Date palm waste-derived biochar composites with silica and zeolite: synthesis, characterization and implication for carbon stability and recalcitrant potential

Abstract

Engineered organo-mineral composites were synthesized from date palm waste biochar and silica or zeolite via mechanochemical treatments. Date palm tree rachis (leaves) waste biomass was pre-treated with silica or zeolite minerals via ball milling and sonication prior to pyrolysis at 600 °C. The resultant organo-mineral composites and pristine materials were characterized using X-ray diffraction, thermogravimetric-differential thermal (TG-DTA), Fourier transform infrared, scanning electron microscope analyses and surface area and porosity analyzer to investigate the variations in physiochemical and structural characteristics. Compared to the resultant composites derived from non-milled date palm biomass, ball milling increased surface area, while decreased crystallinity index and effective particle size of the biochar composites. Silica composited biochars were located near origin in the van Krevelen diagram indicating lowest H/C and O/C molar ratios, thus suggesting higher aromaticity and lower polarity compared to other biochars. TGA thermograms indicated highest thermal stability of silica composited biochars. Ash and moisture corrected TGA thermograms were used to calculate recalcitrance index (R ) of the materials, which speculated high degradability of biomass (R < 0.4), minimal degradability of biochars and zeolite composited biochars (0.5 < R < 0.7) and high recalcitrant nature of silica composited biochars (R > 0.7). Silica composited biochars exhibited highest carbon sequestration potential (64.17-95.59%) compared to other biochars. Highest recalcitrance and carbon sequestration potential of silica composited biochars may be attributed to changes in structural arrangements in the silica-biochar complex. Encapsulations of biochar particles with amorphous silica via Si-C bonding may have prevented thermal degradation, subsequently increasing recalcitrance potential of silica composited biochars.

Turning date palm waste into carbon nanodots and nano zerovalent iron composites for excellent removal of methylthioninium chloride from water

“…A band appearing at 3426 cm −1 in the composite of nZVI-DBC was attributed to -OH stretching vibrations, which indicated the presence of a layer of FeOOH onto the surfaces of nZVI particles. A peak appearing at 2900 cm −1 in DF was designated to aliphatic C-H and O-H stretching owing to cellulose and hemicellulose, which was vanished in DBC 31 . A band around 1750 cm −1 in DF represented the existence of C=O stretching.…”

“…The maximum weight loss was in the following order: DF (81.14%) > nCD-DBC (41.01%) > DBC (62.63%) > nZVI-DBC (41.23%). Thermal stability of the materials was further estimated by calculating the recalcitrance potential (R 50 ) of ash and moisture-free TGA thermograms as reported by Ahmad et al 31 . It has been reported that materials with R 50 < 0.50 are highly degradable, 0.70 > R 50 ≥ 0.50 are marginally stable, and those with R 50 > 0.70 are highly stable 31 .…”

Investigating the Aging Effects of Biochar on Soil C and Si Dissolution and the Interactive Impact on Copper Immobilization

“…Zhao et al [ 46 ] from an adsorption study suggested that the addition of silicon not only enhanced the adsorption capacity of biochar, but also effectively resisted the decrease in the adsorption capacities on BCs after aging (H 2 O 2 and H 2 SO 4 oxidation). Previous studies have also shown that silica particles might affect C arrangement and structural composition by producing a Si-C coupling system in the biochar matrix [ 47 ]. As discussed above, BC modified with silicon shows potential for enhanced metal adsorption.…”

Biochar from co-pyrolysis of urban organic wastes—investigation of carbon sink potential using ATR-FTIR and TGA

“…While among the biochar from UOW blends, 650M s has the highest recalcitrance despite lower graphitization compared to 650P as seen in its FTIR spectrum. 650M s has more silica inherited from M s (sec 3.1), which increases the recalcitrance through Si encapsulation of carbon [113]. In addition, the higher Fe content in 650M s (sec 3.2.2) also promotes graphitization [114] and higher recalcitrance [115].…”