Physical, Chemical and Biological Characterization of Six Biochars Produced for the Remediation of Contaminated Sites

Abstract

The physical and chemical properties of biochar vary based on feedstock sources and production conditions, making it possible to engineer biochars with specific functions (e.g. carbon sequestration, soil quality improvements, or contaminant sorption). In 2013, the International Biochar Initiative (IBI) made publically available their Standardized Product Definition and Product Testing Guidelines (Version 1.1) which set standards for physical and chemical characteristics for biochar. Six biochars made from three different feedstocks and at two temperatures were analyzed for characteristics related to their use as a soil amendment. The protocol describes analyses of the feedstocks and biochars and includes: cation exchange capacity (CEC), specific surface area (SSA), organic carbon (OC) and moisture percentage, pH, particle size distribution, and proximate and ultimate analysis. Also described in the protocol are the analyses of the feedstocks and biochars for contaminants including polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), metals and mercury as well as nutrients (phosphorous, nitrite and nitrate and ammonium as nitrogen). The protocol also includes the biological testing procedures, earthworm avoidance and germination assays. Based on the quality assurance / quality control (QA/QC) results of blanks, duplicates, standards and reference materials, all methods were determined adequate for use with biochar and feedstock materials. All biochars and feedstocks were well within the criterion set by the IBI and there were little differences among biochars, except in the case of the biochar produced from construction waste materials. This biochar (referred to as Old biochar) was determined to have elevated levels of arsenic, chromium, copper, and lead, and failed the earthworm avoidance and germination assays. Based on these results, Old biochar would not be appropriate for use as a soil amendment for carbon sequestration, substrate quality improvements or remediation.

Adsorption of Cadmium Using Biochars Produced from Agro-Residues

“…Biochar pH and electrical conductivity (EC) were determined using a biochar to deionized water mass ratio of 1:10 and a pH/conductivity meter (Orion start A215, Thermo Scientific) . Carbon and nitrogen content were determined using an elemental analyzer (Elementar Analyzer, Germany), and total ash content was determined by loss on ignition procedure by heating the sample at 420 °C in air atmosphere . Thermogravimetric analysis was performed for each biochar type (TGA Q500, TA Instruments) at a heating rate of 10 °C min –1 in an O 2 atmosphere in the temperature range 20–1000 °C.…”

“…31 Carbon and nitrogen content were determined using an elemental analyzer (Elementar Analyzer, Germany), and total ash content was determined by loss on ignition procedure by heating the sample at 420 °C in air atmosphere. 32 Thermogravimetric analysis was performed for each biochar type (TGA Q500, TA Instruments) at a heating rate of 10 °C min −1 in an O 2 atmosphere in the temperature range 20−1000 °C. FTIR analysis was performed using an infrared spectrometer (PerkinElmer, Model Spectrum Two) operating in the spectral range 4000−400 cm −1 to identify the functional groups present in the surface of each biochar type.…”

Oxidised Biochar from Palm Kernel Shell for Eco-friendly Pollution Management

“…The CEC measures the surface charge in a solid sample and indicates its capacity to adsorb cations [30]. Table 2 shows that raw PKS had the highest CEC value, followed by PKS activated carbon and oxidised PKS biochar.…”

Sugarcane bagasse biochar: A suitable amendments for inland saline pond water productivity

“…Sugarcane bagasse biochar application can improve nutrient status, mainly available nitrogen, in saline soil solution through its impact on the abundance and activities of bacteria that enhances nutrient transformation and, hence, the availability of nutrients (Bhaduri et al, 2016). Sugarcane bagasse biochar is ae rich source of available nitrogen (Table 1) in the form of NO -N 3 (Denyes et al, 2014), which was also identified from the FT-IR analysis of bagasse biochar (Fig. 2).…”