A Comparative Study on the Thermal Stability of Lignin-PVA Composites Fabricated under Various Lignin Ratios

( Muhammad Ajaz Ahmed ),( Sadaf Mearaj ),( Joon Weon Choi ) 한국목재공학회 2021 한국목재공학회 학술발표논문집 Vol.2021 No.1

In this study the thermal stability of lignin-PVA composites incorporating epichlorohydrin as well as mxene has been investigated. Initially, a set of experiments was designed to screen out the most feasible soda lignin amount to be incorporated into PVA composites. Interestingly, under ambient convective cooling conditions, 10 wt.% soda lignin exhibited quite brittle and transparent characteristic features but without the addition of either any Epichlorohydrin or Mxene. However, upon the addition of Epichlorohydrin a gradual improvement in the physical features such as ductility as well as shape of the lignin-PVA composites was clearly observed. Additionally, a small amount of Mxene, etched from MAX powder, was added and there was a clear elongation and stretchable trend in the lignin-PVA-Mxene composite as compared with only lignin-PVA only composite. Finally, all the fabricated composites were subjected to thermal stability analysis. It was observed clearly that the addition of both the Epichlorohydrin and Mxene improved the thermal stability of the fabricated composites.

Optimization of twin gear-based pretreatment of rice straw for bioethanol production

Ahmed, Muhammad Ajaz,Rehman, Muhammd Saif Ur,Terá,n-Hilares, Ruly,Khalid, Saira,Han, Jong-In Elsevier 2017 Energy conversion and management Vol.141 No.-

<P><B>Abstract</B></P> <P>A laboratory twin-gear reactor (TGR) was investigated as a new means for the pretreatment of high solid lignocelluloses. Response surface methodology based on Box Behnken Design was used to optimize the enzymatic digestibility with respect to the pretreatment process variables: temperature of 50–90°C, NaOH concentration of 2–6% and no. of cycles of 30–60. The results revealed that the TGR-based pretreatment led to the significant structural alterations through increases in pore size, pore volume, cellulose crystallinity and surface area. SEM images also confirmed the surface modifications in the pretreated rice straw. A response surface quadratic model predicted 90% of the enzymatic digestibility, and it was confirmed experimentally and through the analysis of variance (ANOVA) as well. The TGR extrusion proved to be an effective means for exceedingly high solids lignocellulose.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Twin gear reactor is a continuous high solids pretreatment reactor. </LI> <LI> RSM was applied to optimize twin gear pretreatment for enzymatic digestibility. </LI> <LI> 89% enzymatic digestibility was achieved under optimum conditions. </LI> <LI> Thermomechanical pretreatment altered the structural features of rice straw. </LI> </UL> </P>

MXene-Lignin Composites for Energy Harvesting Applications from the Ambient Water

( Ahmed Muhammad Ajaz ),( Joon Weon Choi ) 한국목재공학회 2022 한국목재공학회 학술발표논문집 Vol.2022 No.1

Lignin is the second most abundant biorenewable feedstock available on the earth. This lignin, upon carbonisation, exhibits poor graphene like structure. This structure can be employed for energy harvesting applications. On the other hand, MXene is a new 2D materials that have quite good features in terms of their conductivity within the small pores. A combination under the synergism of MXene and lignin derived activated carbon can be a good possibility to harness energy from ambient environment. Therefore, in this study, lignin derived activated carbon was employed along with Mxene-carbon black composite to study their possibility for harnessing energy from ambient water. First, Mxene was etched via HF method from their MAX phase and its analyses such as FTIR, XRD and SEM images were performed to confirmed its successful formation. Lignin derived activated carbon was subjected to make a composite with Mxene & carbon black to finally fabricate a moisture driven power generator (MDPG) by coating the composite onto cellulosic sheets. Finally, the performance of the as prepared MDPG was measured by determining their open circuit voltage (Voc) and short circuit current (Isc). The highest voltage generation was measured as 750 mV and current as 12 μA employing lignin derived activated carbon & Mxene composite. It was also observed that the application of small amount of water 1 ml successfully initiated the moisture assisted power generation for almost 60 minutes in a one go. From here it can be suggested that the lignin derived activated carbon along with Mxene can be used for energy harvesting applications.

