The rationale for alternative fertilization: Equilibrium isotherm, kinetics and mass transfer analysis for urea-nitrogen adsorption from cow urine

In an effort to minimize the loss of urea-N through volatilization and concurrently recover urea in a usable form from cow urine, adsorption experiments using bamboo-based activated carbon were performed. Batch studies were undertaken to evaluate the effect of initial concentration, sorption time and temperature on the variation in urea uptake capacity of the prepared carbon. Equilibrium data were tested against various isotherms, kinetics and mass transfer models. The Langmuir monolayer sorption was found to be 146.12 mg.g−1 with nearly 90% urea recovery attained. The process was found to be reversible as seen through regeneration experiments. Thermodynamic parameters indicated that urea sorption was physical, spontaneous and exothermic in nature. Kinetic studies revealed that the rate of urea uptake was limited by both surface adsorption and intra-particle diffusion. It was concluded that the mass transfer of urea molecules over the activated carbon was governed by film diffusion at all concentrations examined

Influence of Microwave and Ultrasound pretreatment on Solvent Extraction of Bio-components from Walnut (Julgans regia L.) Shells

Walnut (Julgans regia L.) shells, an agro-forestry waste, are a rich source of phytochemicals with anti-oxidative and medicinal properties. Whilst recent research efforts focus on waste valorization, the present investigation demonstrates a process to extract and characterize bio-components from physically pretreated walnut shells. Pretreatment was undertaken using microwave irradiation and ultra-sonication with two different solvents (methanol and acetone). The extract obtained was optimized using Response Surface Methodology (RSM). Further, the bio-components in the extract were identified using GCMS and FTIR analyses. Through the experimental runs, it was observed that pretreatment enhanced the total extract yield from the process relative to conventional Soxhlet extraction. As a method of pretreatment, microwave irradiation was found to suit the extraction better than ultra-sonication. In addition, acetone performed better as a solvent than methanol in the bio-components recovery. Relative to conventional Soxhlet extraction, microwave pretreatment allowed for enhanced separation by 4.06 folds for methanol and 5.25 for acetone. The yield was found to be the highest (46 mg/g) while using acetone, when pretreated with microwaves at 180 W for 4 min

Simultaneous resource recovery and ammonia volatilization minimization in animal husbandry and agriculture

The study demonstrates that the minimization of ammonia volatilization and urea recovery could be coupled through the use of physical adsorption processes in continuous packed-bed columns. The potential of using microwave activated coconut shell based activated carbon toward the recovery of urea from cattle urine was investigated. The prepared carbon was immobilized onto etched glass beads to investigate the effect of initial concentration, flow rate and size of carbon support in a continuous, down-flow mode packed column. Further, to describe the sorption behavior, the experimental data were tested against different kinetic models. The analysis of the breakthrough curves allowed identification of the favorable operating parameters as: sorbate flow (8 L·h−1), initial urea concentration (60%) and glass bead support size (ϕ 1.5 cm). An equilibrium sorption of 802.8 mg·g−1 and up to 80% urea recovery was observed. Regeneration studies allowed for nearly 95% urea recovery with sorbent capacity decreasing by 5% over seven cycles of sorption/desorption

Simultaneous resource recovery and ammonia volatilization minimization in animal husbandry and agriculture

AbstractThe study demonstrates that the minimization of ammonia volatilization and urea recovery could be coupled through the use of physical adsorption processes in continuous packed-bed columns. The potential of using microwave activated coconut shell based activated carbon toward the recovery of urea from cattle urine was investigated. The prepared carbon was immobilized onto etched glass beads to investigate the effect of initial concentration, flow rate and size of carbon support in a continuous, down-flow mode packed column. Further, to describe the sorption behavior, the experimental data were tested against different kinetic models. The analysis of the breakthrough curves allowed identification of the favorable operating parameters as: sorbate flow (8 L⋅h−1), initial urea concentration (60%) and glass bead support size (ϕ 1.5 cm). An equilibrium sorption of 802.8 mg⋅g−1 and up to 80% urea recovery was observed. Regeneration studies allowed for nearly 95% urea recovery with sorbent capacity decreasing by 5% over seven cycles of sorption/desorption

On the behaviour, mechanistic modelling and interaction of biochar and crop fertilizers in aqueous solutions

