Ultrasonication coupled electrochemical treatment of sugar industry wastewater: Optimization, and economic evaluation

Ratnesh Kumar Patel,Ravi Shankar,Prateek Khare,Prasenjit Mondal 한국화학공학회 2022 Korean Journal of Chemical Engineering Vol.39 No.7

This study demonstrates the optimization of treatment option, an integrated advanced-oxidation process(AOP) based approach where integration of two processes, ultrasonication (US) and electrocoagulation (EC), wereapplied for sugar industry wastewater (SIW) treatment. Experimental results confirm that the individual US and ECprocesses for SIW treatment are found to be inefficient, as only 16% COD removal (equivalent to COD removal:268mg/L) is achieved with US process in 20min, while 68% COD removal (equivalent to COD removal: 1,142mg/L)is achieved in 60 min operation time with EC process. Encouraging results were obtained after integration of US(10.6% COD removal in 20min equivalent to COD removal from 1,680mg/L to 1,502mg/L) with EC (82% CODremoval in 30 min equivalent to COD removal from 1,502mg/L to 270mg/L) process, which is collectively classified asultrasonication-electrochemical (US+EC) process. Overall integration of US and EC process ultimately increased theCOD removal up to ~84% (equivalent to COD removal from 1,680mg/L to 270mg/L) in comparatively shorter operatingtime (US+EC=30min). Calorific value of sludge and scum obtained after EC treatment was determined as 3.69and 2.87MJ/kg, respectively. Treatment cost of sono-electrochemical is estimated based on 1 kg COD removal or 1m3wastewater as 1.40 or 1.974 $, respectively, which is found on lower ends when compared with the many other availabletreatment technologies.

Structural and electronic properties of 2D‑activated carbon sheet

Ratnesh Kumar,Abhishek Kumar,B. Keshav Rao,Ambrish K. Srivastava,Mohan L. Verma,Neeraj Misra 한국탄소학회 2021 Carbon Letters Vol.31 No.3

A simulation based (DFT) study is performed on activated 2D-carbon sheet without and with vacancies of central carbon atoms, and explored the electronic properties. The inter-atomic distance at the center of activated carbon sheet is gradually increased with increasing number of vacancies. We get lower binding energy with three vacancies, and higher without a vacancy. A covalent bond is found between C–C atoms, density of states exhibit a semiconductor nature of a system without vacancy, and metallic nature in the presence of vacancies. There are higher peaks of resultant anti-bonding states with three vacancy system and it exhibits higher amorphous nature which causes higher electron concentration, mobility and higher electrical conductivity.

Investigation of the cobalt-additive role in improving the performance of formamidium-lead triiodide-based solar cells

Anjan Kumar,Ali K. Al-Mousoi,Mohamed J. Saadh,Mustafa K. A. Mohammed,G. V. S. S. Sarma,Nafis Ahmad,Ratnesh Tiwari 대한금속·재료학회 2023 ELECTRONIC MATERIALS LETTERS Vol.19 No.5

Solar cell devices are one of the most promising technologies for generating green energy. Forefront perovskite-based solar cells have increased worldwide hope for solving global warming issues. Tight bandgap formamidinium lead iodide (TBFAPbI 3 ) perovskite as an active layer to absorb sunlight along with a desired electron transport layer (ETL) can produce effi cient and stable perovskite solar cells (PSCs). Here, TB-FAPbI 3 with tin oxide (SnO 2 ) as an ETL was employed to fabricate PSCs. These PSCs recorded a low champion effi ciency of 18.35%. A cobalt-doped SnO 2 layer was designed to increase the effi ciency of TB-FAPbI 3 solar cells. The modifi ed SnO 2 boosted the solar cell effi ciency to 20.10% due to the improved conductivity of the ETL and increased charge transfer phenomena in the PSCs. From one side, electron transfer is facilitated at the ETL/perovskite interface. On another side, the reduced surface defects on the fabricated perovskite layer over the modifi ed ETL diminish charge traps in the solar cell. In addition, cobalt doping does not hinder the light transmission from the SnO 2 into the perovskite layer. The modifi ed SnO 2 assists in the formation of a more compact TB-FAPbI 3 layer and promotes the stability properties of PSCs.

