Lotus Stalks Research Articles

Instance Segmentation of Lotus Pods and Stalks in Unstructured Planting Environment Based on Improved YOLOv5

Accurate segmentation of lotus pods and stalks with pose variability is a prerequisite for realizing the robotic harvesting of lotus pods. However, the complex growth environment of lotus pods causes great difficulties in conducting the above task. In this study, an instance segmentation model, LPSS-YOLOv5, for lotus pods and stalks based on the latest YOLOv5 v7.0 instance segmentation model was proposed. The CBAM attention mechanism was integrated into the network to improve the model’s feature extraction ability. The scale distribution of the multi-scale feature layer was adjusted, a 160 × 160 small-scale detection layer was added, and the original 20 × 20 large-scale detection layer was removed, which improved the model’s segmentation accuracy for small-scale lotus stalks and reduced the model size. On the medium-large scale test set, LPSS-YOLOv5 achieved a mask mAP0.5 of 99.3% for all classes. On the small-scale test set, the mAP0.5 for all classes and AP0.5 for stalks were 88.8% and 83.3%, which were 2.6% and 5.0% higher than the baseline, respectively. Compared with the mainstream Mask R-CNN and YOLACT models, LPSS-YOLOv5 showed a much higher segmentation accuracy, speed, and smaller size. The 2D and 3D localization tests verified that LPSS-YOLOv5 could effectively support the picking point localization and the pod–stalk affiliation confirmation.

Quantitatively ion-exchange between Mg(II) and Pb(II)/Cd(II) during the highly efficient adsorption by MgO-loaded lotus stem biochar

BackgroundToxic metals such as Pb(II) and Cd(II) have thrown great threat to human health. Adsorption has been drawn more attention due to its low-cost, easy process and extensive raw materials. However, high efficient and environmental-friendly adsorbents are still in great need. Furthermore, the quantitatively adsorption mechanisms of Pb(II) and Cd(II) remain unclear. MgO-loaded lotus stem biochar was proposed as a highly efficient adsorbent to removal aqueous Pb(II) and Cd(II). MethodsMgO-loaded biochar was prepared by using lotus stalk as a precursor to be pyrolyzed with MgCl2 impregnation. Adsorption isotherms, kinetics, thermodynamics experiments were carried out. SEM, XRD, FTIR, XPS, etc. were employed to characterize the adsorbent before and after adsorption. Significant findingsThe adsorption capacities of MgO-loaded biochar for Pb(II) and Cd(II) reached 1379.54 mg/g and 404.04 mg/g, respectively, which were 5 and 20 times higher than that of the original biochar. The adsorption kinetics and thermodynamics indicated that the adsorption process was a chemisorption-based heat absorption reaction, and the characterization results showed the main adsorption mechanisms were ascribed to ion-exchange, precipitation, surface complexation between biochar and Pb(II)/Cd(II) ions, in which the ion exchange mechanism was quantitatively confirmed. Finally, MgO-loaded biochar has been proved to be an efficient adsorbent.

Biomass based N-doped porous carbons as efficient CO2 adsorbents and high-performance supercapacitor electrodes

In this report, a series of N-doped porous carbons were achieved using biomass lotus stalks as the precursor. A two-step synthesis method was employed to prepare carbonaceous adsorbents with different porous structure and surface chemical features. The as-obtained sorbents were characterized by multiple techniques and their CO2 adsorption properties were also comprehensively investigated. At 1 bar, these carbons demonstrate excellent CO2 uptake of 4.25 mmol g−1 at 25 °C and 6.59 mmol g−1 at 0 °C, respectively. The joint effect of narrow microporosity and doped N content was found to govern the CO2 adsorption capacity of these sorbents under 25 °C and 1 bar. Moreover, these biomass-derived carbons also display various other exceptional CO2 capture properties such as high CO2/N2 selectivity, excellent recyclability, suitable heat of adsorption, fast adsorption kinetics, and good dynamic adsorption capacity. The electrochemical study shows that this N-doped porous carbon based electrode possesses substantial specific capacitance (325F/g) and outstanding stability (retain rate of 95% after 5000 cycles). Therefore, these lotus stalk-based N-doped porous carbons have application possibility in CO2 capture and supercapacitor.

