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Nowadays, plastic waste (PW) disposal is one of the serious global problems facing humanity and ecosystem balance. As the population increases continuously, the fuel market has been growing so the demand for plastic is also increased to cover the growing levels of consumption that leads to a serious environmental crisis by the PW accumulation. Therefore, recycling processes take place to clean the environment from these accumulated quantities of waste. Many studies accounted that the most suitable chemical recycling technique is pyrolysis which means conversion of the PW into valuable products in presence of heat. This review explained chemical structures, uses, recycling by thermal and catalytic pyrolysis of the plastic materials and discussed a comparison between two processes above. Moreover, investigation effects of the operating conditions such as temperature, pressure, residence time, and catalyst presence on the product distribution. Also, the reaction mechanism details of the process and work of previous researchers were addressed in this paper. [ABSTRACT FROM AUTHOR]

The well-known frictional effect related to liquid-liquid two-phase flow in pipelines can be reduced using dragreducing additives. In this study, such an effect has been investigated experimentally using a mixture of oil and water. Moreover, numerical simulations have been carried out using the COMSOL simulation software. The measurements were taken in a horizontal pipe with the length and diameter equal to 3 and 0.125 m, respectively. Moreover, Polyethylene oxide with 150 ppm was exploited to reduce the drag effect while considering different water-to-oil fractions (0.3, 0.4, 0.5, and 0.7) and a constant total flow velocity of 2.3 m/s. As made evident by the results, a significant reduction can be obtained in terms of pressure drop, which becomes even more significant as the water to oil fraction is increased. The maximum achieved drag reduction is 70% with a water fraction of 0.7. The results also show that the addition of polymer additives can also have an impact on the flow pattern. Comparison of experimental and numerically determined pressure drop indicates that the error is smaller than 7%. [ABSTRACT FROM AUTHOR]

In this study, Pb2+ removal from wastewater using multiwall carbon nanotubes (MWCNTs) was investigated. XRD, SEM-EDX, BET, and FTIR were employed for MWCNT characterization. The effects of various parameters, including the solution pH, adsorbent dosage, initial concentration of Pb2+, and contact time, on the Pb2+ removal from wastewater were investigated experimentally. Furthermore, the nonlinear relationship among the parameters was predicted using an artificial neural network (ANN) approach. The Levenberg–Marquardt training algorithm showed the best training performance, with a mean-square error of 2.200 × 10−5 and an R2 of 0.998. Combining the ANN models and Monte Carlo simulation, Pb2+ removal efficiency of 99.8% was obtained under the optimum conditions (pH of 10, MWCNT dosage of 0.05 g, contact duration of 60 min, and Pb2+ concentration of 100 mg/L). The high removal efficiency can be attributed to the available adsorption sites (active sites). The results of the reusability of MWCNTs showed that the adsorption efficiency was higher than 90%. Thus, MWCNTs have great potential for recycling and managing Pb2+ from wastewater. [ABSTRACT FROM AUTHOR]

Ethylene production is one of the most abundant activities in petrochemical industries. So, the main objective is to develop detailed models to describe a pyrolysis section in the real ethylene plant furnace located at the petrochemical complex (PC1), Basra, Iraq. Those models were utilized to evaluate the effects of the reaction temperature, steam to ethane ratio (DS/HC), and feedstock flowrate on the ethylene yield using different feedstock compositions. The simulation validity was tested by comparing the simulation results with the real data collected from the PC1 and showed an acceptable similarity and reliability depending on relative error values. A genetic algorithm coded by MATLAB and Aspen Plus optimizer was used to obtain the optimal operating conditions to give a maximum profit. The optimization results of Aspen Plus and GA showed an increase in the profit equal to 10.541 and 9.823% respectively when the reaction temperature, DS/HC and outlet flowrate of hydrocarbons were in the range of 850–920°C, 0.2–0.5, and 2421–1064 Kmole/hr respectively. Also, Increasing the ethane content in feedstock leads to an increase in the feedstock production of 16–19% ethane content. [ABSTRACT FROM AUTHOR]

The presence of ammonia in wastewater from industry activities is an important environmental issue; therefore, an adsorption process is one viable alternative process that can be used to reduce concentrations, and accordingly, 10 resins and 6 zeolites were tested for the removal of ammonia from real wastewater (3.8 to 8 mg/L NH3 − N) containing other cations. In subsequent tests, the performance of the most promising adsorbents (four resins & two zeolites) was further characterized using isotherms and kinetic experiments. Adsorbent equilibrium capacities in the range of 0.2 to 0.4 mg/g were determined for ammonia concentrations of approximately 1 mg/L. [ABSTRACT FROM AUTHOR]

The ammonia component represents a sizable portion of pollutants in mining wastewater (MW) and because of its high selectivity toward ammonia, a LEWATIT resin was tested in the batch adsorption using different masses with 22.7 mg/L NH3 − N and in the continuous adsorption using two fixed-bed columns. Also, resin regeneration was achieved using diluted HCl. The results show the adsorption follows Freundlich isotherm in the batch study and was characterized by both the Bohart–Adams and Thomas models in the fixed-bed column. HCl can be used to regenerate LEWATIT with efficiency 40% and 70% for the small and large column, respectively. [ABSTRACT FROM AUTHOR]

Green synthesis methods using plants have many advantages such as time-saving, chemical-free, and negative effects on the environment. So, extracted Citrus aurantium juice was used to synthesize green CuO/TiO2 and (GCuO/TiO2) nanocatalyst which was characterized by X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Energy Dispersive X-ray (EDX), Fourier Transform Infra Red (FTIR), Brunauer-Emmett-Teller (BET), and Zeta Potential (ZP), and utilized in the degradation of methylene blue (MB) under UV lamps and dark environments. The ANOVA program was used to maximize the photodegradation efficiency (%) of (G-CuO/TiO2) on the MB dye. The four independent variables: Initial dye concentration (10-50 mg/L), pH (3-9), adsorbent dose (200-1000 mg/L), and contact time (30-90 min) served to the model of the photodegradation efficiency (%). The ANOVA results confirmed the high significance of the regression model while the predicted values of the photodegradation efficiency (%) of MB were in good agreement with the corresponding experimental ones. Optimized conditions for the maximum photodegradation efficiency (98.6%) by (G-CuO/TiO2) NPs were the initial dye concentration (10.93 mg/L), pH (8.87), adsorbent mass (986.43 mg/L), and contact time (89.08 min). The validity of the quadratic model was examined, and found in good agreement with the experimental values. Results demonstrated that (G-CuO/TiO2) could be a promising photocatalyst in the degradation of MB dye. [ABSTRACT FROM AUTHOR]