Biochar Adsorbents with Enhanced Hydrophobicity for Oil Spill Removal

Abstract

Oil spills cause massive loss of aquatic life. Oil spill cleanup can be very expensive, have secondary environmental impacts, or be difficult to implement. This study employed five different adsorbents: (1) commercially available byproduct Douglas fir biochar (BC) (SA ∼ 695 m 2 /g, pore volume ∼ 0.26 cm 3 /g, and pore diameter ∼ 13−19.5 Å); (2) BC modified with lauric acid (LBC); (3) iron oxide-modified biochar (MBC); (4) LBC modified with iron oxide (LMBC); and (5) MBC modified with lauric acid (MLBC) for oil recovery. Transmission, engine, machine, and crude oils were used to simulate oil spills and perform adsorption experiments. All five adsorbents adsorbed large quantities of each oil in fresh and simulated seawater with only a slight pH dependence, fast kinetics (sorptive equilibrium reached before 15 min), and high regression fits to the pseudo-second-order kinetic model. The Sips isotherm model oil sorption capacities for these sorbents were in the range ∼3−11 g oil/1 g adsorbent. Lauric acid-decorated (60−2 wt %) biochars gave higher oil adsorption capacities than the undecorated biochar. Lauric acid enhances biochar hydrophobicity and its water contact angle and reduces water influx into biochar's porosity preventing it from sinking in water for 3 weeks. These features were observed even at 2% wt of lauric acid (sinks only after 2 weeks). Magnetization by magnetite nanoparticle deposition onto BC and LBC allows the recovery of the exhausted adsorbent by a magnetic field as an alternative to filtration. Oil sorption was endothermic. Recycling was demonstrated after toluene stripping. The oil-laden adsorbents' heating values were obtained, suggesting an alternative use of these spent adsorbents as a lowcost fuel after recovery, avoiding waste disposal costs. The initial and oil-laden adsorbents were characterized by scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction, Brunauer−Emmet−Teller surface area, contact angle, thermogravimetric analyses, differential scanning calorimetry, vibrating sample magnetometry, elemental analysis, and X-ray photoelectron spectroscopy.

A Role for Newly Developed Sorbents in Remediating Large‐Scale Oil Spills: Reviewing Recent Advances and Beyond

“…Navarathna et al, also reported the product of lauric acid decorated magnetic biochar (MLBC) as a dispersible oil sorbent (Figure 13E). [33] MLBC can fully recycle into fuel, similar to calorimetry with oil fuels. Kang et al, fabricated magnetic carbon nanosphere/nitrogen doped graphene aerogel with a one-step hydrothermal in situ electrostatic selfassembling method under weakly alkaline (Figure 13F).…”

“…[28][29][30][31] Several studies have reported that sorbents with high-performance can easily be obtained by precise tuning of a sorbent's hydrophobicity and swelling capacity. [32,33] Modified sorbents with diverse morphologies, [34][35][36] wettability, [37][38][39][40][41] and specific surface area functions have generated to exploit high oil sorption capacity and reusability, [42][43][44][45][46][47] and these modified sorbents are now playing an important role in oil spill remediation. For example, heating sorbents allow absorption of highly viscous oil efficiently.…”

Efficient and Fast Removal of Oils from Water Surfaces via Highly Oleophilic Polyurethane Composites

“…Sorption is probably one of the most used methods because oil sorbents fall into two very broad categories: synthetic, such as polyanilines and polypyrrole-silica polymer composites [ 21 , 22 ], and natural adsorbents, such as bio-based aerogels and natural adsorbents based on sawdust [ 23 , 24 ]. The latter can be further divided into organic and inorganic [ 25 , 26 ]. Synthesis of composite materials employing both synthetic and natural substances is a developing technique and the amount of published research is fast growing [ 27 , 28 , 29 ].…”

Combination of modified biochar and polyurea microcapsules to co‐encapsulate a fumigant via interface polymerization for controlled release and enhanced bioactivity

“…Biochar (BC) is a pyrogenic carbon (C)‐rich material with good biocompatibility, high specific surface area, and abundant pore structures and functional groups, and it can serve as a promising adsorbent, 19 carrier 20,21 and soil amendment 22 . Outstanding physicochemical properties confer a high loading capacity on BC, yet BC modification has gained massive recent interest, as specific modifications can enhance these properties, providing larger specific surface area, greater pore volume, higher negative zeta potential, more oxygen (O)‐containing functional groups, and stronger pollutant adsorption capacity 23,24 .…”