Capability of Immobilized Clostridium beijerinckii TISTR 1461 on Lotus Stalk Pieces to Produce Butanol from Sugarcane Molasses

Immobilized Clostridium beijerinckii TISTR 1461 was used to enhance the butanol production efficiency from sugarcane molasses. Lotus stalk (LS) pieces were used as carriers for cell immobilization. Sugarcane molasses containing 50 g/L of sugar supplemented with 1 g/L of yeast extract was found to be an appropriate medium for bacterial cell immobilization on the LS pieces. Carrier size (4, 12 and 20 mm in length) and carrier loading (1:15, 1:30 and 1:45, w/v) were optimized for high levels of butanol production using response surface methodology (RSM). The batch fermentation was carried out under anaerobic conditions in 1 L screw-capped bottles at 37 °C and an agitation rate of 150 rpm. It was found that the optimum conditions for the butanol production were the carrier size of 4 mm and carrier loading of 1:31 (w/v). Under these conditions, the butanol concentration (PB) was 12.89 g/L, corresponding to the butanol productivity (QB) of 0.36 g/L∙h and butanol yield (YB/S) of 0.36 g/g. These values were higher than those using free cells (PB, 10.20 g/L, QB, 0.28 g/L∙h and YB/S, 0.32 g/g). In addition, it was found that a 24 h incubation time for cell immobilization was appropriate for the immobilization process, which was confirmed by the results of the scanning electron microscope (SEM) and atomic force microscopy (AFM) images and specific surface area measurement. When the fermentation using the immobilized cells was carried out in a stirred-tank reactor (STR), column reactor (CR) and CR coupled with STR, the results showed that all reactors could be used to produce butanol production from the immobilized cells on LS pieces. However, the PB using CR and CR coupled with STR were only 75% and 45% of those using the screw-capped bottle and STR.

Porous active carbon derived from lotus stalk as electrode material for high-performance supercapacitors

Porous active carbon electrode (PACE) materials in this work were prepared by a two-step method, which includes carbonization and KOH activation of dried lotus stalk at relatively high temperatures in an argon atmosphere. These processes produced a great number of disordered micropores and mesopores, thereby significantly increasing the specific surface area, up to 1022 m2 g−1. Those pores offered a more favorable pathway for electrolyte penetration and transportation, and thus improved the performance of supercapacitors. The electrochemical properties of PACE materials were tested in 6 M KOH electrolyte, and the results indicated that the specific capacitance reached 248.5 F g−1 at the current density of 1 A g−1. The PACE showed a rate capability with specific capacitance retained over 82.5% at a current density of 10 A g−1 and a good long-term cycling stability with the specific capacitance retained 90.6% after 5000 cycles. Meanwhile, the energy density of PACE-based supercapacitors is 34.51 Wh kg−1 at a corresponding power density of 496.94 W kg−1. Lotus stalk manifests itself as a good carbon source candidate for the development of supercapacitor devices, and the facile synthetic process has a bright future for practical applications.

Treatment of Wastewater from Dyeing Process of Weaving Workshop in Inle Lake by Using Lotus Stalk and Coconut Shell Charcoal

Treatment of Wastewater from Dyeing Process of Weaving Workshop in Inle Lake by Using Lotus Stalk and Coconut Shell Charcoal

Sorption of Ni(II) by Fe(II) and EDTA-modified activated carbon derived from pyrophosphoric acid activation

Activated carbon (LSAC) was obtained from lotus stalk by pyrophosphoric acid activation. The LSAC was modified by FeCl2 and Na2EDTA (Fe–EDTA/LSAC) to enhance its ability for Ni(II) sorption from aqueous solutions. The activated carbons were characterized by N2 adsorption and desorption isotherms, Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction. The sorption of Ni(II) from aqueous solution onto the LSAC and Fe-EDTA/LSAC under various conditions of dosage, contact time, initial solution pH, initial Ni(II) concentration, and ionic strength was investigated to illustrate the mechanism and to quantify the sorption parameters. LSAC and Fe-EDTA/LSAC were mainly microporous with pores almost less than 4 nm. Although the surface area of LSAC (824 m2 g−1) was much higher than that of Fe–EDTA/LSAC (445 m2/g), the Ni(II) sorption capacity of Fe–EDTA/LSAC was larger than that of LSAC. The pH and ionic strength studies indicated that the main Ni(II) sorption mechanisms by the carbons were electrostatic attraction and cation exchange. The kinetics and equilibrium data agreed well with the pseudo-second-order kinetics model and Langmuir isotherm model.

