Comparison of Novel Biochars and Steam Activated Carbon from Mixed Conifer Mill Residues

There is increasing demand in environmental remediation and other sectors for specialized sorbents made from renewable materials rather than hard coals and minerals. The proliferation of new pyrolysis technologies to produce bio-based energy, fuels, chemicals, and bioproducts from biomass has left significant gaps in our understanding of how the various carbonaceous materials produced by these systems respond to processes intended to improve their adsorption properties and commercial value. This study used conventional steam activation in an industrial rotary calciner to produce activated carbon (AC) from softwood biochars made by three novel pyrolysis systems. Steam was injected across four heating zones ranging from 816 °C to 927 °C during paired trials conducted at calciner retention times of 45 min and 60 min. The surface area of the three biochars increased from 2.0, 177.3, and 289.1 m2 g−1 to 868.4, 1092.9, and 744.8 m2 g−1, respectively. AC iodine number ranged from 951 to 1218 mg g−1, comparing favorably to commercial AC produced from bituminous coal and coconut shell. The results of this study can be used to operationalize steam activation as a post-processing treatment for biochar and to expand markets for biochar as a precursor in the manufacture of specialized industrial sorbents.

Integrated approach in treatment of solid olive residue and olive wastewater

Olive oil production processes breed two kinds of environmentally detriment waste by-products; the solid olive residue (SOR) and olive waste water (OWW) by-products. The current work aims to treat simultaneously both wastes in the same location. The solid olive residue was converted to activated carbon with pyrolysis at 600°C, followed by steam activation at 600, 700 and 800°C. The produced activated carbons were investigated by FTIR, SEM, BET surface areas analyzer and iodine number. The surface area increases with increasing stream activation temperature up to 800°C (1020 m2/g BET). However, steam activation at 700°C is most environmental and economically feasible, because increasing the activation temperature from 700 to 800°C increases the surface area only from 979 to 1020 m2/g. Activated carbon steam cured at 700°C shows high removal capacity of both polyphenolic compounds and COD of OWW. 95.5% of COD and 84.2% of polyphenolic compounds was removed after equilibrium with activated carbon for 2 hours at room temperature.

Activated carbon preparation from eucalyptus wood chips using continuous carbonization–steam activation process in a batch intermittent rotary kiln

The production of activated carbon from eucalyptus wood chips by steam activation in a 2000 kg batch intermittent rotary kiln with continuous carbonization–steam activation process conducted at 500 °C to 700 °C was studied. The activated carbon products were characterized by FTIR, SEM–EDS, Raman spectroscopy, and BET analysis. Percent yields, iodine number, and methylene blue number of the produced activated carbon materials were measured as well. It was shown that the percent yields of the activated carbon materials made in the temperature range from 500 to 700 °C are 21.63 ± 1.52%–31.79 ± 0.70% with capacities of 518–737 mg I2/g and 70.11–96.93 mg methylene blue/g. The BET surface area and micropore volume of the activated carbons are 426.8125–870.4732 m2/g and 0.102390–0.215473 cm3/g, respectively. The steam used in the process could create various oxygen containing surface functional groups such as –CO and –COC groups. In addition, it could also increase the amorphous nature of the activated carbon product. These properties of the activated carbon products are increased with increasing steam activation temperature from 500 to 700 °C. As a result, the activated carbon materials produced at activation temperatures of 600 °C and 700 °C exhibit higher adsorption.

Evaluation of Porous Carbon Adsorbents Made from Rice Husks for Virus Removal in Water

Porous carbons are well-known efficient adsorbents for a variety of organic and inorganic pollutants; however, they have difficulty in virus removal. In this study, novel porous carbons (NPCs) (NPC-A, NPC-B, and NPC-C) derived from rice husks were compared with commercially available activated carbons (ACs) for their ability to remove MS2 bacteriophages (MS2) in a batch experiment. NPC-A was produced by the silica removal process. NPC-B was prepared with an additional steam activation applied to NPC-A. NPC-C was obtained with an additional acid rinse applied to NPC-B. The NPCs (particularly NPC-C) exhibited effective removal of up to 5.3 log10 of MS2, which was greater than that of less than 2.7 log10 obtained by other ACs under 10 g/L during the same contact time (60 min). The pore size distribution of the porous carbon adsorbents was found to influence their virus removal performance. The adsorbents with a larger proportion of pores ranging from 200–4500 nm in diameter were able to achieve higher virus removal rates. Thus, NPCs (particularly NPC-C), which had a larger volume of pores ranging from 200–4500 nm in size, demonstrated the potential for use as efficient adsorbents for removing viruses during water purification.