Investigation of shear strength models for exterior RC beam-column joint

Kanak Parate,Ratnesh Kumar 국제구조공학회 2016 Structural Engineering and Mechanics, An Int'l Jou Vol.58 No.3

Various models have been proposed by several researchers for predicting the exterior RC beamcolumn joint shear strength. Most of these models were calibrated and verified with some limited experimental database. From the models it has been identified that the joint shear strength majorly depends on ten governing parameters. In the present paper, detailed investigation of twelve analytical models for predicting shear strength of exterior beam-column joint has been carried out. The study shows the effect of each governing parameter on joint shear strength predicted by various models. It has been observed that the consensus on effect of few of the governing parameters amongst the considered analytical models has not been attained. Moreover, the predicted joint strength by different models varies significantly. Further, the prediction of joint shear strength by these analytical models has also been compared with a set of 200 experimental results from the literature. It has been observed that none of the twelve models are capable of predicting joint shear strength with sufficient accuracy for the complete range of experimental results. The research community has to reconsider the effect of each parameters based on larger set of test results and new improved analytical models should be proposed.

Performance assessment of RC frame designed using force, displacement & energy based approach

Onkar G. Kumbhar,Ratnesh Kumar 국제구조공학회 2020 Structural Engineering and Mechanics, An Int'l Jou Vol.73 No.6

Force based design (FBD) approach is prevalent in most of the national seismic design codes world over. Direct displacement based design (DDBD) and energy based design (EBD) approaches are relatively new methods of seismic design which claims to be more rational and predictive than the FBD. These three design approaches are conceptually distinct and imparts different strength, stiffness and ductility property to structural members for same plan configuration. In present study behavioural assessment of frame of six storey RC building designed using FBD, DDBD and EBD approaches has been performed. Lateral storey forces distribution, reinforcement design and results of nonlinear performance using static and dynamic methods have been compared. For the three approaches, considerable difference in lateral storey forces distribution and reinforcement design has been observed. Nonlinear pushover analysis and time history analysis results show that in FBD frame plastic deformation is concentrated in the lower storey, in EBD frame large plastic deformation is concentrated in the middle storeys though the inelastic hinges are well distributed over the height and, in DDBD frame plastic deformation is approximately uniform over the height. Overall the six storey frame designed using DDBD approach seems to be more rational than the other two methods.

Simplified beam-column joint model for reinforced concrete moment resisting frames

Kanak Parate,Onkar Kumbhar,Ratnesh Kumar 국제구조공학회 2024 Structural Engineering and Mechanics, An Int'l Jou Vol.89 No.1

During strong seismic events, inelastic shear deformation occurs in beam-column joints. To capture inelastic shear deformation, an analytical model for beam-column joint in reinforced concrete (RC) frame structures has been proposed in this study. The proposed model has been developed using a rotational spring and rigid links. The stiffness properties of the rotational spring element have been assigned in terms of a moment rotation curve developed from the shear stress-strain backbone curve. The inelastic rotation behavior of joint has been categorized in three stages viz. cracking, yielding and ultimate. The joint shear stress and strain values at these stages have been estimated using analytical models and experimental database respectively. The stiffness properties of joint rotational spring have been modified by incorporating a geometry factor based on dimensions of adjoining beam and column members. The hysteretic response of the joint rotational spring has been defined by a pivot hysteresis model. The response of the proposed analytical model has been verified initially at the component level and later at the structural level with the two actually tested RC frame structures. The proposed joint model effectively emulates the inelastic behavior precisely with the experimental results at component as well as at structural levels.

Shear strength model for reinforced concrete beam-column joints based on hybrid approach

Kanak N. Parate,Ratnesh Kumar 사단법인 한국계산역학회 2019 Computers and Concrete, An International Journal Vol.23 No.6

Behavior of RC beam-column joint is very complex as the composite material behaves differently in elastic and inelastic range. The approaches generally used for predicting joint shear strength are either based on theoretical, strut-and-tie or empirical methods. These approaches are incapable of predicting the accurate response of the joint for entire range of loading. In the present study a new generalized RC beam-column joint shear strength model based on hybrid approach i.e. combined strutand- tie and empirical approach has been proposed. The contribution of governing parameters affecting the joint shear strength under compression has been derived from compressive strut approach whereas; the governing parameters active under tension has been extracted from empirical approach. The proposed model is applicable for various conditions such as, joints reinforced either with or without shear reinforcement, joints with wide beam or wide column, joints with transverse beams and slab, joints reinforced with X-bars, different anchorage of beam bar, and column subjected to various axial loading conditions. The joint shear strength prediction of the proposed model has been compared with 435 experimental results and with eleven popular models from literature. In comparison to other eleven models the prediction of the proposed model is found closest to the experimental results. Moreover, from statistical analysis of the results, the proposed model has the least coefficient of variation. The proposed model is simple in application and can be effectively used by designers.

