Petrochemical Research Articles

Integrated Hybrid Modelling and Surrogate Model-Based Operation Optimization of Fluid Catalytic Cracking Process

Fluid Catalytic Cracking (FCC) is one of the most important conversion processes in oil refineries, widely used to convert high-boiling, high-molecular-weight hydrocarbon components from crude oil into more valuable products like gasoline and diesel. Advanced simulation and optimization technologies are critical for improving the operational efficiency and economic performance of the FCC process. First-principles-based simulators rely on parameter estimation and are computationally intensive, making them unsuitable for online optimization. In recent years, with the development of deep learning, data-driven models have made significant progress in FCC modeling. However, due to their black-box nature and difficulty with extrapolation, they are rarely used for optimization. To bridge this gap, we propose an integrated framework that combines hybrid modeling and surrogate model-based optimization. This approach combines plant and simulation data to train a multi-task learning prediction model, which then serves as a surrogate for operational optimization. Validated on a large-scale FCC unit in southern China, the model predicts product yields with an error margin of under 4.84% for all products. Following optimization, yields of LNG, gasoline, and diesel rose by an average of 0.10 wt%, 1.58 wt%, and 1.05 wt%, respectively, resulting in a 3.67% increase in product revenues. This highlights the substantial potential of this framework for industrial applications.

Study on the Performance of Different Crystal Forms Nano MoS2 as Lubricant Additives in Reducing Wear and Friction

ABSTRACTIn order to investigate the anti‐friction and anti‐wear performance of different crystal forms nano MoS2 in paraffin oil. Freeze‐drying method combined with hydrothermal was used to prepare different crystal forms nano MoS2 and their microstructures were characterised by X‐ray diffraction (XRD) and scanning electron microscopy (SEM). The anti‐friction and anti‐wear performance of MoS2 nanoparticles as lubricat additives under different working conditions was investigated by the ball‐and‐disk friction and wear testing machine and the mechanism of friction and wear reduction was investigated. The results showed that the thickness of the floral sheet MoS2 flakes was about 10 nm and the particle size of the spherical MoS2 was about 90 nm. When the addition concentration was 3 wt%, the friction coefficient of the floral sheet MoS2 in paraffin oil was lower at 0.094, which was 29.3% lower than that of the pure paraffin oil, the width of the abrasion marks was 24.2% lower than that of the pure paraffin oil and the wear rate was 71.6% lower than that of the pure paraffin oil; The friction coefficient of the spherical MoS2 with 2.5 wt% addition was 0.082, which was 38.3% lower than the friction coefficient of pure paraffin oil, 24.1% lower than that of paraffin oil in terms of wear scar width and 81.9% lower than that of paraffin oil in terms of wear rate.

Comparison of the Ability of Woody Plants of Different Species to Accumulate Heavy Metals in Urban Environment

Soil and aerotechnogenic migration of metals into woody plants (birch (Betula pendula) and balsam poplar (Populus balsamifera)) from technogenic zones of Tyumen was studied. Soil and tree leaves were sampled in the conditionally background area, near the airport, railway station and bus station, as well as in the area of enterprises: engine-building, oil refinery, battery and metallurgical plants. The content of acidsoluble form of metals in soils and leaves was determined by atomic emission spectroscopy. It was revealed that the accumulation of metals in soils from the anthropogenic zones of Tyumen compared to the control decreased in the series Pb>Cd>Cr>Cr>Ni>Zn>Cu>Fe>Co>Mn and reached 20 times. The accumulation of metals by birch leaves was found to decrease in the series Pb>Cr>Fe>Co>Cu>Cu>Ni>Zn>Mn>Cd, and by poplar leaves – Cr>Fe>Pb>Zn>Cd>Cu>Co>Mn>Ni. The accumulation and migration of metals in soils and trees from the urban environment were analyzed, which allowed us to identify Cd, Pb and Cr as metals with the “highest ecological risk”.

