Fabrication Of Carbon Aerogels From Coir For Oil Adsorption

Coir, known as coconut fibers, are an abundant cellulosic source in Vietnam, which are mostly discarded when copra and coconut water are taken, causing environmental pollution and waste of potential biomass. In this research, carbon aerogels from chemically pretreated coir were successfully synthesized via simple sol-gel process with NaOH-urea solution, economical freeze-drying, and carbonization. The samples, including pretreated coir, coir aerogels, and carbon aerogels, are characterized using FTIR spectroscopy, SEM, XRD spectroscopy, and TGA. The carbon aerogels exhibit low density (0.034–0.047 g/cm3), high porosity (97.63–98.32 %), and comparable motor oil sorption capacity (22.71 g/g). The properties of carbon aerogels are compared with those of coir aerogels, indicating such better values than those of coir aerogels. Coir-derived carbon aerogels is a potential replacement for the hydrophobically-coated cellulose aerogels in term of treating oil spills.

Fabrication of cellulose-based aerogel for thermal and acoustic insulation applications

A method to prepare aerogels from rice straw and polyvinyl alcohol in the presence of fiberglass and glutaraldehyde is herein reported. The morphology, pore structure and physical properties of the aerogels were characterized by scanning electron microscopy (SEM), thermogravimetric analysis (TGA), thermal conductivity, water contact angle (WCA) measurements, oil adsorption and sound absorption measurements. The obtained aerogels should be considered as a promising material for upcoming applications, since it has high porosity (up to 93.72%), low density (0.083-0.127 g/cm3), super low thermal conductivity (0.032-0.048 W/mK), high Young modulus (0.201-1.207 MPa), high sound absorption (absorption coefficient of 0.87) and a good oil adsorption capacity (4.8 g/g).

Improvised centrifugal spinning for the production of polystyrene microfibers from waste expanded polystyrene foam and its potential application for oil adsorption

A straightforward approach to recycle waste expanded polystyrene (EPS) foam to produce polystyrene (PS) microfibers using the improvised centrifugal spinning technique is demonstrated in this work. A typical benchtop centrifuge was improvised and used as a centrifugal spinning device. The obtained PS microfibers were characterized for their potential application for oil adsorption. Fourier transform infrared spectroscopy results revealed similarity on the transmission bands of EPS foam and PS microfibers suggesting the preservation of the EPS foam’s chemical composition after the centrifugal spinning process. Scanning electron microscopy displayed well-defined fibers with an average diameter of 3.14 ± 0.59 μm. At the same time, energy dispersive X-ray spectroscopy revealed the presence of carbon and oxygen as the primary components of the fibers. Contact angle (θCA) measurements showed the more enhanced hydrophobicity of the PS microfiber (θCA = 100.2 ± 1.3°) compared to the untreated EPS foam (θCA = 92.9 ± 3.5°). The PS microfiber also displayed better oleophilicity compared to EPS foam. Finally, the fabricated PS microfibers demonstrated promising potential for oil removal in water with a calculated sorption capacity value of about 15.5 g/g even at a very short contact time. The fabricated PS fiber from the waste EPS foam may provide valuable insights into the valorization of polymeric waste materials for environmental and other related applications.

Poly(Methyl Methacrylate) Grafted Wheat Straw for Economical and Eco-friendly Treatment of Oily Wastewater.

