Adsorption Studies on Red Mud: Removal and Recovery of Cr (VI) from Wastewater

The addition of any organic, inorganic, biological, or radiological substance to water that changes its physical and chemical properties is known as water pollution. These pollutants come in contact with water by rapid and unplanned industrial progress, overpopulation, discharge of sewage into water bodies, etc and such water is unfit and very harmful to public health, animals, plants, and aquatic life. Water pollution due to heavy metals and organic pollutants has been a major Concern for a long. Heavy metals are nonbiodegradable and are the cause of many dreadful disorders in the long run; on the other hand, many organic pollutants are carcinogenic. Sources, toxicity, and hazardous effects of some important heavy metals are also summarized. Heavy metals are also summarized. Include preliminary treatment, primary treatment, secondary treatment, and tertiary treatment. The main objective of preliminary treatment and primary treatment is the removal of gross solids such as large floating and suspended solid matter, grit, oil, and grease if present in considerable quantities. Secondary treatment is a biological process involving bacteria and other microorganisms removing the dissolved and colloidal organic matter present in the wastewater. Tertiary treatment is the final treatment, meant for “polishing” the effluent from the secondary treatment processes to improve the quality further.


Introduction
The unthoughtful race for industrial development and unlimited exploitation of natural resources have adversely affected all forms of life in the biosphere.This has threatened the survival of all living organisms.Air has become dangerous to breathe, water is unfit to drink, soil is unsuitable for crops and aquatic ecosystems antagonized marine creatures.Industrialization has given us radioactivity, dangerous effluents, poisonous gases, and heavy metals etching our environment.Thanks to pollution, all these are the gifts of industrialization to modern civilization.The term pollution is defined as an undesirable change in chemical, physical, and biological characteristics of air, water and soil which creates a potential health hazard to living organisms and harmfully affects life.

Classification of pollution
Environmental pollution can be classified as Air pollution, Water pollution, Soil pollution, radioactive pollution, noise pollution, and thermal pollution.• Email: editor@ijfmr.com

IJFMR240112252
Volume 6, Issue 1, January-February 2024 2 Water pollution: The addition of any organic, inorganic, biological, or radiological substance to water that changes its physical and chemical properties is known as water pollution.industrial progress, overpopulation, discharge of sewage into water bodies, etc and such water is unfit and very harmful to public health, animals, plants, and aquatic life.Water pollutants can be classified into four major categories.Organic pollutants, inorganic pollutants, suspended solids sediments, and radioactive materials.

Heavy metals pollution:
Heavy metals can be defined in many ways, based on their physical, chemical, and biological properties.Metals with a specific gravity of about 5g/cm3 or greater are generally defined as heavy metals and these include metals from IIA, IIIB, IVB, VB, and VIB of the periodic table.

Environmental effects of heavy metals:
From the environmental point of view, the metals that are of greatest concern are those which, either by their presence or their accumulation, can have a toxic or inhibitory effect on living things.The most efficient methods for heavy metal removal are ion exchange and adsorption.In these methods, various types of adsorbents are used with simple, easy convenient procedures for having high removal efficiency.However, ion exchange is expensive and the use of this technique is limited because of its selectivity for specified metal ions in comparison with other metal ions.
In adsorption, a certain adsorbent is used for the removal of heavy metal from wastewater and it is considered to be the most effective process because of its high efficiency.Adsorption also produces high-quality effluent.Adsorbents can also be regenerated by using suitable adsorption processes.Adsorption is one of the most effective processes of advanced wastewater treatment, which industries employ to reduce hazardous metals present in the effluents.

Equations ADSORPTION ISOTHERMS:
The amount of adsorbate that is adsorbed per amount of adsorbent is determined as a function of concentration at a constant temperature.The resulting function is called the adsorption isotherm.Adsorption experiments are carried out to develop adsorption isotherms in which the amount of the adsorbent is changed while the initial concentration and volume of the adsorbate are kept constant.
The adsorbent phase concentration after equilibrium is computed using the equation given: ( Co -Ce) V qe = ----------------m where, qe = adsorbent (i.e., solid) phase concentration after equilibrium, mg adsorbate/g adsorbent.Co = initial concentration of adsorb ate, mg/L.Ce = final equilibrium concentration of adsorb ate after adsorption has Occurred mg/l V = volume of liquid in the reactor, L m = mass f absorbent, g.Commonly used adsorption isotherms are Langmuir adsorption isotherm and Freundlich adsorption isotherm.

