Efficient removal of methylene blue via two-step modification hazelnut shell biochar: Process intensification, kinetics and thermodynamics

Fanhui Guo,Sixi Guo,Yanjie Niu,Guofeng Qiu,Yang Guo,Yan Li,Liqing Chen,Yixin Zhang,Jianjun Wu 한국공업화학회 2023 Journal of Industrial and Engineering Chemistry Vol.125 No.-

Porous carbon materials with ultra-high specific surface area and adjustable pore structure characteristicswere prepared from food industry waste hazelnut shells for the adsorption of methylene blue (MB)wastewater by two-step activation by impregnation with ZnCl2 followed by chemical activation withKOH. The Fusso effect, which can reduce the size of MB molecules, was further used to enhance theadsorption of MB on porous carbon. The results show that both HSBC-a and HSBC-a-b have ultra-highspecific surface area (2979.59 m2/g for HSBC-a, 2882.73 m2/g for HSBC-a-b). The mesopore ratio ofHSBC-a-b (Vmeso/Vtotal % = 14.05%) was doubled compared to HSBC-a. It showed an excellent adsorptionperformance of 694.03 mg/g for MB. It showed a fast adsorption kinetics and the adsorbed amountincreased to 882.46 mg/g at 0.1 M NaCl solution. In addition, adsorption processes were studied usingadsorption kinetics and adsorption isotherm model fitting. The results of this research confirm that hazelnutshell is a kind of promising and sustainable porous carbon raw material, and its ultra-high specificsurface area and adjustable pore structure characteristics are favorable for the efficient treatment ofMB from dyeing wastewater. This work could provide potential guidance for the high-value utilizationof waste hazelnut shell biochar.

Influence of tip clearance on pressure fluctuations in an axial flow pump

Jianjun Feng,Xingqi Luo,Pengcheng Guo,Guangkuan Wu 대한기계학회 2016 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.30 No.4

Rotor-stator interaction in axial pumps can produce pressure fluctuations and further vibrations even damage to the pump system in some extreme case. In this paper, the influence of tip clearance on pressure fluctuations in an axial flow water pump has been investigated by numerical method. Three-dimensional unsteady flow in the axial flow water pump has been simulated with different tip clearances between the impeller blade tip and the casing wall. In addition to monitoring pressure fluctuations at some typical points, a new method based on pressure statistics was proposed to determine pressure fluctuations at all grid nodes inside the whole pump. The comparison shows that the existence of impeller tip clearance magnifies the pressure fluctuations in the impeller region, from the hub to shroud. However, the effect on pressure fluctuation in the diffuser region is not evident. Furthermore, the tip clearance vortex has also been examined under different tip clearances.

Bacterial Community Diversity and Functional Gene Abundance of Structured Mixed Packing and Inert Packing Materials Based Biotrickling Filters

Duanfang Sun,Jianjun Li,Taicheng An,Meiying Xu,Guoping Sun,Jun Guo 한국생물공학회 2012 Biotechnology and Bioprocess Engineering Vol.17 No.3

