Evaluation of the production of hydrochar from spent coffee grounds under different operating conditions br

An increasing amount of spent coffee grounds (SCG) has resulted in a huge burden on landfills; thus, alternative viable technologies are needed. The hydrothermal carbonization of SCG was studied to determine to produce high-quality hydrochar. The influence of three independent variables (temperature, reaction duration, and solid to liquid ratio) on the yield of hydrochar and conversion was investigated through 15 experimental runs using central composite design (CCD). The most optimized conversion and hydrochar yield results were 89.8 % and 10.1 %, respectively. Higher heating value (HHV) progressed considerably from 19.1 MJ/kg of SCG to 21.2 MJ/ kg of hydrochar. The ultimate analysis results for hydrochar revealed that the quantity of carbon (C) upgraded from 50.1 to 55.9 %, whereas; oxygen (O) content decreased from 40.5 to 38.7 %, hence improving the energy and combustion properties. The Scanning electron microscopy (SEM) analysis portrayed the alteration in the structure of SCG and improved porosity after hydrothermal processing, which was further investigated via Brunauer-Emmett-Teller (BET) analysis. BET surface area improved from 4.4 m2/g (for SCG) to 16.5 m2/g (for hydrochar). The thermal stability of hydrochar was upgraded from 330 degrees C for SCG to 375 degrees C for hydrochar.

Automated summary

This study examined the hydrothermal carbonization of spent coffee grounds to produce high-quality hydrochar. The results showed improved energy and combustion properties, as well as enhanced surface area and thermal stability of the hydrochar.