Band 23, Heft 7

The increased occurrence of antibiotics in wastewater effluents has emerged as a significant environmental and public health issue, as these contaminants contribute to the development of antibiotic resistance and disrupt the balance of natural microbial ecosystems. Traditional wastewater treatment processes frequently prove inadequate in efficiently eliminating these contaminants. The present study reviews photocatalysis and biological treatment methods, as indicated in the literature, as a comprehensive solution for removing antibiotics such as amoxicillin and ciprofloxacin from wastewater, to determine the most successful treatment strategy for our research. Essential strategies include titanium dioxide (TiO 2 ) in the slurry/suspension mode, doped and immobilized for photocatalytic degradation and the employment of microorganisms in biological treatments are highlighted. Focusing on studies in recent years, the study provides a comparative analysis to identify the most effective treatment methods for these antibiotics.

This study explores the microwave pyrolysis characteristics of raw tobacco stems and tobacco stems impregnated with urea using different metal-loaded zeolite catalysts. Due to the cracking effect of HZSM-5 and the dehydrogenation activity of Ni sites, the sum of CO and H 2 yields in both raw tobacco stem and tobacco stem impregnated with urea gas products exceeded 50 %. The 10Ni catalyst reduced the content of organic acids in the raw tobacco stem liquid product from 17.51 % to 10.88 %. The addition of catalysts increased the nitrogen-containing compounds (NCCS) content substantially. Catalytic pyrolysis promoted the decomposition of nicotine, resulting in a rapid decrease of the nicotine content in tobacco stem impregnated with urea liquid products. The content of amines increased rapidly with a maximum 30.79 %. The addition of Cr improved the selectivity of catalysts for indoles with a maximum yield 8.48 %. Cr sites promoted further dehydration, condensation and cyclization of some amines to produce indole. The content of pyridine in the liquid products of tobacco stems impregnated with urea is also high, reaching 27.91 %. This study first introduces the synergistic effect of Ni–Cr co-modification combined with an external nitrogen source (urea) to selectively regulate the formation of NCCs, providing a novel approach for the valorization of tobacco residues, such as tobacco stems.

The present study deals with modeling and simulating the gasification process for syngas production. Equilibrium modeling was done to study the product gas composition by changing the process parameters, viz., reaction temperature, equivalence ratio, and moisture content. Coal, wood waste, eucalyptus, pine, and oak were gasification feedstocks. System model equations have been solved using MATLAB software. The model is studied for the range of temperature (800–1400 K), moisture content (7–40 %), and equivalence ratio (0–1). The results of the simulation study were compared with the values in the literature. The results show that the model is entirely satisfactory for the equivalence ratio range of 0.15–0.35. The variation in operating conditions, i.e., equivalence ratio, temperature, moisture content, and the characteristics of carbonaceous feed material, greatly influences the exit gas composition. A carbonaceous feed with almost the same syngas composition can be used for the same gasification process without changing the parameters. Further, coal-derived syngas has different characteristics from the wood waste of oak, pine, and eucalyptus feedstocks. Under optimal conditions, H 2 and CO concentrations reached 38  and 35 %, respectively. Increasing sulfur content by 2 % led to a 6 % reduction in CO yield, confirming its inhibitory effect on gasification efficiency.

This paper presents a mathematical model for the vertical distribution of suspended sediment concentration in turbulent open-channel flow. The governing equation is derived using the principles of mass and momentum conservation for sediments. A mixing length model, expressed as a function of sediment concentration, is formulated using Reynolds stress. The resulting non-linear ordinary differential equations describing the concentration profiles for steady and uniform flow are solved numerically using the fourth-order Runge–Kutta method. The accuracy of the model is validated through comparisons with experimental data from the literature. The proposed model provides a more precise prediction of sediment concentration, particularly near the bed, where traditional models often show limitations. Its applications extend to hydraulic engineering, environmental management, and sediment transport studies in rivers, estuaries, and reservoirs, aiding in sediment control strategies, dredging operations, and predictive modeling of erosion and deposition processes.

The comparative drug removal study under sunlight irradiation of polyaniline (PANI), polypyrrole (PPy), and polythiophene (PTh) is presented in this report, with a focus on the removal of antibiotics namely Ciprofloxacin and Pefloxacin. Using a UV-visible spectrophotometer, the removal efficiency of Ciprofloxacin and Pefloxacin was investigated for PANI, PPy, and PTh under identical conditions. The structural investigation of PANI, PPy, and PTh was conducted using Field Emission Scanning Electron Microscopy (FESEM) measurements. After 660 min of sunlight irradiation, PANI demonstrated the highest Ciprofloxacin removal 82 %. PPy followed closely with 75 % removal, while PTh exhibited a removal of 70 %. Following the same 660 min sunlight irradiation period, PANI exhibited the 80 % removal capability for Pefloxacin, exceeding PPy’s 74 % and PTh’s 69 % removal efficiencies. For both antibiotics, PANI revealed the highest photocatalytic enactment compared to PPy and PTh. Kinetic analysis revealed that PANI has higher rate constant for the degradation of 5 ppm Ciprofloxacin while a better value of rate constant was identified for PPy for the photodegradation of 5 ppm Pefloxacin. It has been demonstrated that PANI, PPy, and PTh have shown encouraging potential as photocatalysts for the elimination of antibiotic pollutants from wastewater.

