Catalytic Hydrothermal Carbonization of Avocado Peel

The hydrothermal carbonization (HTC) of avocado peel was investigated by varying the reaction temperature, reaction time, and catalyst/feedstock ratio. After the HTC process, there was a drastic change in both the structure and chemical composition of the hydrochar compared to the feedstock. This modification aids hydrochar’s improved fuel characteristics, as seen by a drop in the H/C and O/C ratios, as well as an increase in fixed carbon content. The higher heating value (HHV) increased in the feedstock to a maximum value of 27.15 MJ·kg−1, corresponding to hydrochar, which is obtained at an optimized condition. Notably, the HHV and carbon content of the noncatalytic sample are only higher than those of the feedstock but lower than those of the samples surveyed. The combustion behavior and thermal characteristics of hydrochars show that the HTC of the avocado peel in the presence of FeCl3 catalyst introduces a possible direction of application in converting agro-industrial by-products into fuel.

An Overview and Evaluation of Highly Porous Adsorbent Materials for Polycyclic Aromatic Hydrocarbons and Phenols Removal from Wastewater

Polycyclic aromatic hydrocarbons (PAHs) and phenolic compounds had been widely recognized as priority organic pollutants in wastewater with toxic effects on both plants and animals. Thus, the remediation of these pollutants has been an active area of research in the field of environmental science and engineering. This review highlighted the advantage of adsorption technology in the removal of PAHs and phenols in wastewater. The literature presented on the applications of various porous carbon materials such as biochar, activated carbon (AC), carbon nanotubes (CNTs), and graphene as potential adsorbents for these pollutants has been critically reviewed and analyzed. Under similar conditions, the use of porous polymers such as Chitosan and molecularly imprinted polymers (MIPs) have been well presented. The high adsorption capacities of advanced porous materials such as mesoporous silica and metal-organic frameworks have been considered and evaluated. The preference of these materials, higher adsorption efficiencies, mechanism of adsorptions, and possible challenges have been discussed. Recommendations have been proposed for commercialization, pilot, and industrial-scale applications of the studied adsorbents towards persistent organic pollutants (POPs) removal from wastewater.