AbstractAlthough the benefits of applying biochar for the purposes of soil conditioning and crop productivity enhancement have been demonstrated, relatively few studies have elaborated on its causal mechanisms, especially on the biochar–fertilizer interaction. Thus, in the present study, the ex-situ adsorptive potential of base activated biochar (BAB) towards plant nutrient immobilization and removal from aqueous solutions was investigated. Napier grass (Pennisetum purpureum) was utilized as the precursor to prepare slow vacuum pyrolysed char and its affinity towards adsorption of urea was examined at various process conditions. Low sorption temperatures, moderate agitation speeds and high initial concentration were seen to favour greater urea uptake by BAB. The sorption was exothermic, physical, spontaneous and had a pseudo-second order kinetic fit. Both surface and intra-particle diffusion governed the removal and immobilization of urea. Furthermore, process mass transfer was limited by film diffusion of urea to the external surface of the BAB. Equilibrium studies suggested that Dubinin–Radushkevich is the most appropriate model to describe the urea-BAB behaviour with maximum uptake, estimated to be 1115 mg⋅g−1. Through such ex-situ analysis, it could be possible to have prior knowledge, quantification and differentiation of the potential of chars manufactured from various feedstocks. This could then be used as an effective screening step in designing appropriate biochar–fertilizer systems for soil conditioning and help reduce the time and effort spent otherwise in long-term field studies

Removal of turbidity from washing machine discharge using Strychnos potatorum seeds: Parameter optimization and mechanism prediction

AbstractIn this research an attempt has been made to utilize the Strychnos potatorum seed powder as an environmentally friendly coagulant for the removal of turbidity from washing machine discharge. The performance of this system was also compared with synthetic water. Experimental studies were conducted for the maximum removal of turbidity from washing machine discharge and synthetic turbid water which were varied from 50 to 145 NTU. The effect of operating parameters such as initial turbidity, S. potatorum dosage and pH of the solution was optimized for the maximum removal of turbidity. It was seen that the percentage removal of turbidity lay was between 68–89% and 65–84% for synthetic turbid water and washing machine discharge sample respectively, at an ideal pH of 6–7. The experimental values were compared with the Langmuir and Freundlich isotherm models to understand the extent of influence of the sorption of the particles onto the S. potatorum seed powder. Better results with respect to concordance of experimental data were observed with Langmuir isotherm model, indicating a monolayer sorption of particles onto the S. potatorum seed powder. It was observed from the isotherm study that the sorption may also be influenced in the removal of turbidity to some extent from the washing machine discharge and synthetic water. The prepared material can be effectively utilized for the removal of turbidity from the water

The face behind the Covid-19 mask ??? A comprehensive review

The threat of epidemic outbreaks like SARS-CoV-2 is growing owing to the exponential growth of the global population and the continual increase in human mobility. Personal protection against viral infections was enforced using ambient air filters, face masks, and other respiratory protective equipment. Available facemasks feature considerable variation in efficacy, materials usage and characteristic properties. Despite their widespread use and importance, face masks pose major potential threats due to the uncontrolled manufacture and disposal techniques. Improper solid waste management enables viral propagation and increases the volume of associated biomedical waste at an alarming rate. Polymers used in single-use face masks include a spectrum of chemical constituents: plasticisers and flame retardants leading to health-related issues over time. Despite ample research in this field, the efficacy of personal protective equipment and its impact post-disposal is yet to be explored satisfactorily. The following review assimilates information on the different forms of personal protective equipment currently in use. Proper waste management techniques pertaining to such special wastes have also been discussed. The study features a holistic overview of innovations made in face masks and their corresponding impact on human health and environment. Strategies with SDG3 and SDG12, outlining safe and proper disposal of solid waste, have also been discussed. Furthermore, employing the CFD paradigm, a 3D model of a face mask was created based on fluid flow during breathing techniques. Lastly, the review concludes with possible future advancements and promising research avenues in personal protective equipment

Modeling the adsorption of benzeneacetic acid on CaO2 nanoparticles using artificial neural network

AbstractThe present work reported a method for removal of benzeneacetic acid from water solution using CaO2 nanoparticle as adsorbent and modeling the adsorption process using artificial neural network (ANN). CaO2 nanoparticles were synthesized by a chemical precipitation technique. The characterization and confirmation of nanoparticles have been done by using different techniques such as X-ray powder diffraction (XRD), high resolution field emission scanning electron microscope (HR-FESEM),transmittance electron microscopy (TEM) and high-resolution TEM (HRTEM) analysis. ANN model was developed by using elite-ANN software. The network was trained using experimental data at optimum temperature and time with different CaO2 nanoparticle dosage (0.002–0.05 g) and initial benzeneacetic acid concentration (0.03–0.099 mol/L). Root mean square error (RMS) of 3.432, average percentage error (APE) of 5.813 and coefficient of determination (R2) of 0.989 were found for prediction and modeling of benzeneacetic acid removal. The trained artificial neural network is employed to predict the output of the given set of input parameters. The single-stage batch adsorber design of the adsorption of benzeneacetic acid onto CaO2 nanoparticles has been studied with well fitted Langmuir isotherm equation which is homogeneous and has monolayer sorption capacity