Culture-Dependent Characterization of Hydrocarbon Utilizing Bacteria and Fungi from an Artisanal Crude Oil Refining Site

Crude oil refining is a global insert responsible for the production of a wide array of petroleum based products crucial for various sectors including energy, transportation, and manufacturing. However, the artisanal form of crude oil refining, often characterized by its small scale and limited technological infrastructure, has emerged as a major environmental concern in several regions around the world. Illegal refining of crude oil has led to oil spillages which in turn lead to a disruption of the microbial population of the soil. Hence, the aim of this study was to isolate and characterize the heterotrophic and hydrocarbon utilizing bacteria and fungi from an artisanal crude oil refining site. A total of thirty six (36) soil samples were collected from three (3) artisanal crude oil refining sites at iwofe, ogbogoro and ibaa community all in Rivers State, Nigeria. The samples were collected using soil auger and subjected to standard microbiological procedures such as culturing, isolation and identification. The results revealed significantly elevated levels of heterotrophic and hydrocarbon utilizing bacteria and fungi in the soil samples, with notable variations (p≤0.05) across the different artisanal crude oil refining sites. Total Heterotrophic Bacteria (THB) counts ranged from 3.75x105CFU/g in Iwofe to 2.70x105CFU/g in Ibaa, Total heterotrophic Fungal (THF) counts ranged from 2.80x104CFU/g recorded in Ogbogoro to 1.45x104CFU/g recorded in Iwofe, Hydrocarbon Utilizing Bacteria (HUB) counts ranged from 2.25x103CFU/g in Ibaa to 1.30x103CFU/g in Iwofe and Hydrocarbon Utilizing Fungi (HUF) counts ranged from 2.50x102CFU/g recorded in Ogbogoro to 1.40x102CFU/g recorded in Ibaa community with significant differences (p≤0.05). Bacteria isolated and characterized from the soil include Enterobacter, Pseudomonas putida, Serratia and Bacillus amyloliquefaciens while fungi include Fusarium, Aspergillus, Penicillium and Mucor. The microorganisms identified in this study have been reported to play key roles in the utilization of crude oil. Pseudomonas and Bacillus were the most dominant bacterial isolates and their dominance could imply that the soil could support the growth of crops. Thus, while they utilize the hydrocarbons, they also serve as plant-growth promoting microorganisms. Although some of the microorganisms in the present study have been reported to promote the growth of plant, the dumping of crude oil products legal or illegal should be minimized to avoid the extinction of plant-promoting microorganisms.

Synchronous Construction of Ni/CeO2/C with Double Defects as a Dual Engine for Catalytic Refinement of Lignin Oil Under Hydrogen-Free Condition

Synchronous Construction of Ni/CeO₂/C with Double Defects as a Dual Engine for Catalytic Refinement of Lignin Oil Under Hydrogen-Free Condition

Fossil Fuel Layoff: Capturing Decarbonization Impacts on Workers Through a Refinery Closure

We surveyed and interviewed oil refinery workers who lost their jobs when a refinery in California shutdown in October 2020 to document post-layoff employment outcomes. Workers experienced post-layoff median hourly wage losses of 24 percent, a 26 percent unemployment rate, and reported frustrating job search experiences marked by a difficulty to convey skills to new employers. Our study harbingers future transition experiences of fossil workers and identifies social insurance responses that could inhere within climate change policies to shield workers from economic risk. Workers identified a need for third-party certification of their skills, benefits negotiators, and wage supports.

A Guideline for Cross-Sector Coupling of Carbon Capture Technologies

Many governments around the world have taken action to utilise carbon capture (CC) technologies to reduce CO2 emissions. This technology is particularly important to reduce unavoidable emissions from industries like cement plants, oil refineries, etc. The available literature in the public domain explores this theme from two distinct perspectives. The first category of papers focuses only on modelling the CC plants by investigating the details of the processes to separate CO2 from other gas components without considering the industrial applications and synergies between sectors. On the other hand, the second category investigates the required infrastructure that must be put in place to allow a suitable integration without considering the specific particularities of each carbon capture technology. This review gives a comprehensive guideline for the implementation of CC technologies for any given application while also considering the coupling between different energy sectors such as heating, power generation, etc. It also identifies the research gaps within this field, based on the existing literature. Moreover, it delves into various aspects and characteristics of these technologies, while comparing their energy penalties with the minimum work required for CO2 separation. Additionally, this review investigates the main industrial sectors with CC potential, the necessary transportation infrastructure from the point sources to the end users, and the needs and characteristics of storage facilities, as well as the utilisation of CO2 as a feedstock. Finally, an overview of the computation tools for CC processes and guidelines for their utilisation is given. The guidelines presented in this paper are the first attempt to provide a comprehensive overview of the technologies, and their requirements, needed to achieve the cross-sector coupling of CC plants for a wide range of applications. It is strongly believed that these guidelines will benefit all stakeholders in the value chain while enabling an accelerated deployment of these technologies.

