Recovery of saccharides from lignocellulosic hydrolysates using nanofiltration membranes: A review

Green process for xylo-oligosaccharide production from acetic acid hydrolysis of sugarcane bagasse by an integrated membrane technology and activated carbon adsorption

Xylooligosaccharides (XOS), consisting 2-6 xylose residues, are a new type of prebiotic and functional oligosaccharides, and can usually be produced from the xylan-riched lignocellulosic biomass by acetic acid (HAc) hydrolysis, while the waste HAc was a problem to the environment. In this study, the main aim was to recover and reuse the waste HAc in XOS production. First, it was found that a temperature of 190 °C and a hydrolysis time of 60 min were favorable for XOS production by HAc hydrolysis, and the by-products xylose and furfural were the main inhibitors, hindering the reuse of the waste HAc. Then, xylose can be successfully decreased below to its inhibition concentration (i.e., 0.05 g/L) by a two-stage NF90 membrane process under 25 °C. After diafiltering the NF90 retentate using a triploid volution of a HCl-solution of pH 2.37, the total HAc recovery rate reached 82.87%. Moreover, after the recovered HAc solution was further treated with 25 g/L activated carbon under 25 °C and pH regulator with glacial HAc to 2.37 wherein the furfural concentration was below 0.015 g/L, the recovered HAc solution can be successfully reused in XOS production without affecting the XOS production. Thus, in the developed integrated process, it replaced 82.87% of the pristine HAc with the recovered HAc and simplified extraction process of XOS by HAc hydrolysis on an industrial scale.

Development of a Non-Covalent Molecularly Imprinted Polymer via Precipitation Method for the Selective Separation of D-Xylose From Sugarcane Residues

The agro-industry generates substantial waste, necessitating eco-friendly solutions. This study introduces a novel molecularly imprinted polymer (MIPs) for the selective separation of D-xylose from sugarcane residues. A non-covalent imprinted polymer was synthesized via precipitation and optimized through D-xylose adsorption assays. The polymer demonstrated an Imprinting Factor of 3.34, adsorption equilibrium within 30 min, notable reusability retaining over 95% of its adsorption capacity after three cycles, and high selectivity coefficients (α > 2.00) for all saccharides tested. The adsorption isotherm followed the Langmuir model. Characterization confirmed successful imprinting, with the imprinted polymer exhibiting a surface area of 69.4 m2/g and pore volume of 0.26 cm3/g, compared to 8.7 m2/g and 0.03 cm3/g for the non-imprinted polymer. D-xylose separation was tested using hemicellulosic hydrolysate from sugarcane straw and bagasse. The polymer applied as a sorbent in dispersive solid-phase extraction with the hydrolysate achieved 90.29 ± 1.27% D-xylose adsorption. Desorption in pure water recovered 81.48 ± 1.22% of the adsorbed D-xylose. This method advances separation techniques, offering an efficient solution for sample pre-treatment and expanding the application of MIPs.

Innovative Trends in Modified Membranes: A Mini Review of Applications and Challenges in the Food Sector

Membrane technologies play a pivotal role in various industrial sectors, including food processing. Membranes act as barriers, selectively allowing the passage of one or other types of species. The separation processes that involve them offer advantages such as continuity, energy efficiency, compactness of devices, operational simplicity, and minimal consumption of chemical reagents. The efficiency of membrane separation depends on various factors, such as morphology, composition, and process parameters. Fouling, a significant limitation in membrane processes, leads to a decline in performance over time. Anti-fouling strategies involve adjustments to process parameters or direct modifications to the membrane, aiming to enhance efficiency. Recent research has focused on mitigating fouling, particularly in the food industry, where complex organic streams pose challenges. Membrane processes address consumer demands for natural and healthy products, contributing to new formulations with antioxidant properties. These trends align with environmental concerns, emphasizing sustainable practices. Despite numerous works on membrane modification, a research gap exists, especially with regard to the application of modified membranes in the food industry. This review aims to systematize information on modified membranes, providing insights into their practical application. This comprehensive overview covers membrane modification methods, fouling mechanisms, and distinct applications in the food sector. This study highlights the potential of modified membranes for specific tasks in the food industry and encourages further research in this promising field.

