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The effects of marble processing wastewater physicochemical treatment sludge (K1) on polypropylene (PP) waste pyrolysis were investigated by lab-scale batch pyrolysis system. PP-K1 proportions and pyrolysis temperature were studied as variables and both were found to have influences onto pyrolysis char, oil/tar, gas fractions distribution, as well as pyrolysis char characteristics (determined via SEM, EDX, FTIR, TGA and XRD analyses). The influence of K1 could be related to its high mineral composition (CaCO3, CaMg(CO3)2 and (Mg0.03Ca0.97)(CO3)) which also detected in the char products. K1 acts as catalyst and remained unchanged in thermochemical reactions below 700°C. The main thermal degradation of PP occurs around 400–470°C, although it starts at about 300–350°C, whereas, K1 resulted in more thermal degradation at 300°C pyrolysis. As K1 dose increased, pyrolysis chars became more thermally stable with the pyrolysis temperature. Diverse types of chars in terms of porosity, thermal strength and chemical structure were produced with PP + K1 as compared to the PP chars. For example, with 10%–20% K1 doses, the chars are in aromatic structure while chars become aliphatic when K1 dosage increased to 30% or above. The structural diversity made these chars new products that can be used as raw material for subsequent purposes. This study provided a basis for the chars' physical and chemical properties which are needed for further research to develop new generation evaluation areas for them. Therefore, a new symbiotic upcycling approach has been presented for PP wastes and marble processing wastewater treatment sludge. [ABSTRACT FROM AUTHOR]

Waste vehicle tires (WT) and high density polyetylene (HDPE) were pyrolyzed at 300, 500 and 700°C by slow pyrolysis. Solid product (pyrolysis char) were collected and pyrolysis char was used as adsorbent for COD and Cr(VI) removal. The char samples were characterized by BET, EDS, SEM and XRD analysis. Based on the BET, SEM and XRD results of the char samples, WT 700 can be used as adsorbents for Cr (VI) and organic material adsorptions. Cr(VI) and COD removal efficiency of char adsorbent were investigated. In the adsorption experiments, char was used as 0.1-0.5 g/100 mL doses and at 50°C and 80°C adsorption temperatures. The effects of adsorption temperature and char dosage on the adsorption efficiency were invesitigated. The maximum Cr(VI) adsorption capacity of this new generation char was found to be 14.09 mg/g for 80°C adsorption temperatures. 0.5 g/100 mL adsorbent dose was bettter in COD and Cr (VI) removals. The correlation of PSD1 (pseudo first order kinetic model) was better than PSD2 (pseudo second order kinetic model) for all doses. The Temkin and Langmuir isotherms were better isotherm for COD and Cr(VI) removals, respectively. A new approach were present to evaluation of waste HDPE and waste tires with this study. [ABSTRACT FROM AUTHOR]

High density polyethylene (HDPE) and low density polyethylene (LDPE) plastic wastes were pyrolysed in the temperature range of 300–700 °C, liquid, gas and solid fractions (char) were quantified and pyrolysis char was used as additive in production of epoxy composite. Effects of pyrolysis temperature on products fractions, char quality and composite quality were investigated. In the composite composition, char was included as 10–50 wt% of epoxy to determine the effects of additive dosage on the composite quality. The char additives and produced composites were characterized by FTIR and SEM. Mechanical properties, namely tensile strength, surface hardness and electrical properties were determined for the epoxy composite materials. Epoxy composite materials produced with HDPE pyrolysis char additive obtained at 300 °C (ER300) showed the most ideal behavior in terms of elongation at break and tensile strength. With increasing pyrolysis temperature and char doses elongation at break and tensile strength of composites generally decreased. While tensile strength showed an increase by 32% at 10% wt% dose for composite (ER300) with HDPE char obtained at 300 °C, the increases were 21%, 14%, 14% and 13% for ER400-ER700 composites prepared with 10 wt% HDPE chars obtained at 400–700 °C pyrolysis temperatures, respectively. Despite this, LDPE chars a small decreased the tensile strength of epoxy. The hardness of neat epoxy was improved from 79.8 Shore D up to 86.3 and 87 Shore D by the LDPE and HDPE char additives, respectively. The study offers a new recovery approach for HDPE and LDPE type plastic wastes. [ABSTRACT FROM AUTHOR]