Langmuir Adsorption Isotherm:
The Langmuir adsorption isotherm is given as: x able ---= ---------m 1 + bCe where, x/m = mass of adsorbate adsorbed per unit mass of adsorbent, mg adsorbate /g adsorbent.a , b = empirical constants Ce=equilibrium concentration of adsorbate in solution after adsorption, mg/l The assumptions in the Langmuir isotherm are: (1) Maximum adsorption of the adsorbate occurs at homogeneous saturated monolayer sites on the adsorbent surface.
(2) The energy of the adsorption is constant.Equilibrium in the adsorption process occurs when all the adsorption sites of the adsorbent get saturated with adsorbate (atoms, molecules, ions) or when the rate of the adsorption of the adsorbate molecules becomes equal to the rate of desorption of the adsorbate molecules from the surface of the adsorbent.

Freundlich Adsorption Isotherm:
The Freundlich adsorption isotherm is an empirical relation and is given as: 1/n x/m =Kf Ce Red mud is relatively toxic and always poses a serious pollution hazard; it also has significant alkaline properties.Depending upon the number of mud-washing stages, the water associated with the mud may contain 3-10 g dm-3 alkalinity (expressed as Na2CO3).In addition, the amount produced is significant.Around 1-2 tons of residues are generated per ton of alumina produced.It is estimated that in Greece around 10000 metric tonnes of red mud are produced annually.The fineness of solid particles and the large quantity of residue make further disposal or utilization very difficult.
Red mud is composed mainly of non-toxic fine particles of silica, aluminum, iron, calcium, and titanium oxides along with some other minor components.

Headings
The objective of the present thesis is to evaluate the performance of red mud and fly ash as low-cost adsorbents for the removal of lead from wastewater and it includes the following aspects: • A study of the use of fly ash and red mud to remove heavy metal contaminants from industrial wastes.
• Batch study analysis and isotherms model experiments to assess the adsorption potential of fly ash and red mud for lead.• Elution of metal ions from the adsorbents after adsorption.

I
was highly privileged to thank Under the Guidance of Dr.Ramprasad Naik Desavathu, Professor of the Department of Civil Engineering G.I.E.T UNIVERSITY, GUNUPUR, for his valuable guidance, significant suggestions, and help in every aspect of accomplishing the project work.His novel association of ideas, encouragement, appreciation, and intellectual zeal has motivated us to ensure this work is successful.Also, I would like to take this opportunity to thank our Dean Academics Dr. A.V.N.L SHARMA & Head of Department PROF.ASHISH KUMAR SAMAL for permitting me to do this project and providing me with the facilities in the laboratory for doing this project.Also, I am thankful to all our esteemed faculty of the Department of Civil Engineering and Laboratory technicians of our college.Finally, I would be grateful to our family for their constant encouragement throughout and my friends who helped us in one way or the other in completing the project.

2. Prepare Your Paper before Styling 2.2 TECHNOLOGIES FOR TREATMENT OF WASTEWATER CONTAINING HEAVY METALS:
Metals like cadmium, chromium, copper, zinc, nickel, lead, and mercury, enter the environment through industrial waste,

methods
include reverse osmosis, electrochemical treatment, evaporative recovery, ion exchange, chemical precipitation, membrane filtration, chemical oxidation-reduction, electrodialysis, ultrafiltration, and solvent extraction.The applicability and use of all these common techniques are limited by their low efficiency, critical operating parameters, and production of secondary sludge.

studies on Red Mud: removal and recovery of Cr (VI) from wastewater" under the guidance of Dr.Ramprasad Naik Desavathu in
the Department of Civil Engineering is a bonafide work carried out by us and the results embodied in this report have not been reproduced/copied from any other source and have not been submitted to any other university or institution for the award of any other degree.

the Co Guidance of
Dr. RAKESH ROSHAN DASH, Professor VSS University of Technology Burla, of the Department of Civil Engineering for his valuable guidance, significant suggestions, and help in every aspect of accomplishing the project work.His novel association of ideas, encouragement, appreciation, and intellectual zeal has motivated us to ensure this work successfully.