Oil-based mud waste reclamation and utilisation in low-density polyethylene composites

Abstract

Oil-based mud (OBM) waste from the oil and gas exploration industry can be valorised to tailor-made reclaimed clay-reinforced low-density polyethylene (LDPE) nanocomposites. This study aims to fill the information gap in the literature and to provide opportunities to explore the effective recovery and recycling techniques of the resources present in the OBM waste stream. Elemental analysis using inductively coupled plasma–optical emission spectrometry (ICP-OES) and X-ray fluorescence analysis, chemical structural analysis by Fourier transform infrared (FTIR) spectroscopy, and morphological analysis of LDPE/organo-modified montmorillonite (LDPE/MMT) and LDPE/OBM slurry nanocomposites by scanning electron microscopy (SEM) have been conducted. Further analysis including calorimetry, thermogravimetry, spectroscopy, microscopy, energy dispersive X-ray analysis and X-ray diffraction (XRD) was carried out to evaluate the thermo-chemical characteristics of OBM waste and OBM clay-reinforced LDPE nanocomposites, confirming the presence of different clay minerals including inorganic salts in OBM slurry powder. The microscopic analysis revealed that the distance between polymer matrix and OBM slurry filler is less than that of MMT, which suggests better interfacial adhesion of OBM slurry compared with the adhesion between MMT and LDPE matrix. This was also confirmed by XRD analysis, which showed the superior delamination structure OBM slurry compared with the structure of MMT. There is a trend noticeable for both of these fillers that the nanocomposites with higher percentage filler contents (7.5 and 10.0 wt% in this case) were indicated to act as a thermal conductive material. The heat capacity values of nanocomposites decreased about 33% in LDPE with 7.5 wt% MMT and about 17% in LDPE with 10.0 wt% OBM slurry. It was also noted, for both nanocomposites, that the residue remaining after 1000°C increases with the incremental wt% of fillers in the nanocomposites. There is a big difference in residue amount (in %) left after thermogravimetric analysis in the two nanocomposites, indicating that OBM slurry may have significant influence in decomposing LDPE matrix; this might be an interesting area to explore in the future. The results provide insight and opportunity to manufacture waste-derived renewable nanocomposites with enhanced structural and thermal properties.

Oil-Based Mud Waste as a Filler Material in LDPE Composites: Evaluation of Mechanical Properties

“…It is apparent that this short-range ordering structure split the band at 718 cm −1 , representing a monoclinic phase, and a weak peak emerged at 727 cm −1 , representing the orthorhombic phase (highlighted by the red circle in Figure 6 and Figure 7 ) [ 33 ]. The presence of this new orthorhombic phase is attributed to the decreasing trend in the crystallinity of the LDPE/MMT and LDPE/OBM slurry nanocomposites, which is in agreement with the crystallinity data reported in our previous study [ 7 , 16 , 26 ]. It is interesting to notice in our previous report [ 26 ] that the percentage of crystallinity decreased predominantly in the nanocomposites with higher filler loading (5, 7.5 and 10 wt% filler contents), whereas, in this study, the orthorhombic phase only appeared for the nanocomposites with a similar polymer–filler composition.…”

“…The presence of this new orthorhombic phase is attributed to the decreasing trend in the crystallinity of the LDPE/MMT and LDPE/OBM slurry nanocomposites, which is in agreement with the crystallinity data reported in our previous study [ 7 , 16 , 26 ]. It is interesting to notice in our previous report [ 26 ] that the percentage of crystallinity decreased predominantly in the nanocomposites with higher filler loading (5, 7.5 and 10 wt% filler contents), whereas, in this study, the orthorhombic phase only appeared for the nanocomposites with a similar polymer–filler composition. In addition, the tightly stacked MMT and OBM clay platelets restrict the polyethylene motion during crystallisation due to a reduced viscous flow between the lamellar clay tactoids.…”

“…Both Figure 3 and Figure 4 show the chain formation around the particulate materials due to the presence of LDPE chains, which was also observed regarding similar patterns of polyamide chains on the palygorskite by Saleh et al (2018) [ 28 ]. Furthermore, the energy dispersive spectroscopy analysis of these samples from our previous study [ 26 ] also supports the above-mentioned dispersion and distribution behaviour of the OBM slurry in the LDPE matrix.…”

“…It is anticipated that the cations existing in the clay mineral layers would be replaced, intercalated or compensated by exchangeable cations by amines or quaternary ammonium salts, which are believed to be used in the OBM formulation. In our previous studies [ 16 , 26 ], using the same polymer and OBM clay in both slurry and dry powder form confirms the even distribution of the fillers in the polymer matrix. This observation inspired us to utilise the organophilic nature of clay surfaces that exist in OBM waste in its natural condition and to investigate the effect of this favourable distribution nature of filler in influencing different mechanical properties of LDPE/OBM slurry nanocomposites.…”

“…A sustainable approach to utilise the applicable minerals that exist in this waste is our goal. Thermally treated oil-based mud fillers were successfully embedded into LDPE and PA6 polymer matrices, which was reported in our previous publications [ 16 , 26 ]. It is essential in waste processing, especially hazardous waste management processes, to use materials with the lowest possible degree of processing.…”