Study Area

Pithampur town area is located in the eastern part of the Dhar district of Madhya Pradesh state and 46 KMs far from its district main city Dhar and Pithampur around 28 KMs away from Indore. The district of Dhar lays in the Malwa region of west Madhya Pradesh in central India. Pithampur area is big industrial zone. It is called of Detroit of India. Best part of the Auotomobile companies of India in Pithampur and well developed other industries like textile, food factories, Pharmaceutical Industry, Ten Factories, Automobile manufacturing companies, Tire manufacturing indusries etc.

These industrial wastes will not only heavily contaminate air, water and soil but mobilization of toxic metals and metalloids will place the wholesome loss of drinking water to a very big scale. Release these cruelly toxic metal ions in their effluent contaminating usual streams where into disposed, which is a major concern due to toxicity to many life inclined². The adsorbents may be of biological origin or organics, minerals, zeolites, agriculture wastes, industrial by products, polymeric materials and biomass. The major advantage of an adsorption system for water pollution control are less investment in terms of both initial cost and simple design, operational cost, easy operation and no effect of poisonous substances compared to conventional biological management process. Typical bioadsorbents be able to be derivative from three source as follows:(1) microbial biomass, e.g. fungi, bacteria, and mold; (2) algal biomass; (3) non-living biomass like as krill, lignin, bark, shrimp, squid, crab shield, etc.³. Lately, an idea of the production of safe and low cost natural adsorbents such as sugarcane bagasse^{4 -9}, rice shell^{10- 14,} neem bark¹⁵, sawdust^{16- 18}, oil palm shield¹⁹, coconut shell^4,20, non-living plant materials such as potato peel²¹, sawdust^22, black gram shell²³, egg shield²⁴, seed shields²⁵, coffee shell²⁶, sugar-beet pectin sets²⁷ and citrus peel²⁸ etc., in favor of the elimination of heavy poisonous metal ions from effluent and it has been determined fruitfully. A low cost adsorbent is one which wants a small processing previous to use, a waste matter or by-product, plentiful in character from a different industry. Of course enhanced sorption ability may recompense the cost of supplementary processing²⁹. Consequently, it becomes very very significant to consider all probable horticultural and agro based their possibility for the elimination of poisonous metal ions to be intentional in all compliments and low-cost adsorbents to be explored. Commonly studied with different affecting parameters in detail and investigated by various researchers as potential biosorbents for toxic metal ions elimination from aqueous solutions. The term toxic metal ions refers to any metallic chemical element that has a relatively high density and is toxic or poisonous at low concentrations. Examples of toxic metal ions include cadmium (Cd), chromium (Cr), thallium (Tl), arsenic (As), mercury (Hg), and lead (Pb). Toxic metal ions are usual components of the Earth's crust. They cannot be degraded or destroyed. To a small extent they enter our bodies via food, air and drinking water. A trace elements, some toxic metal ions such as zinc, selenium, copper are vital to maintain the metabolism of the human body. However, at higher concentrations they can lead to poisonous. Toxic metal ions poisoning could result, high ambient air concentrations near production sources, for instance, from drinking-water pollutant e.g. lead pipes or intake via the food chain. Toxic metal ions are hazardous because they tend to bio accumulate. Toxic metal ions can enter a water supply by industrial and consumer waste or even from acidic rain breaking down soils and release toxic metal ions into lakes, rivers, groundwater etc.³⁰.

Adsorption

It is a mass transfer method which involves the buildup of substances at the interface of two phases for case in point liquid – solid, liquid - liquid or gas – solid, gas – liquid interface. Adsorption is a elemental process in the physiochemical management of effluents, a treatment which can inexpensively meet today's higher effluent standards and water use again requirements. The observable fact of the enhancement of chemical substances at the surface of a solid is called adsorption. All adsorption performance processes are depends on mass transfer rates and solid-liquid equilibria. The adsorption operation can be continuous, semi-batch and batch.

Adsorption Dynamics

It contain of the following four successive processes.

(i) Interior (Inter phase) mass transfer by hole transmission from the external surface of the adsorbent to the internal surface of the permeable structure.

(ii) Transportation of adsorbate from the bulkiness solution to outer surface of the adsorbent by transmission through the liquid frontier layer.

(iii) Adsorption of the adsorbate on the interior surface of the pores of the active locations.

