Conversion of microplastics to flocs during estuarine mixing the Aras River with the Caspian Sea

Microplastics originated from various sources are carried by rivers into oceans, seas and lakes. In the last few years, the accumulation of microplastic particles in marine environments has been on the increase which causes irreversible damages to flora, fauna and human health. One of the most considerable processes in an estuary is the flocculation process. The flocculation process converts pollutants to flocs or greater particles. In the present study, the conversion of microplastics to flocs during estuarine mixing of the Aras River water and the Caspian Sea water is investigated for the first time. The results clearly show that a huge percentage of microplastics (99.95%) are converted to greater particles (> 5mm) due to the flocculation process. The maximum flocculation rate of microplastics (47.37%) is observed at the salinity of 0.25 ppt. Moreover, 35.71% of microplastics are flocculated at the salinity of 29 ppt. Salinity enhances the flocculation of microplastics.

Research of the Cleaning Process Regularities for the Model Waste Water Systems with the «Vodokanalniy» Polyacrylamid Flocculant

The article presents for the first time the results of studies on the use of the «Vodokanalny» flocculant for flocculation purification of model wastewater solutions. The process of flocculation of dispersed systems by polyelectrolytes is described. The influence of the nature and concentration of (poly) electrolytes on the flocculation rate was studied using BAU and quartz sand suspensions as an example. Graphical dependences of the described quantities on the concentration of introduced reagents are given. The clarification rates of suspensions in the presence of polyelectrolytes were investigated. The values of the initial particle deposition rates are calculated. The dependences of the value of the cleaning efficiency on the volume of the introduced substance are presented. A comparative analysis of the use of the component with polyacrylamide flocculants of the AK-631 type (A-930 and A-1510) was carried out.

SILICA-REINFORCED NATURAL RUBBER TIRE TREAD COMPOUNDS CONTAINING BIO-BASED PROCESS OILS. I: ASPECTS OF MIXING SEQUENCE AND EPOXIDE CONTENT

ABSTRACT A bio-based process oil for rubber compounds is one of the compounding ingredients to be used toward an eco-friendly and more sustainable rubber technology. This work investigates epoxidized palm oil (EPO) as an alternative for petroleum-based process oil in silica-reinforced natural rubber (NR) tire tread compounds. The effect of different incorporating steps of EPO on the properties of the rubber compounds is first studied, taking into account that the polar functional groups in the oil molecules may interact with the silanol groups on the silica surface. The properties of silica-reinforced NR compounds with EPO oil are compared with that of reference mixes with treated distillate aromatic extract (TDAE) and without oil. The compounds with EPO show a lower viscosity, filler–filler interaction, and flocculation rate constant but higher cure reaction rate constants compared with the compound with TDAE. The results indicate that the epoxide groups in EPO interact with the silanol groups on the silica surface, promoting a greater shielding effect on the polar surface and thus better silica dispersion and less interference with the vulcanization reaction. The different incorporating steps of EPO show no significant effect on the viscosity, filler–filler interaction, or flocculation rate constant but clearly affect the extent of crosslinking, as indicated by the cure torque difference. The presence of EPO in an early stage of the mixing together with the first half addition of silica and silane results in the lowest cure torque difference, modulus, and tensile strength (i.e., the highest tan δ at 60 °C), which indicates a possible obstruction for the interaction between the silanol groups and silane coupling agent by the EPO molecules. Comparing EPO with different epoxide contents in the range of 1–3 mol%, the increase in epoxide content gives similar Payne effects but enhances the cure reaction, resulting in improved tensile properties and tan δ at 60 °C. The results clearly prove that EPO can be used as a TDAE alternative.

Bioflocculation Activity in Harvesting System: A Biotechnology Approach for Microalgae Biomass

A study on Ankistrodesmus sp.—a freshwater green microalgae species—as a bioflocculant based on its physicochemical properties and flocculation rate has been carried out. The molecular identification via 16S rDNA showed 99% resemblance of this green microalga to the Ankistrodesmus fumigatus strain. The optimum batch culture condition for the bioflocculant production was initiated by 10% inoculum (v/v). The low-concentrated bioflocculant of 10% (v/v) is considered as thermostable with a high flocculation rate to harvest the biomass of Chlorella sp. at a pH range of 5 to 9. The source of molasses, the mixture of yeast extract were used as the optimum sources of carbon and Ammonium sulfate were used as the optimum sources of nitrogen in the growth medium. Ankistrodesmus sp. bioflocculant has a high flocculation efficiency over a wide range of pH (5–9) with a low dose requirement of 10% v/v at 25°C. Hence, it is immensely competitive to promote the economic viability of the production process. Accordingly, Ankistrodesmus sp. bioflocculant has a high potential to be applied on an industrial scale in tropical regions as it does not require additional production cost.

Comparison of Ultrasonic Wave Radiation Effects on Asphaltene Aggregation in Toluene–Pentane Mixture Between Heavy and Extra Heavy Crude Oils

In this study, it is aimed to compare the efficiency of ultrasonic wave technology on asphaltene flocculation inhibition of crude oils with different American Petroleum Institute (API) gravities. A set of confocal microscopy test is performed and a series of statistical analysis is done. According to the results of this study, there is an optimum radiation time for both crudes at which the viscosity and the flocculation rate of asphaltenic crude oils reduces to its minimum. This optimum appears at later times of radiation for extra heavy oil. Also, it is shown that the rate of changes in the properties measured in this study is sharper for extra heavy crude oil. It could be concluded that the alternations caused by this technology is more significant for Kouh-e-Mond, which is heavier oil than Sarvak crude oil. Derjaguin–Ladau–Verwey–Overbeek (DLVO) kinetic model was also studied and it was understood that this model cannot be a validate model for radiated samples.