Improving tribological efficiency of isopropyl palmitate oil with cellulose nanocrystals: a sustainable approach for high-performance lubricants

AbstractThis article explores the potential of cellulose nanocrystals (CNCs) as a lubricant additive for isopropyl palmitate (IPP) oil to enhance its tribological performance. CNCs, derived from renewable sources, offer a sustainable and environmentally friendly alternative to traditional lubricant additives. A two-step method was used to prepare the nanolubricants, with visual control and dynamic light scattering measurements to assess their temporal stability. The viscous behavior of the nanolubricants, in terms of viscosity and viscosity index, was evaluated at different temperatures. The study assesses the effectiveness of CNC/IPP oil blends as lubricants through tribological tests, including evaluations under pure sliding and rolling–sliding conditions. Studies on worn surfaces were conducted using surface roughness analysis, Raman mapping, and XPS, and the thermal stability was examined to determine their suitability for different operating conditions. CNCs significantly reduce friction by up to 44% and improve wear resistance compared to the neat IPP base oil, presumably due to a self-repairing effect. Furthermore, an improvement of the thermal conductivity of pure IPP base oil has been revealed with increasing CNC concentration. This study enhances the understanding of cellulose nanocrystals as lubricant additives and their potential to transform traditional lubricating oils into high-performance and sustainable solutions.

Heavy Metal Content in the Soil of Baiji Refinery and Surrounding Area, Controlling its Distribution Factors

This study was conducted to analyze the presence of heavy metals within the soil inside and around Baiji Oil Refinery and their factors that control the spatial distribution of metals in soils existed as (organic matter (OM), iron-manganese, pH, clay minerals). In this study, geochemical analysis of Baiji Oil Refinery soil and nearby areas was conducted by Atomic Absorption Spectrophotometer (AAS). Twenty two samples were analysed in which the results showed heavy metal as (Cd, Pb, Cr, Ni, Fe, Mn, Zn and Cu) concentrations that most of these metals were found to be higher than their global limits in the soil, except (Fe, Mn and Zn) found to be within those limits. Controlling factors were conducted for six samples, three of highest concentrations and three of lowest one. The results reveal that the mean concentration of OM in the highest concentrations was 1.64% while the lowest concentrations was 1.59%, the mean concentration of Fe-Mn was in the highest concentrations 23380-359 ppm and in the lowest samples was 11304-114 ppm, respectively. The mean concentration for the pH in the highest concentrations was 8.5 and for the samples within the lowest concentrations was 7.9. However, the mean clay for the samples within the highest concentration were 1.04%, whereas the samples within the lowest concentration were 1.48%. The results showed that the controlling factors did not affect the soil heavy metal distribution of Baiji Oil Refinery and their nearby areas. Therefore, such results indicate the role of industrial processes (oil industries) in increasing the concentration of heavy metals in the soils in addition to the elements inherited from the parent rocks.

Identification of Sulfur Dioxide (SO2) Hotspots of Gujarat state using Sentinel 5P-TROPOMI

Sulphur dioxide (SO2) is a widely recognized pollutant with far-reaching consequences for human health, climate, and the environment. This study aims to identify SO2 hotspots within the state of Gujarat located in the western part of India using the Sentinel 5P TROPOMI satellite data. Based on the analysis of the satellite data from January 2019 to 2023, 16 hotspot regions were identified in Gujarat with significantly high concentration of SO2. Majority of these hotspots were located in industrial areas and petroleum refineries, including Mundra port, Ahmedabad, Vadodara, Surat, and the Alang shipbreaking yard. Notably, some scattered hotspots were found near Eco-sensitive zones like Purna and Narayan Sarovar. The observed SO2 concentrations in these hotspots vary between ~ 10 to ~ 1000 µmol/m2, with an average concentration of ~ 300 µmol/m2. It is also observed that SO2 concentration is significantly elevated during winter and pre-summer months, with a marked reduction during the monsoon season. The average monthly SO2 concentrations exhibit a distinct seasonal cycle, with the lowest levels during the monsoon and the highest during winter. Furthermore, impact of COVID induced lockdown is also perceived across the state.

