ABSTRACT
Metal-blending of biomass prior to pyrolysis is investigated in this work as a tool to modify biochar physico-chemical properties and its behavior as adsorbent. Six different compounds were used for metal-blending: AlCl3, Cu(OH)2, FeSO4, KCl, MgCl2 and Mg(OH)2. Pyrolysis experiments were performed at 400 and 700⯰C and the characterization of biochar properties included: elemental composition, thermal stability, surface area and pore size distribution, Zeta potential, redox potential, chemical structure (with nuclear magnetic resonance) and adsorption behavior of arsenate, phosphate and nitrate. Metalblending strongly affected biochars' surface charge and redox potential. Moreover, it increased biochars' microporosity (per mass of organic carbon). For most biochars, mesoporosity was also increased. The adsorption behavior was enhanced for all metal-blended biochars, although with significant differences across species: Mg(OH)2-blended biochar produced at 400 °C showed the highest phosphate adsorption capacity (Langmuir Qmax approx. 250â¯mgâ¯g-1), while AlCl3-blended biochar produced also at 400 °C showed the highest arsenate adsorption (Langmuir Qmax approx. 14â¯mgâ¯g-1). Significant differences were present, even for the same biochar, with respect to the investigated oxyanions. This indicates that biochar properties need to be optimized for each application, but also that this optimization can be achieved with tools such as metal-blending. These results constitute a significant contribution towards the production of designer biochars.
Subject(s)
Biomass , Charcoal/chemistry , Metals/chemistry , AdsorptionABSTRACT
UNLABELLED: Treatment of phenylketonuria involves a restriction in the intake of natural proteins. This can lead to growth impairment. Weight, height and body mass index of 109 hyperphenylalaninemic patients (mild hyperphenylalaninemia (HPA) and phenylketonuria (PKU)) were determined from birth until 18 years, every 6 months, and differences to the healthy population, depending on the age, sex and phenotype, were analyzed. Data collection was longitudinal retrospective during 31 years. Statistical analysis of z-score values was performed by advanced statistical tools. Long-term evolution of anthropometric z-scores showed no significant statistical differences between PKU and mild HPA individuals, according to the general population. For PKU individuals, height is slightly lower and weight slightly higher than in the healthy population, but differences are smaller than one standard deviation. Nevertheless, over-time evolutions of female height z-scores are different in each type of pathology, with a crossover between 8 and 12 years (p = 0.0186). CONCLUSIONS: It is nowadays possible to achieve a long-term normal growth in PKU patients with appropriate dietary treatment. There is however an acceleration of growth up to 8 years old for PKU female patients that leads to a slightly lower final height. Detection of this behaviour was possible by using nonlinear mixed effects models.
Subject(s)
Adolescent Development/physiology , Child Development/physiology , Diet, Protein-Restricted , Phenylketonurias/diet therapy , Adolescent , Body Height/physiology , Body Mass Index , Body Weight/physiology , Child , Child, Preschool , Female , Humans , Infant , Infant, Newborn , Longitudinal Studies , Male , Nonlinear Dynamics , Retrospective StudiesABSTRACT
Biochar properties vary, and characterization of biochars is necessary for assessing their potential to sequester carbon and improve soil functions. This study aimed at assessing key surface properties of agronomic relevance for products from slow pyrolysis at 250-800 °C, hydrothermal carbonization (HTC), and flash carbonization. The study further aimed at relating surface properties to current characterization indicators. The results suggest that biochar chemical composition can be inferred from volatile matter (VM) and is consistent for corncob and miscanthus feedstocks and for the three tested production methods. High surface area was reached within a narrow temperature range around 600 °C, whereas cation exchange capacity (CEC) peaked at lower temperatures. CEC and pH values of HTC chars differed from those of slow pyrolysis biochars. Neither CEC nor surface area correlated well with VM or atomic ratios. These results suggest that VM and atomic ratios H/C and O/C are good indicators of the degree of carbonization but poor predictors of the agronomic properties of biochar.
