A Meticulous Perspective...

A battery is an arrangement of several electrochemical cells connected in series that can be used as a source of direct electric current. A cell is one that contains only one anode and cathode, but a battery contains several anodes and cathodes.   TYPES OF BATTERIES: (a) Primary Battery or Primary Cells In the case of a primary battery, the electrode and the electrode reactions cannot be reversed by passing an external electrical energy. The reactions occur only once and after use, they become dead. Therefore, they are not rechargeable. Example: Dry cell, Mercury cell (b) Secondary Battery or Secondary Cells In case of a Secondary battery, the electrode reactions can be reversed by passing an external electrical energy. Therefore, they can be recharged by passing an electrical current and used again again. These are called storage cells or accumulators. Example: Lead-acid storage cell, nickel-cadmium cell

  ADVANTAGES of Reverse Osmosis: This method has greater advantages of removing ionic, non-ionic, colloidal and high-molecular weight organic matter. The lifetime of the membrane is quite high (2 years). The membrane can be replaced within a few minutes. It provides nearly uninterrupted water supply. Due to low capital cost, low operating cost and high reliability, this method is superior than other methods. DISADVANTAGES of Reverse Osmosis: Reverse Osmosis plays a major role in providing portable water defined by the WHO criterion of < 500 ppm of total dissolved solids (TDS). Extremely high-quality water required for nuclear power plants can be made from sea water by the reverse-osmosis process. Sugar concentration, waste-water recovery and beverage uses are a few of the current popular applications of the reverse-osmosis process.

  It is a membrane process by which water is separated from saline water. Osmosis is defined as the spontaneous flow of 'water' from dilute to more concentrated solution through a semipermeable membrane. The driving force in this phenomenon is called osmotic pressure . A semipermeable membrane is one which permits only water molecules to pass through it. Examples of semipermeable membranes are cellulose acetate, polyamide, polymide, etc. This natural process can be reversed by applying pressure higher than the osmotic pressure on the concentrated side. Thus the solvent is forced to move from concentrated side to dilute side across the membrane. This principle is known as r everse osmosis. In the reverse osmosis process, the pure water (free from ions) is separated from the contaminated brine water (salty water). This membrane filtration is also called super filtration (or) hyper filtration. For advantages and disadvantages of reverse osmosis refer  https://meticulousperspectiv

  ZEOLITES: Zeolites are naturally occuring hydrated sodium alumino silicate minerals. LIMITATIONS of Zeolite Process: If the supplied water is turbid, the suspended matter must be removed first by coagulation, filtration, etc. Otherwise, the turbidity will clog the pores of zeolite bed making it inactive. If the water contains coloured ions (Mn2+, Fe2+), these ions should be removed first because these ions produce manganese and iron zeolite, which cannot be regenerated. If any mineral acid present in the water, it will destroy the zeolite bed, therefore it is neutralised first with soda (Na2CO3). ADVANTAGES of Zeolite Process: Water quality of below 5 ppm hardness is obtained. This equipment is compact and occupies small space. It requires less time for softening.  It requires less skill for maintenance and operation. No sludge is formed during this process. Its operation is also easy. DISADVANTAGES of Zeolite Process: This process cannot be used for turbid and acidic water as they w

  Zeolites are naturally occuring hydrated sodium alumino silicate minerals.  Na2O. Al2O3. xSiO2. yH2O where x = 2 to 10 and   y = 2 to 6. Natural zeolites are nonporous. The synthetic form of zeolite is known as permutit. Synthetic zeolite is represented by Na2Ze. Synthetic zeolites are porous and have a jelly structure. They are prepared by heating together china clay, feldspar and soda ash. These zeolites have higher exchange capacity per unit weight than natural zeolites. In this synthetic zeolite process, the hard water is allowed to percolate through sodium zeolite. The sodium ions which are loosely held in Na2Ze are replaced by Ca2+ and Mg2+ ions present in the water. Process: In   this process , the hard water is passed through a bed of sodium zeolite (Na2Ze). The hardness-causing ions (Ca2+, Mg2+) in hard water is replaced by loosely held sodium ions in zeolite bed. The outgoing soft water contains only sodium ions. Na2Ze + Ca(HCO3)2  --> CaZe + 2NaHCO3 Na2Ze + Mg(HCO3)2  -

  Hardness is the characteristic of water which does not give good lather with soap. This property of water is due to the presence of bicarbonates, chlorides and sulphates of calcium, magnesium and other salts. Some important disadvantages of hard water are the following: Hard water is not useful for various domestic purposes, viz washing, bathing, drinking, etc. The ions responsible for the hardness convert soluble soaps to insoluble precipitates. This causes wastage of soap in washing and bathing. Also, presence of iron salts may result in staining of cloth. Hard water is harmful for many industries such as textile, sugar, paper, laundry, etc. Dissolved calcium, magnesium and iron salts may react and affect the following properties: May cause coloured spots on fabrics in textile industry.  May cause difficulties in the crystallisation of sugar in sugar industry. May cause wastage of lot of soap in laundry. Giving a smooth and glossy finish to paper in paper industry.  Hard water is a

  Galvanizing is the process of coating of zinc or iron or stainless steel sheets. Process: The iron or stainless-steel article surface is first cleaned by acid pickling with dilute H2SO4 solution for 15-20 minutes at 60-90 degree celsius. This treatment removes any scale, rust (oxide layer) and impurities on the metal surface. The article is then washed well with water and dried. It is then dipped in the bath containing molten zinc maintained at 425-430 degree celsius. The surface of the bath is kept covered with a flux, i.e. ammonium chloride, which is used for cleaning the surface of the metal and also to prevent oxide formation. When the article is taken ort, it is found to have been coated with a thin layer of zinc. In order to get uniform thickness, it is passed through a pair of hot rollers, which removes any superfluous (excess) of zinc. Then, it is annealed at a temperature of 650 degree celsius and finally, cooled slowly. Uses: It is most widely used for protection of iron fr