Forward Black Liquor Acid Precipitation: Lignin Fractionation by Ultrafiltration.

Lignin recovery from black liquor is an important task for producing valuable chemical products. Acidification processes are currently applied by pulp and paper industries for black liquor treatment, in which two main streams are produced: the precipitated lignin fraction and a lignin-lean black liquor. Membrane filtration is a suitable alternative for lignin recovery from black liquor, but studies on lignin-lean black liquor filtration are scarce. Here, we evaluated the ultrafiltration process for lignin recovery from the both fractions of black liquor acidification. The lignin-lean black liquor presented 22 wt% of total solids with 4.6 wt% of lignin. Lignin retention from the lignin-lean black liquor by the 5 kDa ultrafiltration membrane was equal to 85%, with reduction in total solid concentration from 219.8 to 68.1 g L-1. Due to the relatively high solid concentration in the lignin-lean black liquor, cake formation was the main fouling mechanism during ultrafiltrations. The precipitated lignin solution presented 4.8 wt% of total solids with equivalent lignin concentration (4.7 wt%). The used membrane was able to retain almost 100% of solids and lignin from the solution prepared from the precipitated lignin. All fouling mechanisms were responsible for flux decay in ultrafiltration of the precipitated lignin solution. Steady state fluxes for lignin-lean black liquor and precipitated lignin solution were 0.9 and 15.9 L h-1 m-2, respectively. According to TGA analyses up to 800 °C, precipitated lignin and lignin-lean black liquor presented total mass losses of 63.5% and 44.3%, respectively. Also, the permeate samples presented lower mass losses than their respective feed samples. The ultrafiltration process reduced the average weight molar mass (Mw) of the precipitated lignin solution and lignin-lean black liquor from 1817 to 486 g mol-1and from 2876 to 1095 g mol-1, respectively. Thus, the 5 kDa ultrafiltration membrane was efficient for lignin recovery from the lignin-lean black liquor, while membranes with lower cut-off should be proposed for lignin purification from the precipitated fraction.

Kraft lignin fractionation by organic solvents: Correlation between molar mass and higher heating value.

The new concept of integrated biorefineries has significantly changed pulp and paper industries. Lignin, which until then was only burned to generate energy, is now an important raw material for new products production. Kraft lignin (KL) fractions obtained by sequential fractionation with five organic solvents. This sequence allows to extract fractions from lower molar mass to higher molar one, resulting in more homogeneous samples. Lignin's fractions were characterized by FTIR, GPC, TGA and Higher Heating Value (HHV). HHV for KL was 24966, the lowest being 17,891 (F5) and the highest being 27051 J/g (F1), inversely proportional to the molar masses of fractions. This is a very important result indicating that the lower HHV fractions can be used for certain applications, such as antioxidants, additives, polymers, among others, adding value to kraft lignin. Fractions with higher HHV could be used for energy generation in the cellulose paper industry.

Biological properties of volatile oil from Brazilian brown propolis

ABSTRACT Propolis, is a bee product collected from exudates and flower buds of several plants, has strong aroma and several biological applications. This study aimed at evaluating the chemical composition and in vitro antioxidant, antibacterial and cytotoxic properties of volatile oil from Brazilian brown propolis. It was extracted by hydrodistillation and analyzed by gas chromatography-flame ionization detection and gas chromatography-mass spectrometry. Volatile oil from brown propolis exhibited strong antibacterial activity against H. pylori (MIC 3.25 µg/ml), Mycobacterium tuberculosis (MIC 50 µg/ml) and M. avium (MIC 62.5 µg/ml). It was evaluated in vitro for antioxidant activity by DPPH (IC50 25.0 µg/ml) and ABTS (IC50 30.1 µg/ml) methods. Its cytotoxic property was evaluated in normal (human fibroblasts, GM07429A) and tumor (MCF-7-human breast adenocarcinoma; HeLa-human cervical adenocarcinoma and M059J-human glioblastoma) cell lines. IC50 values were 81.32 µg/ml for GM07429A and 85.00, 129.40 and 84.12 µg/ml for MCF-7, HeLa and M059J cells, respectively. Three major dereplicated components of volatile oil from brown propolis were acetophenone (15.2%), nerolidol (13.3%), and spathulenol (11.6%). Our results contribute to a better understanding of the chemical and biological properties of Brazilian brown propolis and provide evidence for its potential medicinal use.