Mild Acidolysis Fractionation of Pinewood Biomass for Lignin Extraction

이자스 ( Muhammad Ajaz Ahmed ),최준원 ( Joon Weon Choi ) 한국목재공학회 2020 한국목재공학회 학술발표논문집 Vol.2020 No.1

Lignocelluloses are the most abundent and readily collectable biomass feedstcoks on this earth and even more with an enough theoratical potential to replace existing fossilfuels based economy. In their typical nature configuration, they are composed of polysaccharides as well as lignin. This lignin is the second most abundant component in their structure and is often a biorefinery waste in a typical 2G bioethanol production schemes. This lignin, actually, is a rich diverse feedstock for the production of various composites, sustainable materials, epoxies and even can be used in medicine and for drug delivery. For this lignin to be isolated with as much little modification as possible is still a challenge for the establishment of lignin-first 2G biorefineries. Therefore, we are trying to adapt and develop such processes that are able to extract/ isolate lignin from the native structure with least and/or no modification. We are applying several organsolv fractionation processes like a green solvent gamma valerolactone (GVL), ethanol, acetone, dioxane and combinations of ethanol, GVL, dioxane and acetone and the synergetic effects of GVL, ethanol under mild acidic and thermal conditions. We have used mild temperature conditions ranging from 50 °C to 90 °C and time ranges from 3 hrs to 6 hrs. In order to induce mild acidic conditions Hcl was employed as a catalyst with few drops only. The lignin fractions separated via this method are subjected to their qualitative analyses such as (Defunctionalization Followed by Random Carbonization) DFRC and Gel permeation chromatography (GPC) to further sort out any clue with their effect on lignin purity and yield.

Physicochemical Characterization of Chemically Modified Lignin/PLA Bio Composites for Active Food Packaging Applications

( Sadaf Mearaj ),( Ahmed Muhammad Ajaz ),( Joon Weon Choi ) 한국목재공학회 2022 한국목재공학회 학술발표논문집 Vol.2022 No.1

In this study soda lignin (SL) and acetylated soda lignin (ASL) were used to develop composites for food packaging applications. Both SL and ASL were mixed with PLA in different concentrations (5%, 10%, 15%, 20%, 25% and 30%) by a twin-screw extruder. PLA, PLA/SL and PLA/ASL composites were analyzed via Fourier transform infrared spectroscopy (FT-IR), SEM, tensile test, thermogravimetric analysis, UV-analysis, anti-oxidant, anti-microbial test and water contact angle (WCA). ASL reduced the size of lignin aggregates in the PLA matrix leading to improvement of tensile properties of all the PLA/ASL composites. The Tonset of ASL (296 ℃) was higher than SL (257 ℃) because of the higher thermal stability of ASL, all the PLA/ASL composites had higher Tonset than PLA/SL composites. PLA/SL10, PLA/SL15, PLA/SL20 showed UV-transmittance of less than 10% at 400nm demonstrating excellent UV-protection. The UV-transmittance of PLA/ASL composites was higher than PLA/SL composites. The result of the anti-oxidant test showed that the anti-oxidant properties of all the PLA/SL composites increased with increasing lignin content. PLA/SL10, PLA/SL15 and PLA/SL20 showed RSA (%) of around 30%, 58% and 86% respectively. This study demonstrates the potential of lignin for food packaging applications because of its excellent UV-shielding and anti-oxidant properties.

A novel method for the fabrication of silver nanowires-based highly electro-conductive membrane with antifouling property for efficient microalgae harvesting

Mushtaq, Azeem,Cho, Hoon,Ahmed, Muhammad Ajaz,Rehman, Muhammad Saif Ur,Han, Jong-In Elsevier 2019 Journal of membrane science Vol.590 No.-

<P><B>Abstract</B></P> <P>In this study, a new method of fabricating highly electro-conductive membranes, namely electroplating, was developed and its product performance was examined via microalgae harvesting. In this method, a layer of silver nanowires (AgNWs) was first vacuum-deposited on a poly(ether sulfone) support, followed by electroplating of silver layer. The electroplated membrane (C-AgNWs) found to exhibit surpassingly enhanced electrical conductivity (3.9 × 10<SUP>4</SUP> S/cm) and a satisfactory level of mechanical stability under prolonged filtration. When microalgae, <I>Chlorella</I> sp. HS-2, was harvested via electro-filtration, the membrane exhibited the intended effect of fouling mitigation, both in continuous and intermittent electric fields. This was attributed to the enhanced electrostatic repulsive forces between foulants and membrane along with in-situ electro-bubble generation from the membrane, reducing the overall blockage of the membrane surface. The intermittent mode was able to effectively mitigate fouling and recover flux to its initial level, with the effect compromised in successive steps. The continuous mode, however, did not display such performance degradation over time, but an increase of 480% in permeate flux at 20 V/mm. All this supported that the electroplating can serve as a promising route for the sake of fabricating the workable electro-membranes, conductive membranes that have boundless application potentials.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Electroplating can be a useful method for workable electro-membrane fabrication. </LI> <LI> Highly electro-conductive (3.9 × 10<SUP>4</SUP> S/cm) yet stable electro-membrane can be synthesized by this method. </LI> <LI> The AgNWs-based electroplated membrane can be used for efficient microalgae harvesting. </LI> <LI> The fabricated membrane can exhibit good antifouling property in continuous and intermittent modes of electro-filtration. </LI> </UL> </P>

