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Highly efficient [C8mim][Cl] ionic liquid accompanied with magnetite nanoparticles and different salts for interfacial tension reduction

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Chinese Journal of Chemical Engineering 2020年第1期28卷 46-53页

作者： sajjad Hashemi Javad Saien Department of Applied Chemistry Bu-Ali Sina UniversityHamedanIran

The 1-octyl-3-methylimidazolium chloride, [C8 mim][Cl] ionic liquid(IL) was used as a novel surfactant in n-heptane/water system. The interfacial tensions(IFT) were measured and corresponding variations were investigated. An IFT reduction of 80.8% was appropriate under the IL CMC of about 0.1 mol·L^-1 and stronger effects were achieved when magnetite nanoparticles and salts were present profoundly under alkaline p *** equilibrium IFT data were accurately simulated with the Frumkin adsorption model. Hereafter, the saturated surface concentration, equilibrium constant and interaction parameter were obtained and their variations were demonstrated. Further, emulsion stability and contact angle of oil/water interface over quartz surface were studied. The oil/water emulsion stability was hardly changed with nanoparticles;however, the stability of oil/water + IL emulsions was significantly improved. It was also revealed that the presence of sodium and calcium chloride electrolytes fortifies the IL impact, whereas sodium sulfate weakens. From dynamic IFT data and fitting with kinetic models, it was found that the IL migration toward interface follows the mixed diffusion–kinetic control model. Consequently, the IL diffusion coefficient and the appropriate activation energy were determined.

关键词： Imidazolium ionic liquids Interfacial tension Magnetite nanoparticle Emulsion stability Frumkin adsorption model Adsorption kinetic model

Strong interfacial charge transfer between hausmannite manganese oxide and alumina for efficient photocatalysis

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Chinese Journal of Chemical Engineering 2021年第5期34卷 147-159页

作者： Aisha Kanwal Shamaila sajjad sajjad Ahmed Khan Leghari Muhammad Naeem Khan International Islamic University H-10 IslamabadPakistan Pakistan Institute of Engineering and Applied Sciences Islamabad 44000Pakistan Department of Chemistry Government College of ScienceLahorePakistan

Well crystalline manganese oxide(Mn_(3)O_(4))nanoparticles anchored on gamma alumina(γ-Al_(2)O_(3))have been successfully tailored via a proficient and cost effective chemical process as an efficient material for photo *** indicated the composite formation ofγ-Al_(2)O_(3) and hausmannite structure of Mn_(3)O_(4).SEM and TEM revealed that hetero structure of Mn_(3)O_(4)/γ-Al_(2)O_(3) exhibits an amalgam of aggregated nanoparticles and *** demonstrated the chemical states of binary *** band gap tuning has been performed withγ-Al_(2)O_(3) nanoparticles by assimilating hausmannite Mn_(3)O_(4) particles into flower like microstructure of Al_(2)O_(3).The photoluminescence spectra affirmed the enhancement in charge separation in Mn_(3)O_(4)/γ-Al_(2)O_(3) binary hybrid *** band gap becomes narrow with the increase in concentrations of Mn_(3)O_(4).The narrowing of band gap is concorded with crystalline domains of primary aggregated *** elucidate the mechanism of the photocatalytic activity linear sweep voltammetry was *** results showed that Mn_(3)O_(4)/γ-Al_(2)O_(3) nanocomposite revealed the enhancement in current density as compared to pureγ-Al_(2)O_(3) which confirmed the electron transfer from Mn_(3)O_(4) toγ-Al_(2)O_(3) through the interfacial potential gradient in conduction *** optimum concentration of 6.0%Mn_(3)O_(4)/γ-Al_(2)O_(3) for hybrid structure showed an excellent photocatalytic activity under visible light due to narrow band gap *** degree distribution of Mn_(3)O_(4) nano architects overlying onγ-Al_(2)O_(3) induces a significant synergic effect betweenγ-Al_(2)O_(3) and hausmannite phase of manganese oxide(Mn_(3)O_(4)).This strong interfacial contact betweenγ-Al_(2)O_(3) and Mn_(3)O_(4) endures the quick transfer of photo generated charge carriers across interface.

关键词： Hausmannite Mn_(3)O_(4) Alumina Band gap tuning Interfacial charge transfer Nanomaterials Catalysis

Effects of Welding and rotational speeds on the Microstructure and Hardness of Friction Stir Welded Single-Phase Brass

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Acta Metallurgica Sinica(English Letters) 2015年第6期28卷 766-771页

作者： sajjad Emami Tohid Saeid Materials Engineering Faculty Sahand University of Technology

This study focuses on the effects of rotational and welding speeds on the microstructure and hardness of joints in friction stir welded single-phase brass. Welds were achieved under low heat input conditions at rotational and welding speeds of 400-800 r/min and 100-300 mm/min, respectively. In order to characterize the obtained welds, optical microscopy and Vickers hardness measurements were taken on the weld cross sections. According to the obtained results, increasing the welding speed and/or decreasing the rotational speed caused the grain size of the stir zone to decrease and, hence, improved the average hardness of this region. These results are discussed with respect to the interplay between the welding parameters and the peak temperature in the weld thermal cycle.

