Removal of metal ions using a new magnetic chitosan nano-bio-adsorbent; A powerful approach in water treatment.

Cadmium (Cd) and lead (Pb) contaminations are disturbing environmental issues, which causes serious harm to aqueous systems and human health. Therefore, removing them from aqueous solution is essential to prevent its damage to the environment. Environmental adsorption research as one solution has seen a boom over the past decade. Using modified biochar has proved to be more suitable for the adsorption of cadmium and lead. Most of the studies apply a routine method such as kinetic and isotherm modelling to demonstrate the macroscopic trend of adsorption, often without elaborative evaluation of the effectiveness and characteristics of the models. This review compiles different adsorption kinetics and isotherms models and also presents their origins, modified versions, and their applicability in the liquid adsorption situation. The effect of experimental parameters and adsorption mechanisms are discussed to study the adsorption performances of modified biochar. The adsorption mechanism was majorly by surface precipitation, ion exchange, electrostatic attraction, complexation and physical adsorption. The adsorption was majorly endothermic and spontaneous. Additionally, preparation and regeneration of modified biochar are also presented to provide a direction for sustainable improvement. This paper summarizes with a note on challenges, prospects and future perspectives of adsorption of cadmium and lead pollutions.

Adsorption of cadmium and lead from aqueous solution using modified biochar: A review

The current development of chemical looping combustion (CLC) technology is presented in this paper. This technique of energy conversion enables burning of hydrocarbon fuels with dramatically reduced CO2 emission into the atmosphere, since the inherent separation of carbon dioxide takes place directly in a combustion unit. In the beginning, the general idea of the CLC process is described, which takes advantage of solids (so-called oxygen carriers) being able to transport oxygen between combustion air and burning fuel. The main groups of oxygen carriers (OC) are characterized and compared, which are Fe-, Mn-, Cu-, Ni-, and Co-based materials. Moreover, different constructions of reactors tailored to perform the CLC process are described, including fluidized-bed reactors, swing reactors, and rotary reactors. The whole systems are based on the chemical looping concept, such as syngas CLC (SG-CLC), in situ Gasification CLC (iG-CLC), chemical looping with oxygen uncoupling (CLOU), and chemical looping reforming (CLR), are discussed as well. Finally, a comparison with other pro-CCS (carbon capture and storage) technologies is provided.

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Chemical Looping Combustion: A Brief Overview

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Photocatalytic activity of CuO nanoparticles for organic and inorganic pollutants removal in wastewater remediation.

Prospects of titanium carbide-based MXene in heavy metal ion and radionuclide adsorption for wastewater remediation: A review

Rapid industrialization, with economic prosperity set as the prime goal, has always created some secondary intolerable problems such as heavy metal contamination, wastewater that need remediation. Industrial wastewater is the major contributors to contamination of aquatic and terrestrial ecosystems with toxic heavy metals like arsenic, copper, chromium, cadmium, nickel, zinc, lead, and mercury whose hazardous bio-accumulative nature in biotic systems is attributed to their high solubility in the aquatic environments. There has, therefore, always been a need for the removal and/or recovery of these toxic, non-biodegradable, and persistent heavy metals from the industrial wastewater. For several decades, extensive investigations have been performed for easy, efficient, and economic removal of heavy metals with a varying degree of success. Chemical precipitation, adsorption, ion floatation, ion-exchange, coagulation/flocculation and electrochemical methods have been the most readily available conventional methods for the removal of these heavy metals. These methods however have posed some serious shortcomings such as high sludge production needing further treatment, low removal efficiency and high energy requirements. In the present years, newer more efficient, more economic and innovative technologies are being investigated. Recently photocatalysis, electrodialysis, hydrogels, membrane separation technique and introducing newer adsorbents have been developed for better adsorption. Hence in this paper, we have reviewed efforts and technological advances achieved so far in the pursuit of more efficient removal and recovery of heavy metals from industrial wastewaters and have evaluated their efficiency dependence on various parameters such as pH, temperature & initial dosing.

Technological trends in heavy metals removal from industrial wastewater: A review

Climate change is among the most urgent and serious problems that humanity must address. Climate change is driven by the atmospheric accumulation of several greenhouse gases (GHGs). Among these gases, CO2 has been showing the most alarming global accumulation rate and as predicted by IPCC its global concentration may reach up to 570 ppm raising the global temperature by around 1.5 °C near the year 2100. With a need for mitigation of the adverse effects accredited to it, carbon capture and utilization (CCU) technologies based on thermal, chemical, biochemical, photochemical and electrochemical pathways have had major appeal among the scientific community and the industries. These technologies, while reducing the rate of global CO2 emission, also valorize the CO2 for producing several products that complement the chemical industries. Despite low temperature application favor noble metals for thermal utilization of CO2, their high cost has led researchers to focus towards the development of catalysts based on earth abundant metals and their adaptability to a suitable support. Electrochemical transformation systems have yielded for example, formic acid whose production can lead to 95.01% reduction in global warming alongside formation of oxalic acid, CO, ethylene, ethanol etc. through electrical reduction within ambient conditions. Furthermore, the technology is based on utilizing renewable perpetual sources of electricity with development works focusing on increasing catalytic life. CO2 has also been photochemically reduced with absorbed radiation generating an excited state followed by transferring the charge to a functional ligand. Developments related to for example photosensitizer, catalysts, and obtained yield are presented, describing various factors affecting the photochemical transformation. In the biochemical pathway; by selecting desired route and manipulating strains, CO2 can be enzymatically transformed to other products with optimization in yields. In this review, an overview on advancements achieved so far in the aforementioned technologies and future course of action are presented.

Technological Advances in the Transformative Utilization of CO2 to Value-added Products

This study presents a detailed design, cost estimation and sensitivity analysis to determine the commercial viability of a Jatropha biodiesel plant with Nepal as a representative case. Here, we present a biodiesel production process utilizing dolomite PB-20, an inexpensive solid catalyst, that allows easy retrieval of catalysts for reuse and easier product separation compared to the conventional liquid catalyst based production process. The transesterification and the subsequent separation processes were simulated using Aspen Plus to determine the amount of raw materials, the sizes of the equipment's and the total utility required for producing 43 million liters biodiesel per year. The total capital cost and the production cost for the plant of this scale was calculated to be $23 million and $51 million respectively. Similarly, the final biodiesel selling price was calculated to be $1.23/l. The selling price of the biodiesel was found to be highly sensitive to the purchase cost of the Jatropha oil. A 25% reduction in the Jatropha oil purchase cost from the base case price of $0.97/l will lower the biodiesel selling price to $1.00/l making it competitive with petro-diesel (current selling price of $1.02/l). The economic viability of the dolomite catalyst based biodiesel production plant and thus, the adoption of biodiesel as a substitute for petro-diesel is strongly dependent on the purchase cost of the Jatropha oil. This study illustrates the potential of dolomite catalyst based biodiesel production process and provides an important reference value for a more detailed policy level study to develop appropriate biofuel policies and to make investment decisions. 

Sagar Ban

Papers

Technological trends in heavy metals removal from industrial wastewater: A review

Technological Advances in the Transformative Utilization of CO2 to Value-added Products

Process Simulation and Economic Analysis of Dolomite Catalyst Based Biodiesel Production from Nepalese Jatropha Curcas

Techno-economic analysis of hydropower based green ammonia plant for urea production in Nepal