Co-pyrolysis of mixed date pits and olive stones: Identification of bio-oil and the production of activated carbon from bio-char

Abstract

The essential objective of this investigation is to inspect the possibility of exploiting an equivalent blend of locally available bio-wastes, namely date pits (DP) and olive stones (OS), for the production of bio-oil (BO) and bio-char (BC) through thermal pyrolysis route in a semi-batch lab-scale reactor. The pyrolysis products yields from mixed (DP + OS) were optimized by tuning the experimental variables. Co-pyrolysis of mixed (DP + OS) exhibited the maximum output of liquid products (51.11 %, with a BO yield of 37.17 %) at 500 °C using feed particle size of 60 mesh for 80 min at 20 °C/min heating rate. For comparison, the pyrolysis of DP or OS at the previously obtained conditions was also achieved. The liquid products yield from the pyrolysis of DP was (52.30 %, with a BO yield of 31.0 %) compared to (46.0 %, with a BO yield of 24.55 %). FTIR spectroscopy, GC–MS, and elemental analysis were employed to analyze the BO from mixed (DP + OS). The GC–MS outcomes revealed that the produced BO contains phenols, high molecular mass acids, fatty acid esters, aromatics, and alcohols. The BC produced by the pyrolysis of mixed (DP + OS) at the typical pyrolysis conditions mentioned above was exploited to create active carbon (AC) by the optimized ZnCl2 activation method. The AC was identified by BET surface area, FTIR, FESEM, EDX, and XRD. Also, it was exploited to remove dibenzothiophene (DBT) from model gasoline and commercial gasoline. The maximum removal efficiency of DBT reached (90.01 %± 0.50) using 25 mL of 200 mg/L DBT solution employing (0.30 g) of the as-created AC at 50 °C for 80 min. The DBT adsorption results by the AC obeyed the Freundlich isotherm, and best fit the pseudo-first-order kinetic model. For comparison, the BC samples produced through the pyrolysis of DP and OS individually at the typical pyrolysis conditions were also utilized to create AC at the optimal conditions obtained to prepare the best AC sample from mixed (DP + OS) by the ZnCl2 activation method. The so-prepared AC samples were identified for their iodine number and morphology using FESEM technique. The AC samples produced from the BC from DP and OS have also implemented to eliminate DBT from model gasoline using the optimum conditions obtained previously.