关键词： Friction stir welding Single-phase brass Dynamic recrystailization Hardness

Effects of the deep rolling process on the surface roughness and properties of an Al-3vol%SiC nanoparticle nanocomposite fabricated by mechanical milling and hot extrusion

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International Journal of Minerals,Metallurgy and Materials 2017年第7期24卷 814-825页

作者： sajjad Sattari Amir Atrian Department of Mechanical Engineering Najafabad Branch Islamic Azad University Najafabad Iran Modem Manufacturing Technologies Research Center Najafabad Branch Islamic Azad University Najafabad lran

Deep rolling is one of the most widely used surface mechanical treatments among several methods used to generate compressive residual stress. This process is usually used for axisymmetric components and can lead to improvements of the surface quality, dimensional accuracy, and mechanical properties. In this study, we deduced the appropriate deep rolling parameters for Al-3vol%Si C nanocomposite samples using roughness and microhardness measurements. The nanocomposite samples were fabricated using a combination of mechanical milling, cold pressing, and hot extrusion techniques. Density measurements indicated acceptable densification of the samples, with no porosity. The results of tensile tests showed that the samples are sufficiently strong for the deep rolling process and also indicated near 50% improvement of tensile strength after incorporating Si C nanoparticle reinforcements. The effects of some important rolling parameters, including the penetration depth, rotation speed, feed rate, and the number of passes, on the surface quality and microhardness were also investigated. The results demonstrated that decreasing the feed rate and increasing the number of passes can lead to greater surface hardness and lower surface roughness.

关键词： deep rolling nanocomposite mechanical milling hot extrusion roughness hardness

Competitive role of nitrogen functionalities of N doped GO and sensitizing effect of Bi_(2)O_(3)QDs on TiO_(2)for water remediation

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Journal of Environmental Sciences 2021年第10期33卷 107-119页

作者： Saima Noor Shamaila sajjad sajjad Ahmed Khan Leghari Cristina Flox Saeed Ahmad International Islamic University Islamabad 44000Pakistan Department of Chemistry and Materials Science Aalto UniversityEspoo 16100Fl-00076Finland Pakistan Institute of Engineering and Applied Sciences Islamabad 44000Pakistan Department of Applied Physics Aalto UniversityEspoo 15100Fl-00076Finland

The promising solar irradiated photocatalyst by pairing of bismuth oxide quantum dots(BQDs)doped TiO_(2)with nitrogen doped graphene oxide(NGO)nanocomposite(NGO/BQDs-TiO_(2))was *** was used for degradation of organic pollutants like 2,4-dichlorophenol(2,4-DCP)and stable dyes,*** B and Congo Red.X-ray diffraction(XRD)profile of NGO showed reduction in oxygenic functional groups and restoring of graphitic crystal *** characteristic diffraction peaks of TiO_(2)and its composites showed crystalline anatase TiO_(2).Morphological images represent spherical shaped TiO_(2)evenly covered with BQDs spread on NGO *** surface linkages of NO-O-Ti,C-O-Ti,Bi-O-Ti and vibrational modes are observed by Fourier transform infrared spectroscopy(FTIR)and Raman *** and NGO modified TiO_(2)results into red shifting in visible region as studied in diffused reflectance spectroscopy(DRS).NGO and BQDs in TiO_(2)are linked with defect centers which reduced the recombination of free charge carriers by quenching of photoluminescence(PL)intensities.X-ray photoelectron spectroscopy(XPS)shows that no peak related to C-O in NGO/BQDs-TiO_(2)is *** indicated that doping of nitrogen into GO has reduced some oxygen functional *** functionalities in NGO and photosensitizing effect of BQDs in ternary composite have improved photocatalytic activity against organic *** byproducts during photo degradation process of 2,4-DCP were studied through high performance liquid chromatography(HPLC).Study of radical scavengers indicated that O_(2)^(·-) has significant role for degradation of 2,*** investigations propose that fabricated nanohybrid architecture has potential for degradation of environmental pollutions.

关键词： Bi_(2)O_(3)quantum dots Nitrogen doped graphene oxide Nitrogen defects TiO_(2) 2,4-Dichlorophenol Water treatment

Performance evaluation of hybrid constructed wetlands for the treatment of municipal wastewater in developing countries

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Chinese Journal of Chemical Engineering 2020年第6期28卷 1717-1724页

作者： sajjad Haydar Mehwish Anis Misbah Afaq Institute of Environmental Engineering&Research(IEER) University of Engineering&Technology(UET)LahorePakistan

In developing countries,high cost of conventional wastewater treatment is a major hindrance in its *** wetlands(CWs)offer low-cost and effective solution to this *** current study aimed to evaluate an innovative maneuver of CWs *** flow constructed wetlands(HCWs)for municipal wastewater(MWW).The HCWs included two lab scale CWs;one horizontal and one vertical,in *** plant species were *** were operated in both,batch and continuous *** mode was used to(1)optimize detention time and(2)find pollutants removal *** operation(at batch optimized retention time)was carried out for the evaluation of mass removal rate,r(g·m-2·d-1),volumetric rate constant,Kv(per day)and areal rate constant,Ka(m·d-1).Among two local plants tested,Pistia stratiotes gave better removal efficiency than *** detention time in HCWs was found to be 8 days(4+4 each).The optimum COD,BOD,TSS,TKN and P removal observed for Pistia stratiotes planted HCWs was 80%,84%,82%,71%and88%*** standards for COD,BOD and TSS were met at optimum *** values of Kaand Kv demonstrated that more removal occurred in vertical flow as compared to horizontal flow CW.