The sustainable development of oil-gas and petrochemical industries necessitates the development of cost-effective and eco-friendly technologies to treat mass-produced oily wastewater discharge from these industries. This study applied a simple radical polymerization to enhance the oil adsorption efficiency of agricultural waste biomass wheat straw (WS) by grafting biocompatible PMMA. Diesel oil adsorption from oil-in-water emulsion using the PMMA grafted WS was thoroughly studied for the first time in the quest of developing an economical and eco-friendly adsorbent for the adsorptive treatment of oily wastewater. Initially, the pristine WS was subjected to alkaline hydrogen peroxide pre-treatment to remove the materials that can lead to secondary pollution during operation, to expose the reactive cellulose surface sites that can enhance grafting efficiency, and to break the inner interconnected tubular pore channel walls; otherwise, the tubular pore channels will not be accessible to viscous oil due to limited capillary penetration. The success of pre-treatment of pristine WS and the subsequent PMMA grafting were evaluated by SEM morphology, BET analysis, EDX and XPS elemental analysis, FTIR, and contact angle measurements. SEM images indicated that the inner interconnected tubular pore channels of WS are exposed significantly upon alkaline hydrogen peroxide pretreatment. PMMA grafting substantially improved oil adhesivity, as evident from the 0º oil contact angle for WS-g-PMMA film. Oil absorptivity was thoroughly evaluated by batch oil adsorption study using variable adsorbent dosages and oil emulsion concentrations. The WS-g-PMMA exhibited explicitly higher adsorption capacity (ca. 1129 mg/g) compared to that of the pristine (ca. 346 mg/g) and pretreated (ca. 741 mg/g) due to high accessibility to exposed inner interconnected tubular pore channels and strong hydrophobic interactions between the WS-g-PMMA surface and oil droplets. Langmuir and Freundlich adsorption isotherms were applied to evaluate the adsorption mechanism. The experimental data fit well with the Freundlich isotherm, clearly indicating the heterogeneity of adsorption sites, as well as multilayer adsorption of oil. The experimental adsorption data fit well with the pseudo-second-order rate equation with R2 as high as 0.999, which confirmed the multilayer adsorption of oil. The high oil adsorption capacity of the WS-g-PMMA makes it a very promising material for oily wastewater treatment. This will simultaneously resolve issues with the treatment of oily wastewater and facilitate the recycling of abundant quantities of waste WS. This study serves as a reference for analyzing the suitability of wheat straw for treating extremely challenging waste streams, such as SAGD produced water containing BTEX and PAHs that are also hydrophobic like diesel oil.

Facile Synthesis of Silica Composites with Oil Sorption Efficiency from a Vital Agricultural Waste of Corn Stalk Cultivated in Bishoftu, Ethiopia

This study is attempted to extract the amorphous silica composites using the combined HNO3 leaching-calcination (600°C/6 h) method from corn stalk harvested in Bishoftu, Ethiopia, owning to its profuse dumping, less cost, and negative environmental implications. The resultant composite characteristics such as amorphous nature are connected via the grain boundary which produces an agglomerated structure that has a disordered morphology, and the presence of siloxane and silanol groups, as well as additional functional groups, is reported. The synthesized product is applied in the removal of oil from synthetic oily wastewater (SYOWW) using batch mode delivering a maximum oil removal of up to 99%. The outcome of the study features the potential acclimatization of the Ethiopian corn stalk as a substitute precursor for the production of silica composites which has a potential oil adsorption capacity that can be used for oil spill cleanup.

Removal of oil spills by novel developed amphiphilic chitosan-g-citronellal schiff base polymer

A novel chitosan grafted citronellal (Ch-Cit) schiff base amphiphilic polymer was developed for the adsorptive removal of oil spills. The chemical structure was verified by FT-IR spectroscopy and 1H NMR spectrometer, while the morphological changes and surface area were investigated by SEM and BET analysis tools. The amphiphilic character of Ch-Cit schiff base was controlled through variation of the grafting percentage (G%) of citronellal from 11 to 61%. Dramatic changes in the ion exchange capacity (IEC), solubility and water uptake profiles were established, while the oil adsorption capacity was founded in direct relation with the G (%) of citronellal. Operational conditions such as oil amount, adsorption time, adsorbent dose and agitation speed were investigated. The developed Ch-Cit schiff base exhibited a higher surface area (115.94 m2/g) compared to neat chitosan (57.78 m2/g). The oil adsorption capacity of the Ch-Cit schiff base was greatly improved by 166% and 120% for light crude and heavy crude oil, respectively. Finally, the adsorption process was optimized using response surface methodology (RSM).The results substantiate that the amphiphilic Ch-Cit schiff base could be efficiently applied as a low-cost oil-adsorbent for the removal of crude oil spills from sea-water surfaces.