A comparative study of equilibrium and non-equilibrium models for ethyl acetate production in reactive distillation Mallaiah Mekala Indian Journal of Chemical Technology, 2026 The mathematical modeling and simulation have been performed to an esterification of Acetic Acid (AA) with Ethyl Alcohol (EOH) for production of Ethyl Acetate (EA) and water in a Reactive Distillation Column (RDC). The equilibrium and non-equilibrium (rate based) models have been applied to perform simulations for an esterification system. The ethyl alcohol and acetic acid reacts with sulphuric acidin reactive zone for the production of ethyl acetate and water. The in-situ separations of components in reaction section improves conversion and purity. The feeds entered into the column are at a temperature of 25ºC and a pressure of 1 bar. The feed flow rates are adjusted from 0.02 L/min to 0.09 L/min. The acetic acid is fed on 8th stage and ethanol is fed on 14th stage. The composition and temperature profiles have compared for the equilibrium and rate based models from condenser stage to reboiler stage. Sensitivity analysis was performed under various operating conditions for the equilibrium and rate based models. From the simulations it is found that mole fraction of ethyl acetate is 71.41% from rate based model which is higher than equilibrium model.
A review on bioethanol production: first generation to fourth generation Yashraj Delhiwala, Sai Mani Yogesh Kosuru, Prasad Babu Koorla, Mallaiah Mekala Chemical Product and Process Modeling, 2026 The supply of energy to all the sectors is difficult nowadays due to increase of its demand and depletion of fossil fuels. Fossil fuels have to be replaced by an alternative energy sources due to creation of ill environment by fossil fuels. Bioethanol has developed as one of the leading renewable fuels with through generations. In the first-generation, Bioethanol is produced from food crops like corn or sugarcane, however it faced numerous obstacles such as food security and land competition. In the second-generation, bioethanol derived from lignocellulosic biomass to replace the first-generation feed stocks. This, unfortunately, also faced the same challenge. Feedstock recalcitrance, high processing costs, and limited commercial viability. Third-generation bioethanol, based on engineered microbial or algal systems, represent a more sustainable pathway with lower land use and higher yields, though it still faces constrains in the form of high energy inputs and the need for advanced bioreactor design. Fourth generation bioethanol addresses the issues of all three generations of bioethanol production. The main findings of these processes include genetic engineering of microbial strains, improved enzymatic hydrolysis, and integrated bio refinery concepts that enhance efficiency and reduce waste. Technologically, Bioethanol advances highlight the optimization challenges between conversion efficiency, resource availability, and cost-effectiveness. Environmentally, adoption of Bioethanol paves the way to reduced greenhouse gas emissions, increased circular use of biomass, and reduced dependence on fossil fuels.
Electrochemical reduction of CO2to value added products Santhosh Kumar Mahankali, Ali Furqan, Umesh Chandra Banoth, Mallaiah Mekala, Gubbala V. Ramesh Chemical Product and Process Modeling, 2026 To investigate how the chemistry of an electrolyte impacts the surface behaviour and electro catalytic performance of copper electrodes during the electrochemical reduction of carbon dioxide (CO 2 ), experiments were performed using varying concentrations of potassium hydrogen carbonate (KHCO 3 ) in near neutral solutions, at open circuit and through the use of several types of electrochemical techniques; specifically, linear sweep voltammetry, chronoamperometry, and measurements of open circuit potential. The results demonstrate that the open circuit potential of copper immersed in these solutions is shifted upward when exposed to CO 2 as compared to when exposed to nitrogen, while increased cathodic current density was observed. These results confirm that the presence of CO 2 causes the formation of a conditioned electrode/solution interface on copper. Increased KHCO 3 solution concentrations result in higher cathodic current densities and better stability of the cathodic process, indicating that the ability of the electrolyte to act as a buffer, or to increase the strength of the ions within it, are important factors controlling the rate and efficiency of this reaction.
