Investigation on the recycling of sulfuric acid from pretreatment of cellulose for nanocellulose preparation

TAPPI Journal ◽  
2020 ◽  
Vol 19 (2) ◽  
pp. 103-111
Author(s):  
CHAOYU DUAN ◽  
YANGYANG PENG ◽  
SHIYU FU ◽  
LUCIAN LUCIA
Keyword(s):  
Thermal Stability ◽  
Sulfuric Acid ◽  
Zeta Potential ◽  
Surface Properties ◽  
Value Chain ◽  
Solid Residue ◽  
Number Of Cycles ◽  
The Relationship

Sulfuric acid is often used to pretreat cellulose prior to homogenization and conversion to nanocellulose. It would be economically significant to reuse the acid to close the overall value chain loop. The target of this work was to investigate the effect of recovery and recycling frequency of sulfuric acid from the pretreatments on the pretreatment yield of water-insoluble cellulose solid residue, and to explore the relationship between the nanocellulose size prepared by recovery of acid and number of cycles. The surface properties of the nanocelluloses were measured, including content of sulfate groups, absolute zeta potential, crystallinity, and thermal stability.

An Experimental Investigation on Thermal Conductivity and Viscosity of Graphene doped CNTs /TiO2 Nanofluid

2020 ◽  
Vol 17 (3) ◽  
Author(s):  
A.M. Zetty Akhtar ◽  
M.M. Rahman ◽  
K. Kadirgama ◽  
M.A. Maleque
Keyword(s):  
Thermal Conductivity ◽  
Zeta Potential ◽  
Base Fluid ◽  
Minimum Quantity Lubrication ◽  
Cutting Fluid ◽  
Cutting Zone ◽  
Observation Method ◽  
The Stability ◽  
The Relationship ◽  
Zeta Potential Analysis

This paper presents the findings of the stability, thermal conductivity and viscosity of CNTs (doped with 10 wt% graphene)- TiO2 hybrid nanofluids under various concentrations. While the usage of cutting fluid in machining operation is necessary for removing the heat generated at the cutting zone, the excessive use of it could lead to environmental and health issue to the operators. Therefore, the minimum quantity lubrication (MQL) to replace the conventional flooding was introduced. The MQL method minimises the usage of cutting fluid as a step to achieve a cleaner environment and sustainable machining. However, the low thermal conductivity of the base fluid in the MQL system caused the insufficient removal of heat generated in the cutting zone. Addition of nanoparticles to the base fluid was then introduced to enhance the performance of cutting fluids. The ethylene glycol used as the base fluid, titanium dioxide (TiO2) and carbon nanotubes (CNTs) nanoparticle mixed to produce nanofluids with concentrations of 0.02 to 0.1 wt.% with an interval of 0.02 wt%. The mixing ratio of TiO2: CNTs was 90:10 and ratio of SDBS (surfactant): CNTs was 10:1. The stability of nanofluid checked using observation method and zeta potential analysis. The thermal conductivity and viscosity of suspension were measured at a temperature range between 30˚C to 70˚C (with increment of 10˚C) to determine the relationship between concentration and temperature on nanofluid’s thermal physical properties. Based on the results obtained, zeta potential value for nanofluid range from -50 to -70 mV indicates a good stability of the suspension. Thermal conductivity of nanofluid increases as an increase of temperature and enhancement ratio is within the range of 1.51 to 4.53 compared to the base fluid. Meanwhile, the viscosity of nanofluid shows decrements with an increase of the temperature remarks significant advantage in pumping power. The developed nanofluid in this study found to be stable with enhanced thermal conductivity and decrease in viscosity, which at once make it possible to be use as nanolubricant in machining operation.

ANALYSIS OF THE INFLUENCE OF DIMENSIONS OF THE ROPE MIDWATER TRAWLS ON THEIR PERFORMANCE SUBJECT TO GEOMETRIC PROPERTIES OF CONE SHELLS

2017 ◽  
pp. 25-33
Author(s):  
Alexander Vasilievich Dvernik
Keyword(s):  
Surface Properties ◽  
Conical Shell ◽  
Side Surface ◽  
Theoretic Analysis ◽  
Good Convergence ◽  
Large Size ◽  
Quality Coefficient ◽  
Geometric Quality ◽  
The Relationship ◽  
Parameters Calculation

