suspended solid (TSS), turbidity, Electrical conductivity (EC), Total dissolved solid (TDS), COD, Temperature, pH, cyanide WAD with <11°C (ppm). Atomic absorption spectroscopy study indicated that heavy metals found in the wastewater were in the order Fe2+> Cu (II) >Pb (II) >Mn> Cr (VI) >Zn > Co > Ni > Cd in ppm. The selected parameters were pH, adsorbent dosage and contacting time. The highest percentage of Cu (II) removal achieved was 92%. In this study, the adsorption data were well-fitted to the Langmuir isotherm model.

Biosorption of chromium and nickel from aqueous solution using pine cones, Eucalyptus bark, and moringa pods: a comparative study

Low-cost local plants (Eucalyptus Bark, Moringa Pods, Pine cones) have been successfully used to remove heavy metals from simulated wastewater. Two types of heavy metals were chosen to study the removal capacity, Nickel (Ni) and Chrome (Cr), with a concentration of 400, 600, 900 ppm. The results show that Moringa pods have the best removal capacity for heavy metals with percentages of 90–99% for both metals, Ni and Cr, for the Eucalyptus Bark the removal capacity percentages reach 50–98%, while for the pine cones revealed a lower removing capacity with percentages of 40–99%, indicating that this is the lowest removal capacity. The data has been best fitted to the Langmuir adsorption model for all plants, while the Freundlich adsorption model could not fit the obtained results at the experimental conditions. The kinetic study has revealed that the first-order kinetic model successfully describes the kinetics of Ni adsorption, while the second-order describes the kinetics of Cr adsorption. The removal of heavy metals (Ni, Cr) was obtained when moringa was used; its highest removal efficiency was reached within 20 minutes. On the other hand, other plants (Eucalyptus Bark, Pine cone) removal efficiency was attained in more than two hours. The removal is remarkable even at a high concentration of heavy metals, especially with the moringa plant.