Experimental design and statistical modeling of bagasse kraft pulping process Mallaiah Mekala, Baburao Gaddala, Muthalagu R, Venkateswarlu Chimmiri Results in Engineering, 2025 • The experiments have conducted for Kraft pulping method. • statistical regression models are developed for bagasse pulping process. • Response surface models for bagasse pulping process are built using temperature, NaOH as Na 2 O and liquor to material ratio as design variables. • Experimental and model predictions compared for kappa numbers and pulp yield. • Kraft pulping process with yield obtained as 46.31 %. Sugarcane residue (bagasse) is a raw material available in large quantities from sugarcane extraction plants and offers an interesting opportunity to create value addition in terms of its conversion to pulp and paper. This work aims at designing and conducting experiments for a bagasse Kraft pulping process and develops a response surface model to optimize the pulping process conditions. Experimental design based response surface modelling is an interesting alternative to conventional models of pulping processes. This work presents a response surface methodology that involves designing and performing experiments and developing statistical regression models for bagasse kraft pulping process. Response surface models for bagasse pulping process are built using temperature, NaOH as Na 2 O and liquor to material ratio as design variables, and pulp yield and kappa number as response variables. Eight full factorial experiments are designed by considering effective alkali (4 %, 3 %), liquor to material ratio (1:20, 1:25) and temperature (160 °C, 170 °C) as factors. The analysis of the results show the models that account interactions in design variables provide better predictive performance for bagasse pulping process.
Evaluation of the predictive capability and process optimization of pectin extraction from lemon waste peels Mallaiah Mekala, Venkateswarlu Chimmiri Chemical Product and Process Modeling, 2025 Pectin is a natural biopolymer that has gained popularity in the pharmaceutical and biotechnology industries. This study investigated pectin extraction from lemon waste peel under various process parameters, such as temperature, pH, and extraction time. The effects of these parameters on pectin yield were investigated using Response Surface Methodology (RSM). These experiments were conducted under various parameter ranges, such as 60 °C–80 °C, pH 1–3, and extraction time of 1–3 h. The experimental data were used to develop a quadratic regression model using the RSM and a Central Composite Design (CCD).The interaction effect of pH and extraction time had a significant (p<0.0001) effect on the pectin yield compared to that of temperature. A ramp analysis was performed to determine the optimal parameter conditions for maximum pectin yield. The predicted pectin yields and experimental values are close agreement each other, confirming that the regression model accurately predicts the data within the error for the model. The calculated R 2 and adjusted R 2 values are, with slight variation, 0.99 and 0.975, respectively. The experimental and predicted pectin yields are 26.80 % and 28.86 %, respectively, under the optimum conditions of a temperature of 66.4 °C, pH of 1.01, and extraction time of 1.4 h.
Visible emissions through upconverting nanodots of NaYF4:Er3+; Yb3+nanocrystals: A brief study in their upconversion mechanism and energy transfers Monami Das Modak, Pradip Paik, Mallaiah Mekala Chemical Product and Process Modeling, 2025 Here we report the formation of upconverting nanodots of Er3+/Yb3+ codoped NaYF4 nanocrystals confining diameter as calculated to be 3.4 ± 0.15 nm and are evolved as single crystalline particles with monodisperse particle size distribution. These nanodots are obtained with appearance of major cubic phases and minor prehoxagonal phases via thermal decomposition heat treatment. The bright green visible emissions for 2H11/2–4I15/2/4S3/2–4I15/2 energy transfers resulting from a three-photon excitation process, are obtained under 980 nm laser diode excitation sources, employed with an inexpensive diode laser with a maximum power density of about 150 mW/cm2. The synthesized nanodots are well characterized by high resolution transmission electron microscopy (HRTEM), X-ray diffraction study (XRD), Raman spectroscopic analysis, fluorescence spectroscopy for confirming their sizes, shapes; crystallinity; phases present and emissions respectively. Additionally, we also report the vis-vis photoluminescence (PL-study) under 450 nm excitations followed by two-photon excitation process. These nanocrystals are efficient enough to be dispersed in nonpolar organic solvents and could be of a great potential candidate for using as imaging probes or in fluorescent labels.
Green synthesis of fluorescent carbon dots from watermelon peel waste for sensing applications Ganesh Botla, Praveen BVS, Mallaiah Mekala Chemical Product and Process Modeling, 2025 Carbon dots (CDs) are versatile nanomaterials valued for their fluorescence, biocompatibility, and potential in bioimaging and drug delivery. Current synthesis methods, such as hydrothermal or microwave techniques, often require specialized equipment and energy-intensive processes, limiting their accessibility. This study presents an efficient, sustainable approach to synthesizing CDs from watermelon peel, an abundant waste biomass, using a round-bottom flask. Watermelon peel was sun-dried, crushed, and boiled with distilled water (1:10 w/v) for 5 h, followed by centrifugation. The resulting CDs exhibited blue fluorescence under a fluorometer, indicative of small particle sizes (<10 nm), and a UV-vis absorption peak at 250 nm, consistent with π-π* transitions of conjugated C=C and C=O bonds. This method leverages simple equipment and a renewable precursor, offering a cost-effective, eco-friendly alternative to conventional techniques. The CDs’ optical properties suggest suitability for biomedical applications, though further optimization (e.g., quantum yield, size distribution) is needed. This work highlights the potential of waste-derived CDs, contributing to sustainable nanotechnology development.
