A dominant contribution to light absorption by methanol-insoluble brown carbon produced in the combustion of biomass fuels typically consumed in wildland fires in the United States

The light-absorption properties of brown carbon (BrC) are often estimated using offline, solvent-extraction methods. However, recent studies have found evidence of insoluble species of BrC which are unaccounted for in...

Extraction and Characterization of Biogenic Silica Obtained from Selected Agro-Waste in Africa

Increased amounts of available biomass residues from agricultural food production are present widely around the globe. These biomass residues can find essential applications as bioenergy feedstock and precursors to produce value-added materials. This study assessed the production of biogenic silica (SiO2) from different biomass residues in Africa, including cornhusk, corncob, yam peelings, cassava peelings and coconut husks. Two processes were performed to synthesize the biogenic silica. First, the biomass fuels were chemically pre-treated with 1 and 5% w/v citric acid solutions. In the second stage, combustion at 600 °C for 2 h in a muffle oven was applied. The characterization of the untreated biomasses was conducted using Inductively coupled plasma—optical emission spectrometry (ICP-OES), thermal analysis (TG-DTA) and Fourier-transform infrared spectroscopy (FTIR). The resulting ashes from the combustion step were subjected to ICP, nitrogen physisorption, Energy dispersive X-ray spectroscopy (EDX) as well as X-Ray diffraction (XRD). ICP results revealed that the SiO2 content in the ashes varies between 42.2 to 81.5 wt.% db and 53.4 to 90.8 wt.% db after acidic pre-treatment with 1 and 5 w/v% acid, respectively. The relative reductions of K2O by the citric acid in yam peel was the lowest (79 wt.% db) in comparison to 92, 97, 98 and 97 wt.% db calculated for corncob, cassava peel, coconut husk and cornhusk, respectively. XRD analysis revealed dominant crystalline phases of arcanite (K2SO4), sylvite (KCl) and calcite (CaCO3) in ashes of the biomass fuels pre-treated with 1 w/v% citric acid due to potassium and calcium ions present. In comparison, the 5 w/v% citric acid pre-treatment produced amorphous, biogenic silica with specific surface areas of up to 91 m2/g and pore volumes up to 0.21 cm3/g. The examined biomass residues are common wastes from food production in Africa without competition in usage with focus application. Our studies have highlighted a significant end-value to these wastes by the extraction of high quality, amorphous silica, which can be considered in applications such as catalyst support, construction material, concrete and backing material.

Experiment analysis on the characteristic of empty fruit bunch, palm kernel shell, coconut shell, and rice husk for biomass boiler fuel

It has been a necessary option for most developing countries moving towards renewable energy options as part of the Paris Agreement, which minimizes conventional energy sources’ reliance. In Malaysia, biomass is a profitable renewable option compared to solar and hydro sources for energy production due to the abundance of agricultural biomass availability for immediate use. However, most of the biomass power plants in Malaysia depend on empty fruit bunch as fuel, causing problems when there is a shortage of fuel supply and other circumstances. Variations in the fuels’ properties provide a new challenge to the power plant output; however, mixing biomass fuels can overcome the issue. Hence, this article aims to study the empty fruit bunch (EFB) with other abundant biomass fuels like “palm kernel shell (PKS),” “rice husk (RH),” and “coconut shell (CS)” for biomass boiler fuel. Therefore, the biomass’s composition and characteristics need to be known, which was done through the proximate analysis (PA), ultimate analysis (UA), and high heating value (HHV). As a result of PA, UA, and HHV, RH is the least favourable fuel due to lowest ((moisture (4.92%), volatile matter (63.20%), carbon (42.50%), hydrogen (5.42%), nitrogen (0.43%) and sulphur (0.01%)) and highest ash content (18.19%), whereas CS exhibits the most favourable option with highest (carbon (50.25%) and oxygen (42.57%)) and second highest in HHV (20.53%) compared with PKS. Thus, the experiments have provided the least and highest favourable feedstock ratios option for biomass boiler fuel application.

Heavy metals content in ashes of wood pellets and the health risk assessment related to their presence in the environment

Efforts to reduce air pollution in developing countries may require increased use of biomass fuels. Even biomass fuels are a sustainable alternative to fossil fuels there is limited quantitative information concerning heavy metal content in their ashes. Therefore, this study focuses on the determination of the heavy metal concentrations in wood pellet ash obtained from the combustion of 10 pellet brans from Bosnia and Herzegovina and Italy, the effects of adding the ashes to soils, and the assessment of health risk assessment. Ash content was determined by gravimetric method. The amount and composition of ash remaining after combustion of wood pellets varies considerably according to the type of biomass and wood from which the pellet is made. Samples were prepared by wet digestion using HNO3, and heavy metals are determined by atomic absorption spectroscopy-flame and graphite furnace. The results showed that the lowest concentration in ashes was obtained for Co 0.01 mg kg−1 and the highest for Fe 571.63 mg kg−1. The Hazard Index (HI), calculated for non-cancerous substances for children was 2.23E−01, and the total Risk index was 4.54E−05. As for adults, HI was 1.51E−02, while the Risk index value was 3.21E−06. Human health risk calculated through HI and Risk index for children and adults associated with analyzed pellets is not of significant concern. The calculated enrichment factor and metal pollution index for wood pellet ashes indicate the risk of soil contamination with heavy metals. From this point of view, analyzed samples of ashes could be a serious contaminant of soil, so further monitoring is required.