Acidic process fluid from hydrothermal carbonization improves dechlorination of waste PVC and produces clean solid and liquid fuels.

Dechlorination of waste PVC (WPVC) by hydrothermal treatment (HTT) is a potential technology for upcycling WPVC in order to create non-toxic products. Literature suggests that acids can improve the HTT process, however, acid is expensive and also results in wastewater. Instead, the acidic process fluid (PF) of hydrothermal carbonization (HTC) of orange peel was utilized in this study to enhance the dechlorination of WPVC during HTT. Acidic HTT (AHTT) experiments were carried out utilizing a batch reactor at 300-350 °C, and 0.25-4 h. The finding demonstrated that the dechlorination efficiency (DE) is high, which indicates AHTT can considerably eliminate chlorine from WPVC and relocate to the aqueous phase. The maximum DE of 97.57 wt% was obtained at 350 °C and 1 h. The AHTT temperature had a considerable impact on the WPVC conversion since the solid yield decreases from 56.88 % at 300 °C to 49.85 % at 350 °C. Moreover, AHTT char and crude oil contain low chloride and considerably more C and H, leading to a considerably higher heating value (HHV). The HHV increased from 23.48 to 33.07 MJ/kg when the AHTT time was raised from 0.25 to 4 h at 350 °C, indicating that the AHTT time has a beneficial effect on the HHV. The majority fraction of crude oil evaporated in the boiling range of lighter fuels include gasoline, kerosene, and diesel (57.58-83.09 wt%). Furthermore, when the AHTT temperature was raised from 300 to 350 °C at 1 h, the HHV of crude oils increased from 26.11 to 33.84 MJ/kg. Crude oils derived from AHTT primarily consisted of phenolic (50.47-75.39 wt%), ketone (20.1-36.34 wt%), and hydrocarbon (1.08-7.93 wt%) constituents. In summary, the results indicated that AHTT is a method for upcycling WPVC to clean fuel.

E-waste plastic liquefaction using supercritical Toluene: Evaluation of reaction parameters on liquid products.

Solvothermal liquefaction (STL) is a thermochemical conversion technique that employs solvents other than water to transform waste plastics into valuable compounds. The objective of this study was to explore the potential use of supercritical toluene, a nonpolar solvent, for the depolymerization of four electrical waste (e-waste) thermoplastics, namely polyamide (PA), polycarbonate (PC), polyoxymethylene (POM), and polyether ether ketone (PEEK), into liquid products. Depolymerization experiments were carried out in batch reactors at three reaction temperatures (325, 350, and 375 °C), and three residence times (1, 3, and 6 h). The findings revealed that increasing STL temperature and extending the reaction time enhances the depolymerization of e-waste thermoplastics. The highest STL conversation (100 %) was observed for POM, and the lowest STL conversation (32.23 %) was observed for PEEK. Additionally, the ultimate analysis showed that the liquid product obtained from STL at 375 °C and 6 h exhibited higher heating values (HHV) within the range of 31.43 to 35.31 MJ/kg. Thermogravimetric analysis (TGA) demonstrated that the boiling point distributions of liquid products are highly dependent on thermoplastic type. Finally, the reaction mechanisms of STL for PA, PC, POM, and PEEK were proposed based on gas chromatography-mass spectrometry (GCMS) analysis.

Role of acidic hydrochar on dechlorination of waste PVC in high temperature hydrothermal treatment and fuel properties enhancement of solid residues.

In this study, the chlorine mitigation from waste polyvinyl chloride (WPVC) during high temperature co-hydrothermal treatment (co-HTT) and the properties of the generated solid products were assessed. WPVC was co-fed with acidic hydrochar (AHC), which was produced via hydrothermal carbonization of pineapple waste in the presence of citric acid water solution. High temperature co-HTT experiments were performed at 300-350 °C, 0.25-4 h of reaction time, and 0-20 wt% AHC loading. Co-HTT solid products (co-HTT_SP) were characterized via proximate analysis, ultimate analyses, combustion analysis, and ash analysis. The results show that the addition of 5% AHC enhances the dechlorination efficiency (DE) of WPVC from 89.35% to 97.66% at 325 °C and 0.5 h. The highest DE, reaching 99.46%, was achieved at 350 °C and 1 h in the presence of 5 wt% AHC. Furthermore, loading 5% AHC improved the higher heat value (HHV) of the solid products from 23.09 to 31.25 MJ/kg at 325 °C and 0.5 h. The maximum HHV (34.77 MJ/kg) of a solid product was achieved at 350 °C, 4 h, in the presence of 5 wt% of AHC. The co-HTT solids shown low slagging indices, fouling indices, alkali indices, and medium chlorine contents. These findings support the viability of WPVC conversion into clean solid fuel via co-HTT.

Adsorption isotherm models: A comprehensive and systematic review (2010-2020).

Among numerous methods developed in purification and separation industries, the adsorption process has received considerable attention due to its inexpensive, facile, and eco-friendly nature. The importance of the adsorption process causes extraordinary endeavors for modeling the adsorption isotherms during the years; thus, myriads of research have been conducted and many reviews have been published. In this paper, we have attempted to gather the most widely used adsorption isotherms and their related definitions, along with examples of correlated work of the recent decade. In the present review, 37 adsorption isotherms with about 400 references have been collected from the research published in the period of 2010-2020. The adsorption isotherms utilized are alphabetically organized for ease of access. The parameters of each isotherm, as well as the applicable definitions, are presented in the table, in addition to being discussed in the text. Another table is provided for the practical use of researchers, featuring the usage of the related isotherms in peer-reviewed studies.