Different petroleum operations produce huge amount of oil sludge annually. For instance, US EPA estimates the annual sludge production of each US refinery of 30,000 tons, while the average oily sludge produced from petrochemical industries in China is estimated about 3 million tons per year. In the last year, our center could recover about 30,206 barrels of raw oil from 32,786 barrels of tank bottom sludge (TBS) for different petroleum companies. This sludge causes huge economic losses besides its negative environmental impacts. The accumulation of sludge in the tanks results in reducing the tanks’ capacity for storing liquid crude, accelerating the corrosion of the tanks, delay in the production schedule, and disturbing the whole production operation. There are diverse treatment methodologies such as solvent treatment, addition of certain chemicals, and centrifuging. Of course, the environmental regulations and the overall cost limitations are very important in deciding the preferred applicable method(s). Although several works handled the problem of sludge deposition and treatment from different aspects, we intend to introduce a different work. First, composition, formation, types, and properties of TBS were reviewed. Then, environmental and economic problems caused by TBS were revised. At last, different methodologies applied for treatment of oily TBS to recover oil and safe disposal of hazardous remains were investigated focusing on the most straightforward and environmentally friendly protocols. It is expected that this review attracts the experts in petroleum chemistry, and other relevant fields and provides a comprehensive understanding of current sludge control and treatment research. Graphical abstract

Hydrogel composites comprised of N,O carboxymethyl chitosan crosslinked with different weight ratios of acrylic acid and fabricated with nanoclay particle were prepared via gamma irradiation at 25 kGy irradiation dose. The prepared composites were coded as CsAA₁Cl, CsAA₂Cl and CsAA₃Cl based on the weight ratio of acrylic acid to the chitosan derivative. The claimed hydrogels were characterized by FTIR, TGA and XRD. The TGA data implied that the incorporation of clay nanoparticles enhanced the thermal stability of the composites; the decomposition temperature increased up to 500 °C for CsAA₃Cl. Three AFM outcomes were used to compare the surface features of the samples; topography, height and surface roughness. The topography data reveals that the nanoclay particles incorporated in CsAA₃Cl are intercalated and exfoliated. Then, the optimized sorbent (CsAA₃Cl) was investigated as green sorbents for chromium (VI) and lead (II). The data revealed that CsAA₃Cl displayed maximum removal performance towards both lead and chromium with removal efficiencies 125 mg/g and 205 mg/g respectively at the optimum application conditions within 90 min only. Also, it was found that the optimum pH value was 9 for chromium and 8 for lead. The data proved that the adsorption of both cations followed pseudo-first order kinetic model. The prepared composites showed acceptable metal uptake capacity at three successive cycles.Graphical Abstract

In the present work, some polymeric additives based on styrene-maleic anhydride copolymer were prepared and evaluated as multifunction lube oil additives (viscosity index improvers, pour point depressants, and detergent-dispersant additives). The styrene-maleic anhydride copolymer reacted with different alcohols (dodecyl alcohol, hexadecyl alcohol, octadecyl alcohol, and docosanol) to prepare four different types of esters and aminated with different types of amines (dodecyl amine, hexadecyl amine, and octadecyl amine) to prepare another three co-polymeric additives. Structure of the prepared compounds was confirmed by I.R. spectroscopy. The molecular weights of the prepared copolymers were determined by using gel permeation chromatograph and the percentage of esterification and amination were determined by ¹HNMR. The efficiencies of the prepared compounds as viscosity index improvers, pour point depressants, and detergents-dispersants were investigated. It was found that the efficiency of the prepared compound as viscosity index improvers increases with increasing the concentration of additives in the solution and with increasing the molecular weight of prepared compounds, while the efficiency of the prepared compounds as pour point depressants increases with decreasing the concentration of the prepared polymers. On the other hand, the prepared compounds showed excellent dispersion power.

In the present work, some Mannich bases have been prepared by using different polyethylenepolyamines. Phosphosulphurized Mannich bases have been also prepared by reaction of prepared Mannich bases with P₂S₅. Structure of the prepared compounds was confirmed by infrared spectroscopy and the molecular weights determination. The efficiency of the prepared additives as antioxidants and detergents/dispersants was investigated. It was found that the efficiency increases with increasing the NH groups in the amine used. The best prepared additive as antioxidant and detergent/dispersant was obtained by using triethylenetetramine.