A Review of Chemicals to Produce Activated Carbon from Agricultural Waste Biomass

Abstract

The choice of activating agent for the thermochemical production of high-grade activated carbon (AC) from agricultural residues and wastes, such as feedstock, requires innovative methods. Overcoming energy losses, and using the best techniques to minimise secondary contamination and improve adsorptivity, are critical. Here, we review the importance and influence of activating agents on agricultural waste: how they react and compare conventional and microwave processes. In particular, adsorbent pore characteristics, surface chemistry interactions and production modes were compared with traditional methods. It was concluded that there are no best activating agents; rather, each agent reacts uniquely with a precursor, and the optimum choice depends on the target adsorbent. Natural chemicals can also be as effective as inorganic activating agents, and offer the advantages that they are usually safe, and readily available. The use of a microwave, as an innovative pyrolysis approach, can enhance the activation process within a duration of 1–4 h and temperature of 500–1200 °C, after which the yield and efficiency decline rapidly due to molecular breakdown. This study also examines the biomass milling process requirements; the influence of the dielectric properties, along with the effect of washing; and experimental setup challenges. The microwave setup system, biomass feed rate, product delivery, inert gas flow rate, reactor design and recovery lines are all important factors in the microwave activation process, and contribute to the overall efficiency of AC preparation. However, a major issue is a lack of large-scale industrial demonstration units for microwave technology.

RETRACTED: Activated Carbons From Winemaking Biowastes for Electrochemical Double-Layer Capacitors

“…Practically any raw materials with high carbon content, including several wastes, may yield interesting and useful materials (Deiana et al, 2009 ). Various waste sources have been proposed for the preparation of activated carbon, from biodiesel (Gonçalves et al, 2019 ) to food processing waste (Ramón-Gonçalves et al, 2019 ; Senophiyah-Mary et al, 2019 ; Yaglikci et al, 2020 ) or agriculture industry residues (Ukanwa et al, 2019 ), all of them with great attractiveness owing to their large-scale production and low price. Winemaking-derived waste is a major issue in the wine industry, being Spain, the origin of the precursor wine used in this work, the third world producer of wine (Maicas and Mateo, 2020 ).…”

Improving the Efficiency of Pyrolysis and Increasing the Quality of Gas Production through Optimization of Prototype Systems

“…Oxidation and reduction are important processes for gas quality [4]. Noncombustible gases in the pyrolysis space, as well as carbon dioxide and water, pass through the oxide field and on the glowing charcoal in the lower layer, which reduces them during further chemical reactions [5][6][7][8][9][10][11][12]. In the quality zone, the endothermic process takes place, removing heat from the environment.…”

Nano-Size Biomass Derived from Pomegranate Peel for Enhanced Removal of Cefixime Antibiotic from Aqueous Media: Kinetic, Equilibrium and Thermodynamic Study

“…Despite the applicability of commercial ACs for wastewater treatment and contaminant removal from aqueous environments, commercial ACs are an expensive option [26,27]. Consequently, research in recent years has sought to produce ACs from affordable natural biomass materials from agricultural wastes such as coconut shell, papaya peel, vine wood, macadamia nut shells, coffee endocarp, olive stones, and walnut shells [28][29][30]. Regeneration of adsorbents is the key parameter: which ACs can be regenerated with low cost thermal and hydrothermal processes after saturated with pollutants [31,32].…”