Biomass-Derived Carbonaceous Adsorbents for Trapping Ammonia

Abstract

The preparation of low-cost carbonaceous adsorbents for nitrogen recovery is of interest from agricultural and waste management perspectives. In this study, the gaseous ammonia (NH3) and aqueous ammonium (NH4+) sorption capacities have been measured for different types of carbonaceous chars produced under different conditions. The study includes a comparison of an oak-based hydrochar produced from hydrothermal carbonisation (HTC) at 250 °C with two biochars produced from slow pyrolysis at 450 °C and 650 °C, respectively. The chars were also chemically modified with H2SO4, H3PO4, H2O2, and KOH to investigate the potential for sorption enhancement. The highest sorption capacities for NH3 were observed for the hydrochars with typical uptake capacities ranging from 18–28 mg g−1 NH3. Sorption capacity for oak biochars is significantly lower and ranges from 4–8 mg g−1 for biochars produced at 450 °C and 650 °C, respectively. Hydrochar showed a substantially higher sorption capacity for NH3 despite its lower surface area. The CaCl2 extractable NH4+ following ammonia adsorption is incomplete. Typically, only 30–40% of the N is released upon washing with CaCl2 in form of NH4+. Post chemical modification of the chars resulted in only limited enhancement of char NH3 and NH4+ sorption. H3PO4 treatment showed the greatest potential for increasing NH3/NH4+ sorption in biochars, while KOH and H2O2 treatment increased NH3 sorption in the hydrochar. As only marginal increases to char surface area were observed following char treatment, these findings suggest that char surface functionality is more influential than surface area in terms of char NH3/NH4+ sorption.

Mitigation of Gaseous Emissions from Swine Manure with the Surficial Application of Biochars

“…Even though manure pH changed for all treatments, there were no significant differences in pH between the control and biochar-treated manures after each trial, so it cannot be stated that biochar inhibited NH [47]. Assuming this sorption capacity, the RO biochar would be fully saturated by day 7-14.…”

Remediation of heavy metal polluted waters using activated carbon from lignocellulosic biomass: An update of recent trends

“…Based on previous studies examining solutions with higher pH values, carboxyl groups have been shown to affect the adsorption of heavy metal ions onto the surface of biomass-derived carbonaceous adsorbents (Takaya et al, 2019) (D.-P. . The availability of carboxylic acid on the surface of AC facilitates an improved acidic dissociation and formation of chelating agents in forming complexes from the interaction of the heavy metal ions and surface functional groups.…”

Engineered Magnetic Carbon-Based Adsorbents for the Removal of Water Priority Pollutants: An Overview

“…HTC offers some advantages in comparison to the conventional thermal treatments because not only helps to generate a surface area rich in functional groups but it also implies a reduced energy consumption and low-cost. Raw HC obtained at common operating conditions has a low spe-cific surface area (<100 m 2 /g) but contains a significant amount of oxygenated functionalities if water is the reaction medium to prepare this adsorbent [23,[60][61][62][63]. For example, Cai et al [64] reported the preparation of a magnetic BC for chromium adsorption using peanut shells, deionized water, hexamethylenediamine, and FeCl 3 •6H 2 O.…”