Redox-mediated polymerization and removal of benzidine from model wastewater catalyzed by immobilized peroxidase

Peroxidase from Momordica charantia was highly effective, active and stable for the oxidation of benzidine from model wastewater. There was no oxidative polymerization of benzidine without any redox mediator. Various experimental parameters were standardized for the maximum oxidation of benzidine by peroxidase. The maximum oxidation of this pollutant was observed in the presence of 0.05 mM phenol, 0.75 mM H2O2 and 0.2 U mL-1 bitter gourd peroxidase (BGP) in a buffer of pH 5.0 at 40°C. Comparative study was performed by soluble as well as surface immobilized bitter gourd peroxidase on Con A layered calcium alginate-starch beads for the degradation of benzidine from model wastewater. Immobilized bitter gourd peroxidase was used for the successful and effective removal of water polluted with benzidine in batch as well as in continuous reactor. The effect of detergents and some water miscible organic solvent was also reported for the oxidation of benzidine from polluted water. Oxidation of benzidine in batch process by soluble and immobilized peroxidase was highly effective and it could remove 72 and 100% benzidine by soluble and immobilized bitter gourd peroxidase, respectively. The reactor filled with immobilized enzyme retained more than 45% benzidine removal efficiency even after 30 days of its continuous operation. The absorption spectra of the treated benzidine exhibited a marked difference in absorption at its λmax as compared to untreated benzidine polluted water.Keywords: Alginate, bitter gourd peroxidase, concanavalin A, removal, immobilizatio

Isolation and characterization of nanocrystalline cellulose from roselle-derived microcrystalline cellulose

Roselle fiber is a renewable and sustainable agricultural waste enriched with cellulose polysaccharides. The isolation of Nanocrystalline cellulose (NCC) from roselle-derived microcrystalline cellulose (MCC) is an alternative approach to recover the agricultural roselle plant residue. In the present study, acid hydrolysis with different reaction time was carried out to degrade the roselle-derived MCC to form NCC. The characterizations of isolated NCC were conducted through Fourier Transform Infrared Ray (FTIR), Transmission Electron Microscopy (TEM), Field Emission Scanning Electron Microscopy (FESEM), Atomic Force Microscopy (AFM), Dynamic Light Scattering (DLS), Energy Dispersive Spectroscopy (EDS), X-ray Diffraction (XRD), Thermogravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC). As evaluated from the performed morphological investigations, the needle-like shape NCC nanostructures were observed under TEM and AFM microscopy studies, while irregular rod-like shape of NCC was observed under FESEM analysis. With 60 min hydrolysis time, XRD analysis demonstrated the highest NCC crystallinity degree with 79.5%. In thermal analysis by TGA and DSC, the shorter hydrolysis time tended to produce NCC with higher thermal stability. Thus, the isolated NCC from roselle-derived MCC has high potential to be used in application of pharmaceutical and biomedical fields for nanocomposite fabrication

Poly(lactic acid)/poly(butylene succinate) dual-layer membranes with cellulose nanowhisker for heavy metal ion separation

In this study, poly(lactic acid) (PLA)/poly(butylene succinate) (PBS) dual-layer membranes filled with 0–3 wt% cellulose nanowhisker (CNWs) were fabricated with aim to remove metal ions from wastewater. An integrated method was employed in the membrane fabrication process by combining water vapor-induced and crystallization-induced phase inversions. The membrane thickness was measured in between 11 and 13 μm, which did not pose significant flux deviation during filtration process. The 3% CNW filled membrane showed prominent and well-laminated two layers structure. Meanwhile, the increase in CNWs from 0 to 3% loadings could improve the membrane porosity (43–74%) but reducing pore size (2.45–0.54 μm). The heat resistance of neat membrane enhanced by 1% CNW but decreased with loadings of 2–3% CNWs due to flaming behavior of sulphated nanocellulose. Membrane with 3% CNW displayed the tensile strength (23.5 MPa), elongation at break (7.1%), and Young's modulus (0.75 GPa) as compared to other samples. For wastewater filtration performance, the continuous operation test showed that 3% CNW filled membrane exhibited the highest removal efficiency for both cobalt and nickel metal ions reaching to 83% and 84%, respectively. We concluded that CNWs filled dual-layer membranes have potential for future development in the removal of heavy metal ions from wastewater streams