Development of biochars from pyrolysis of lotus stalks for Ni(II) sorption: Using zinc borate as flame retardant

In this work, zinc borate (ZB) was employed as flame retardant for preparation of biochar (BC). A series of BC samples were generated by varying the ZB to lotus stalks (LS) ratio (0.25, 0.5 and 1.0) under different temperatures (300, 350 and 400°C) for 1h. The BCs were analyzed for their surface morphologies, surface areas, surface elemental compositions and yields. The results indicated that, after charring, ZB kept the structures of the produced BCs as its starting material (LS), dramatically enhancing their yields, and promoting their surface oxygen content. The BCs were used as adsorbent for removal of Ni(II) from aqueous solutions. Sorption of Ni(II) on the BCs was enhanced about 3–10 times compared with that of BCs derived from pyrolysis of LS without adding ZB.

Preparation and evaluation of activated carbons from lotus stalk with trimethyl phosphate and tributyl phosphate activation for lead removal

The present research explored the feasibility of preparation of activated carbons from lotus stalks (LS) by trimethyl phosphate (TMP) and tributyl phosphate (TBP) activations (producing AC-TMP and AC-TBP) and compared their physiochemical and Pb(II) adsorptive properties with the activated carbon (AC-PPA) obtained from phosphoric acid (PPA) activation of LS. The carbons were characterized by N2 adsorption/desorption, Boehm’s titration, FTIR and XPS. Physical and chemical analysis results indicated that activations with TMP and TBP dramatically enhanced the SBET and concentrations of O-containing surface functional groups of the AC-TMP and AC-TBP compared to the carbon (LS-C) derived from pyrolysis of LS. AC-TMP and AC-TBP displayed much less SBET than AC-PPA, but they contained much higher acidic groups on their surfaces. The Pb(II) adsorption capacities of the carbons were also investigated at different contact times, pHs, ionic strengths and initial Pb(II) concentrations. The adsorption equilibrium data of the carbons were well fitted to the Freundlich model. The maximum Pb(II) adsorption capacities of AC-TMP (240.6mg/g) and AC-TBP (229.1mg/g) were much higher than that of AC-PPA (139.0mg/g), resulting from their higher content of O-containing functional groups that could adsorb more Pb(II) species by electrostatic attraction, cation exchange and surface complexation.

Preparation and characterization of activated carbon from lotus stalk with guanidine phosphate activation: Sorption of Cd(II)

The preparation of activated carbon (AC-GPP) from lotus stalks (LS) by guanidine phosphate (GPP) activation was studied, with a particular focus on the differences in the physical and chemical characterizations and Cd(II) sorption properties of AC-GPP and the activated carbon (AC-PPA) derived from phosphoric acid (PPA) activation of LS. The carbons were systematically examined by N2 adsorption/desorption, Boehm's titration, and FTIR and XPS analyses. The results of Boehm's titration showed that AC-GPP contained much more total and basic functional groups than AC-PPA. FTIR and XPS analyses revealed that NH2 and CONH groups were effectively introduced on AC-GPP's surface. Cd(II) sorption behaviors on AC-PPA and AC-GPP under different Cd(II) concentration, ionic strength and solution pH conditions were investigated. Although AC-PPA had much higher SBET than AC-GPP, its Cd(II) sorption capacity was 3–4 times less than AC-GPP per unit surface area. For the carbons, sorption isotherms at different ionic strength were very well described by the Langmuir model. According to the results of the sorption studies and XPS analysis, the surface complexation, electrostatic attraction and cation exchange between Cd(II) and O/N-containing functional groups on the carbons were the dominant mechanisms responsible for Cd(II) sorption.

Activated carbons with well-developed microporosity and high surface acidity prepared from lotus stalks by organophosphorus compounds activations

Eight organophosphorus compounds, trimethyl phosphate (TMP), tributyl phosphate (TBP), triphenyl phosphate (TPP), trimethyl phosphite (TMPI), tributyl phosphite (TBPI), triphenyl phosphite (TPPI), diethyl phosphite (DEPI) and diphenyl phosphoryl chloride (DPPC), were employed as activating agents to prepare activated carbons (AC-OPCs) from lotus stalks (LS). AC-OPCs contained mostly micropores with only a small contribution of mesopores and their pore sizes were mainly below 4nm. Physical and chemical analysis results indicated that activations with OPCs dramatically enhanced the porosity, yield and surface acidity of AC-OPCs.