Biodiesel production from waste cooking oil using Indion-140 catalyst: optimization studies Mallaiah Mekala, Prasad Babu Koorla, Ramesh Kola, Bhavani Pokala, Anwar Shaik, Sai Mani Yogesh Kosuru, Yashraj Delhiwala Chemical Product and Process Modeling, 2025 Heterogeneous transesterification of Waste Cooking Palm Oil (WCPO) to biodiesel over ion exchange resin solid acid catalyst, Indion-140 in a batch reactor and the optimization of the process conditions have been investigated. The reaction is conducted under various parameters like temperature in the range of 40 °C–80 °C, catalyst loading in the range of 1 g/cc – 5 g/cc based on volume of reaction mixture and mole ratios of reactants in the range of 1:1 – 1:10. The experimental design of the influencing parameters is modeled by using Central Composite Design (CCD) with Response Surface Methodology (RSM). The experiments are performed as per the combinations of influencing parameters designed by aforementioned CCD methodology. The experimental data used the power law regression in a quadratic model. An ANN was trained on the experimental data. ANOVA is used to test the regression model for biodiesel yield. The maximum biodiesel yield achieved was 86.63 % experimentally, while the model predicted a yield of 79.243 % under optimal conditions.
Aerobic granular sludge-based sustainable wastewater treatment: Process, bottlenecks, and knowledge gap through scientometric perspective Pingili Vydehi, Gobinath Ravindran, G. Shyamala, Sri Bala G, Vamsi Nagaraju T, Mallaiah Mekala, Rama Rao Karri Journal of Hazardous Materials Advances, 2024 • Aerobic Granular Sludge is effective biological wastewater treatment method. • Several challenges are associated in maintaining the AGS plant. • Scientometric perspective provide the current active research on this area. By 2030, the UN General Assembly issued Sustainable Development Goal 6 (SDG 6), which calls for the provision of safe drinking water; however, little progress has been made. Wastewater treatment and reuse have garnered significant attention owing to the increasing demand for sanitation and sustainable development practices. Multiple methods have been designed and tested, among which Aerobic Granular Sludge-based treatment is rapidly emerging as a promising treatment option. Aerobic Granular Sludge (AGS) plants have been the focus of research due to their low energy consumption, small footprint, and low unit costs. However, the full-scale application of AGS may be hindered by constraints such as strict nitrogen and phosphorus discharge standards, frequent and large temperature fluctuations, and fluctuating influent flow volume. Despite the existence of a few reviews related to AGS technology, there is a need for an extensive review coupled with a research progress analysis that provides comprehensive information on the nuances of AGS, which prompted this article. AGS technique and research progress in AGS are identified through a scientometric lens is reviewed in this article. The topics covered include the generation of AGS through the use of technology, usage, challenges associated with managing AGS plants, and a comparison between AGS and other methods of energy storage. An analysis was conducted to understand the keywords for which research is currently active: authors who have conducted more research, collaboration, and other bibliometric factors associated with AGS research.
Experimental studies of a continuous catalytic distillation column from startup to steady state for the production of methyl acetate Mallaiah Mekala International Journal of Chemical Reactor Engineering, 2024 Esterification of acetic acid with methanol to produce methyl acetate and water has been studied in a continuous packed bed catalytic reactive distillation. The key challenge is the startup method of the experiments fora continuous reactive distillation as well as reactive zone height selection. In the present study, the effect of various operating conditions on the methyl acetate composition (mole fraction) is studied. Indion 180 ion-exchange resin solid catalyst is used in the reactive zone. The catalyst is immobilized by using a novel equivalent Katapak-S in the reactive section. Experiments were performed under different operating conditions to find the high purity methyl acetate product in the distillation. The experiments were performed for various conditions like total feed flow rate, reboiler temperature, reflux ratio, methanol to acetic acid mole ratio and catalyst loading with the time. The experiments were carried out till the system reaches to the steady state under different conditions. The maximum methyl acetate concentration is obtained at 80 °C reboiler temperature, 2.01 reflux ratio, 16.3 g/min flow rate, 60 g catalyst loading and 1 mol ratio of methanol to acetic acid. The highest purity of methyl acetate obtained under optimal condition is 95 % by mole.
Reactive distillation and reactive separations Mallaiah Mekala, Srinath Suranani Process Intensification for Chemical and Biotechnology Industries Fundamentals and Applications to Critical and Advanced Processes, 2023
