Membranska filtracija kao ekološki prihvatljiva metoda pročišćavanja sirovog biodizela

Abstract

Biodizel je prvo alternativno gorivo čija su fizikalno-kemijska svojstva regulirana odgovarajućim standardima: američkim ASTM D 6751 i europskim standardom EN 14214. Proces proizvodnje biodizela sastoji se od tri glavne faze: 1) pripreme sirovine, 2) transesterifikacije i 3) obrade produkta reakcije – pročišćavanje sirovog biodizela kako bi se zadovoljile specifikacije koje su navedene u prethodno spomenutim standardima. Proces pročišćavanja sirovog biodizela obično se provodi dvjema tehnikama: vlažnim i suhim pranjem. Najčešće primjenjivani postupak je mokro pranje. Glavni nedostatak u upotrebi vode u procesu pročišćavanja je stvaranje velike količine otpadne vode koja uvelike povećava troškove proizvodnje biodizela nakon čega slijedi sušenje proizvoda, što zahtijeva dodatni utrošak energije i vremena. Najveći nedostatak suhog pranja s različitim ionsko-izmjenjivačkim smolama je nemogućnost uklanjanja glicerola i metanola iz sirovog biodizela do onih granica koje su propisane EN 14214 te problem odlaganja iskorištenih ionsko-izmjenjivačkih smola. Zbog toga se kao alternativa postojećim tehnikama pročišćavanja pojavila primjena membranske tehnologije u procesu pročišćavanja biodizela. Membranska filtracija je ekološki prihvatljiva i zahtijeva manje energije. Membranskom filtracijom može se smanjiti udio glicerola, metanola i vode u biodizelu do količina propisanih standardima. U okviru ovog rada prikazan je kratki pregled mogućnosti primjene ultra i/ili mikrofiltracije u procesu pročišćavanja biodizela.

Membrane Technology for Energy Saving: Principles, Techniques, Applications, Challenges, and Prospects

“…This necessitates membrane cleaning to remove residual components and extend membrane life, efficiency, and repeatability. [ 146 ] In the context of developing membrane materials for biogas separation applications, the focus should shift toward improving compatibility with a broad spectrum of biogas components, prioritizing product stability over excessively high selectivity. Table 4 outlines the performance enhancement and effects of various nanofillers on membranes.…”

Biodiesel Refining and Processing Strategies

“…As glycerol and FAAE are immiscible due to their polarity differences, the lipid/oil droplets can be filtered through ceramic membranes owing to their large droplet size compared to the biodiesel [61]. These membranes have also been successful removing other common contaminants such as soap, to reach the quality defined in standard specifications [76]. However, it is often necessary to clean the membranes after each purification process either physically, chemically (hydrogen peroxide, chlorine, etc.…”

“…However, it is often necessary to clean the membranes after each purification process either physically, chemically (hydrogen peroxide, chlorine, etc. ), or hydraulically [77], to extend the reusability, efficiency, and repeatability of the membrane [76], otherwise, fouling and clogging can occur [74]. Furthermore, the membrane performance can be affected by physical operating parameters, including temperature requirements.…”

“…Furthermore, the membrane performance can be affected by physical operating parameters, including temperature requirements. Depending on membrane tolerance of operating conditions scale-up strategy and process design can be limited [76]. Computational modeling has also shown promising results in utilizing reverse osmosis filtration to remove impurities present in crude biodiesel [78].…”