Abstract
Removal of heavy metal ions such as cadmium, lead, chromium, and iron from industrial wastewater is one of the most critical environmental problems. In this research, natural and low-cost adsorbents like the tangerine peel, bovine gut, tea waste, and sunflower seed hull were used for adsorption of heavy metals, such as chromium and iron, from contaminated solutions. The effects of environmental factors such as contact time, pH, the amount of adsorbent dose, and the initial concentration of metal ions in synthetic solution were investigated to obtain optimal conditions for the adsorption of heavy metal ions. For separation of chromium metal ion from aqueous solution, tea waste, tangerine peel, bovine gut, and sunflower seeds hull showed adsorption capacity of 85%, 51%, 46%, and 34%, respectively, while for the adsorption of iron (III), the adsorption capacities of tea waste, bovine gut, tangerine peel, and sunflower seeds hull were 96%, 96%, and 87%, respectively. The adsorption isotherms were in decent correlation with the Langmuir and Freundlich isotherm models. The adsorption kinetics of iron and chromium has a proper validation with the pseudo-second-order kinetic model. The BET and FTIR analyses were also reported to investigate the adsorption properties. This study suggests these adsorbents as low-cost and economical materials for the adsorption of chromium and iron ions with a high adsorption rate.
Highlights
Nowadays, with the development of industries and increasing the population, especially in developing countries, the release of heavy metals by the wastewater of these industries into the environment is one of the most critical environmental problems
In order to optimize the conditions for removal of heavy metals with low-cost adsorbents, chromium and iron metal ions were extracted from the wastewater by tea waste, tangerine peel, bovine gut, and sunflower seed hull. e effects of pH, the dose of adsorbents, adsorption time, and initial metal ions concentrations were investigated
Optimal pH for Adsorption of Chromium. e pH value of the solution is an effective parameter in the adsorption process [52]
Summary
With the development of industries and increasing the population, especially in developing countries, the release of heavy metals by the wastewater of these industries into the environment is one of the most critical environmental problems. 0.01000 0.20000 0.80000 0.00003 0.00600 0.05000 0.05000 0.02500 maximum permitted levels of heavy metals in the industrial wastewaters [11] Many conventional methods such as chemical precipitation, coagulation and flocculation, adsorption, electrochemical treatment, flotation, ion exchange, and membrane filtration are used to remove metal ions from aqueous solutions [12, 13]. Four cheap adsorbents including tea waste, tangerine peel, bovine gut, and sunflower seed hull were used to measure and optimize adsorption conditions to remove iron and chromium ions from the aqueous solutions. These materials are organic and they do not pose any danger to the environment, their annual rate of production and disposal is very high For this reason, in this study, we used these four substances as inexpensive adsorbents to absorb metal ions from wastes. The kinetics of adsorption were investigated and compared with pseudo-first and pseudo-second-order models
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