Effects of biomass type, carbonization process, and activation method on the properties of bio-based activated carbons

Abstract

Activated carbons (AC) serve as adsorbents in various applications requiring specific functionalities. In this study, the effects of biomass type, pre-carbonization process, and activation method on the properties of ACs were investigated. Chemical (KOH and H3PO4) and physical (CO2) activations were performed on slow pyrolyzed and hydrothermally carbonized (HTC) biochars produced from two feedstocks, willow and Scots pine bark (SPB). In addition, the adsorption capacities of the ACs were tested with two dyes and zinc metal. Distinct differences were found between the biochars and ACs regarding pore size distributions, surface area (238 – 3505 m2 g-1), and surface chemistry. KOH activation produced highly microporous ACs from all biochars, whereas with H3PO4 and CO2 there was also increase in the meso- and macroporosity with the HTC biochars. Adsorption capacity for dyes was dependent on the surface area, while for zinc it depended on AC’s pH. The results provide interesting insights into tailoring ACs for specific applications.

Rapid Removal of Toxic Remazol Brilliant Blue-R Dye from Aqueous Solutions Using Juglans nigra Shell Biomass Activated Carbon as Potential Adsorbent: Optimization, Isotherm, Kinetic, and Thermodynamic Investigation

“…Therefore, out of three different impregnation ratios of various activation agents, the HNO 3 -treated walnut shell powder activated carbon (1:3 ratio) was found to exhibit better results, and hence was considered for further investigation. A similar observation has been reported elsewhere [ 19 ].…”

“…The properties of activated carbon strongly depend on the precursor material, type of carbonization and activation, activation temperature, and duration. The physical treatment includes carbonizing the material at high temperatures (1073 K) under an inert atmosphere using nitrogen or argon supply [ 19 ]. The carbonized material is then activated at high temperatures using suitable activating agents like steam or CO 2 .…”

Biochars and Activated Biocarbons Prepared via Conventional Pyrolysis and Chemical or Physical Activation of Mugwort Herb as Potential Adsorbents and Renewable Fuels

“…Research on the manufacturing, physicochemical properties and possibilities of practical application of biochars and activated biocarbons have been conducted for many years by scientists from around the world. Biochars can be produced by pyrolysis, torrefaction or hydrothermal carbonization of various types of organic materials, using different time and temperature variants of thermochemical treatment [ 1 , 2 , 3 , 4 , 5 ]. In turn, for the production of activated carbons, the method of physical activation with CO 2 and water vapor as well as chemical activation with KOH, K 2 CO 3 , ZnCl 2 or H 3 PO 4 are mainly used [ 6 , 7 , 8 , 9 , 10 ].…”

Adsorptive Removal of Potentially Toxic Elements From Wastewater Using Peanut Shells Biochar

“…The band at 1120 cm -1 was assigned to C-O bond stretching for alcohols and ether. The bands at 684 and 486 cm -1 were attributed to C-H stretching vibration [21].…”