(iv) Surface transmission along the permeable surface.

Classification of Adsorption

At molecular level, adsorption is due to attractive interactions between the species being adsorbed and a surface.

Physical adsorption:

This is a consequence of intermolecular forces of magnetism between molecules of the adsorbate and adsorbent. It is occurs when the intermolecular attractive forces between molecules of the gas and a solid are better than those between molecules of the gas itself. Additionally, it occurs close or lower to the critical temperature of the adsorbed matter.

Chemisorptions:

It is an effect of chemical interaction between the adsorbed substance and the solid. It is also called activated adsorption. Commercial adsorbents rely on physical adsorption; catalysis relies on chemisorptions.

Adsorption Isotherm

A methodical approach due to the data are taken over a range of fluid concentrations at a constant temperature, a plot of solute loading on the adsorbent against partial pressure or concentration in the fluid, called an adsorption isotherm. This equilibrium isotherm spaces a limit on the extent to which a solute is adsorbed from a given fluid mixture on an adsorbent of given geometry and chemical composition for a given set of situations. The rate at which the solute is adsorbed is also a significant consideration. Adsorption isotherms are significant for the explanation of how adsorbate will interact with adsorbent and are critical in optimizing the utilize of adsorbent.

Langmuir Model

Normally, used model for monomolecular layer adsorption. Such model is consequent from simple mass-action kinetics. Such model is based on hypothesis that the surface of the pores of the adsorbent is homogeneous and that the forces of interaction between the adsorbed molecules are negligible. It is a semi-empirical isotherm derived from a planned kinetic mechanism.

Let f be the fraction of the surface covered by adsorbed molecules. Consequently 1- f is the fraction of the bare surface. Then, the net rate of adsorption is the variation between the rates of adsorption on the naked outside and desorption from the covered surface:

q /dt=k_a p (l- f ) – k_d d f

At equilibrium, dq/dt = 0 and equation reduces to

f = K p/1+ K p. Where: K= adsorption-equilibrium constant

K = K_a /K_d

Also, f = qlq_m; and q_m is the maximum loading corresponding to complete coverage of the adsorbent surface by the solute.

Freundlich Model

The representation attributed to Freundlich, but which was in fact devised previous by Boedecker and Van Bemmelen, nonlinear in pressure and is experimental:

log q = log k + (l/n) log p

Whenever the graphical method is working, the data are plotted as log p vs. log q. The most outstanding straight line through the data has an intercept of log k and a slope of (l/n). In general, n increases with increasing temperature, while k decreases with increasing temperature and approaches a value of 1 at high temperatures.

Adsorbent

There are different types of Adsorbent is used in electroplating industries for removal of heavy metal according to availabilities and requirement.

Natural Adsorbent : There are several types of natural adsorbents some of these have been explained as:

Zeolites

Essentially zeolites are an obviously occurring crystalline aluminosilicates (Al₂SiO₅) consisting of a structure of tetrahedral molecules, linked with each other by shared oxygen atoms. During 1970s, natural zeolites gained an important interest, due to their ion-exchange capability to preferentially eliminate unnecessary toxic metal ions such as cesium and strontium Grant et al. Zeolites are applied in drying of CO₂ elimination from natural gas, process air, catalytic cracking and catalytic synthesis, air separation, CO elimination from reforming gas. Adsorption in zeolites is actually so surface area is not a pertinent factor, a selective and reversible filling of crystal cages. While naturally occurring zeolite minerals have been known for more than 200 years, molecular-sieve zeolites were first synthesized by Milton, who used very reactive materials at temperatures of 25-100°C.

Clay

There are three essential types of clay: kaolinite, micas and smectites (such as montmorillonite); out of which montmorillonite has the maximum cation exchange capability and its current sell price is measured to be 20 times cheaper than that of activated carbon Virta. While the elimination effectiveness of clays for toxic metal ions may not be as good as that of zeolites, their simple accessibility and low cost may recompense for the related drawbacks.

Peat Moss

Peat moss, a complex soil material containing cellulose and lignin as major constituents, is a natural substance widely available and abundant, Peat moss has a large surface area (>200m2/g) and is highly porous so that it can be used to bind toxic metal ions.