Celluphot: hybrid cellulose : bismuth oxybromide membrane for pollutant removal

The simultaneous removal of organic and inorganic pollutants from wastewater is a complex challenge and requires usually several sequential processes. Here, we demonstrate the fabrication of a hybrid material that can fulfill both tasks: i) the adsorption of metal ions due to the negative surface charge, and ii) photocatalytic decomposition of organic compounds. The bio-inorganic hybrid membrane consists of cellulose fibers to ensure mechanical stability and of Bi4O5Br2/BiOBr nanosheets. The composite is synthesized at low temperature of 115 °C directly on the cellulose membrane (CM) in order to maintain the carboxylic and hydroxyl groups on the surface that are responsible for the adsorption of metal ions. The composite can adsorb both Co(II) and Ni(II) ions and the kinetic study con- firmed a good agreement of experimental data with the pseudo-second-order equation kinetic model. CM/Bi4O5Br2/BiOBrshowed higher affinity to Co(II) ions than to Ni(II) ions from diluted aqueous solutions. The bio-inorganic composite demonstrates a synergistic effect in the photocatalytic degradation of rhodamine B by exceeding the removal efficiency of single components. The fabrication of the biologic-inorganic interface was confirmed by various analytical techniques including SEM, STEM EDX mapping, XRD, and XPS. The presented approach for controlled formation of the bio-inorganic interface between natural material (cellulose) and nanoscopic inorganic materials of tailored morphology (Bi-O-Br system) enables the significant enhancement of materials functionality

Nanocellulose based affinity membranes for water purification: Processing technologies for optimal adsorption of dyes and metal ions

The aim of current study was to fabricate high flux affinity membrane with mechanical stability, porosity and high functionality for capturing of contaminants (dyes and metal ions) from water. Cellulose nanocrystals (CNCSL) and cellulose nanofibers (CNFSL) as well as a special grade of cellulose nanocrystals (CNCBE) isolated following bioethanol pilot scale process were used for the membrane fabrication. To improve the functionality and adsorption capacity of the membranes, enzymatic phosphorylated CNCSL (PCNCSL) and in situ TEMPO functionalized CNCBE (TEMPO-CNCBE) membranes were adopted. The removal of water contaminants via adsorption on carboxyl, sulphonic and phosphoryl functional groups on nanocellulose based membranes was evaluated. Freeze-drying was used as one approach to fabricate CNCSL based hybrid membranes. In spite of high percentage removal of positively charges dyes, low water flux and mechanical stability was recorded. Very fast and effective process, viz. vacuum-filtration was further used to fabricate layered membranes with improved mechanical properties. CNFSL based support layer was coated with more functional nanomaterials (CNCSL and CNCBE) via dipping. The study showed that it was possible to tailor the specific surface area, pore sizes, water flux and wet strength of the membranes based on drying conditions (105 °C at a load of 100kN and 28 oC at ≈20N) and acetone treatment. This study was further extended to fabricate high flux bi-layered membrane having support layer of micro-sized cellulose sludge and top layer of CNCSL, CNCBE and PCNCSL within gelatin matrix for adsorption. The aim of this approach was to provide mechanical stability without decreasing the water flux significantly. In the final study, to increase the adsorption capacity of CNCBE layered membranes; in situ functionalization (TEMPO oxidation) of top layer was performed. Furthermore, CNFSL was introduced in support layer to understand the structural and functional behavior of CNFSL. All membranes were subjected to pollutants removal [dyes and Ag(I), Cu(II), Fe(II)/Fe(III) metal ions]. Remarkable increase in adsorption capacity towards metal ions was recorded after modification of nanocellulose (phosphorylation and in situ functionalization). The outstanding performance of nanocellulose reveals the possibility of next generation affinity membranes for water purification.Godkänd; 2016; 20160509 (zohkar); Nedanstående person kommer att disputera för avläggande av teknologie doktorsexamen. Namn: Zoheb Karim Ämne: Trä och bionanokompositer /Wood and Bionanocomposites Avhandling: Nanocellulose Based Affinity Membranes for Water Purification: Processing Technologies for Optimal Adsorption of Dyes and Metal Ions Opponent: Professor Monica Ek, Avd för träkemi och massateknologi, Skolan för kemivetenskap, Kungliga tekniska högskolan, Stockholm. Ordförande: Biträdande professor Aji Mathew, Avd för materialvetenskap, Institutionen för teknikvetenskap och matematik, Luleå tekniska universitet, Luleå. Tid: Torsdag 16 juni, 2016 kl 10.00 Plats: E632, Luleå tekniska universite

Processing and characterization of membranes based on cellulose nanocrystals for water purification : Nanocellulose as functional entity