Strengthening calcium alginate microspheres using polysulfone and its performance evaluation: Preparation, characterization and application for enhanced biodegradation of chlorpyrifos

Khalid, Saira,Han, Jong-In,Hashmi, Imran,Hasnain, Ghalib,Ahmed, Muhammad Ajaz,Khan, Sher Jamal,Arshad, Muhammad Elsevier 2018 Science of the Total Environment Vol.631 No.-

<P><B>Abstract</B></P> <P>Bacterial cell immobilization offer considerable advantages over traditional biotreatment systems using free cells. Calcium alginate matrix usually used for bacterial immobilization is susceptible to biodegradation in harsh environment. Current study aimed to produce and characterize stable macrocapsules (MCs) of Chlorpyrifos (CP) degrading bacterial consortium using biocompatible calcium alginate matrix coupled with environmentally stable polysulfone. In current study bacterial consortium capable of CP biodegradation was immobilized using calcium alginate in a form of microcapsule (MC) reinforced by being coated with a synthetic polymer polysulfone (PSf) through phase inversion. Consortium comprised of five bacterial strains was immobilized using optimized concentration of sodium alginate (2.5gL<SUP>−1</SUP>), calcium chloride (6gL<SUP>−1</SUP>), biomass (600mgL<SUP>−1</SUP>) and polysulfone (10gL<SUP>−1</SUP>). It has been observed that MCs have high thermal, pH and chemical stability than CAMs. In synthetic media complete biodegradation of CP (100–600mgL<SUP>−1</SUP>) was achieved using macrocapsules (MCs) within 18h. CAMs could be reused effectively only upto 5cycles, contrary to this MCs could be used 13 times to achieve more than >96% CP degradation. Shelf life and reusability studies conducted for MCs indicated unaltered biomass retention and CP biodegradation activity (95%) over 16weeks of storage. MCs achieved complete biodegradation of CP (536mgL<SUP>−1</SUP>) in real industrial wastewater and reused several times effectively. Metabolites (3,5,6-trichloro-2-pyridinol (TCP), 3,5,6-trichloro-2-methoxypyridine (TMP) and diethyl-thiophosphate (DETP) were traced using GC–MS and possible metabolic pathway was constructed. Study indicated MCs could be used for cleanup of CP contaminated wastewater repeatedly, safely, efficiently for a longer period of time.</P> <P><B>Highlights</B></P> <P> <UL> <LI> MCs were more tolerant to temperature, pH and chemically harsh environment than CAMs. </LI> <LI> MCs can be used for complete biodegradation of CP upto 600mgL<SUP>−1</SUP>. </LI> <LI> CAMs can be reused for 5cycles only whereas MCs could be reused for 13 times. </LI> <LI> MCs have shelf life upto 16weeks with unaltered cell retention and CP biodegradation activity. </LI> <LI> MCs have potential to protect cells from shock loads of metal ions and organic solvents. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Hydrodynamic cavitation-assisted alkaline pretreatment as a new approach for sugarcane bagasse biorefineries

Terá,n Hilares, Ruly,dos Santos, Jú,lio Cé,sar,Ahmed, Muhammad Ajaz,Jeon, Seok Hwan,da Silva, Silvio Silvé,rio,Han, Jong-In Elsevier 2016 Bioresource technology Vol.214 No.-

<P><B>Abstract</B></P> <P>Hydrodynamic cavitation (HC) was employed in order to improve the efficiency of alkaline pretreatment of sugarcane bagasse (SCB). Response surface methodology (RSM) was used to optimize pretreatment parameters: NaOH concentration (0.1–0.5M), solid/liquid ratio (S/L, 3–10%) and HC time (15–45min), in terms of glucan content, lignin removal and enzymatic digestibility. Under an optimal HC condition (0.48M of NaOH, 4.27% of S/L ratio and 44.48min), 52.1% of glucan content, 60.4% of lignin removal and 97.2% of enzymatic digestibility were achieved. Moreover, enzymatic hydrolysis of the pretreated SCB resulted in a yield 82% and 30% higher than the untreated and alkaline-treated controls, respectively. HC was found to be a potent and promising approach to pretreat lignocellulosic biomass.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Hydrodynamic cavitation (HC) was combined with an alkaline pretreatment. </LI> <LI> HC-assisted pretreatment was statistically optimized and experimentally verified. </LI> <LI> High enzymatic digestibility of 97.2% was achieved. </LI> <LI> The HC increased enzymatic digestibility by 30%. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>