Chitosan

Amongst different biosorbents, Chitin is the second mainly plentiful usual biopolymers after cellulose. However, more significant than chitin is chitosan, which has a molecular structure like to cellulose. Currently, chitosan is attracting an increasing quantity of research curiosity, as it is an efficient searcher for toxic metal ions. Chitosan is produced by alkaline N-deacetylation of chitin, which is widely found in the crustaceans and exoskeleton of shellfish. It was probable that chitosan could be formed from fish and crustaceans.

Rice husk

Rice husk farming waste derivative plentifully available in rice originating countries, mainly in Asia continental. It is reported that the annually globe rice produce is something like of which 10 – 20% is rice shell, 500 million metric tons. Dehydrated rice shell include 70– 85% of organic substance (sugar, cellulose, lignin etc) and present in the cellular covering, the remainder consists of silica³¹. At present a day the investigators contain focused going on the consumption of unchanged or adapted rice shell as an adsorbent for the elimination of toxic metal ions³². It was reported that tartaric acid adapted rice shell is a potentially useful adsorbent in batch studies for the elimination of Lead and Copper from aqueous solutions, the different affecting parameters such as pH, particle size, contact time, initial concentrarion of adsobate, temperature etc were as well studied. The speedy uptake and high adsorption capacity create the rice shell a substitute and very attractive adsorbent. The uptake of Pb and Cu was maximum when pH was increased from 2 to 3, and subsequently remained comparatively constant¹². Rrported that adsorption of Cd²⁺ and Ni²⁺ was superior when PRH was used as adsorbent. Adsorption of Cd²⁺ was dependent on pH of the solution, contact time, concentration, temperature, adsorbent doses. It was also reported that the highest adsorption (> 90%) was obtained at a pH value of 12¹⁰. Commercial carbons respectively, for Cr⁴⁺ elimination and eliminated Cr through rice crust carbon, equipped through carbonization of rice crust with sulphuric acid followed via CO₂ creation resulting 88% elimination of total chromium and larger than 99% elimination of hexavalent chromium. Column studies showed capability of 8.9 mg/g and 6.3 mg/g for rice crust¹³. Study going on the utilize of dyestuff-treated rice crust for elimination of toxic metal ions from effluent. Rice shell, when covered with the reactive dye of Procion Red and Procion Yellow, was found to be well successful for elimination of several toxic metal ions from aqueous solutions both in column and batch methods. The high effective for eliminations for red dyestuff-treated shell are on Cd²⁺ and Pb²⁺ at 99.2% and 99.8% respectively, for yellow dyestuff-treated shell are on Hg²⁺ and Pb²⁺ at 93.3% and 100% respectively¹¹. Eliminate poisonous metal ions from effluent using rice shell information’s at most favorable conditions the zinc, copper, Chromium and cadmium ions from aqueous solution³³. Adsorption of toxic metal ions by land rice crust also green algae reported that, metal ions adsorption by rice shell biomass and algal, was better than 90% for all the metals analyzed,( Ni, Cr, Cd, Zn, Fe ,Co, Pb,) excluding Ni, with 80% elimination³⁴. Reported, that the rice crust carbon is a excellent sorbent for the elimination of Chromium ions as of aqueous solution range from 5 to 60 mg/l with adsorbent quantity of 0.8 g/lat pH < 5 under the lowest amount equilibration moment of 120 minutes and Studied on adsorption of Chromium ion on meso and micro- porous rice shell-based stimulated carbon and higher than pH 5.0 a sharp reduced adsorption by means of additional higher pH range approximately insignificant adsorption. Greatest reported adsorption is 95% elimination of Chromium (VI) ion³⁵. Evaluated in addition to characterized two type of sorbents prepared from rice shell. The effectiveness of both sorbents in the elimination of the complex matrix containing six toxic metal ions was almost 100%. These metal ions are Cd, Mn, Fe, Pb, Zn, and Cu, which are found in the drain containing the sewage effluent and farming³⁶. Indicated to the highest elimination 66% of Cr⁴⁺ for unprocessed rice shell was obtain at pH 2, outstanding fit to Freundlich isotherm with 1/n value of 2.863, while it is given adsorbent quantity of 70 g/l for 120 minutes.

Saw dust

Showed notable enlarge in sorption capability of Chromium (VI) as evaluate to raw sawdust.

