Sustain. Chem., Volume 1, Issue 1 (June 2020) – 6 articles

Dichlorodiphenyltrichloroethane (DDT) residue in Ontario soil is expected to be found at trace levels, since it has been banned for over 45 years in Canada. This presents challenges to the efficiency and accuracy of conventional detection methods. This study intensified the conventional DDT detection method, in the characterization of aged soil samples collected from historically-treated sites in Ontario. Recovery, time consumption, and labor intensity were considered for the intensification evaluation. Ultrasonic probe extraction was found to significantly shorten the extraction time, with similar yield compared to ultrasonic water bath extraction and homogenized extraction. Homogenized extraction for 24 h following ultrasonic probe extraction can increase yield over 27%. Rotary evaporator concentration was used, since it can reduce the operating time with comparable recovery. The Florisil clean-up column used in the conventional method was removed from the intensified method, due to its negligible effect and high time consumption. The intensified method may be valuable for further investigation to determine other trace level organochlorine pesticide residues in soil samples. Full article

Trialkyl-2,3-dihydroxypropylammonium chloride salts have been investigated as liquid eutectic-forming salts for the extraction of phenol from aromatic-rich model oil (toluene), demonstrating how the increased partitioning of phenol from oil-phases can be combined with reduced co-miscibility of the salt with aromatic hydrocarbons through the introduction of the dihydroxypropyl-function. Full article

Alkali-based CO₂ sorbents were prepared from a novel material (i.e., Laminaria hyperborea). The use of this feedstock, naturally containing alkali metals, enabled a simple, green and low-cost route to be pursued. In particular, raw macroalgae was pyrolyzed at 800 °C. The resulting biochar was activated with either CO₂ or KOH. KOH–activated carbon (AC) had the largest surface area and attained the highest CO₂ uptake at 35 °C and 1 bar. In contrast, despite much lower porosity, the seaweed-derived char and its CO₂-activated counterpart outweighed the CO₂ sorption performance of KOH–AC and commercial carbon under simulated post-combustion conditions (53 °C and 0.15 bar). This was ascribed to the greater basicity of char and CO₂–AC due to the presence of alkali metal-based functionalities (i.e., MgO) within their structure. These were responsible for a sorption of CO₂ at lower partial pressure and higher temperature. In particular, the CO₂–AC exhibited fast sorption kinetics, facile regeneration and good durability over 10 working cycles. Results presented in the current article will be of help for enhancing the design of sustainable alkali metal-containing CO₂ captors. Full article

Background: We have determined previously that the water extract of sugar maple bark contained an important quantity of a complex sugar. In this study, we investigated the organosolv pulping of pre-extracted bark to follow the acid conversion of sugars into major products, furfural and 5-hydroxymethyl-2-furfural (HMF), while comparing the structures of organosolv lignins. Methods: The bark particles were pre-extracted with an ethanol–water mixture or water only. The extractives-free barks were then converted into cellulosic pulp and lignin by a patented organosolv process. The composition of residual liquor was determined by using HPLC-UV. Results: The pre-extraction with water was more efficient for complex sugars recovery than with the ethanol–water system. HMF was determined to be more abundant in residual liquor than furfural after ethanol–water pre-extraction while their quantities were comparable in the residual liquor after water pre-extraction. The higher yield of HMF from ethanol–water pre-extracted bark (1.18%) than from water pre-extracted (0.69%) could be related to the efficiency of complex sugar removal during the pre-extraction step. Conclusions: The pre-extraction before pulping affected, at least in part, the composition of residual liquor in terms of HMF production. These results demonstrate how the bark can be converted into valuable products and intermediates for organic synthesis. Full article

Plastics are an indispensable material with numerous benefits and advantages compared to traditional materials, such as glass and paper. However, their widespread use has caused significant environmental pollution and most plastics are currently nonrenewable. Biobased polymers represent an important step for tackling these issues, however, the end-of-life disposal of such materials needs to be critically considered to allow for a transition to a circular economy for plastics. Poly(lactic acid) (PLA) is an important example of a biobased polymer, which is also biodegradable. However, industrial composting of PLA affords water and carbon dioxide only and in the natural environment, PLA has a slow biodegradation rate. Therefore, recycling processes are important for PLA, particularly chemical recycling, which affords monomers and useful platform chemicals, maintaining the usefulness and value of the material. This review covers the different methods of PLA chemical recycling, highlighting recent trends and advances in the area. Full article