Molecular Structure of Corncob‐Derived Biochars and the Mechanism of Atrazine Sorption

Abstract

This study evaluated the sorption of atrazine [6‐chloro‐N‐ethyl‐N′‐(1‐methylethyl)‐1,3,5‐triazine‐2,4‐diamine] to biochars and thereby explored their potential use as an efficient and low‐cost soil amendment for mitigating and removing agricultural contaminants. Biochars derived from corncobs (Zea mays L.) produced at incremental pyrolysis temperatures (350–650°C in 100°C intervals) were characterized using elemental analysis, specific surface area, scanning electron microscopy, x‐ray diffractometry, and Fourier‐transform infrared spectra to estimate the relationship between the physical and chemical properties of biochars and the treatment temperature. Generally, carbonization, aromatization, and specific surface area increased with the elevation of temperatures, whereas the occurrence of polar functional groups and crystallinity decreased. The sorption isotherms fit the Freundlich equation well. A negative correlation between the logarithm of the concentration‐dependent distribution coefficient Koc and H/C and (O + N)/C ratios suggested that the presence of aromatic C and hydrophobic structures are advantageous for biochars to sorb atrazine in aqueous solutions. Biochar prepared at 650°C has a relatively developed void space structure and therefore a much larger surface area than when prepared at lower pyrolysis temperatures, indicating that pore filling has occurred. These results may provide a reference for biochar design and application in agricultural pollution control.

Nitrate removal from aqueous solutions by adsorption onto hydrogel‐rice husk biochar composite

“…As shown in Figure , a higher rate of nitrate adsorption in the early minutes is possibly due to availability of more free binding sites on the surface of hydrogel‐biochar composites (Huang, Song, et al, ). In order to study the adsorption process and the factors that control the adsorption of nitrate on the hydrogel composite of biochar, various adsorption kinetic models such as pseudo‐first‐order (Equation ) (Ho & McKay, ) and pseudo‐second‐order (Equation ) (Azizian, ), intra‐particle diffusion (Equation ) (Hao et al, ), and film diffusion (Equation ) (Tarawou & Young, ) were applied.where q e and q t represent the amount of nitrate adsorbed per unit weight of the adsorbent (mg/g) at equilibrium and time t intervals. K 1 (L/min) and K 2 (g/mg .…”

The potential role of biochar in the removal of organic and microbial contaminants from potable and reuse water: A review

“…But, micropores and small mesopores (2-20 nm) are suggested to contribute the majority to the surface area of biochar, and are more influential for biochar's uptake of organic compounds (Pignatello et al, 2006). The sorption of organic sorbates onto biochar by pore-filling mechanisms is a function of its total micropore and mesopore volumes (Nguyen et al, 2007;Hao et al, 2013). At relatively low solute concentrations, or in biochars with low volatile matter content, the sorption of organic compounds on biochar among other mechanisms, is presumably dominated by pore filling mechanisms (Kasozi et al, 2010).…”

Investigation on Prospective Energy Power from Corncob Husk Biomass and its Biochars by Kinetic Parameters and Isoconversional Models

“…As shown in Figure 6, the main components were CO 2 , CO, CH 4 , CH 3 OH, phenols and C=O (carbonyl groups). The organic oxygen in the samples is evolved during the pyrolysis according to the level of hemicelluloses and lignin breakdown.…”

“…The rate of transformation from solid-state to volatile product is described by the following expression: 11,12 (3) where α is the conversion degree of the process; k(T) is the time of process; f(α) is the rate constant and the reaction model. Conversion (α) represents the normalized form of weight loss data of decomposed sample and is defined as follows:…”

“…2 Biochar is also known as a multifunctional material in agro-systems which is employed primarily as a soil conditioner for immobilizing metals, improvement of drought resistance, recovery and fertilization of the soil. 3 Both biomass and biochar can be used to design and fulfill a lifecycle favoring a competitive agricultural based world economy, inside farms and overall agro and energy based industries. However, the energy content of biochar is also a safety matter, since the physical and chemisorption of oxygen during its storage can lead and induce to self-ignition at room or lower temperatures.…”