Optimization of Steam Boiler Airflow Control System in a Typical Oil Refinery Power Plant

This paper presents optimization of Steam Boiler Airflow Control System in a Typical Oil Refinery Power Plant. The power plant is equipped with four steam boilers using a damper-louvers airflow control system. Analysis has revealed significant energy wastage due to inefficiency and over-air supply, with the system requiring 59,904,436 kWh annually at a financial cost of N1, 093,255,884. The existing system's inefficiency results in an annual electrical energy waste of 8,502,302 kWh. This inefficiency is attributed to the Force Draft Fan (FDF) motor operating at maximum speed continuously, regardless of the steam profile or airflow requirements. This study aimed at optimizing the steam boiler airflow control system in a typical oil refinery power plant for improved power efficiency, energy conservation, and cost savings citing Port Harcourt Refinery Company (PHRC) at Alesa-Eleme, Rivers State, Nigeria. To address this, the damper-louvers system was replaced with a Variable Frequency Drive (VFD), which would adjust the motor speed to match the required airflow, thereby reducing energy wastage. The process was simulated and VFD/FDF motor analyzed in MATLAB Simulink, determining the optimal speed, airflow, and power requirements. Results obtained show that the VFD control system improves the FDF motor's power efficiency from 47.7% to 85%, with an annual energy saving of 8,502,302 kWh (8.5 GWh). This results in a total cost benefit of N478.18 million annually, representing a 43.8% cost saving. The implementation cost of the VFD infrastructure was estimated at N111, 440,000, with a payback period of approximately eleven months. The findings suggest deployment of higher FDF motor speed ratings to enhance speed control and energy efficiency in Oil refinery power plant.

Composite Risk Assessment of HNS Discharged from Marine Industrial Facilities: A Case Study on Incheon Port, South Korea

This study conducted a composite risk assessment to evaluate the environmental impacts of phenol, a Hazardous and Noxious Substance (HNS) released or leaked from port facilities. The study area was designated as the vicinity of Incheon Port, South Korea, where the volume of petrochemical-related materials is substantial and various industrial facilities are located. For the composite risk assessment, various vulnerability maps were developed, incorporating the dispersion range of phenol calculated through numerical modeling. The vulnerability maps were generated by classifying socio-environment, legally protected areas, habitats, and species, followed by integrating these individual vulnerability maps to construct an integrated vulnerability map. The composite risk assessment was conducted by considering both the integrated vulnerability map and the dispersion range of phenol. The assessment results indicated that the highest risk by depth was observed in the lower layers due to the settling characteristics of phenol. Spatially, areas where islands and coastlines converge exhibited relatively higher risks. This was attributed to the high concentrations of phenol released from industrial facilities, such as crude oil refineries, petrochemical plants, and organic compound manufacturers, in regions characterized by intense human activity, sensitive habitats, and legally protected areas. Continuous monitoring of these high-risk areas is crucial for assessing the environmental impacts of HNS substances like phenol.

