Enhancing the Pore Properties and Adsorption Performance of Cocoa Pod Husk (CPH)-Derived Biochars via Post-Acid Treatment

Abstract

In this work, the cocoa pod husk (CPH) was converted into biochar products at higher carbonization temperatures (i.e., 400–800 °C). The pore and chemical properties of the resulting biochars and its post-leaching biochars by acid washing, including specific surface area, total pore volume, pore size distribution, true density, and scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS) and Fourier Transform infrared spectroscopy (FTIR) were studied. Based on the pore properties, pyrolysis temperature at around 800 °C seemed to have the most profound impact on the pore development for producing biochar, where its Brunauer–Emmet–Teller (BET) surface area is 101 m2/g. More noticeably, more pores in the CPH-based biochar could be significantly created during the acid-washing, resulting in an increase of BET surface area from 101 to 342 m2/g. According to the data on the EDS and FTIR, the resulting biochars seemed to have oxygen-containing functional groups on the surface. Furthermore, the methylene blue (MB) adsorption performance of the optimal biochar product with maximal BET surface area was tested to fit its kinetics by the pseudo-second order model, showing a strong interaction between the biochar adsorbent and the cationic adsorbate.

Preparation of Porous Biochar from Soapberry Pericarp at Severe Carbonization Conditions

“…As summarized above, the temperature should be the most important process parameter for determining the pore properties of the biochar products as more pores were generated in severe carbonization conditions. The findings were consistent with those reported by the other feedstocks such as cocoa pod husk [11], rice husk [12], goat manure [21], biogas digestate [33] and dairy manure [34]. The maximal BET surface area of about 300 m 2 /g can be obtained by using these feedstocks in the biochar production when the carbonization temperature reached 800 or 900 • C. In addition, the average pore diameter was obtained from the data on the BET surface area and the total pore volume assuming the pore is of cylindrical and uniform geometry, showing that the pore diameter of the SP-BC-800 product was close to the boundary limit (2.0 nm) between micropores and mesopores.…”

“…On the other hand, the elemental distributions and functional groups of the resulting biochar products with high pore properties were observed by energy-dispersive X-ray spectroscopy (EDS) (7021-H; HORIBA Co., Kyoto, Japan) and Fourier-transform infrared spectroscopy (FTIR) (FT/IR-4600; JASCO Co., Tokyo, Japan), respectively. The biochar sample preparation and analytical conditions have been stated in the previous study [11].…”

“…Concerning its porous structure and surface characterization, biochar has high adsorption potential for the removal of pollutants from water streams [3][4][5][6][7]. In recent years, there is an increasing interest in exploiting biochar as an excellent carbon material for environmental applications, or reusing different lignocellulosic feedstocks for producing biochar with high pore properties (e.g., specific surface area), which includes wood [8], oil palm shell [9], maize straw [10], cocoa pod husk [11], rice husk [12] and so on.…”

Bioactive Compounds from Cocoa Husk: Extraction, Analysis and Applications in Food Production Chain

“…To date, only some research has been conducted utilizing this solid waste after extraction (SWE). Moreover, some research has been to utilize the cocoa pod husk for preparing compost [60] and biochar [61,62], which was further used as a plant nutrient/fertilizer [63,64] and for the bioremediation of toxic chemicals from an aqueous medium [65,66]. In line with this, the SWE residues remaining after the extraction could be treated to remove chemical entities and then processed to form compost and biochar products for their complete utilization in a circular economy approach.…”

Cocoa pod husks as potential sources of renewable high-value-added products: A review of current valorizations and future prospects

“…A study by Tsai and Huang (2018) improved the adsorption capacity of AC from ground CPH, and the authors reused the solution as a liquid fertilizer after acid leaching. The effectiveness of pyrolysis techniques for the heat treatment of CPH has been demonstrated from the thermochemical conversion and characterization of CPH (Adjin-Tetteh et al 2018;Tsai et al 2020). The authors used rapid pyrolysis technologies that had notable advantages over other biomass-and wastetreatment technologies.…”