Many adsorbents have been used for the removal of anions such as nitrate and phosphate. However, their availability, variation in their composition, and low adsorption ability have limited their usability. Hence, there is a need for new and readily obtainable adsorbents for the recovery of nitrate and phosphate. In the present investigation, we focused on the removal of nitrate and phosphate using modified palm fruit husks, which are available in many tropical countries such as India. The exterior was updated by employing a surface activation group, cetyl trimethyl ammonium bromide (CTAB) which enhanced the uptake efficiency of anions such as nitrate and phosphate. The nitrate and phosphate uptake reached a maximum at pH 4.0 and 2.0, respectively. The Langmuir and Dubinin Radushkevich isotherms are well suited to the experimental uptake equilibrium details. Desorption investigation showed that the adsorbed nitrate and phosphate can be gradually discharged under various pH atmospheres. Coexisting negatively charged ions, such as Cl − , SO 4 2− , CO 3 2− and PO 4 3− interfere with the adsorption of anions. The column leaching test indicated that nitrate and phosphate discharge was prolonged, and it is feasible to use nitrate and phosphate-loaded SAPFH as a control-release fertilizer.

Mercury contamination in wastewater is a critical environmental issue due to its high toxicity, persistence and bioaccumulation in the ecosystem. Conventionally, sawdust activated carbon (SDAC) is used for mercury ion adsorption. However, its adsorption efficiency could be improved by surface modification and incorporation of new materials. Thus, this study investigates the efficacy of a novel surface modified SDAC namely, chitosan coated sawdust activated carbon (CCSDAC) for mercury removal. A higher percentage of Hg (II) adsorption from waste water was achieved due to the presence of chitosan in CCSDAC when compared to SDAC. The adsorption mechanism was analysed through kinetic and adsorption model. Batch mode adsorption studies were performed to assess the impact of carbon dose, initial metal ion concentration and temperature on Hg (II) adsorption. CCSDAC exhibited significantly higher mercury adsorption efficiency compared to SDAC. Optimal conditions that favoured efficient mercury removal are pH of 6.0, carbon particle size of 150 μm, agitation time of 180 min and temperature above 303 K. The adsorption kinetics was evaluated using the pseudo-first-order, pseudo-second-order and intra-particle diffusion models. Furthermore, various isotherm models were applied to elucidate the adsorption equilibrium behaviour of mercury removal.

This work is oriented on the photocatalytic ozonation of azo dye solution for its decolorization using UV light (UV/FeT/O 3 ) and solar light (solar/FeT/O 3 ). In this study Fe doped TiO 2 nanocatalyst (FeT) was prepared successfully in laboratory scale by molten salt method, was used as a catalyst during the treatment. For the optimization of process parameters, response surface methodology (RSM) is used in term of central composite design (CCD). Different operating parameter such as concentration of ozone, initial pH of solution, initial dye concentration of solution, dosing of FeT catalyst, and color reduction as a response of the process were inspected with a model development using CCD. ANOVA was also applied to statistically observation for the developed regression model. The developed CCD model was found statistically significant. This is confirmed by determination coefficient value (R 2  = 0.9778). The optimum color reduction 95.12 % for UV/FeT/O 3 was obtained at ozone concentration of 70 mgL −1 ; initial pH of 08; initial dye concentration of 200 mgL −1 ; catalyst dose of 1 gL −1 for 20 min of treatment process. A synergy index value of the UV photocatalytic ozonation process is 1.12, which indicates the rate between ozonation and photocatalysis. Kinetics is analyzed at two different concentrations of dye: 200 mg/L and 400 mg/L for both UV/FeT/O 3 and Solar/FeT/O 3 based treatment. First order reactions are observed for all experiments. Photocatalytic ozonation is cost-efficient than individual ozonation or individual photocatalysis.

The dross, an invaluable co-product replete with substantial metal content, is generated within the hot-dip galvanization process. In this study, we meticulously investigate the design and simulation of a novel reactor tailored to the separation of hot-dip galvanizing dross, characterized by diminished residual metal content, employing the technique of supergravity separation. The investigation unfolds through an intricate numerical simulation, with the computed results rigorously validated through the prism of water modeling. A new method for evaluating liquid level fluctuations was proposed and a comprehensive analysis is undertaken to scrutinize the effects of various pivotal factors, including the direction of rotation, angular velocity, liquid depth, and reactor dimensions, on the dynamic behavior of the liquid medium. It is observed that, under the influence of clockwise rotation, the galvanizing dross seamlessly infiltrates the novel reactor. Furthermore, as the angular velocity escalates from 0 radians per minute to an astounding 900 radians per minute, while maintaining a liquid depth exceeding 5 cm, the region enveloping the reactor experiences a remarkable augmentation in the extent of liquid zinc exhibiting velocities equal to or surpassing 0.2 m per second. This augmentation persists as the reactor dimensions expand. The assessment of these variables is facilitated through the utilization of the liquid fluctuation index, providing a discerning evaluation of their impact on rotation rate, liquid depth, and reactor size. Consequently, this study incontrovertibly attests to the feasibility of the newly devised reactor in the noble pursuit of liberating metal from the clutches of hot-dip galvanizing dross.

In the quest for sustainable energy, biofuels emerge as a viable alternative to fossil fuels. Edited by Vivek Dave and Arindam Kuila, Nanomaterials as a Catalyst for Biofuel Production explores the transformative role of nanomaterials in biofuel production, covering biodiesel, bioethanol, biogas, and biohydrogen. The book also delves into environmental bioremediation and techno-economic analysis, offering a comprehensive blend of fundamental concepts and practical applications. It serves as a crucial reference for advancing efficient, sustainable biofuel technologies to drive the global shift toward green energy. This article outlines the main content of each chapter in the book and summarizes the key points of the book. Furthermore, it points out the advantages and disadvantages of this book. The book review is helpful in guiding readers to read the key content of the book and grasp the latest research directions of biofuel production, which is meaningful.