Ferritin
Ferritin storage protein is highly soluble, and its size is less than 10 nm. It consists of 24 subunits, each with a molecular weight of about 20,000, and its density is 2.5 times that of apoferritin. It comprises molecules with varied iron content that does not exceed 3000. The storage protein is colorless and sharp. Its boundary consists of iron-free protein. The ferritin structure is shown in Fig. 1.
(Source: chemistry.wustl.edu).
Ferritin has unique properties both chemically and physically. It is able to withstand temperatures up to 75 °C, and it is very stable for various denaturants. It has the ability to break down at a pH of 2.5 in an acidic environment and gets restored to a pH of 7.5. This unique finds to be very effective in water purification and also maintains the pH. Ferritin storage protein deals with environmental pollutants in two ways. The exchange of electrons and the production of oxygen are the two processes that involve water pollutant reduction. When excess irons are exposed to the atmosphere, they react and generate radicals which in turn destroy the protein. When it is used at a lower level, the cell generates superoxide, which also stops the affinity of the pollutants to the protein. Hence the correct proportion of ferritin has to be utilized for the given environment.
Ferritin protein is of size less than 10 nm, and it is available in powder form when it is used in an open environment. The wind is the only factor that is likely to affect the spreading of ferritin protein into the water evenly. Hence while using the storage protein, some closed arrangement has to be done to use it effectively. Pyrococcus furiosus ferritin is the source of ferritin-NP, which has ferric phosphate as its main component. The ferritin from Pyrococcus furiosus is structurally comparable to ferritins from other bacteria and eukaryotes. It’s a 24-mer with 20 kDa subunits totaling 480 kDa in size. Pyrococcus furiosus ferritin protein belongs to the type of Non-heme ferritin. The ferritin from Pyrococcus furiosus is particularly thermostable. The half-life of ferritin activity is 48 h at 100 °C and 85 min at 120 °C. There was no apparent melting temperature up to 120 °C. The exceptional thermostability of Pyrococcus furiosus ferritin could be beneficial in biotechnology.
Inside cells, ferritin is a 24-mer iron (Fe) storing protein. The molecular weight was higher than expected at 474 kDa, and the hydrodynamic size was 18 nm. It was discovered that there was a negative charge present. The quality of a nanoparticle is influenced by particle size, shape, solid-state characteristics, and physical stability. Other characteristics that influence nanoparticle quality include further chemical structural degradation, dissolving, and solubility testing. The study employed ferritin-NP particles with a diameter of 1.7 nm to 0.9 nm and an irregular pyramidal form with a base side of 150 m and a height of 250 m. Iron is the most important element in the nanoparticle, and it is extremely thermally stable in nature.
Study area
Chennai is a well-known and attractive city due to its urbanization. Today it has attained the status of being called a Metro City in India. It is located with a latitude of 13.0827° N, and a longitude of 80.2707° E. It covers a geographical area of about 174 Sq.km with a population of around 68 lakhs and an average annual rainfall of 1200 mm. The observation wells were selected from the available data, and these were close to the Metro Rail Corridors. The observation wells in the study area are shown in Fig. 2.
The observation wells in the study area of the underground Metro Rail Corridor, Chennai, Tamilnadu, India.
The map consists of ten observation wells selected in and around the Metro Rail Corridors and the Metro stations. The elevated and the underground Metro Rail Corridors have been differentiated with different colors. The Metro Rail Corridors are buffered for a distance of about 5 km, and the Adyar and Coovam Rivers are located.
The observation wells are selected to be on the two sides of the underground corridors to study the impact of the construction. The aquifer damage and the breakdown of the heterogeneous layers are considered to be the predominant factors that might cause the changes in the water quality. Hence the wells which are identified should be in the vicinity enough to have the effect of ferritin protein spread in the water.
Climate
Chennai is in the south of the nation, where it is frequently hot and muggy. The three main seasons in Chennai are summer, monsoon, and winter. The summer season in Chennai is seen as lasting from March to June. The NE monsoon period is the time between October and December. The months of June through September make up the monsoon season. The brief winter season in Chennai lasts from November to February.
