Microstructural Characterization of Prefabricated Hempcrete Blocks

Sustainable building materials have been developed to reduce the polluting emissions and the exploitation of natural resources of the building sector. Among these materials, an outstanding category is that of nature-based solutions which are produced recovering waste or by-products of agricultural cultivations and using them as vegetal aggregates to replace the traditional ones. This paper focusses on hempcrete which is produced mixing the by-product of industrial hemp cultivation (i.e., shives) and lime to obtain a sustainable, breathable and insulating material. The strength of hempcrete develops through carbonation of the binder that, leading to the formation of calcium or magnesium carbonates and mineralization of shives, determines the microstructure and hence most of the characteristic properties of the material. The aim of this research is to investigate how carbonation influences the microstructure of hempcrete when different recipes are used for blocks production. This study consists in the characterization of the material through techniques such as XRD (X-ray Diffractometry), SEM (Scanning Electron Microscopy) and TG-DTG (thermogravimetric analyses). Moreover, the evolution of carbonation is studied analyzing samples at different maturation times. The investigation of the carbonation reaction degree is also crucial to evaluate the environmental performances of the material because it allows the quantification of the carbon dioxide uptake. Also, periodic characterization allows to assess the durability of hempcrete and to select the best formulation according to the designed application and the corresponding service conditions.

Improving Jatropha curcas L. photosynthesis-related parameters using poultry litter and its biochar

Poultry litter and biochar contribute to improved plant growth due to their high nutrient content. However, to the best of our knowledge, how incorporating poultry litter and its biochar in soil affects photosynthesis-related parameters of Jatropha curcas L. has not been reported. Therefore, a greenhouse pot experiment was conducted using a complete randomised design with three replicates per treatment to determine the effects of poultry litter, biochar pyrolysed at 350 °C and 750 °C at different application rates (0, 0.5, 1, 2, 3 gkg-1) on Jatropha curcas L. photosynthesis parameters. The control plants recorded the lowest values of photosynthesis-related parameters compared to the treated plants except for water use efficiency. The study observed a significant (P < 0.05) increase in leaf surface area (1807 m2, PL), dark-adapted Fv/Fm ratio, carbon dioxide uptake, and transpiration rate for PL and BC350 with increased application rates, compared to BC750 treatments. BC350 treated plants exhibited higher values (0.79) of Light-adapted Fv’/Fm’. The quantum yield of PSII electron transport displayed an increase with an application rate of 3 gkg-1in PL (0.75) treated soils. Comparing organic amendments used, BC350 exhibited a significantly higher value of carbon dioxide uptake rate (2.67 μmol m-2 s-1) and transpiration rate (2.20 mmol m-2 s-1); however, WUE increased at an application rate of 3 gkg-1 in BC750 (3.8 µmol (CO2) mol-1(H2O)) treated plants. The study results indicate that poultry litter and biochar produced at a lower temperature significantly improved photosynthesis parameters than biochar produced at a higher temperature.

Effect of Gas Holdup on CO2 Biofixation by Spirulina sp. in the 20-liter Airlift Bioreactor

The rise of CO2 concentration in the Earth is a major environmental problem, which cause global warming. To solve this issue, several methods have been applied, but among these solutions using microalgae is an eco-friendly and cost-effective way of reducing carbon dioxide, as they can efficiently sequestrate CO2 and produce biomass as valuable products. In this study, hydrodynamic parameters, bubble sizes and carbon dioxide uptake were investigated in an airlift bioreactor. Experiments were studied at two different superficial gas velocities (0.185 and 0.524 cm/s) for Spirulina sp. microalgae into a 20-liter airlift bioreactor to find out the amount of carbon dioxide sequestration and cyanobacterial biomass. The highest efficiency of carbon dioxide removal and maximum dry weight of Spirulina sp. were achieved 55.48% and 0.86 g/L respectively at 5% CO2 (v/v) and superficial velocity of 0.185 cm/s. This experiment was conducted in 7 days, light intensity (2600 lux/m2), temperature (30\(\pm\)2 °C) and a light-dark cycle (12–12), which all were constant. The hydrodynamic parameters studied by Spirulina sp. demonstrated a capability of CO2 sequestration in this airlift photobioreactor.

