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. 2023 Feb 16;16(4):1672.
doi: 10.3390/ma16041672.

Synthesis of Carbon Microspheres from Inedible Crystallized Date Palm Molasses: Influence of Temperature and Reaction Time

Mohanad El-Harbawi  1 , Saeed Alhawtali  1 , Abdulrhman S Al-Awadi  2 , Lahssen El Blidi  1 , Maher M Alrashed  1 , Abdulrahman Alzobidi  1 , Chun-Yang Yin  3
Affiliations

Synthesis of Carbon Microspheres from Inedible Crystallized Date Palm Molasses: Influence of Temperature and Reaction Time

Mohanad El-Harbawi et al. Materials (Basel). .

Abstract

In this work, carbon microspheres (CMs) were prepared by hydrothermal carbonization (HTC) of inedible crystallized date palm molasses. The effects of temperature and reaction time on the prepared materials were studied. Experiments were carried out at different temperatures (180, 200, 230 and 250 °C) with reaction times ranging from 2 to 10 h. It was found that temperature had the greatest influence on the mass yield of the CMs. No solid products were observed at a temperature of 180 °C and a reaction time less than 2 h. The highest yield was found to be 40.4% at 250 °C and a reaction time of 6 h. The results show that the CMs produced were approximately 5-9 μm in diameter. The results also show that the largest diameter of the CMs (8.9 μm) was obtained at a temperature of 250 °C and a reaction time of 6 h. Nonetheless, if the reaction time was extended beyond 6 h at 250 °C, the CMs fused and their shapes were deformed (non-spherical shapes). The synthesized materials were characterized using Scanning Electron Microscopy (SEM), Fourier Transform Infrared (FTIR), Branuer-Emmett-Teller (BET) and thermogravimetric analysis (TGA). BET surface areas for the four samples were found to be less than 1 m2/g. The methylene blue adsorption studies indicated that the equilibrium adsorption capacity was reached after 15 min, with a maximum adsorption capacity of 12 mg/g. The recycling of date palm molasses (a known processed waste) to generate a useable carbon microsphere represents a beneficial step in the application of sustainable processing industries in the Middle East.

Keywords: carbon microspheres; hydrothermal carbonization; inedible crystallized date palm molasses; reaction time; temperature; yield.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Effect of HTC temperature on the CMs yields obtained from date molasses.
Figure 2
Figure 2
Effect of HTC reaction time on the CMs yields obtained from date molasses.
Figure 3
Figure 3
SEM images of the synthesized CMs with variations in temperature and reaction time. (a) Molasses at 180 °C and 2 h. (b) Molasses at 180 °C and 30 h. (c) Molasses at 200 °C and 2 h. (d) Molasses at 200 °C and 10 h. (e) Molasses at 230 °C and 2 h. (f) Molasses at 230 °C and 8 h. (g) Molasses at 250 °C and 2 h. (h) Molasses at 250 °C and 6 h. (i) Molasses at 250 °C and 8 h.
Figure 3
Figure 3
SEM images of the synthesized CMs with variations in temperature and reaction time. (a) Molasses at 180 °C and 2 h. (b) Molasses at 180 °C and 30 h. (c) Molasses at 200 °C and 2 h. (d) Molasses at 200 °C and 10 h. (e) Molasses at 230 °C and 2 h. (f) Molasses at 230 °C and 8 h. (g) Molasses at 250 °C and 2 h. (h) Molasses at 250 °C and 6 h. (i) Molasses at 250 °C and 8 h.
Figure 4
Figure 4
(a) Effects of HTC temperature on the size of CMs (reaction time = 6 h). (b) Effects of HTC reaction time on the size of CMs.
Figure 4
Figure 4
(a) Effects of HTC temperature on the size of CMs (reaction time = 6 h). (b) Effects of HTC reaction time on the size of CMs.
Figure 5
Figure 5
FT-IR spectra for the four CM samples.
Figure 6
Figure 6
TGA profiles for raw molasses and synthesized CMs.
See this image and copyright information in PMC

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