Textural properties and surface chemistry of lotus stalk-derived activated carbons prepared using different phosphorus oxyacids: Adsorption of trimethoprim

The preparation of activated carbons (AC-HxPyOz) by four kinds of oxyacids of phosphorus (H3PO4, H4P2O7, HPO3 and H3PO3) activation of lotus stalk (LS) was studied, with a particular focus on the effect of these HxPyOz on both surface chemistry and porous texture. The XRD analysis of the samples after HxPyOz impregnation showed H4P2O7 had the strongest influence on the crystallinity of LS. Thermo gravimetric studies of the pyrolysis of LS-HxPyOz indicated that these HxPyOz had a very different influence on the thermal degradation of LS. The prepared activated carbons were characterized by SEM, N2 sorption/desorption isotherms, XRD, FTIR and Boehm's titration. Batched sorption studies were performed to compare adsorptive properties of the carbons toward trimethoprim (TMP). The surface area and pore volume of AC-H3PO4 and AC-H4P2O7 were much higher than AC-HPO3 and AC-H3PO3. Boehm's titration results indicated that AC-H4P2O7 and AC-H3PO3 possessed more acidic oxygen functionalities than AC-H3PO4 and AC-HPO3. The structure of the AC-HPO3 was kept as its starting material after activation. Activation with H3PO3 would result in the aromatization of the carbon. The sorption affinities of TMP follows an order of AC-H4P2O7>AC-H3PO4>AC-H3PO3>AC-HPO3.

Preparation of activated carbon from lotus stalks with the mixture of phosphoric acid and pentaerythritol impregnation and its application for Ni(II) sorption

Activated carbons were prepared from lotus stalks impregnated with H3PO4 solution or the H3PO4 solution mixed with pentaerythritol (PER), producing AC and AC-PER. The results of thermogravimetric analysis and SEM suggested that PER enhanced the depolymerization of lignocelluloses and the degree of cross-linked structure in activation process. The physicochemical properties of AC and AC-PER were characterized by N2 adsorption/desorption, Boehm’s titration, Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). AC exhibited much higher values of the BET surface area (1418.78m2/g) and total pore volume (1.253cm3/g) than that of AC-PER (342.67cm2/g and 0.273cm3/g). Nevertheless, the results of FTIR, Boehm’s titration and XPS showed that AC-PER contained much more surface oxygen-containing functional groups. The sorption equilibrium data for Ni(II) sorption onto the carbons agreed well with the Langmuir model. The maximum sorption capacity derived from Langmuir model was 0.5800mmol/g for AC and 0.9184mmol/g for AC-PER (I=0mM). Based on the results of sorption studies, FTIR and XPS analysis, several possible mechanisms for these sorption systems were elaborated further. Cation exchange, electrostatic attraction and surface complexation were likely important mechanisms for Ni(II) sorption onto the carbons.

Adsorption of Cd(II) on lotus stalks-derived activated carbon: batch and column studies

This paper reports a study of adsorption of Cd(II) from aqueous solutions using activated carbon made from lotus stalks (LSAC). The properties of LSAC were characterized by scanning electron microscopy and BET surface area. Zeta potential was also determined. The batch Cd(II) adsorption on LSAC was performed to study the different sorption parameters (time, pH, temperature and ionic strength) that influence the adsorption of Cd(II) onto LSAC and to explore the adsorption mechanisms. Bench-scale column tests were also carried out to determine breakthrough curves with varying flow rates and fixed-bed heights. In general, the theoretical qe calculated using the pseudo-second-order kinetic model agreed better with the experimental data than the first-order one. Among the three widely-used isotherms (Langmuir, Freundlich, and Temkin models), the Langmuir model appeared to describe the experimental results best. The Adam–Bohart equation was appropriate for relative concentration ranging from 0.01 up to 0.5 in this study. The pH of the initial solution affected the sorption of Cd(II) on LSAC to the greatest extent, and presence of Mg2+ resulted in a larger competition to the active sites than Na+, implying ion exchange and electrostatic attraction adsorption mechanisms.

