Present paper involved the review of fixed-bed column studies for removal of various contaminants from synthetic wastewater. Basic concept of adsorption, its types (i.e., chemisorption and physisorption) and its mechanism, adsorbents and adsorbates were included. Comparison of batch and column adsorption study is mentioned. Complete study of breakthrough curve for designing adsorptive column is interpreted. This paper explicates the detailed explanation of various process parameters and isotherm models for column study. Fixed-bed adsorption studies using various adsorbates, i.e., metal, ion, dye and other hazardous materials, are reviewed, in which adsorption of chromium metal is most exploitable. Conclusion and some challenges for utilization in real world are also exposed.

In recent times, metal oxide nanoparticles (NPs) have been regarded as having important commercial utility. However, the potential toxicity of these nanomaterials has also been a crucial research concern. In this regard, an important solution for ensuring lower toxicity levels and thereby facilitating an unhindered application in human consumer products is the green synthesis of these particles. Although a naïve approach, the biological synthesis of metal oxide NPs using microorganisms and plant extracts opens up immense prospects for the production of biocompatible and cost-effective particles with potential applications in the healthcare sector. An important area that calls for attention is cancer therapy and the intervention of nanotechnology to improve existing therapeutic practices. Metal oxide NPs have been identified as therapeutic agents with an extended half-life and therapeutic index and have also been reported to have lesser immunogenic properties. Currently, biosynthesized metal oxide NPs are the subject of considerable research and analysis for the early detection and treatment of tumors, but their performance in clinical experiments is yet to be determined. The present review provides a comprehensive account of recent research on the biosynthesis of metal oxide NPs, including mechanistic insights into biological production machinery, the latest reports on biogenesis, the properties of biosynthesized NPs, and directions for further improvement. In particular, scientific reports on the properties and applications of nanoparticles of the oxides of titanium, cerium, selenium, zinc, iron, and copper have been highlighted. This review discusses the significance of the green synthesis of metal oxide nanoparticles, with respect to therapeutically based pharmaceutical applications as well as energy and environmental applications, using various novel approaches including one-minute sonochemical synthesis that are capable of responding to various stimuli such as radiation, heat, and pH. This study will provide new insight into novel methods that are cost-effective and pollution free, assisted by the biodegradation of biomass.

The textile dyeing industry consumes large quantities of water and produces large volumes of wastewater from different processes in dyeing and finishing processes. The low-cost, easily available naturally prepared coagulants like Surjana seed powder (SSP), Maize seed powder (MSP) and Chitosan as an ideal alternative to recent expensive coagulant methods for Congo Red (CR) dye removal has been investigated in this study. Various process parameters like pH, coagulant dose, flocculation time and temperature and also its optimization were exploited. The maximum percentage CR removal was found to be 98.0, 94.5 and 89.4 for SSP, Chitosan and MSP, respectively, at pH 4.0, coagulant dose of 25 mg/l, flocculation time 60 min and temperature of 340 K. The Sludge Volume Index (SVI) and turbidity were calculated for these parameters including process optimization. SSP found more preferable for CR removal and Chitosan was a better coagulant, which corresponds to SVI than the other coagulants investigated

The present investigate was intended for adsorption of heavy metals i.e. Pb, Cu, Cr, Zn, Ni and Cd onto activated charcoal prepared from neem leaf powder (AC-NLP) using batch and column studies. Batch adsorption was performed using different variables like adsorbent dose, temperature and contact duration. Thermodynamic analysis of batch treatment concluded that adsorption is thermodynamically feasible and endothermic. This adsorption followed the Pseudo second-order kinetic model derived from correlation coefficient values of chemical kinetic studies. For column study, interpretation of breakthrough curves and parameters were conducted by varying flow rate, initial concentration and bed height; and reveal that optimum conditions were lower flow rate (5 mL/min) and lower initial concentration (5 mg/L) and higher bed height (20 cm). Comparisons of batch and column study through isotherm models were evaluated and column study is more preferred than batch treatment. Maximum Thomas adsorption capacity was achieved upto 205.6, 185.8, 154.5, 133.3, 120.6, 110.9 mg/g for Pb, Cu, Cd, Zn, Ni and Cr respectively. This removal pattern is elucidated by metal ionic properties. Various adsorbing agents such as acids and bases were utilized for adsorption–desorption of AC-NLP.

Environmental problems due to the textile industry are mainly associated with the need for large amounts of fresh water and discharging highly polluted wastewater. This wastewater contains several types of pollutants, such as dispersants, leveling agents, salts, carriers, acids, alkali, and various dyes. The wastewater quality is variable and depends on the kind of process that generates the effluent. In addition, color is the first recognizable pollutant, which has a negative effect on the ecosystem. Many methods are available for removing the contaminant; among the various methods, adsorption is significantly important and is the major method adopted in chemical and process industries. In recent times, there has been a drastic increase in the use of various types of charcoals as adsorbent. This review article focuses on textile wastewater; adsorption; preparation of charcoals and its activated forms using various materials; and treatment of textile wastewater using various types of charcoals. Treatment of real and synthesized wastewater (i.e., dye solution) is included and a feasibility study of utilizing charcoal is performed by comparing adsorption capacities or percentage removal.