The article studies different shell constructions of mid-water trawls and their properties. The problem settled is suggested to be solved taking into account real geometric interrelations between spacious and surface properties of cone shells. The author suggests to accept a so-called geometric quality coefficient as a criterion of the properties of a conical shell, which represents the ratio of the shell to the area of its side surface and by analogy to use it to the shell of the trawl. The relationship between the trawl dimensions and geometric quality coefficient have been studied. Comparing these figures with the actual characteristics of trawls showed good convergence. According to the results of theoretic analysis and parameters calculation, trawl large-size shells will always have advantages in geometric characteristics over mid-size and, especially, small-size shells. The results of the analysis can be used for approximate calculations of the parameters of the trawl and justification of ways to improve the performance of existing mid-water trawls.

scholarly journals Investigation of Deformation Inhomogeneity and Low-Cycle Fatigue of a Polycrystalline Material

2021 ◽  
Vol 11 (6) ◽  
pp. 2673
Author(s):  
Mu-Hang Zhang ◽  
Xiao-Hong Shen ◽  
Lei He ◽  
Ke-Shi Zhang
Keyword(s):  
Cyclic Loading ◽  
Low Cycle Fatigue ◽  
Strain Tensor ◽  
Equivalent Strain ◽  
Differential Entropy ◽  
Strain Components ◽  
Deformation Inhomogeneity ◽  
Standard Deviations ◽  
Number Of Cycles ◽  
The Relationship

Considering the relationship between inhomogeneous plastic deformation and fatigue damage, deformation inhomogeneity evolution and fatigue failure of superalloy GH4169 under temperature 500 °C and macro tension compression cyclic loading are studied, by using crystal plasticity calculation associated with polycrystalline representative Voronoi volume element (RVE). Different statistical standard deviation and differential entropy of meso strain are used to measure the inhomogeneity of deformation, and the relationship between the inhomogeneity and strain cycle is explored by cyclic numerical simulation. It is found from the research that the standard deviations of each component of the strain tensor at the cyclic peak increase monotonically with the cyclic loading, and they are similar to each other. The differential entropy of each component of the strain tensor also increases with the number of cycles, and the law is similar. On this basis, the critical values determined by statistical standard deviations of the strain components and the equivalent strain, and that by differential entropy of strain components, are, respectively, used as fatigue criteria, then predict the fatigue–life curves of the material. The predictions are verified with reference to the measured results, and their deviations are proved to be in a reasonable range.

scholarly journals Dye Separation and Antibacterial Activities of Polyaniline Thin Film-Coated Poly(phenyl sulfone) Membranes

Membranes ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 25
Author(s):  
Javed Alam ◽  
Arun Kumar Shukla ◽  
Mohammad Azam Ansari ◽  
Fekri Abdulraqeb Ahmed Ali ◽  
Mansour Alhoshan
Keyword(s):  
Zeta Potential ◽  
Surface Properties ◽  
Antibacterial Activities ◽  
Pani Film ◽  
Force Microscopy ◽  
Water Permeation ◽  
Membrane Pores ◽  
Membrane Performance ◽  
Phenyl Sulfone ◽  
The Impact

We fabricated a nanofiltration membrane consisting of a polyaniline (PANI) film on a polyphenylsulfone (PPSU) substrate membrane. The PANI film acted as a potent separation enhancer and antimicrobial coating. The membrane was analyzed via scanning electron microscopy and atomic force microscopy to examine its morphology, topography, contact angle, and zeta potential. We aimed to investigate the impact of the PANI film on the surface properties of the membrane. Membrane performance was then evaluated in terms of water permeation and rejection of methylene blue (MB), an organic dye. Coating the PPSU membrane with a PANI film imparted significant advantages, including finely tuned nanometer-scale membrane pores and tailored surface properties, including increased hydrophilicity and zeta potential. The PANI film also significantly enhanced separation of the MB dye. The PANI-coated membrane rejected over 90% of MB with little compromise in membrane permeability. The PANI film also enhanced the antimicrobial activity of the membrane. The bacteriostasis (BR) values of PANI-coated PPSU membranes after six and sixteen hours of incubation with Escherichia coli were 63.5% and 95.2%, respectively. The BR values of PANI-coated PPSU membranes after six and sixteen hours of incubation with Staphylococcus aureus were 70.6% and 88.0%, respectively.

scholarly journals Low-Cycle Fatigue Crack Growth in Ti-6242 at Elevated Temperature