关键词： Constructed wetlands Municipal wastewater Hybrid Pistia Typha Batch mode Continuous mode

Image-based fall detection and classification of a user with a walking support system

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Frontiers of Mechanical Engineering 2018年第3期13卷 427-441页

作者： sajjad TAGHVAEI Kazuhiro KOSUGE School of Mechanical Engineering Shiraz University Shiraz 71936- 16548 Iran Department of Bioengineering and Robotics Tohoku University Sendai 980-8579 Japan

The classification of visual human action is important in the development of systems that interact with humans. This study investigates an image-based classifica- tion of the human state while using a walking support system to improve the safety and dependability of these systems. We categorize the possible human behavior while utilizing a walker robot into eight states （i.e., sitting, standing, walking, and five falling types）, and propose two different methods, namely, normal distribution and hidden Markov models （HMMs）, to detect and recognize these states. The visual feature for the state classification is the centroid position of the upper body, which is extracted from the user＇s depth images. The first method shows that the centroid position follows a normal distribution while walking, which can be adopted to detect any non-walking state. The second method implements HMMs to detect and recognize these states. We then measure and compare the performance of both methods. The classification results are employed to control the motion of a passive-type walker （called ＂RT Walker＂） by activating its brakes in nonwalking states. Thus, the system can be used for sit/stand support and fall prevention. The experiments are performed with four subjects, including an experienced physiotherapist. Results show that the algorithm can be adapted to the new user＇s motion pattern within 40 s, with a fall detection rate of 96.25% and state classification rate of 81.0%. The proposed method can be implemented to other abnormality detection/classification applications that employ depth image-sensing devices.

关键词： fall detection walking support hidden Markov model multivariate analysis

Photoactive area modification in bulk heterojunction organic solar cells using optimization of electrochemically synthesized ZnO nanorods

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Chinese Physics B 2015年第11期24卷 422-427页

作者： Mehdi Ahmadi sajjad Rashidi Dafeh Department of Physics Faculty of Science Vali-e-Asr University of Rafsanjan

In this work, ZnO nanorod arrays grown by an electrochemical deposition method are investigated. The crucial parameters of length, diameter, and density of the nanorods are optimized over the synthesize process and nanorods growth time. Crystalline structure, morphologies, and optical properties of ZnO nanorod arrays are studied by different techniques such as x-ray diffraction, scanning electron microscope, atomic force microscope, and UV-visible transmission spectra. The ZnO nanorod arrays are employed in an inverted bulk heterojunction organic solar cell of Poly （3-hexylthiophene）：[6- 6] Phenyl-（6） butyric acid methyl ester to introduce more surface contact between the electron transporter layer and the active layer. Our results show that the deposition time is a very important factor to achieve the aligned and uniform ZnO nanorods with suitable surface density which is required for effective infiltration of active area into the ZnO nanorod spacing and make a maximum interfacial surface contact for electron collection, as overgrowing causes nanorods to be too dense and thick and results in high resistance and lower visible light transmittance. By optimizing the thickness of the active layer on top of ZnO nanorods, an improved efficiency of 3.17% with a high FF beyond 60% was achieved.

关键词： electrochemical deposition density-controlled ZnO nanorods inverted polymer solar cells active area modification

Influence of welding speed on microstructure formation in friction-stir-welded 304 austenitic stainless steels

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International Journal of Minerals,Metallurgy and Materials 2020年第11期27卷 1517-1524页

作者： Mohsen Hajizadeh sajjad Emami Tohid Saeid Faculty of Mechanical Engineering Sahand University of TechnologyTabrizIran Faculty of Materials Engineering Sahand University of TechnologyTabrizIran

The influence of welding speed on the joint microstructures of an austenitic stainless steel(ASS)produced by friction stir welding(FSW)was *** FSW process was conducted using a rotational speed of 400 r/min and welding speeds of 50 and 150 mm/*** study was carried out using electron backscattered diffraction(EBSD)technique in different regions of the resultant stir zones(SZs).The results show that the texture of the advancing side(AS)was mainly composed of C{001}〈110〉and cube{001}〈100〉texture components along with partial B/B{112}〈110〉*** from the AS toward the center and the retreating side(RS),the cube texture component disappeared and the A;/A*{111}(112)component developed and predominated the other *** welding speed greatly affected and decreased the intensity of the textures in the resultant ***,higher welding speed(lower heat input)resulted in lower frequency of cube texture in the AS.

关键词： friction stir welding stainless steels welding speed dynamic recovery shear texture continuous dynamic recrystallization