Packing is the most important factor in biofilter design. A structured mixed packing (SMP) material, combined with various organic and inorganic materials (mineral matter is 80.18 ± 0.48%, w : w), was constructed by ureaformaldehyde resin in order to minimize the disadvantages of these materials when used as stand-alone components. The performance of the toluene biotrickling filter (BTF)packed with SMP was compared with the other BTFs packed with a ceramic raschig ring, ceramic pall ring, and lava rock, respectively, for 217 day under various operating conditions. Real-time PCR and DGGE techniques were applied to reveal the gene coding for the toluene-degrading enzymes and the bacterial community structure in the BTFs. The toluene-degradation gene copies exponentially increased, and bacterial diversity significantly decreased with the improving elimination capacities of the BTFs. The overload and shutdown operations resulted in insignificant fluctuations in the toluene-degradation gene copies at equal levels as well as a slight variation in the bacterial community structures in the BTFs. Various putative toluenedegrading bacteria were found using sequencing bands from the DGGE gels; some bacteria, such as Burkholderia spp., were further confirmed by real-time PCR; other bacteria,such as Alcaligenes spp., might not have been reported. The packing properties of SMP material supported more toluene-degradation gene copies in the biofilm, and higher toluene-degrading bacterial diversity of the BTF, than did inert packing. Thus, the BTF with SMP demonstrated excellent performance, suggesting the suitability of SMP for real applications, whereas the capabilities of inert packing materials are more suited to the treatment of steady low VOC loads. Packing is the most important factor in biofilter design. A structured mixed packing (SMP) material, combined with various organic and inorganic materials (mineral matter is 80.18 ± 0.48%, w : w), was constructed by ureaformaldehyde resin in order to minimize the disadvantages of these materials when used as stand-alone components. The performance of the toluene biotrickling filter (BTF)packed with SMP was compared with the other BTFs packed with a ceramic raschig ring, ceramic pall ring, and lava rock, respectively, for 217 day under various operating conditions. Real-time PCR and DGGE techniques were applied to reveal the gene coding for the toluene-degrading enzymes and the bacterial community structure in the BTFs. The toluene-degradation gene copies exponentially increased, and bacterial diversity significantly decreased with the improving elimination capacities of the BTFs. The overload and shutdown operations resulted in insignificant fluctuations in the toluene-degradation gene copies at equal levels as well as a slight variation in the bacterial community structures in the BTFs. Various putative toluenedegrading bacteria were found using sequencing bands from the DGGE gels; some bacteria, such as Burkholderia spp., were further confirmed by real-time PCR; other bacteria,such as Alcaligenes spp., might not have been reported. The packing properties of SMP material supported more toluene-degradation gene copies in the biofilm, and higher toluene-degrading bacterial diversity of the BTF, than did inert packing. Thus, the BTF with SMP demonstrated excellent performance, suggesting the suitability of SMP for real applications, whereas the capabilities of inert packing materials are more suited to the treatment of steady low VOC loads.

Toluene Removal Efficiency, Process Robustness, and Bacterial Diversity of a Biotrickling Filter Inoculated with Burkholderia sp. Strain T3

Duanfang Sun,Jianjun Li,MEI-YING XU,Taicheng An,GUO-PING SUN,JUN GUO 한국생물공학회 2013 Biotechnology and Bioprocess Engineering Vol.18 No.1

Microorganisms determine the overall biofilter performance under specific operating conditions. The toluene removal and process robustness of a laboratoryscale,ceramisite-based biotrickling filter inoculated with Burkholderia sp. strain T3 (BTFb) were compared with those of another biotrickling filter inoculated with activated sludge (BTFa) for 3 months under various operating conditions. Denaturing gradient gel electrophoresis was applied to visualise the bacterial community of the BTFa and BTFb. Real-time polymerase chain reaction was performed to determine the genes coding for toluenedegrading enzymes. Burkholderia sp. strain T3, which possesses the major toluene-degrading genes in BTFb, was traced in the BTFb bacterial community. The strain was found to stabilize the relative quantity steadily at higher than 60% during toluene biofiltration. Thus, BTFb performed more efficiently than BTFa as evidenced by achieving 98.86% toluene removal efficiency (RE) on 3 day, critical elimination capacity (EC) of 234.23 ± 10.54 g/m3/h, and rapid restoration of the initial RE and EC levels within 3 day of reoperation, even after 1 month of shutdown. The efficiency of BTFb is also evident by the stabilised RE and EC levels within a wide temperature range and a gradually decreasing system pH. Maintaining the pressure drop levels below 150 Pa during prolonged operation also contributed to the efficiency of BTFb. Thus, based on the study results,we propose that Burkholderia sp. strain T3 is a highly efficient and applicable inoculum for toluene biofiltration.

