Microwave-assisted co-pyrolysis of chlorella vulgaris and polypropylene: Characteristic and product distribution analyses

Utilizing Chlorella vulgaris algae as an eco-friendly coagulant for efficient removal of polyethylene microplastics from aquatic environments

Polyethylene (PE) microplastics (MPs) are small particles of plastic made from polyethylene, which is a commonly used type of plastic. These microplastics can be found in water sources, such as rivers, lakes, and oceans. They are typically less than 5 mm in size. Chlorella vulgaris (C. vulgaris) is an excellent, simple and inexpensive biocoagulant that can effectively remove a wide range of pollutants through the coagulation and flocculation mechanism. In this study, C. vulgaris algae were used to remove PE MPs. The experiments were designed using the Behnken Box model. The evaluated parameters were the initial PE concentration (100-400 mg/L), the C. vulgaris dose (50-200), and the pH (4-10). The findings showed that increasing the concentration of polyethylene had a positive effect on the efficiency of removal. In addition, the dose of C. vulgaris and pH parameters were inversely and directly related to removal efficiency, respectively. The highest removal efficiency was observed under alkaline conditions. Overall, the maximum PE removal efficiency was 84 % when the concentration of PE was 250 mg/L, the dose of C. vulgaris was 50 mg/L, and the pH was 10. It can be concluded that algae can be used as an environmentally friendly coagulant for effectively removing MPs from aquatic environments.

A systematic review on plastic waste conversion for a circular economy: recent trends and emerging technologies

Our biosphere has been adversely affected by plastic waste pollution, especially non-biodegradables in landfills, which induces hazardous chemical leaching and toxic gas emissions on burning into the atmosphere.

Microwave catalytic co-pyrolysis of Chlorella vulgaris and high density polyethylene over activated carbon supported monometallic: Characteristics and bio-oil analysis

Activated carbon (AC) has attracted much attention owing to its low cost and abundant sources. In this paper, three monometallic supported catalysts were prepared using AC as support (Ce/AC, Fe/AC, Ni/AC), and the effects of three catalysts on the microwave co-pyrolysis of Chlorella vulgaris (C. vulgaris) with high density polyethylene (HDPE) were studied. The results showed that the co-pyrolysis characteristics of C. vulgaris/HDPE = 1:1 (C1HP1) were significantly improved by three catalysts at high additions (>20 %). Among them, the C1HP1 group with 50 % Fe/AC addition had the shortest co-pyrolysis reaction time (2901 s). Besides, Ce/AC and Fe/AC have a promoting effect on bio-oil yields, while Ni/AC has an inhibiting effect. The maximum bio-oil yield (25.6 %) was obtained under 40 % addition of Fe/AC. Moreover, Ce/AC obtained the highest hydrocarbons content (66.68 %), while Fe/AC obtained the highest aromatic hydrocarbons content (36.64 %). Additionally, Ce/AC had the highest deoxygenation efficiency (47.33 %) and denitrification efficiency (42.28 %).

Microwave catalytic co-pyrolysis of chlorella vulgaris and oily sludge: Characteristics and bio-oil analysis

Co-pyrolysis of Chlorella vulgaris (CV) and Oily sludge (OS) under different mixing ratios were investigated by microwave furnace. NiO, activated carbon (AC) and their 1:1 compound (N1A1) with different additions (5%, 10%, 15% and 20%) were selected as microwave additives to study the effects on optimum mixing ratio of co-pyrolysis. The results indicated that mixing ratio of CV/OS = 1:1 (C1O1) was optimum for co-pyrolysis. Besides, 10% AC was optimal on improving pyrolysis characteristics of the C1O1 group. The most significant synergistic interaction of NiO and AC occurred in the 10% N1A1 group. Moreover, hydrocarbons in bio-oil of the C1O1 group increased by 31.84% compared with theoretical values, while nitrogenous, oxygenated compounds decreased by 74.18% and 19.01%. Addition of 10% N1A1 in the C1O1 group increased aliphatic hydrocarbons by 22.44%, and decreased nitrogenous, oxygenated compounds by 41.79% and 36.58%. Overall, 10% N1A1 was conducive for the C1O1 group to obtain high-quality bio-oil.

Study on co-pyrolysis and products of Chlorella vulgaris and rice straw catalyzed by activated carbon/HZSM-5 additives

The weight loss characteristics, product distribution and bio-oil composition of co-pyrolysis of rice straw (RS) and Chlorella vulgaris (CV) were investigated by microwave oven. Then, the catalytic effect of activated carbon (AC) and HZSM-5 on these characteristics were studied. Results showed that AC strongly improved co-pyrolysis weight loss characteristics and obtained maximum average weight loss rate (R_a) at 30% addition with 0.01639 wt.%/s. While HZSM-5 promoted the characteristics as addition was lower than 10%. In the case of compound additives, 20% A7H3 obtained the maximum R_a (0.01413 wt.%/s). Furthermore, both single AC and HZSM-5 showed negative effect on bio-oil production, while 20% A7H3 (AC/HZSM-5 = 7:3) achieved the maximum production (24%). For bio-oil composition, 30% A10H0 showed strong selectivity for phenol and N-heterocycle and 10% A0H10 showed strong aromatization capacity, and the addition of 20% A7H3 increased the hydrocarbons content from 20.79% to 31.63% compared with the blank group.