Design & development of adulteration detection system by fumigation method & machine learning techniques

A novel method for discovery of adulteration in edible oil is proposed based on concept of refractive index and electronic sensors. The research work focusses on two distinct methodologies like employing datasets and implementing a fumigation technique that integrates real-time hardware for testing Edible oil Impurities. In the first method, the dataset taken into consideration contains spectral data collected using Advanced ATR-MIR Spectroscopy for pure oil and various levels of adulteration with Vegetable oil. Each and every edible oil has a certain value of refractive index. When such oils are contemned in a change adding adulterants, the value of its refractive indices also changes. This value of refractive index serves as a feature for testing the oil and helps us in detecting the adulteration. If Oil is adulterated with vegetable oils, the refractive index will be lower and with animal fats, the refractive index will be higher than that of pure Oil. While in Fumigation Method a hardware module is develop in which adulterated & pure oil samples are heated at 40–50 °C for 4.66 min and the volatiles that are generated by varying gas concentrations are forcefully passed through to the MEMS Gas Sensor-MISC-2714 and Multichannel Gas sensor. The conductance of the sensors changes according to the gases sensed by the sensors contributes to features extraction. The conductance value serves as a feature for the classifier to determine whether the sample is highly, moderately, or lowly contaminated. Thus, in proposed methods we use different algorithms based on machine learning like KNN, Random Forest, CATBOOST and XGBOOST to accurately reveal the adulteration. Amongst all the applied algorithm Random Forest (RF) Classifier & XGBOOST algorithm outperform well and gives 100% accuracy. The proposed work is used for identifying food adulteration in edible food products which helps us to feed Society with high-quality food.

Manifesting the hidden pollutants: Quantifying emissions and environmental impact of petroleum refinery on PM2.5

This research thoroughly examined the emissions of primary fine particle and precursors of secondary particles (VOCs, SO2 and NOx) originating from the petroleum refinery operation. The central aim was to quantify the emission factors of fine particulate matter and analyze their spatial dispersion and source contributions, in order to evaluate their environmental impacts.The VOCs emission measurement appeared that the wastewater treatment plant unit was the most significant source of VOCs emissions, with pentane, cyclopentane, and propane being the dominant VOCs species released. The study employed the secondary organic aerosol potential (SOAP), sulfur oxidation ratio (SOR), and nitrogen oxidation ratio (NOR) methodologies to calculate the emissions of secondary PM2.5. The combustion stacks were the principal contributor to secondary PM2.5 emissions, with SO2 being the predominant secondary PM2.5 precursor species contributing to fine particulate matter, accounting for 82.5% of the total secondary PM2.5 emissions. The overall emission factor for the refinery was determined to be 0.31 g secondary PM2.5 per kg of refined crude oil. Furthermore, the analysis indicated that the combustion stacks were the primary contributors to PM2.5 concentrations at all receptor sites, accounting for 64.4%–80.8% of the total contribution, followed by the wastewater treatment unit and storage tanks. The study underscored the importance of focusing on secondary PM2.5 precursor emissions to effectively reduce emissions and environmental concentrations of PM2.5, highlighting the potential for more effective management and mitigation strategies targeting these precursors.

Evaluating the efficiency of oil waste treatment plant in AL- Qayyarah Refinery - Iraq

The study included an evaluation of the efficiency of AL-Qayyarah refinery oil waste treatment plant. For this purpose, monthly samples were collected for a period of six months from October 2023 until March 2024, the first station (before treatment) represents the water coming out of the crude oil filter units. As for the second station (after treatment) it is located in the refinery waste treatment unit, the site represents the treated water. many physical and chemical tests were conducted on water, they ranged of temperature values ​​before the treatment ranged between (17-33) compared to its value after the treatment (15-31), and the electrical conductivity values ​​before the treatment ranged between (295-405)µS/cm, while after the treatment it was (349-471)µS/cm. As for total dissolved solids, their average before the treatment was(182.5)mg/L, while their average after the treatment was(194.6)mg/L as for salinity, its values ​​ranged between(0.7-0.75) mg/L before the treatment and between (0.6 -0.8) mg/L after the treatment ,pH value before the treatment was between)6.12- 7.91( compared to its value after the treatment as it ranged between (6.81-7.95), while the values ​​of the chemical requirement for oxygen before the treatment were (85108)mg/L, Their concentrations values ​​after the treatment amounted to(73_125) mg/L, and polycyclic aromatic hydrocarbons (PAHs) (73.46-155.17) mg/L before the treatment, and after the treatment it reached (35.53-52.53) mg/L, while oils and greases reached values ​​that ranged between (26.16-165.68) mg/L before the treatment compared to their results after the treatment which ranged between (94.15-23.18)mg/L. Finally, the total organic carbon had an average value before treatment (134.1) mg/L, while after treatment their average values ​​reached (120.8) mg/L

CH4 Carbonylation to Acetic Acid Using H2O as an Oxidant on a Rh-Functionalized UiO-67 Combined with Oriented External Electric Fields: Selectivity and Mechanistic Insights from DFT Calculations.

