A new valorization route for Olive Mill wastewater: Improvement of durability of PP and PBS composites through multifunctional hybrid systems

Abstract

Olive Mill Wastewater (OMW) is a food waste stream resulting from the production of virgin olive oil, rich in valuable natural biocompounds, such as vanillic acid, ferulic acid, protocatechuic acid, etc. In order to decrease its environmental impact and to exploit the antioxidant properties of its phenol-type molecules, OMW was intercalated into ZnAl-LDH, as well as some biomolecules composing OMW, for a general concept purpose. Such organomodified LDHs were then employed for the preparation of poly(butylene succinate) (PBS) and polypropylene (PP) composites through melt blending, to obtain materials with improved antioxidant properties and, subsequently, a better durability. A full characterization of LDHs in terms of thermal stability (TGA), morphology (XRD) and chemical modification (FT-IR) has been carried out. The composites were exposed to UV irradiation through accelerated photo-ageing and the molecular modifications were scrutinized by IR spectroscopy, revealing a strong protective role of LDH hybrid filler against oxidative process.

Olive Mill Wastewater Valorization in Multifunctional Biopolymer Composites for Antibacterial Packaging Application

“…A full characterization of the prepared LDH samples, as well as the total organic compound (TOC) of the biowaste (4.51 ± 0.65 g GA eq/L, GA = gallic acid) were reported elsewhere [17]. Briefly, HPLC analysis revealed the presence of protocatechuic acid, vanillic acid, trans-cinnamic acid, gallic acid, and chlorogenic acid in OMW.…”

“…In the current study, 5 wt% of the organic/inorganic (O/I) hybrid fillers was employed to prepare PBS bionanocomposites by in situ polymerization, which is an effective method to reach a good state of dispersion for the LDH filler. Such loading was reported to be appropriate, in similar systems, to assure the persistence of bioactivity [16,17,21]. Scheme 1 shows the monomers employed and the conditions of the in situ polymerization process.…”

“…The LDHs were prepared by coprecipitation following a procedure described elsewhere [17] with OMW, VA, FA, and PA. Two co-intercalated LDHs with mixtures of FA + PA and VA + FA + PA were also prepared. Briefly, 50 mL of deionized water solution containing 31.2 mmol of Zn(NO 3 ) 2 ∙6H 2 O and 15.6 mmol of Al(NO 3 ) 3 ∙9H 2 O was added dropwise for 3 h in a reactor containing 62.4 mmol of the anion in 100 mL of ethanol/deionized water (60/40) under vigorous stirring.…”

“…In a previous work [17], olive mill wastewater (OMW), without any pretreatment, was successfully intercalated into a Zn 2 Al-LDH with the aim of enhancing the durability of polypropylene (PP) and poly(butylene succinate) (PBS) melt-blended composites. In the current study, the antibacterial and thermomechanical properties of similar systems have been further investigated.…”

“…OMW is a high-organic-load and recalcitrant waste stream of great environmental concern and its management is a very important issue in Mediterranean countries because of the huge amount of olives: more than 2.4 million tons/year, 90% of which is meant for olive oil production, thus generating up to 30 million m 3 per year of OMW [17,18]. The composition of OMW consists of 80–90% water, 4–16% organic compounds (such as tyrosol, hydroxytyrosol, p-coumaric acid, ferulic acid, syringic acid, protocatechuic acid, vanillic acid tannins, anthocyanins, etc.…”