Removal of cephalexin from aqueous solutions by original and Cu(II)/Fe(III) impregnated activated carbons developed from lotus stalks Kinetics and equilibrium studies

Lotus stalk activated carbon (AC) was produced by ultrasound digestion of lotus stalks in H 3PO 4. Copper nitrate and iron nitrate were used to impregnate AC, producing Cu(II)-impregnated AC (AC–Cu) and Fe(III)-impregnated AC (AC–Fe). The modified ACs were characterized by N 2 adsorption–desorption isotherms, Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). The adsorption kinetics and isotherms of cephalexin (CEX) in aqueous solution were studied for AC, AC–Cu and AC–Fe. The kinetics and equilibrium data agreed well with the pseudo-second-order kinetics model and Freundlich isotherm model for all three adsorbents. The results also showed that the adsorption capacities of AC–Cu and AC–Fe were larger than the capacity of AC and AC–Fe was found to be the most effective at the removal of CEX in solution. Furthermore, batch experiments were conducted to study the effects of pH (2.5–10.5), initial concentration of CEX (4–16 mg/L), ionic strength (10–1000 mM) on CEX removal.

Adsorption behavior of Ni (II) on lotus stalks derived active carbon by phosphoric acid activation

The adsorption behavior of Ni (II) on activated carbon prepared from lotus stalks by H 3PO 4 activation has been investigated. Scanning electron microscopy and BET surface area were characterized to provide insight into the properties of lotus stalks activated carbon (LSAC). The adsorbent prepared was found to have a porous structure with surface area of 1220 m 2/g. Adsorption results revealed that the removal speed of Ni (II) by lotus stalks derived active carbon was rapid. The pseudo-second-order kinetic model fitted well with kinetic data, showing high determination coefficients ( R 2) of over 0.999. The adsorption isotherms of Ni (II) on this adsorbent were well described by Langmuir and the maximum adsorption capacity calculated from Langmuir isotherm model was up to 31.45 mg/g. The negative Δ G and the positive Δ H suggested the spontaneous and endothermic nature of the process. The effect of pH and ionic strength and desorption studies could help explain the electrostatic attraction and ion-exchange adsorption mechanism. Desorption studies also represented that LSAC had a good regeneration capacity. The results showed that LSAC could be used to effectively adsorb Ni (II) from aqueous solutions.

Lotus Fiber Production and its Property

Lotus fiber is produced from lotus stalks with pool dipping，sodium hydroxide boil degum and hydrogen peroxide bleach methods. The spinning properties of specific gravity, linear density, relative strength, relative strength variation coefficient and break elongation were tested. The components and structure of the lotus fiber have been analyzed and indicated with chemical, infrared spectroscopy (IR), X-ray diffractometer (X-RD) and scanning electron microscope (SEM). The results show that the lotus fiber has similar components, properties and spinning performance with jute and belongs to natural cellulose fiber.

An Archaeological Discovery in Rajashahi

THE ATTENTION of scholars is drawn to an unique specimen of Surya image recently acquired by the Museum of the Varenda Research Society of Rajashahi, Bengal, through the joint efforts of Mr. Santosh Kumar Mukerji and Mr. Rampada Chakravarthi, the Society's assistant. The image comes from the interior of Varendra or North Bengal. It is a sculpture in high relief on a stone slab measuring three feet by one foot six and a half inches and is in a fair state of preservation in spite of some mutilations. The two fore-arms which held lotus stalks and two below them are knocked off and the face of the main figure and the crown have both been damaged.

An Archaeological Discovery in Rajashahi

THE ATTENTION of scholars is drawn to an unique specimen of Surya image recently acquired by the Museum of the Varenda Research Society of Rajashahi, Bengal, through the joint efforts of Mr. Santosh Kumar Mukerji and Mr. Rampada Chakravarthi, the Society's assistant. The image comes from the interior of Varendra or North Bengal. It is a sculpture in high relief on a stone slab measuring three feet by one foot six and a half inches and is in a fair state of preservation in spite of some mutilations. The two fore-arms which held lotus stalks and two below them are knocked off and the face of the main figure and the crown have both been damaged.