2014 ◽  
Vol 891-892 ◽  
pp. 422-427 ◽  
Author(s):  
Rebecka Brommesson ◽  
Magnus Hörnqvist ◽  
Magnus Ekh
Keyword(s):  
Crack Length ◽  
Crack Growth ◽  
Low Cycle Fatigue ◽  
High Strength ◽  
Cycle Fatigue ◽  
Load Drop ◽  
Actual Measure ◽  
Smooth Bars ◽  
Number Of Cycles ◽  
The Relationship

During low-cycle fatigue test with smooth bars the number of cycles to initiation is commonly defined from a measured relative drop in aximum load. This criterion cannot be directly related to the actual measure of interest - the crack length. By relating data from controlled crack growth tests under low-cycle fatigue conditions of a high strength Titanium alloy at 350°C and numerical simulation of these tests, it is shown that it is possible to determine the relationship between load drop and crack length, provided that care is taken to consider all relevant aspects of the materials stress-strain response.

scholarly journals Modelling the contribution of sea salt and dimethyl sulfide derived aerosol to marine CCN

2002 ◽  
Vol 2 (1) ◽  
pp. 17-30 ◽  
Author(s):  
Y. J. Yoon ◽  
P. Brimblecombe
Keyword(s):  
Sulfuric Acid ◽  
Dimethyl Sulfide ◽  
Marine Boundary Layer ◽  
Cloud Condensation Nuclei ◽  
Accommodation Coefficient ◽  
Sea Salt ◽  
Wind Speeds ◽  
Transfer Processes ◽  
Clean Air ◽  
The Relationship

Abstract. The concentration of cloud condensation nuclei (CCN) in the marine boundary layer (MBL) was estimated from dimethyl sulfide (DMS) flux, sea salt (SS) emission, and aerosols entrained from the free troposphere (FT). Only under clean air conditions, did the nucleation of DMS derived sulfur (DMS CCN) contribute significantly to the MBL CCN. The accommodation coefficient for sulfuric acid mass transfer was found to be a very important parameter in the modeling the contribution of DMS to MBL CCN. The relationship between seawater DMS and MBL CCN was found to be non-linear mainly due to the transfer processes of sulfuric acid onto aerosols. In addition, sea salt derived CCN (SS CCN) and entrained aerosol from the FT (FT CCN) affected the MBL CCN directly, by supplying CCN, and indirectly, by behaving as an efficient sink for sulfuric acid. The SS CCN explained more than 50% of the total predicted MBL CCN when wind speeds were moderate and high. Sea salt and FT aerosol may often be more efficient sources of MBL CCN than DMS.

scholarly journals Modified Carbon Nanotubes: Surface Properties and Activity in Oxygen Reduction Reaction

Catalysts ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1354
Author(s):  
Vera Bogdanovskaya ◽  
Inna Vernigor ◽  
Marina Radina ◽  
Vladimir Sobolev ◽  
Vladimir Andreev ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Zeta Potential ◽  
Oxygen Reduction Reaction ◽  
Oxygen Reduction ◽  
Surface Area ◽  
Surface Properties ◽  
Reduction Reaction ◽  
Wave Potential ◽  
Half Wave Potential ◽  
Half Wave

In order to develop highly efficient and stable catalysts for oxygen reduction reaction (ORR) that do not contain precious metals, it is necessary to modify carbon nanotubes (CNT) and define the effect of the modification on their activity in the ORR. In this work, the modification of CNTs included functionalization by treatment in NaOH or HNO3 (soft and hard conditions, respectively) and subsequent doping with nitrogen (melamine was used as a precursor). The main parameters that determine the efficiency of modified CNT in ORR are composition and surface area (XPS, BET), hydrophilic–hydrophobic surface properties (method of standard contact porosimetry (MSP)) and zeta potential (dynamic light scattering method). The activity of CNT in ORR was assessed following half-wave potential, current density within kinetic potential range and the electrochemically active surface area (SEAS). The obtained results show that the modification of CNT with oxygen-containing groups leads to an increase in hydrophilicity and, consequently, SEAS, as well as the total (overall) current. Subsequent doping with nitrogen ensures further increase in SEAS, higher zeta potential and specific activity in ORR, reflected in the shift of the half-wave potential by 150 mV for CNTNaOH-N and 110 mV for CNTHNO3-N relative to CNTNaOH and CNTHNO3, respectively. Moreover, the introduction of N into the structure of CNTHNO3 increases their corrosion stability.

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