Rainfall
Nearly 65% of the rain falls during this season; the NE monsoon is a major factor in Chennai’s weather. An annual average of 1,300 mm of moderate rainfall falls in Chennai city. Figure 3 displays the annual average rainfall from 1995 to 2017. In the city, 213.87 mm of rainfall per year on average was observed in 2005. Due to the enormous storm that hit Chennai recently, the city experienced its highest average annual rainfall in 2015.
Yearly average rainfall in the study area (1995–2017).
Temperature
The summer starts around the end of March and continues till June, with late May to June being the hottest months. Temperatures frequently get above 40 degrees Celsius during this time. The climate and weather in Chennai are rather stable, with little seasonal temperature variance, because of the city’s closeness to the sea and the thermal equator. The city typically faces heat in the summer months, with average maximum temperatures ranging from 38 to 42 degrees Celsius. The city experiences a brief winter, with January being the coolest month, with lows of 18 to 20 degrees Celsius.
Geology
The Geological Survey of India, Chennai, provided a map of the research region at a scale of 1:50,000, which was used for digitizing the area’s geology. Figure 4 depicts the various geological formations of the research region. The study area comprises marine beds of Neocomian age and the earliest marine transgression layers of the middle Cretaceous of Upper Albianage, as well as coastal sediments on the bank side and a portion of archean rocks composed of Chamockites, Granite, and Gneisses. The second subterranean section runs from Thirumangalam to Egmore Metro and is made up of newer alluvium with thicknesses ranging from 3 to 30 m and tertiary rock from the Eocene to Pliocene eras that contain the composition of sandstone.
Geological classifications of Study area.
Ferrite treatment using a reaction chamber
Magnetic seeding is an efficient process that makes magnetic suspended particles bind by themselves, and the pollutants are removed under various procedures. Various methods like coagulation and ferromagnetic suspension are done for particles of very fine sizes. The ferritin-NP is used at the rate of 0.3 × 10–3 kg/m3 in the polluted water of the underground corridor. The required amount of ferritin –NP needed for the investigation was procured in the research conducted in the chemical department AC-Tech of Anna University. The particles which are finer than the silt are removed through adhesion, magnetic separation, and absorption techniques. These techniques are considered to be the primary phase in the ferrite treatment procedure. The investigations involved in the treatment of water below the underground corridors with the ferrite solution are also conducted.
Aggregate distribution modeling is the challenging part before it gets into the mechanical mixer. In the reaction chamber, the magnetic aggregates and the ferrite solution water has to mix in the proper volume ratio so that it meets the uniform distribution of the aggregates in the reaction chamber. The process of gravity and diffusion turbulence is used to observe the magnetic aggregates distribution, and the vertical transfer regularities in the presence of light were investigated. Inertial force is found to be modest when compared to hydrodynamic force. It ensures uniform and regular distribution across the diameter of the mixer for the mixer height. The following modeling equation expresses fluxes in the particle arrangement and their movement in the opposite direction. It is represented as.
$$Dtfrac{dC}{{dh}} + WagC = 0$$
(1)
Dt, Coefficient of turbulent diffusion [m2/s]; C, Concentration of the particle at height h [kg/m3]; Wa, Aggregates settling velocity [m/s].
By integrating Eq. (1) with boundary conditions C = Co, h = const,
We obtain
$$C = Coexp left( {frac{Wagh}{{Dt}}} right)$$
The water-soluble ferritin powder is used in the selected wells around the Metro Rail Corridor. The dosage will be determined according to the water level of the wells. Using the area and the height of the water level, the volume is determined. According to the volume ratio the required dosage of the ferritin is determined, and it is added to the wells. Leaving the well for a period of one week, the effect of ferritin in reducing the pollutant level was analyzed by properly locating the borehole points around the Metro Rail Corridor.
The sampling points are located around the foundation of the structure, and the water sampling is done based on Indian standards. The sampling water was taken to the laboratory, and the pollutant levels were analyzed.