Functional study of C-terminal domain of the thermoacidophilic raw starch-hydrolyzing α-amylase Gt-amy

Jing Zeng,Jianjun Guo,Yikun Tu,Lin Yuan 한국식품과학회 2020 Food Science and Biotechnology Vol.29 No.3

Since the thermoacidophilic raw-starch hydrolyzing a-amylase Gt-amy can effectively hydrolyze corn starch under starch liquefaction conditions, it has potential for many industrial applications. To identify the raw starch-binding domain of Gt-amy, a C-terminal domain (CTD)-truncated mutant (Gt-amy-T) was constructed, and its enzymatic properties were compared with Gt-amy. In comparison to CTD of Gt-amy, which could effectively bind corn starch, the Gt-amy-T could not bind to and hydrolyze corn starch under similar conditions. In addition, Gt-amy-T showed significantly lower thermal activity and thermal stability. Using soluble starch as the substrate, the kcat of Gt-amy-T at 80 C was approximately 77.9% of that of Gt-amy. The half-life of Gt-amy at 80 C was 3 h, while that of Gt-amy-T was 2 h. These results reveal that the CTD plays a vital role in raw starch binding and degradation by Gt-amy and helps Gt-amy maintain thermal activity and stability.

Evaluation of the Performance of Structured Mixed Packing and Inert Packing Materials in Toluene Biotrickle-filtration

Duanfang Sun,Jianjun Li,Taicheng An,Meiying Xu,Guoping Sun,Jun Guo 한국생물공학회 2011 Biotechnology and Bioprocess Engineering Vol.16 No.5

Packing materials play a key role in waste gas treatment. Organic and inert packing materials have their disadvantages, which may be minimized by mixed packing. In this study, various operating conditions were applied to evaluate the performance of structured mixed packing and inert packing materials in toluene biotricklefiltration. Four biotrickle filters were packed with structured mixed packing materials, namely, ceramic pall rings,ceramic rashig rings, and lava rock. Their toluene removal capacity was studied for 217 day using a laboratory-scale reaction under various operating conditions. The key elimination capacity (removal efficiency > 95%) ranking of the biotrickle filters was as follows: Structured mixed packing (306.20 ± 7.90 g/m^3/h) > pall ring (156.71 ± 7.84 g/m^3/h)> rashig ring (153.31 ± 6.14 g/m^3/h) > lava rock (150.32 ±9.19 g/m^3/h). The structured mixed packing and inert packing resulted in excellent toluene-degrading biofilter performance under long-term operation. The structured mixed packing provided a more rapid startup rate and better process robustness than the inert packing did. The biotrickle filter with mixed packing materials had a high elimination capacity which makes it suitable for various real-life applications, whereas the capability of the inert packing material was more suitable for treating a steady low toluene load.

Treatment of Volatile Organic Compounds from a Typical Waste Printed Circuit Board Dismantling Workshop by a Pilot-scale Biotrickling Filter

Dongqi Liao,Jianjun Li,Duanfang Sun,Meiying Xu,Taicheng An,Guo-Ping Sun 한국생물공학회 2015 Biotechnology and Bioprocess Engineering Vol.20 No.4

A pilot-scale biotrickling filter (BTF) was designed to treat volatile organic compounds (VOCs) emitted from a typical waste printed circuit board (WPCB) pyrolysis workshop. Measured by gas chromatography-mass spectrometry (GC-MS), the main components of VOCs and their concentrations were benzene, toluene, chlorobenzene, ethyl-benzene, xylene, styrene, benzaldehyde, and trimethyl-benzene. The removal efficiencies of the BTF for these compounds ranged from 81.1 to 97.8% after 90 days of operation. The maximum elimination capacity of 25.94 g/m3 h was obtained with the inlet loading of 30.72 g/m3 fixed the fixed empty-bed residence time (EBRT) of 9.80 sec. Hazard ratio index based on threshold limit value for time weighted average (TLV-TWA) and VOCs concentrations indicated that the cancer risk of VOCs was significantly reduced after the BTF treatment. The microbial community analysis revealed initial inoculum and some emerging bacteria played crucial roles in the improvement of BTF performance with the biodegradation of this kind of VOCs by the polymerase chain reactiondenaturing gradient gel electrophoresis (PCR-DGGE) technique and pyrosequencing analyses indicated that proteobacteria phylum was the dominant in the BTF. All above results indicated that VOCs with multicomponent and fluctuant concentrations from a typical waste printed circuit board pyrolysis workshop were removed efficiently and in an environmentally friendly way by the biofiltration method.

