Production of modified bentonite via adsorbing lignocelluloses from spent liquor of NSSC process

Naficy

et al. 2018

ACS Appl. Bio Mater.

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Lignin is a low-cost, natural polymer with abundant polar sites on its backbone that can be utilized for physical cross-linking of polymers. Here, we use lignin for additional cross-linking of hydrophilic polyether-based polyurethane (HPU) hydrogels, aiming to improve their mechanical properties and processability. Without reducing the swelling, simple addition of 2.5 wt % lignin increases the fracture energy and Young's modulus of HPU hydrogels from, respectively, 1540 ± 40 to 2050 ± 50 J m −2 and 1.29 ± 0.06 to 2.62 ± 0.84 MPa. Lignin also increases the lap shear adhesiveness of hydrogels and induces an immediate load recovery of 95%. We further confirm that hydrogen bonding is the dominant toughening mechanism and elucidate the toughening mechanism by applying the Lake-Thomas and a recently developed sequential debonding theory. We show that unlike the Lake−Thomas theory, the latter model is able to capture the impact of lignin on toughening of hydrogels. Moreover, the lignin-loaded HPU hydrogels are easily processable by various techniques, such as fiber spinning, casting, and 3D printing and are biocompatible with primary human dermal fibroblasts.

Section: ■ Results and Discussionmentioning

confidence: 99%

Section: Results and Discussionmentioning

confidence: 99%

Tough and Processable Hydrogels Based on Lignin and Hydrophilic Polyurethane

Naficy

et al. 2018

ACS Appl. Bio Mater.

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“…The hemicellulose (sugar) content of the SL was determined following 3,5‐dinitrosalicylic acid (DNS) method, as explained previously . However, the DNS reagent can only indicate monomeric sugars . In this regard, all samples were hydrolyzed in a 4 wt% sulfuric acid solution in a Haak‐S45 oil bath at 121°C for 1 h so that all oligomeric sugars were broken to monomeric sugars .…”

Section: Methodsmentioning

confidence: 99%

“…Previous studies reported that the extraction of lignocelluloses from SLs would significantly reduce the chemical oxygen demand (COD) and turbidity of lignocellulosic wastewater effluents . The application of lignocelluloses extracted from SL as an energy source, fillers, flocculants, composites and resins were reported in the past.…”

Section: Introductionmentioning

confidence: 99%

PDADMAC as a flocculant for lignosulfonate of NSSC pulping process

Sitter

Fatehi

2016

Biotechnology Progress

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The spent liquor (SL) of neutral sulfite semi-chemical (NSSC) pulping process contains about 8 wt% lignocelluloses that can be extracted and used in the production of value-added materials. In this work, a flocculation process followed by centrifugation was considered for isolating lignosulfonate and hemicelluloses from SL. It was observed that, by adding 20 mg/g of polydiallyldimethylammuniom chloride (PDADMAC) with 100,000-200,000 g/mol molecular weight to SL, 45% of lignosulfonate and 39% of hemicelluloses were removed at 30°C. The lignocellulose removal was more efficient for the dual flocculation system of low and high molecular weights PDADMAC than for individual PDADMAC systems. Overall, 49% of lignosulfonate, 47% of hemicelluloses and 97% of turbidity were removed from SL from the dual system when 10 mg/g low molecular weight PDADMAC and 10 mg/g high molecular weight PDADMAC were added to the SL at 30°C, subsequently. The thermogravimetric analysis (TGA) of generated flocs showed that all samples had similar thermal behaviour and 13-16 wt% of flocs remained as ash after burning at 700°C in nitrogen. As the flocs are made of lignocellulosic materials and they are thermally stable, they could be used as fillers in paper board production. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 32:686-691, 2016.

“…The temperature of these experiments was fixed at 30 °C, as an earlier study showed that the adsorption of lignin on activated carbon was the maximum at 30 °C . The stirring rate was chosen based on previous studies on SL and prehydrolysis liquor. ,,− However, more studies on the effect of stirring rate should be considered in order to investigate if the adsorption/coagulation process of lignocelluloses on fly ash were possible under different conditions. The treated SLs were centrifuged at 1000 rpm for 10 min using a Survall ST16 centrifuge.…”

Section: Materials and Methodsmentioning

confidence: 99%

Process for Treating Spent Liquor of the TMP Process with Biomass-Based Fly Ash

Fatehi

2015

Ind. Eng. Chem. Res.

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The spent liquor (SL) of the thermomechanical pulping (TMP) process has a high effluent load. In this work, biomass-based fly ash was used for adsorbing lignin of SL and thus for reducing the COD and turbidity of SL prior to sending SL to a wastewater treatment system. By treating SL with fly ash in a one-stage adsorption process under the conditions of a fly ash/ SL ratio of 55 mg/g and 3 h at 30 °C, 67 mg/g of lignin was adsorbed on fly ash at room temperature. Adjusting the pH of SL had an insignificant influence on the lignin isolation from the system but affected the turbidity of SL. The lignin removal was 68% in a two-stage fly ash adsorption process, while the COD and turbidity removal were 70% and 94%, respectively. On the basis of the results, a process for reducing the effluent load of SL using fly ash was proposed.