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Wax crystallization and deposition is a major flow assurance problem in production and transportation of waxy crude oil. Conventional flow improvers are mainly high molecular weight synthetic polymers, many of which are eco-toxic. Bio-based flow improvers derived from natural products are promising as inexpensive, eco-friendly alternatives to existing products. In this study, natural cashew nut shell liquid (CNSL) extracted from waste shells ofAnacardium occidentalewas esterified with polyethylene glycol (PEG). CNSL derivative reduced the pour point of waxy crude oil by 12 °C at 1000 ppm. The effects of CNSL derivatives on wax crystal morphology and micro-structure were studied by cross-polarized microscopy. Micrographs were processed and analyzed with ImageJ software. Addition of CNSL derivatives to oil resulted in changes in wax crystal morphology and micro-structure evidenced by a reduction in average crystal Feret diameter and aspect ratio and increase in boundary fractal dimension, indicative of formation of increasing number of smaller, rounder crystals. Effect of the additives on flow properties of the waxy oil was determined using a co-axial cylinder rotational viscometer. Dynamic viscosity of oil at shear rate of 17 s−1was reduced by 79.7–90.5%. CNSL-PEG esters show good prospects as low-cost additives for production, storage and pipeline transportation of waxy crude oil.

Purpose This study aims to synthesize pigment and resin from agro-wastes and use them in the formulation of eco-friendly surface coatings. Design/methodology/approach The pigments and resin were synthesized through a chemical modification of agro-wastes. The pigments were characterized by infrared spectroscopy (FTIR) and were screened for their antimicrobial activities. The physicochemical characteristics of the cashew nutshell liquid (CNSL)-modified resin were evaluated. These precursors and other natural additives were used to formulate surface coatings, and their drying and adhesive properties were evaluated using international testing methods. Findings It was observed that the curing of the CNSL-modified resin depended on time and temperature. The pigments exhibited antimicrobial activity against E. coli and S. aureus and had high melting points, affirming their stability. The chemically modified precursors successfully yielded surface coatings with acceptable drying times and adhesion to the base substrate. Practical implications The use of agro-wastes as the main components of the surface coatings implies waste valorization, a reduction in production costs and the creation of job opportunities for sustainable development. To increase the chemical, physical, corrosion resistance and antimicrobial qualities of paint compositions, chemically modified peanut skin extracts and CNSL can be used as pigments and resins, respectively. This could be a green approach to achieving the targets of Sustainable development goals 11 and 12. Originality/value The paper outlines a prospective approach to use unwanted waste (peanut skin, cashew nutshells) and other natural additives as industrial raw materials. These novel surface coating precursors are cost-effective, readily available, eco-friendly and could replace conventional precursors.

Wax formation creates flow assurance problems in the production and transportation of waxy crude oil. Flow improvers are added to waxy crude in order to reduce handling cost. Bio-based flow improvers derived from cheap renewable resources are attractive as cost-effective, eco-friendly alternatives to the conventional additives. Natural cashew nut shell liquid extracted from waste biomass (Anacardium occidentale shells) was derivatized and applied as flow improver for waxy crude oil. Effect of the additive on wax formation in crude oil was studied by cross-polarized microscopy, while the change in oil flow properties was evaluated using a rotational coaxial cylinder viscometer. Micrographs of the waxy crude were processed and analyzed with image J software. The microscopic properties of the wax crystals were characterized using Feret diameter, crystal area, aspect ratio, circularity, solidity and boundary fractal dimension. The pour point of doped crude oil was depressed by − 18 °C and the wax area fraction reduced by 40% due to wax inhibitive effect of the additive. The presence of the additive resulted in evolution of smaller, rounder and more regular wax crystals with smoother and more even surfaces indicated by reduction in the Feret diameter, aspect ratio and boundary fractal dimension of wax crystals in doped oil, and an increase in crystal circularity and solidity. The shear stress and viscosity of doped oil were reduced by 86.8% and 85.0%, respectively. The flow improvement effect of the CNSL derivative is linked to its effect on morphology and microstructure of wax crystals in the crude oil.