Membrane technology is being extensively used in water purification as an energy efficient and low cost process. Nanostructured (NSM) and nanoenabled (NEM) membranes are favored in this context as nanoscaled entities are expected to provide high surface area, high mechanical properties and versatile surface chemistry as well as provide better control on the pore size and distribution, flux and selectivity of the membrane. Biobased nanoparticles as nanocrystals are expected to have a significant advantage in this context. Thus, the main aim of this work was to explore the use of cellulose nanocrystals as functional entities for the fabrication of nanoenabled composite membranes and apply these fabricated membranes for the removal of dyes and metal ions from polluted water. The first study deals with the isolation of cellulose nanocrystals (CNCBE) from wood using the bioethanol pilot scale setup. Cellulose was prepared from wood by diluted acid treatment in the bioethanol plant followed by dewaxing and bleaching. The cellulose was converted into cellulose nanocrystals by mechanical grinding using lab scale homogenizer. The isolated nanoparticles had a diameter of 5-15 nm and formed a thick gel at 2 wt%. X-ray photoelectron spectroscopy illustrated the presence of O=C-O surface functional groups, directly related to the negative zeta-potential values. Fabricated films of CNCBE denoted good mechanical properties, optical properties and cytocompatibility. Thus, a new isolation route that can be followed to produce nanocrystals in large quantities (600 g/ day) has been developed. In a second study, fully biobased nanocomposite membranes of cellulose nanocrystals and chitosan have been fabricated by freeze-drying and crosslinking with gluteraldehyde in vapor phase. The chitosan bound the CNCSL in a stable and nanoporous membrane network with thickness of 250-270 μm. Homogenous dispersion of CNCSL within chitosan matrix was reported based on scanning electron microscopy (SEM). The Brunauer Emmett and Teller (BET) studies showed a decrease in surface area (3.1 to 2.9 m2/g) and average pore size (17 to 13 nm) after crosslinking. The mechanical performance of composite membranes was low, being 0.98 ± 0.4 and 1.1 ± 0.3 MPa of tensile strength for uncross-linked and cross-linked membranes, respectively. In spite of low water flux (64 L m−2 h−1), the composite membranes successfully removed 98%, 84% and 70% respectively of positively charged dyes like Victoria Blue 2B, Methyl Violet 2B and Rhodamine 6G, from a model wastewater after a contact time of 24 h. In the third study layered membranes containing a highly porous support layer and a dense functional layer has been fabricated following a filtration and hot pressing method. Microsized cellulose fibers from sludge bioresidues was used as the support layer to provide mechanical stability and allow water flow without any hindrance. A nanocomposite system of nanocrystals (CNCSL, CNCBE and PCNCSL) with gelatin as matrix was used as the functional layer. Bubble point measurement confirmed the membrane pore sizes (5-6 m), in microfiltration range, which resulted in high water permeability < 4000 Lh-1m-2 at 1.5 bars. Efficient removal of Ag+, Cu2+ and Fe3+ from industrial wastewater was achieved using these membranes. The removal of metal ions was expected to be driven by the electrostatic attraction between negatively charged nanocellulose and the positively charged metal ions. The work has demonstrated that highly efficient water treatment membranes can be fabricated from nanocellulose via tailoring their ability to interact and selectively adsorb heavy metal ions and dyes.Godkänd; 2014; 20141023 (zohkar); Nedanstående person kommer att hålla licentiatseminarium för avläggande av teknologie licentiatexamen. Namn: Zoheb Karim Ämne: Trä- och bionanokompositer/Wood and Bionanocomposites Uppsats: Processing and Characterization of Membranes Based on Cellulose Nanocrystals for Water Purification Examinator: Biträdande professor Aji P Mathew, Institutionen för teknikvetenskap och matematik, Luleå tekniska universitet Diskutant: Forskare Marielle Henriksson, SP Technical Research Institute of Sweden, SP Trä, Stockholm Tid: Fredag 28 november 2014 kl 10,00 Plats: E632, Luleå tekniska universite

Immobilization of peroxidase on a cost free support from salt fractionated proteins of bitter gourd

352-359This study presents direct immobilization of peroxidases from ammonium sulphate fractionated proteins of bitter gourd on cost free support, fly ash. Activated fly ash (, 0.84) was quite effective in high yield immobilization of peroxidase from bitter gourd and it bind nearly 1113 enzyme units per g of support in sodium acetate buffer, pH 5.0. This enzyme bound very strongly on this support and it did not detach even in the presence of 1.0M NaCl. Fly ash adsorbed bitter gourd peroxidase retained 50% activity after treatment with 2.5 mg trypsin/ml of incubation mixture for 1 h at 40°C while soluble enzyme lost nearly 65% of initial activity under similar incubation conditions. FT-IR spectra of fly ash and adsorbed peroxidase showed different peaks at respective wavenumbers

Low concentration of silver nanoparticles not only enhances the activity of horseradish peroxidase but alter the structure also.

Chemical synthesis of Ag-NPs was carried out using reduction method. The reduction mechanistic approach of silver ions was found to be a basic clue for the formation of the Ag-NPs. The nanoparticles were characterized by UV-vis, FT-IR and TEM analysis. We had designed some experiments in support of our hypothesis, "low concentrations of novel nanoparticles (silver and gold) increases the activity of plant peroxidases and alter their structure also", we had used Ag-NPs and HRP as models. The immobilization/interaction experiment had demonstrated the specific concentration range of the Ag-NPs and within this range, an increase in HRP activity was reported. At 0.08 mM concentration of Ag-NPs, 50% increase in the activity yield was found. The U.V-vis spectra had demonstrated the increase in the absorbance of HRP within the reported concentration range (0.06-0.12 mM). Above and below this concentration range there was a decrease in the activity of HRP. The results that we had found from the fluorescence spectra were also in favor of our hypothesis. There was a maximum increase in ellipticity and α-helix contents in the presence of 0.08 mM concentration of Ag-NPs, demonstrated by circular dichroism (CD) spectra. Finally, incubation of a plant peroxidase, HRP with Ag-NPs, within the reported concentration range not only enhances the activity but also alter the structure