Acetic acid (CH3COOH), as an industrially important petrochemical product, is predominantly produced via multistep energy-intensive processes. The development of a rhodium single-site heterogeneous catalyst has received considerable attention due to its potential to transform CH4 into CH3COOH in a single step. Herein, the reaction mechanism for the generation of CH3COOH from CH4, CO, and H2O catalyzed by Rh-functionalized metal-organic framework (MOF) UiO-67 and the selectivity of products CH3COOH, formic acid (HCOOH), methanol (CH3OH), and acetaldehyde (CH3CHO) under the oriented external electric fields (OEEFs) were systematically explored by density functional theory (DFT) calculations. The results reveal that the insertion of CO into Rh-CH3 is the rate-determining step with a free energy barrier of 21.0 kcal/mol in CH4 carbonylation to CH3COOH. Upon applying an OEEF of Fx = +0.0050 au along the C-C bond, the rate-determining step shifts toward H2O decomposition with the barrier of 19.6 kcal/mol, significantly improving the selectivity for CH3COOH production, compared to the major competitive HCOOH route. The Brønsted-Evans-Polanyi (BEP) relationships between key transition states, field strength, and NPA charge transfer were established. This study may guide the rational design of atomically dispersed MOF catalysts for the selective coconversion of CH4 and CO to CH3COOH using H2O as the oxidant under the OEEF.

The adsorption performance of high crystallinity Na-p zeolites prepared from oil shale ash for the waste water treatment

ABSTRACTS The Na-p type zeolite has been prepared by the alkali fusion hydrothermal synthesis method using the pure oil shale ash (OSA) and mixture of OSA and coal fly ash (CFA) as raw materials, which was used for adsorption of methylene blue (MB). The XRD spectra of zeolite synthesized from pure oil shale residue under different conditions indicated that the optimal experimental conditions were determined as follows: acid leaching concentration of 10%, sodium hydroxide dosage of 7 g, crystallization temperature of 130°C, and crystallization time of 12 h. Under the same conditions, zeolite was synthesized using the mixture of OSA and CFA, and its properties were characterized using XRD, SEM, and BET techniques. The results showed that the specific surface area and crystallinity of the zeolite prepared from the mixture were 59.6 m2/g and 86.32%, respectively, which were higher than that of pure OSA (20.6 m2/g and 64.07%). When 0.05 g of zeolite was added to the 35 mg/L MB solution and adsorbed for 180 min, the removal rates of MB by pure OSA, single-source zeolite and zeolite prepared from the mixture were 27.6%, 83.4%, and 99.2%, respectively. The adjusted R square verified that the pseudo-second-order kinetics and Langmuir isotherm model were the best fitting models. The maximum adsorption capacity (Qmax) of zeolite prepared from the mixture for MB was 55.5 mg/g. The above results proved that the novel material prepared in this study could be a potential effective wastewater treatment material.

Use of the droplet convergence effect of under-medium superlyophilic membranes in designing a system for on-demand separations of oil-in-water and water-in-oil emulsions

Separation using superwetting membranes that have discrepant interactions with water and oil, primarily those that display extreme liquid repellence, is a facile approach for oily wastewater treatment and purification of water-containing oil. However, these kinds of membranes suffer from size-sieving limitation. Owing to greater affinity toward dispersed droplets over liquid media, under-medium superlyophilic membranes have greater flexibility in the design of superwetting interfaces for oil–water separation. Herein, two membranes with completely opposite superwettabilities both in air and under oil/water media were utilized to create an integrated system for effective, on-demand separation of oil-in-water and water-in-oil emulsions. At superwetting interfaces, the under-medium superlyophilic membrane facilitates convergence of emulsion droplets while the other membrane intercepts converged droplets. As a result, the integrated membranes exhibit high purification capabilities of water and oil in surfactant-stabilized emulsions (e.g., > 99.97 % oil purification under gravity). The viscosity-dependent fluxes are > 550 L m−2h−1 when the viscosities of the liquid media are ≤ 1 mPa s. In contrast, an integrated system in which conventional in-air superhydrophilic membranes are utilized in place of the under-medium superlyophilic membranes does not efficiently separate the emulsions. The unique affinity profiles will endow under-medium superlyophilic membranes with a high potential for liquid–liquid separation.

