Hydrothermal carbonization of vegetable-tanned leather shavings (HTC-VTS) for environmental remediation: optimization of process conditions

Herein, the response surface methodology (RSM) has been used to study
simultaneously the effects of carbonization temperature, residence time,
and moisture content on the activated hydrochar preparation-based
vegetable-tanned leather shavings (VTS) using hydrothermal carbonization
method (HTC). Owing to the desirability chosen, three responses were
analysed, namely: the hydrochar yield, iodine, and methylene blue numbers.
The analysis of experimental results revealed that the hydrochar yield was
decreased with an increase in carbonization temperature which led to
micropores formation inside the hydrochar network. The optimal preparation
conditions retained were: 83.10%, 390.44 mg/g, and 259.63 mg/g for the
hydrochar yield, iodine, and methylene blue number respectively. The
hydrochar micrograph showed the presence of external pores, whereas the
FTIR analysis recorded the presence of acidic functional groups found on
hydrochar surface. The findings revealed that the VTS is a good precursor
for the hydrochar preparation useful in the removal of organic and
inorganic pollutants in aqueous media.