Water-soluble polymers can be used as key ingredients of both drilling fluids for virgin fields and polymer-enhanced oil recovery in underperforming reservoirs. The efficacy of hydrophobically associating heteropolymer (HAH-Polymer) as an agent for petroleum resource recovery was examined in this study. The hydrophobically associating heteropolymer (HAH-Polymer) comprising acrylamide, sodium 2-acrylamido-2-methylpropanesulfonate, hydroxyethyl methacrylate and lauryl methacrylate was synthesized in micellar medium by free-radical polymerization. The hydrophobically associating heteropolymer (HAH-Polymer) was characterised by FTIR and 1H NMR spectral analyses. The effects of temperature, pH and shear on the solution behavior of the HAH-Polymer were also examined. Rheological and fluid loss properties of HAH-Polymer-incorporated water-based drilling fluids were assessed. The HAH-Polymer improved the thermal stability between 25 and 160 °C of the drilling mud and maintained mud fluid loss of 8.4–8.6 cm3 compared with the polymer-free blank of 43.5–107.0cm3. In a salt-contaminated mud, the heteropolymer enhanced rheological properties and significantly reduced API filtration loss to 7.6–8.8 cm3 after hot aging between 25 and 150 °C. Under high temperature–high pressure filtration testing of muds, the HAH-Polymer demonstrated excellent fluid loss reduction by providing about eightfold fluid loss control (14.7 cm3) compared to the polymer-free blank (113.2 cm3) at 150 °C.

There has been a global concern about the use of tributyltin-based coatings in combating biofouling in the marine industry. Although there have been alternatives to tributyltin in preventing biofouling, the emphasis is now on the use of nontoxic and/or ecofriendly natural materials which do not negatively affect the environment upon application. Natural materials are ecofriendly, biodegradable, cost-effective, and can be employed as precursors in the synthesis and formulation of biodegradable antifouling coatings. Consequently, many researchers are investing time into the synthesis and formulation of natural, ecofriendly antifouling coatings, comprised of higher biofiber, which would perform analogous antifouling like other conventional coatings, thus minimizing the more toxic base polymer proportion. A safe environment is surely the signal of a bright future; hence, cost-effective, biodegradable raw materials result in a long-term attainment of sustainability of these products to replace the expensive conventional ones. This review presents an overview of ecologically friendly, cost-effective, and legally acceptable ways of preventing and mitigating the growth of algae and other marine organisms from settling on the hull of a ship and other static constructions in oilfields.

In this study, cashew nut shell liquid has been extracted from cashew nut shells using an accelerated solvent extraction technique and was employed as a precursor for the synthesis of cashew nut shell liquid resin. The extract was a dark brown viscous liquid with an average yield of 30.61±0.200%. Results of the physical analysis showed a moisture content of 4.45±0.020% and a density of 0.95±0.300 gcm-3. The percentage brix and refractive index were 76.20±0.001 and 1.47 ±0.010 respectively. Chemical characterization showed a pH of 5.65±0.003; acid value of 8.25± 0.200 mg KOH/g; ash content of 1.80±0.6%; free fatty acid of 4.12±0.400 mg KOH/g; ester value of 247.01±0.100 mg KOH/g and a saponification value of 255.26±0.800 mg KOH/g. The FTIR spectra revealed that cashew nut shell liquid is polymeric. These findings confirm that higher phenolic compounds which can be used as potential precursors in industrial applications could be obtained from agro wastes. Practical Applications: Cashew nut shell liquid, an extract from cashew nut shell, an agro waste has a wide range of functional products. A practical application is synthesis of a high viscous, flexible cashew nut shell liquid resin with physical properties that are consistent with literature and could also be further used in other industrial applications. Further processing of cashew nut shell for the development of value added products like resin can be a better option.

Peanut skin extract, an agro-waste and a source of flavonoids has been extracted from peanut skin and employed as a precursor for the synthesis of novel azo compounds and metal complexes. The new ligand, peanut skin extract-azo-compound, was synthesized under suitable experimental conditions by diazotization of aniline and coupling with an alkaline solution of peanut skin extract. The reaction of the ligand with metal chlorides of iron and manganese under reflux yielded novel azo metal complexes. The yields of the compounds ranged from 42% to 95%. All compounds were coloured, insoluble in water but soluble in methanol, ethanol, acetone and ethyl acetate. Morphology and composition of ligands and metal complexes were corroborated by spectroscopic techniques including Fourier transform infrared spectroscopy, scanning electron microscope-energy dispersive spectrometry and UV-visible spectroscopy. The azo complexes were found to possess potent antimicrobial activities against E. coli (gram-negative bacteria) and Staphylococcus aureus (gram-positive bacteria) and hence recommended for application as antimicrobial agent, and corrosion inhibitors in anti-corrosion paints and pigments for surface coatings.