Using of carbon/lignin biocomposite as recyclable sorbent in-situ for elimination of VOCs from oily wastewaters

Y. M. M. Moustafa

Abstract

Using of carbon/lignin biocomposite as recyclable sorbent in-situ for elimination of VOCs from oily wastewaters

In this review, it was shown how by developing a facile one-pot co-precipitation process, the granule activated carbon (GAC)/Kraft lignin (KL) biocomposite (gAC/KL_x) was constructed from recycling industrial wastes of both palm-date pits and pulping black liquor as a new eco-friendly sorbent. The ATR-FTIR, XRD, SEM, BET, TGA, DLS and Zeta potential analyses were used to characterize the gAC/KLbiocomposite prepared to be used as an effective sorbent of environmentally toxic (BTX) compounds (benzene, toluene, and xylene) from petroleum wastewater effluents. Also, using high-performance liquid chromatography (HPLC), the sorption behavior of BTX over gAC/KL_xbiocomposites with different ratios of Kraft lignin (x = 33, 50, and 67%) in batch experiments was evaluated. It was noticed that the gAC/KL showed the highest sorption capacity of BTX at a lignin blended ratio of 50%, even from broad ranges of water salinity (up to 100,000 mg/L) and pH values (pH 4 - 9). The sorption behavior of BTX compounds was found to fit better to a type two pseudo-second kinetic (adsorption kinetic rate of BTX at 0.104 g.mg^-1.min^-1) and Langmuir isotherm models, as confirmed by the higher coefficient of R²> 0.98. The sorption affinities of the gAC/KL_0.5biocomposite with respect to 250 mg/L BTX can be ordered in the sequence Xylene > Toluene ≥ benzene with the highest monolayer capacities reached to 170.5, 160.5, and 159.7 mg/g, respectively after 6 h. The adsorption mechanism was found to follow the diffusion and hydrophobic sorption mechanisms. Particularly, the possibilities of BTX elution for gAC/KL_0.5 reuse were evaluated up to five cycles without high significant loss in sorption efficiencies during multiple wastewater treatments. As such, on the basis of batch BTX sorption studies, the gAC/KL_0.5 is expected to be a promising low cost and high-performance new sorbent to be reutilized for real wastewater treatment process and petroleum hazardous decontamination with higher thermal stability (up to 350 ^oC) and aqueous stability (10% - 21% efficiency loss).

Author(s):

Y. M. M. Moustafa

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