Torsional Vibration Analysis of Hydro-Generator Set Considered Electromagnetic and Hydraulic Vibration Resources Coupling

Zhiqiang Song,Yunhe Liu,Pengcheng Guo,Jianjun Feng 한국정밀공학회 2018 International Journal of Precision Engineering and Vol.19 No.7

The torsional vibration characteristics of the hydro-generator set considering the electromagnetic and hydraulic vibration resources coupling are studied. The moment of rotation consists of water flow driving and magnetic torques caused by the air gap magnetic field in the generator rotor in the case of ignoring the mechanical friction. A coupling torque vibration model of hydro-generator shaft system was established. The model considered the coupling action of hydraulic and electromagnetic excitations, as well as the elastic effect of rotor spiders. The influences of the rotor moment inertia, rotor stiffness, and mass of turbine water added into the torsional natural vibration of the unit shaft system were studied. The effect of hydraulic excitation frequency on torsional vibration response was also investigated. The frequency response curves of shaft torque, torsional vibration angle, and electromagnetic torque were presented. The electromagnetic and hydraulic coupling resonance was studied when hydraulic excitation frequency was equal to zero and first-order frequencies. The excitation electric current and internal active power angle on torsional vibration was further analyzed. This study provides an analysis model and method considering the coupling of electromagnetic and hydraulic vibration resources for design and stable operation of water turbine generator sets.

Nonlinear wind-induced instability of orthotropic plane membrane structures

Changjiang Liu,Feng Ji,Zhoulian Zheng,Yuyou Wu,Jianjun Guo 한국풍공학회 2017 Wind and Structures, An International Journal (WAS Vol.25 No.5

he nonlinear aerodynamic instability of a tensioned plane orthotropic membrane structure is theoretically investigated in this paper. The interaction governing equation of wind-structure coupling is established by the Von Kármán\'s large amplitude theory and the D\'Alembert\'s principle. The aerodynamic force is determined by the potential flow theory of fluid mechanics and the thin airfoil theory of aerodynamics. Then the interaction governing equation is transformed into a second order nonlinear differential equation with constant coefficients by the Bubnov-Galerkin method. The critical wind velocity is obtained by judging the stability of the second order nonlinear differential equation. From the analysis of examples, we can conclude that it\'s of great significance to consider the orthotropy and geometrical nonlinearity to prevent the aerodynamic instability of plane membrane structures; we should comprehensively consider the effects of various factors on the design of plane membrane structures; and the formula of critical wind velocity obtained in this paper provides a more accurate theoretical solution for the aerodynamic stability of the plane membrane structures than the previous studies.

Topology optimization of unsymmetrical complex plate and shell structures bearing multicondition overload

Yangyang Zhang,Yixiao Qin,Jinpeng Gu,Qianqian Jiao,Feng Wang,Zhenshan Guo,Hao Zhang,Jianjun Wang,Chenghong Mi,Huaipeng Zheng 대한기계학회 2021 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.35 No.8

Unsymmetrical complex plate and shell structure is one of the common engineering structures. In practice, more redundant materials exist because of the irrationality of this kind of structure with heavy load and multiple working conditions, and the study of its topology optimization has become an engaging topic. Using the SIMP model, topological results show that one side of the main web is a hollow structure, and the other side of the auxiliary web is a truss structure. According to the topological results and considering manufacturable processing, a new structure is redesigned, the size and shape of the redesigned structure is secondary optimized, and the final structure is obtained. The method in this paper not only meets the performance requirements of the unsymmetrical complex plate and shell structures, but also realizes the topology and lightweight. The effectiveness scientific research value of the proposed method is verified by engineering examples.