Damage states of yielding and collapse for elevated water tanks supported on RC frame staging

Lakhade, Suraj O.,Kumar, Ratnesh,Jaiswal, mprakash R. Techno-Press 2018 Structural Engineering and Mechanics, An Int'l Jou Vol.67 No.6

Elevated water tanks are inverted pendulum type structures where drift limit is an important criterion for seismic design and performance evaluation. Explicit drift criteria for elevated water tanks are not available in the literature. In this study, probabilistic approach is used to determine maximum drift limit for damage state of yielding and damage state of collapse for the elevated water tanks supported on RC frame staging. The two damage states are defined using results of incremental dynamic analysis wherein a total of 2160 nonlinear time history analyses are performed using twelve artificial spectrum compatible ground motions. Analytical fragility curves are developed using two-parameter lognormal distribution. The maximum allowable drifts corresponding to yield and collapse level requirements are estimated for different tank capacities. Finally, a single fragility curve is developed which provides maximum drift values for the different probability of damage. Further, for rational consideration of the uncertainties in design, three confidence levels are selected and corresponding drift limits for damage states of yielding and collapse are proposed. These values of maximum drift can be used in performance-based seismic design for a particular damage state depending on the level of confidence.

Damage states of yielding and collapse for elevated water tanks supported on RC frame staging

Suraj O. Lakhade,Ratnesh Kumar,Omprakash R. Jaiswal 국제구조공학회 2018 Structural Engineering and Mechanics, An Int'l Jou Vol.67 No.6

Elevated water tanks are inverted pendulum type structures where drift limit is an important criterion for seismic design and performance evaluation. Explicit drift criteria for elevated water tanks are not available in the literature. In this study, probabilistic approach is used to determine maximum drift limit for damage state of yielding and damage state of collapse for the elevated water tanks supported on RC frame staging. The two damage states are defined using results of incremental dynamic analysis wherein a total of 2160 nonlinear time history analyses are performed using twelve artificial spectrum compatible ground motions. Analytical fragility curves are developed using two-parameter lognormal distribution. The maximum allowable drifts corresponding to yield and collapse level requirements are estimated for different tank capacities. Finally, a single fragility curve is developed which provides maximum drift values for the different probability of damage. Further, for rational consideration of the uncertainties in design, three confidence levels are selected and corresponding drift limits for damage states of yielding and collapse are proposed. These values of maximum drift can be used in performance-based seismic design for a particular damage state depending on the level of confidence.

Estimation of response reduction factor of RC frame staging in elevated water tanks using nonlinear static procedure

Suraj O. Lakhade,Ratnesh Kumar,Omprakash R. Jaiswal 국제구조공학회 2017 Structural Engineering and Mechanics, An Int'l Jou Vol.62 No.2

Elevated water tanks are considered as important structures due to its post-earthquake requirements. Elevated water tank on reinforced concrete frame staging is widely used in India. Different response reduction factors depending on ductility of frame members are used in seismic design of frame staging. The study on appropriateness of response reduction factor for reinforced concrete tank staging is sparse in literature. In the present paper a systematic study on estimation of key components of response reduction factors is presented. By considering the various combinations of tank capacity, height of staging, seismic design level and design response reduction factors, forty-eight analytical models are developed and designed using relevant Indian codes. The minimum specified design cross section of column as per Indian code is found to be sufficient to accommodate the design steel. The strength factor and ductility factor are estimated using results of nonlinear static pushover analysis. It was observed that for seismic design category „high‟ the strength factor has lesser contribution than ductility factor, whereas, opposite trend is observed for seismic design category „low‟. Further, the effects of staging height and tank capacity on strength and ductility factors for two different seismic design categories are studied. For both seismic design categories, the response reduction factors obtained from the nonlinear static analysis is higher than the code specified response reduction factors. The minimum dimension restriction of column is observed as key parameter in achieving the desired performance of the elevated water tank on frame staging.