Roles of London Dispersive and Polar Components of Nano-Metal-Coated Activated Carbons for Improving Carbon Dioxide Uptake

Adsorption using carbonaceous materials has been considered as the prevailing technology for CO2 capture because it offers advantages such as high adsorption capacity, durability, and economic benefits. Activated carbon (AC) has been widely used as an adsorbent for CO2 capture. We investigated CO2 adsorption behaviors of magnesium oxide-coated AC (MgO-AC) as a function of MgO content. The microstructure and textural properties of MgO-AC were characterized by X-ray diffraction and nitrogen adsorption–desorption isotherms at 77 K, respectively. The CO2 adsorption behaviors of MgO-AC were evaluated at 298 K and 1 atm. Our experimental results revealed that the presence of MgO plays a key role in increasing the CO2 uptake through the interaction between an acidic adsorbate (e+) and an efficient basic adsorbent (e−).

Interannual variability in net ecosystem carbon production in a rain-fed maize ecosystem and its climatic and biotic controls during 2005–2018

Interannual variability (IAV) in net ecosystem carbon production (NEP) plays an important role in the processes of the carbon cycle, but the long-term trends in NEP and the climatic and biotic control of IAV in NEP still remain unclear in agroecosystems. We investigated interannual variability in NEP, expressed as annual values and anomalies, and its climatic and biotic controls using an eddy-covariance dataset for 2005–2018 for rain-fed spring maize in northeastern China. Average annual NEP was 270±31 g C m−2yr −1, with no significant changes over time. The effects on interannual variability in NEP of gross ecosystem productivity (GEP) that was mainly controlled by soil water content (SWC) and leaf area index (LAI), were more than those of respiration (RE) that was controlled by temperature and LAI. Further, maximum daily NEP (NEPmax) that was dominated by summer vapor pressure deficit explained the largest fraction of annual anomalies in NEP, followed by carbon dioxide uptake period (CUP) that was defined by the beginning date (BDOY) and the end date (EDOY) of CUP. The variability in BDOY was mainly determined by spring precipitation and the effective accumulated temperature, and the variability in EDOY was determined by autumn precipitation, SWC and LAI. NEP may decrease with declining precipitation in the future due to decreasing GEP, NEPmax, or CUP, and irrigation and residues cover may be useful in efforts to maintain current NEP levels. Our results indicate that interannual variability in NEP in agroecosystems may be more sensitive to changes in water conditions (such as precipitation, SWC and VPD) induced by climate changes, while temperature may be an important indirect factor when VPD is dominated.

KARBON TERSIMPAN DI TATA GUNA LAHAN SUB-SUB DAS KHILAU DAS SEKAMPUNG

The khilau is one of sub-watershed of the sekampung watershed. The area was very important due to its function as catchment area which is also located close to TAHURA (great forest park ) Wan Abdurrachman, there for sub-watershed khilau plays a very strategic role in the preservation of biodiversity and climate change. The study aims were to analyze the carbon determine the total carbon dioxide uptake and oxygen release in the khilau sub-watershed. The carbon stored was extimated by using allometric equation the biomass tree. The biomass expantion factor was employed estimated of biomass. The carbon conten multiplication with the value of the conversion of carbon elements to carbon dioxide, while for the oxigen release was estimated by multiplying the value of carbon squestration by the conversion value of carbon atoms to oxygen based on atomic weight. The result showed that carbon stored in the forest was 141,69 tons/ha, it was greater than agroforetry (75,33 tons/ha), shrubs (24,74 tons/ha), annual plant (11,13 tons/ha) and paddy fields (3,45 tons/ha) with a total area of forest 52,22 ha, agroforestry 457,86 ha, shrub 28,74 ha, annual plant 84,8 ha and paddy fields 2,36 ha. The total carbon dioxide absorbtion was 159.832,73 tons and oxygen release was 426.220,61 tons.