Sawdust a low-cost substance has been utilized as an adsorbent for the elimination of Cu²⁺ from effluent.

Mangifera indica (Mango)

It is seed shell powders were studied for their possible application in the elimination of Cu²⁺ by effluent. The adsorption of Cu²⁺ on the powder of Mango seed shell was found maximum at pH 6 and followed Freundlich adsorption Isotherm. The adsorption activities of different toxic metal ions on mustard oil cake (MOC) was studied. The maximum adsorption of Cu²⁺ was experiential followed by Ni^2,Zn²⁺, Cr⁴⁺, Pb²⁺, Cd²⁺, and Mn²⁺. The adsorption of Cu²⁺was found to be dependent on adsorbent dose, initial concentration of solution, temperature, contact time and pH.

Treatment

Several methods have been applied for the treatment of industrial effluent; there are so several methods accessible for the elimination of toxic metal ions from effluents; the normally used procedures for eliminating metal ions from aqueous streams consist of lime coagulation, membrane separation, solvent extraction, chemical precipitation, chemical decrease, Evaporation, cementation, reverse osmosis, ion substitute with electro deposition. The application of the membrane process is limited due to pretreatment necessities, primarily, for the elimination of suspended solids. Membrane separation processes have been applied to inorganic effluent management. These processes involve ionic concentration by the utilize of selective membrane with a specific driving force. The methods are exclusive and requiring a superior level of technical expertise to operate. Solvent extraction or Liquid-liquid extraction of metals from solutions on a large scale has knowledgeable a phenomenal growth in current years due to the introduction of selective complexing agents. In arrange to make progress the extracted metal, the organic solvent is contacted through an aqueous solution whose composition is such that the metal is uncovered from the organic stage and is extracted into the stripping solution; such method become inefficient whenever pollutants are present in trace concentration. Chemical reduction has been used for recovery of chromium from metallurgical effluent waste stream. The electrochemical chromium reduction procedure utilizes unpreserved iron electrodes and an electric present to create ferrous ions that respond with hexavalent chromium to provide trivalent chromium. Reduction of hexavalent chromium can also be accomplished with electro-chemical components. Main disadvantage of chemical reduction process is the high operational cost relative to another process. Substance precipitation of metals is achieved by the adding of coagulants like as lime, alum, salts, iron and supplementary natural polymers. Chemical precipitation of poisonous metal ions as their hydroxides using sodium hydroxide or lime is widely used; ease of pH control in the range of 8.0 –10, due to the low cost of precipitant. Reported superior results using carbonate precipitate for Pb²⁺and Cd²⁺ from electroplating waste matters. Since most of the toxic metal ions form stable sulphides, excellent metal elimination can be obtained by sulphide precipitation. The large amount of sludge containing poisonous compounds formed through the procedure is the major disadvantage. Evaporation process have used for metal recovery in the electroplating industry. Recovery is skilled from boiling suitable water by the collect clean stream to agree to the concentrate to be come back to the plating bath. Both funds and operational expenses for disappear revival structures are high. Cementation is the dislocation of a metal from solution by a metal superior in the electromotive series. Water and chemical use again values must counterbalance these costs for evaporative revival to become inexpensively possible. It offers an attractive opportunity for treating some effluent containing reducible metallic ions. In put into practice, a significant increase in the electromotive strength between toxic metal ions is needed to make sure sufficient cementation capability. Due to its prepared accessibility and low cost, fragment iron is the metal ion used frequently. The restriction of such process is that it is appropriate only use for small effluent run because an extended contact moment is necessary. Elimination of Cr⁴⁺was studied by means of nitric acid treated Pongamia Leaf residue (APLP) and Crude Pongamia Leaf residue as adsorbents through batch studies. The authors reported that both adsorbents were efficient for the uptake of Cr ⁴⁺at pH 2.0 and write to time 165 minutes. APLP was create to be additional well-organized than Crude Pongamia Leaf residue with a preliminary Chromium (VI) concentration of 5mg/l. The authors also reported that the facts was create to follow both Freundlich and