Analysis of Acid Options in the Purification of Spent Motor Engine Oil Using Acidified Clay

Abstract: This research is centered on the purification of Spent Shell Helix (HX3 20W-50) lubricating oil using acidified clay treatment with three acids options: mineral sulfuric acid (H2SO4), organic acetic acid (CH3COOH), and organic citric acid (C6H8O7), (a novel washing agent). The clay mineral, spent, purified, and fresh lubrication oil samples were characterized to determine their physicochemical properties. The clay mineral was characterized using Energy-Dispersive X-Ray Fluorescence (EDXRF). The result indicated that the clay was bentonite clay and it was successfully acidified. The result also indicated that properties of the spent lubricating oil such as Kinematic viscosities at 40 oC and 100 oC increased from 118.9 cSt and 13.9 cSt for the spent oil to 169.7 cSt and 15.2 cSt, 178.2 cSt and 16.3 cSt, 183.4 cSt and 16.8 cSt for the oil samples purified with C6H8O7, CH3COOH and H2SO4 respectively Also, the flash point increased from 106 oC for the spent oil to 133 oC, 180 oC, 189 oC for the oil samples purified with C6H8O7, CH3COOH and H2SO4 respectively. The FTIR analysis of the spent oil revealed the presence of primary oxidized products, absent in spent engine oil purified with mineral sulphuric acid (H2SO4), organic acetic acid (CH3COOH), and fresh oil. Acidified clay effectively purified the spent engine oil, bringing its physicochemical properties closer to those of fresh oil. However, the effectiveness of the treatment varied depending on the specific acid used.

Selenocyanate removal using combined system of TiO2- photocatalysis and Fe(III)/SiO2 adsorption {UV-TiO2/[Fe(III)/SiO2]}: Complex destruction and simultaneous selenium species adsorption

Selenocyanate (SeCN‾) species, commonly found in industrial effluents from crude oil refineries and mining operations, present substantial health risks to humans and animals. This study investigates the treatment of selenocyanate-contaminated streams using a combination of TiO2 photocatalysis and Fe(III)/SiO2 binary oxide adsorption {UV-TiO2/[Fe(III)/SiO2]}. The Fe(III)/SiO2 binary oxide was synthesized and characterized using X-ray diffraction (XRD) and Fourier Transform Infrared (FTIR) spectroscopy. XRD analysis revealed non-crystalline Fe-oxide phases, while FTIR indicated the presence of various Fe and O functional groups on the Fe(III)/SiO2 surface. Adsorption studies using Fe(III)/SiO2 showed its selenocyanate uptake capacity ∼ 2.1 mg/g, with the respective data closely aligning with the Langmuir isotherm model. This Fe(III)/SiO2 adsorption feature was successfully combined in the {UV-TiO2/[Fe(III)/SiO2]} system in which the hydroxyl radicals (●OH) generated by the UV-TiO2 facilitated the breakdown of the selenocyanate complex, while the resulting selenite and selenate were simultaneously adsorbed by the Fe(III)/SiO2 within a 240-min reaction time. A mathematical model developed using a face-centered central composite design-response surface methodology (FCD-RSM) showed significant predictive capability with an insignificant lack of fit. Optimal conditions for selenium removal were determined to be 20 mg/L selenocyanate, 1 g/L TiO2, and 1 g/L Fe(III)/SiO2, at pH 5, within a 240-min reaction time. Kinetic analysis demonstrated that selenocyanate degradation followed pseudo-first-order kinetics, while total selenium removal adhered to pseudo-second-order kinetics, confirming the proposed selenium species removal mechanism. Overall, this integrated approach offers a promising solution for effective selenocyanate remediation in industrial wastewater.