Determination of water quality parameters
The various water quality parameters are determined in the laboratory by the following methods. The well water was collected either by pumping or by hand, and samples were taken from the well bottoms in clean polyethylene bottles, carried in iceboxes, and refrigerated until assessment at 4 °C. Quality assurance and quality control was assured by doing repeated calibrations, and accuracy was obtained both in devices and also in the titration methods. Separate samples were obtained for Physico-chemical analysis. The study’s physical parameters included pH, Total Dissolved Solids (TDS), and Total Hardness (TH). The chemical parameters included anions such as Fluoride (Fl) and Chloride (Cl). The various detection methods are given in Table 1.
Centre Ground Water Board and Institute of Water Studies, Chennai, are the data sources used to collect the water quality data for the concerned observation wells around the underground Metro Rail Corridor. The period from 1995–2014 was used for the data collection. The construction of Chennai Metro Rail was started in the year 2008; hence two periods of data such as (1995–2008) and (2009–2014) that are is before and after the construction, were taken for the determination of the values of pH, EC, TDS, TH, Ca, Mg, TA, Cl, F, and SO4. The Mean values were tabulated, and the comparison is shown in Table 2.
The values of pH, Total alkalinity, calcium, and chloride were decreased in the 2009–2014 phase when compared to 1995–2008. The decrease in rainfall and the underground tunneling reduced runoff, and hence the suspended form of organic and inorganic substances, i.e., Total dissolved solids got, increased. Since electrical conductivity and total dissolved solids are directly related to each other, it also showed an increase in pattern. Bentonite slurry, which consists of minerals like Potassium, Sodium, Calcium, and Aluminium was issued for tunneling work, confirming the presence of calcium. The sulphate concentration showed an increase in nature; it may be due to the use of gypsum (CaSo4) in the binder during construction. The natural weathering of the rocks induces the fluoride concentration in an abundant manner. Tunneling invokes artificial weathering by breaking down the rocks, and this may be a cause of the increase in the fluoride content in the later phase. The processes of separation of the pollutants are given in Fig. 5.
The process of separation of pollutants in the reaction chamber.
The water pollutants in the samples of the underground Metro Rail Corridor were collected according to the standard sampling procedure. It was subjected to the reaction chamber. In the reaction chamber, the ferritin petals are added to the wastewater volume ratio. It’s been initially subjected to an adsorption process where the cohesive particles are stuck to the surface of the chamber. This process is still activated by stirring. After the adsorption process, the liquid is subjected to a separation process. The decanted residue was subjected to a desorption process where the pollutants are dissipated, followed by a separation process which will give the pollutant level reduced water.
Figure 6 clearly shows the water quality parameters comparison before the ferritin treatment and after the ferritin treatment process in the observation wells around the underground Metro Rail Corridor.
Comparison between the mean value parameters.
Efficiency achieved by the ferritin in the removal of pollutant levels
The volume of the water allowed in the reaction chamber is at the rate of 1–9 m3/h. The dosage of ferritin was determined according to the volume of the wastewater ratio. The pollutant levels of the water collected from the Metro Rail Corridor was observed from the various laboratory test, and the mean values of the levels are noted for the phase from 1995 to 2008.
The contaminants of water, when subjected to ferritin petals, react with water and disintegrate the pollutants, the adsorption process makes the pollutants get dispersed and it is attached to the surface. Hence the pollutant levels, which are at their worse, deteriorate, the foundation of the structure will be get reduced, and the life of the structure will be increased. Basically, ferritin is an iron storage protein that absorbs alkali salts and reduces the pH value. The electrical conductivity and the Total Dissolved solids will be increased only in the presence of salts. Once the ferritin nanoparticles absorb the salts, the electrical conductivity and total hardness are reduced. The water-soluble protein reduces excess fluoride and sulphate salts. Hence the hardness of the water is also very much decreased.
As ferritin protein nanoparticles are of size less than 10 nm. It is available in the finest powder form. The concentration of the particle weight has to be carefully mixed with water for better results. In the open environment, the wind is the one predominant factor that reduces the effectiveness of mixing with the water. Hence care should be taken to mix up the chemicals in the closed environment for the précised outcome.
