Separation properties of aluminium-plastic laminates in post-consumer Tetra Pak with mixed organic solvent

Solvothermal liquefaction of Tetra Pak waste into biofuels and Al2O3-carbon nanocomposite

This study explores a novel solvothermal disposal technique of Tetra Pak waste for the co-synthesis of value-added bio-oil and alumina-carbon nanocomposite. The impact of residence time (10-50 min.), temperature (240-360 °C), and substrate-to-solvent ratio (1:4-1:10) on the solvothermal liquefaction of Tetra Pak waste with supercritical ethanol were investigated on a batch scale. Initially rise in operating temperature and residence time positively influenced the bio-oil yield. However, a decline in yield was seen beyond a certain point. A higher substrate-to-solvent ratio enhanced the bio-oil yield as the solvent demonstrated its effective capabilities to depolymerize the feedstock. The favorable condition for the highest bio-oil yield (34.41 %) and HHV (30.51 MJ/Kg) were found to be at 320 °C, 30 min, and a substrate-to-solvent ratio of 1:10. The synergetic effect of solvent (ethanol) and aluminium present in Tetra Pak leads to the formation of in-situ generated active hydrogen that enhances the bio-oil yields and inhibits residue formation. XRD and XPS analysis confirms the transformation of aluminium from (Al (0)) to (Al (+3)) in the presence of ethanol forming in-situ generated alumina-carbon nanocomposite that has the potential to be used as a catalyst. NMR, GC-MS, and FTIR analysis confirmed the richness of bio-oil in various organic compounds including alcohol, esters, ketones, ethers, acids, and phenols. The recovered ethanol from the process exhibits a significant potential to be reused as a solvent or as a fuel additive.

Recovery, separation and production of fuel, plastic and aluminum from the Tetra PAK waste to hydrothermal and pyrolysis processes

The establishment of a method of separation of materials from Tetra Pak waste to obtain products for use as raw material, fuel or other purposes was investigated in this study. First, the feasibility of hydrothermal treatment for the production of a solid fuel (hydrochar) and solid fraction formed by polyethylene and aluminum, called composite was analyzed. The results indicated that hydrothermal treatment performed at 240 °C yield the formation of hydrochar with good properties for its use as fuel and a composite of polyethylene and aluminum. The best conversion and separation of the cardboard and polyethylene/aluminum were obtained using 120 min as operating time. Then, the recovery of the aluminum fraction from the composite by using spent olive oil waste was studied. A partial separation of the composite layers (polyethylene and aluminum) was accomplished with improved aluminum purity for higher operating temperatures. Finally, the operating conditions of the pyrolysis process for the production of a solid (char) and high purity composite (aluminum) were optimized. The characterization results indicated that both char and aluminum resulting from the pyrolysis of the Tetra Pak at 400 °C still have a significant amount of polyethylene while higher purity levels of aluminum can be obtained at temperatures equal of higher than 500 °C.

Circular Economy in Conjunction with Treatment Methodologies in the Biomedical and Dental Waste Sectors

In this review, life cycle assessment (LCA) principles are coupled with circular economy (CE) in order to address LCA examples in the biomedical sector worldwide. The objectives were (1) to explore the application of LCA in the medical, pharmaceutical, and dental fields; (2) to describe the ways of biomedical waste management; (3) to emphasize on the problem of dental waste in private and public dental sectors; and (4) to propose ways of “green circulation” of the dental waste. A literature search was performed using the Google Scholar, PubMed, and Scopus search engines covering the period from January 2000 until May 2020, corresponding to articles investigating the LCA and circular economy principles and legislation for biomedical and dental waste, their management options, and modern ways of recycling. The results showed that incineration seems to be the best management way option involved despite the mentioned drawbacks in this technology. Different adopted models are well defined for the dental field based on the 3Rs’ module (reduce, reuse, recycle). Replacing disposable products with reusable ones seems to be a good way to tackle the problem of waste in medical and dental sectors. Interventions on the selection and better biomedical and dental waste management will ensure eco-medicine and eco-dentistry of the future. These new terms should be the new philosophies that will change the way these fields operate in the future for the benefit of the professionals/patients and the community.

Recycling of Aseptic Beverage Cartons: A Review

Aseptic beverage cartons are multilayer polymer-coated paperboards with a layer of aluminum foil. Due to their multilayer structure it is commonly assumed that they cannot be recycled. This is not the case and this review details the multifarious processes that are used to recycle aseptic beverage cartons. Hydrapulping to recover the paper fibers that constitute 75% of the carton is the most widespread process, followed by the manufacture of construction materials such as boards and tiles which utilize the complete carton. A range of mechanical, chemical and thermal processes are used to separate the PolyAl (polyethylene and aluminum) residual that remains after the paper fibers have been recovered. The simplest process involves agglutination followed by extrusion to obtain pellets that can then be used in industrial and consumer products or combined with other materials such as lignocellulosic wastes. Chemical approaches involve the solubilization of polyethylene and the removal of aluminum. Various thermal processes have also been investigated and a novel microwave-induced pyrolysis process appears the most commercially viable. It is concluded that the focus in future years is likely to be on recycling cartons into construction materials where there is a theoretical yield of 100% compared with 75% for hydrapulping.

