Iron Oxide Nanoparticles Embedded in Activated Carbons Prepared from Hydrothermally Treated Waste Biomass

Abstract

Particles of iron oxide (Fe3O4 ; 20–40 nm) were embedded within activated carbons during the activation of hydrothermally carbonized (HTC) biomasses in a flow of CO2. Four different HTC biomass samples (horse manure, grass cuttings, beer production waste, and biosludge) were used as precursors for the activated carbons. Nanoparticles of iron oxide formed from iron catalyst included in the HTC biomasses. After systematic optimization, the activated carbons had specific surface areas of about 800 m2g1. The pore size distributions of the activated carbons depended strongly on the degree of carbonization of the precursors. Activated carbons prepared from highly carbonized precursors had mainly micropores, whereas those prepared from less carbonized precursors contained mainly mesopores. Given the strong magnetism of the activated carbon–nano-Fe3O4 composites, they could be particularly useful for water purification.

Biochar amendment to soil changes dissolved organic matter content and composition

“…Further washing with acid increased the surface area for the cacao shell biochar, but decreased the surface area for the rice husk biochar. Activation of carbonaceous materials with CO 2 could collapse pores, thereby reducing the surface area (Hao et al, 2014). The same effect could explain a reduction in surface after washing of biochar with acid, as previously results have also shown (Klasson et al, 2014).…”

Tailored activated carbons for supercapacitors derived from hydrothermally carbonized sugars by chemical activation

“…First, the HTC-sugar was impregnated with a KOH solution (0.5 g mL À1 ; weight ratio of KOH : HTC ¼ 4 : 1) under constant stirring at room temperature overnight. Second, the mixture was dried in an oven at a temperature of 150 C. Third, the dried and grounded mixture was thermally treated (activation) in a custom-made stainless steel reactor, 36 which was placed in a vertical tube furnace. The temperature was increased at a rate of 10 C min À1 from room temperature to the set temperature (600, 700 or 800 C) and held there for four hours (or otherwise stated), aer which the reactor was cooled down in the protective nitrogen ow (200 standard cubic centimeters per minute) used during the activation.…”

Influence of pressure and temperature on key physicochemical properties of corn stover-derived biochar

“…It will overestimate the amount of non-aromatic carbons. However, a clear band of the CH2-O in cellulose was detected at a chemical shift of 74 ppm [42,45]. For the biochar produced at a peak temperature of 400 ºC and an absolute pressure of 1.6 MPa (run 2) most of the aliphatic bands were absent from the spectrum.…”