Quantitative analysis of microplastics coagulation-removal process for clean sea salt production

Abstract

Sea salt is produced from the evaporation of seawater containing harmful microplastics, and this process leads to sea salt enrichment with microplastics. To solve this issue, the coagulation method for seawater microplastics removal was studied, and Fourier transform infrared spectrometer spectrum was adopted to analyze the amounts of MPs in coagulated flocs. AlCl 3 , Al 2 (SO 4 ) 3 , FeCl 3 , CH 3 (CH 2 ) 3 SiCl 3 , and CH 3 (CH 2 ) 7 SiCl 3 were employed as coagulants. The salinities of simulated seawater were manipulated using commercial sea salt. Micron-size poly(n-butyl methacrylate) spheres were used as representative microplastics after confirming their stabilities in seawater. The results indicated that the high microplastic removal efficiencies (exceeding 60%) were achieved by all coagulants. Further, the removal efficiency of silane-based coagulants was enhanced via NaCl addition, whereas the removal performance of AlCl 3 was reduced in the presence of excess NaCl. The best performance was obtained using CH 3 (CH 2 ) 7 SiCl 3 : microplastic removal efficiency > 98% for 3 and 15% salinities. Quantitative analysis of coagulated microplastic by Fourier transform infrared spectrometer was in good agreement with experimental data and confirming that aggregated flocs were mainly composed of MPs. Therefore, this coagulation method can be applied for seawater microplastic coagulation, and employing CH 3 (CH 2 ) 7 SiCl 3 in 15% saline seawater is considered the most efficient process. Furthermore, the developed Fourier transform infrared spectrometer method would be an effective analytical tool for quantitative analysis of microplastic removals from seawater, and optimization of coagulants dosage for the microplastic coagulation-flocculation process.

Microplastic removal by coagulation: a review of optimizing the reaction conditions and mechanisms

“…The removal of MPs from the C-577 system reached a maximum of 65%, and the researchers found a connection between this removal rate and the system's absolute zeta potential value. This shows that organic polymeric coagulants may cause the removal of MP via charge neutralization to become unstable [62] . PAM has been found to significantly enhance the removal of MPs by aluminum and iron-based coagulants, with anionic PAM being more effective than cationic PAM [20,40] .…”

“…Table 2 demonstrates the use of various coagulants for the removal of MPs in water and wastewater treatment. Several inorganic coagulants such as aluminum and iron-based coagulants, MgCl 2 , magnetic coagulants, as well as organic polymer coagulants and bio-flocculants have all been used for MP removal from water and effluent [62] . It has been found in previous studies that aluminum-based coagulants perform better than iron-based coagulants in MP removal [15,37,40,52] .…”

“…In all circumstances where the dosage was between 5-35 mg/L, FeCl 3 .6H 2 O eliminated between 5.9% and 73.1% of MPs, whereas PAC removed only 3.5% to 53.6% of MPs. microspheres used in the experiments lacked a charge, so wrap sweeping was more effective than charge neutralization in removing MPs [62] . Different mechanisms of action are expected to affect the removal efficiency of MPs due to factors affecting the coagulation process.…”

Dual Functionality of MFI Zeolite Nanosheets as a PET Depolymerization Catalyst and a Flame Retardant in Repolymerized Polyurethane

“…To illustrate, the average American consumes approximately 167 plastic bottles annually. − This increase in plastic consumption has led to a significant environmental predicament, primarily centered around the slow degradation of PET waste, posing threats to ecosystems, the environment, and the circular economy. An example of this environmental issue is the emergence of microplastics, micron-sized particles degraded from plastic waste, known as microplastics, are now a major pollutant in the ocean, threatening hundreds of thousands of aquatic species that are affected by ingestion, entanglement, and asphyxiation. − Given constraints on landfill capacity and environmental concerns regarding incineration, there is a pressing need for an ecologically sustainable and cost-efficient method for recycling PET.…”

Complementary Analysis for Undetectable Microplastics from Contact Lenses to Aquatic Environments via Fourier Transform Infrared Spectroscopy

“…With the increasing use of plastic products by human activity, natural environments are becoming increasingly exposed to discharged microplastics (MPs). For instance, MPs have been detected in ecosystems [1][2][3] as well as in food items such as fish [3,4], salt [5,6], seaweed [7], and seafood [8]. These MPs may have originated from wastewater treatment process (WWTP) effluents and the indiscreet disposal of plastic waste into the ocean and soil environments [9][10][11].…”