Construction of Clostridium tyrobutyricum strain and ionic membrane technology combination pattern for refinery final molasses recovery and butyric acid production

Introduction

Clostridium tyrobutyricum has considerable prospect in the production of organic acids. Globally, refinery final molasses is rich in sugar and reported to have high levels of accumulation and high emission costs, recognized as an excellent substrate for C. tyrobutyricum fermentation, but there is no suitable method available at present.

Methods

In this study, an acid-base treatment combined with a new green membrane treatment technology - a dynamic ion-exchange membrane -was used to pretreat refinery final molasses, so that it could be used for C. tyrobutyricum to produce butyric acid. A high-performance liquid chromatography method was established to determine the conversion of a large amount of sucrose into fermentable sugars (71.88 g/L glucose and 38.06 g/L fructose) in the treated refinery final molasses. The process of sequential filtration with 3, 1, and 0.45 μm-pore diameter dynamic ion-exchange membranes could remove impurities, pigments, and harmful substances from the refinery final molasses, and retain the fermentable sugar.

Results and discussion

This means that refinery final molasses from the sugar industry could be utilized as a high-value by-product and used for the growth of C. tyrobutyricum, with industrial feasibility and economic competitiveness. Using the treated refinery final molasses as a carbon source, C. tyrobutyricum was screened by the method of adaptive evolution. The strain with butyric acid yielded 52.54 g/L, and the yield of the six carbon sugar was increased from 0.240 to 0.478 g/g. The results showed that combination of C. tyrobutyricum and ionic membrane technology broke through the bottleneck of its utilization of refinery final molasses. This study provided an innovative idea for the C. tyrobutyricum fermentation to produce butyric acid.

Inhibitor formation and detoxification during lignocellulose biorefinery: A review

For lignocellulose biorefinery, pretreatment is needed to maximize the cellulose accessibility, frequently generating excess inhibitory substances to decline the efficiency of the subsequent fermentation processes. This mini-review updates the current research efforts to detoxify the adverse impacts of generated inhibitors on the performance of biomass biorefinery. The lignocellulose pretreatment processes are first reviewed. The generation of inhibitors, furans, furfural, phenols, formic acid, and acetic acid, from the lignocellulose, with their action mechanisms, are listed. Then the detoxification processes are reviewed, from which the biological detoxification processes are noted as promising and worth further study. The challenges and prospects for applying biological detoxification in lignocellulose biorefinery are outlined. Integrated studies considering the entire biorefinery should be performed on a case-by-case basis.

Preparation of boronic acid and carboxyl-modified molecularly imprinted polymer and application in a novel chromatography mediated hollow fiber membrane to selectively extract glucose from cellulose hydrolysis

A novel boronic acid and carboxyl-modified glucose molecularly imprinted polymer (glucose-MIP) was prepared through suspension polymerization, which is based on 1.0 mmol glucose as a template, 1.2 mmol methacrylamidophenylboronic acid, and 6.8 mmol methacrylic acid as monomers, 19 mmol ethyleneglycol dimethacrylate, and 1 mmol methylene-bis-acrylamide as crosslinkers. The prepared glucose-MIP had a particle size of 25-70 μm, and was thermally stable below 215°C, with a specific surface area of 174.82 m^2. g^-1 and average pore size of 9.48 nm. The best selectivity between glucose and fructose was 2.71 and the maximum adsorption capacity of glucose-MIP was up to 236.32 mg^. g^-1 which was consistent with the Langmuir adsorption model. The similar adsorption abilities in 6 successive runs and the good desorption rate (99.4%) verified glucose-MIP could be reused. It was successfully used for extracting glucose from cellulose hydrolysis. The adsorption amount of glucose was 2.61 mg^. mL^-1 and selectivity between glucose and xylose reached 4.12. A newly established chromatography (glucose-MIP) mediated hollow fiber membrane method in time separated pure glucose from cellulose hydrolysates on a large-scale, and purified glucose solution with a concentration of 3.84 mg^. mL^-1 was obtained, which offered a feasible way for the industrial production of glucose from cellulose hydrolysates. This article is protected by copyright. All rights reserved.

Membrane applications in the food industry

Current trends in the food industry for the application of membrane techniques are presented. Industrial solutions as well as laboratory research, which can contribute to the improvement of membrane efficiency and performance in this field, are widely discussed. Special attention is given to the main food industries related to dairy, sugar and biotechnology. In addition, the potential of membrane techniques to assist in the treatment of waste sources arising from food production is highlighted.