Catalytic Pyrolysis of Tetra Pak over Acidic Catalysts

The thermal and catalytic pyrolysis of two kinds of Tetra Pak waste (TP-1 and TP-2) over three different acidic catalysts—HZSM-5(SiO2/Al2O3, 30), HBeta (38), and Al-MCM-41(20)—were investigated in this study. Tetra Pak (TP) wastes consist of composite material comprising kraft paper, polyethylene (PE) film, and aluminum foil. Thermal decomposition behaviors during the pyrolysis of TPs were monitored using a thermogravimetric (TG) analyzer and tandem micro reactor-gas chromatography/mass spectrometry (TMR-GC/MS). Neither the interaction between the non-catalytic pyrolysis intermediates of kraft paper and PE, nor the effect of aluminum foil have been monitored during the non-catalytic TG analysis of TPs. The maximum decomposition temperatures of PE in TP-1 shifted from 465 °C to 432 °C by HBeta(38), 439 °C by HZSM-5(30), and 449 °C by Al-MCM-41(20), respectively. The results of the TMR-GC/MS analysis indicate that the non-catalytic pyrolysis of TPs results in the formation of large amounts of furans and heavy hydrocarbons and they are converted efficiently to aromatic hydrocarbons over the acidic catalysts. Among the three catalysts, HZSM-5(30) produced the largest amount of aromatic hydrocarbons, followed by HBeta(38) and Al-MCM-41(20) owing to their different acidity and pore size. Compared to TP-1, TP-2 produced a larger amount of aromatic hydrocarbons via catalytic pyrolysis because of its relatively larger PE content. The synergistic formation of aromatic hydrocarbons was also enhanced during the catalytic pyrolysis of TPs due to the effective role of PE as hydrogen donor to kraft paper. In terms of their catalytic effectiveness, HZSM-5(30) had a longer lifetime than HBeta(38).

Green solvents in recovery of aluminium and plastic from waste pharmaceutical blister packaging

Pharmaceutical blister packages usually comprise of aluminium and plastic layers. Due to their multi-material structure, the discarded packages are typically landfilled, although when separated, both metallic and polymeric fractions would be recyclable. In the present study, separation of aluminium and polymeric layers of waste pharmaceutical blisters was conducted by exploitation of deep eutectic solvent (DES, lactic acid - choline chloride) and pure lactic acid, both of which are considered green solvents. The separation of aluminium and plastic was investigated at different temperatures, solvent concentrations, solid-liquid ratios and agitation speeds. The complete separation was achieved with both studied solvents. The fastest separation was obtained when temperature was increased, more solvent with respect to solid was used and when agitation was introduced to the system. The effect of solvent concentration varied depending on the used solvent. Separation by lactic acid was the fastest with pure solvent (90 wt%), and separation by DES was the fastest with diluted solvent (50 wt%) due to strong dissolution of aluminium and formation of aluminium lactate precipitate. Polyvinyl chloride (PVC) and acrylic based adhesive were detected in all the investigated samples. After the separation by pure DES, the recovered aluminium fraction was corroded, containing 65 wt% of aluminium and 23 wt% of oxygen whereas after lactic acid treatment, aluminium surfaces contained at its best about 95% of aluminium (aluminium foil contains 96% of Al). The results showed that the DES used and lactic acid can offer viable green separation methodology for aluminium and plastic from blister packages.

High adsorption performance for As(III) and As(V) onto novel aluminum-enriched biochar derived from abandoned Tetra Paks

In order to develop promising sorbents for value-added application of solid wastes, low-cost aluminum-enriched biochar was prepared from abandoned Tetra Pak used to hold milks, a paper-polyethylence-Al foil laminated package box, after acid pretreatment and subsequent slow pyrolysis under an oxygen-limited environment at 600 °C. The basic physicochemical properties of the resultant biochar were characterized and the sorption performance of aqueous As(III) and As(V) was investigated via batch and column sorption experiments. Carbon (49.1%), Ca (7.41%) and Al (13.5%) were the most abundant elements in the resultant biochar; and the specific surface area and the pH value at the point of zero charge (pHPZC) were 174 m² g^-1 and 9.3, respectively. Batch sorption showed excellent sorption performance for both As(III) (24.2 mg g^-1) and As(V) (33.2 mg g^-1) and experimental data were fitted well with Langmuir model for the sorption isotherms and pseudo-second order kinetic model for the sorption kinetics. The residual concentrations of As(V) after sorption were below the limited value of arsenic in WHO Guidelines for Drinking water Quality (0.01 mg L^-1) even if coexistence of PO₄^3-. Column sorption confirmed the high sorption performance for As(III) and As(V). So the slow pyrolysis of abandoned Tetra Paks as low-cost and value-added sorbents is a sustainable strategy for solid waste disposal and wastewater treatment.

Changing Tetra Pak: from waste to resource

In recent years, the problem caused by Tetra Pak waste (TPW) has became a topic of great concern to scientists and environmentalists, and commercial companies have also begun to take an interest in developing processes for tackling this issue. In this article, the challenges in the recycling of TPW are described. This article presents the major conclusions of previously published works focussed on the utilisation of TPW for energy and material purposes. The commercial utilisation of TPW is also described. Some suggestions for better recycling of TPW are given in the latter part of this work.