Langmuir isotherms; though it was well fit in Freundlich isotherm³⁷. Elimination of zinc and cadmium from metal concluding industrialized waste matters with low cost adsorbents was studied. The researchers used Powdered. Grainy Activated Carbon (GAC size- 1.3mm) Activated Carbon (PAC) and Fly powder (FP), experiential the effect of pH and contact time, adsorbent dosage and primary metal ion concentration to eliminate Cd²⁺ and Zn²⁺ ions from the synthetic solutions by batch studies. Authors statement that the most favorable pH for FP and PAC 2.0 and 5.0 respectively. The contact time for all the 3 adsorbents was between 3.0 and 2.5 hours with a adsorbent dosage of 20 g/l³⁸. The effect of a few parameters like as the flow rate, column bed deepness and primary solute concentration on fluoride elimination was studied by Bhargava and Killedar using fishbone charcoal. The study was conducted using the fixed bed column with continuous flow operation. The helpful treated waste matter volume (effluent concentration of 1mg/l) of fluoride is a column bed deepness, function of flow rate and primary fluoride concentration. An experimental association was established to predict the helpful waste matter volume for several value of column bed depth (20-65 cm), flow rate (3.06 to 15.3 ml/min/cm2) primary fluoride concentration (range 2.5 to 20.0 mg/l). The authors fulfilled from the association the superior co-efficient of association between the experimental and values the projected³⁹. Adsorption studies on Pb²⁺ and Cr⁴⁺ elimination from aqueous solutions using areca nut shield (farming solid waste by produced) was conducted by Geetha et.al. The utmost elimination of Pb²⁺ and Cr⁴⁺ was create at pH 5.0 and 4.0 respectively. The researchers achieved 86 and 100% elimination of Pb²⁺ and Cr⁴⁺ respectively at preliminary toxic metal ions concentration of 20 mg/l. utmost desorption of 92% for Pb²⁺and 87% for Cr ⁴⁺ were achieved. The authors reported that Areca shield can be utilize to eliminate the toxic metal ions from the effluent⁴⁰. Examined the mechanism of the toxic metal ions biosorption by means of the Langmuir adsorption model with chemically pretreated coniferous barks like adsorbent losing their metal required capabilities. In the physico-chemical situation the metal similarity of bark was create in the following declining order copper, chromium, zinc, nickel, lead ⁴¹. Treated through phosphate salt (10%) or zinc chloride (25%), sulphuric acid (1:1) on various temperatures to eliminate chromium ion (VI) from effuent in addition to the condition optimized for the mostly prepared activated carbons and effective carbons from Casuarina equisetifolia leaves carbonised. The farming waste substance like potential adsorbent for sequestering toxic metal ions from aqueous solutions. The symmetry data fixed well with the Freundlich adsorption isotherm. Activated Carbons possibly will be use again without modify in the adsorption capability²⁴. Reviewed the elimination of toxic metal ions from effluents by chemically adapted plant wastes as adsorbents⁴². Reviewed the use of low cost adsorbents for toxic metal ions uptake from polluted water⁴³. Investigated the kaolinite clay obtained from China. Longyan to eliminate toxic metal ions Cu²⁺, Ni²⁺, Pb²⁺ and Cd²⁺ from effluent. The uptake is rapid with highest adsorption being experiential within 30 minutes and kaolinite clay was used for eliminating toxic metal ions from actual effluent containing Pb²⁺, where its concentration was reduced from 160.00 mg/L to 8.00 mg/L⁴⁴. Reported copper and zinc elimination from aqueous solutions using salt water sawdust, sediments and mixture of both materials. The maximum adsorption capacity was found to be 4.70, 2.30 and 4.34 mg/g for copper and 4.80, 2.56 and 5.58 mg/g for zinc respectively, using an adsorbent/solution ratio of 1/40. Biosorption of toxic metal ions from aqueous solution is a comparatively latest method that has been completed an extremely hopeful method for the toxic metal ions polluted effluent management. The make use of low-cost bio adsorbents and the most important applications of biosorption are its high effectiveness in decreasing the toxic metal ions. Biosorption method are mostly suitable to treat reduce toxic metal ions effluent⁴⁵.

CONCLUSION:

During the preparation of this article it was observed that several agricultural waste and horticultural waste, biosorbent, biological origin or organics, algae, chiton, egg shell waste, natural adsorbents materials used as low cost adsorbent in the treatment of effluents were reported in hundredth of journal papers. This article has attempted to cover a wide range of those materials used in eliminating some selected divalent toxic metal ions. Parameters such as biosorption capacity of sorbent, biosorbent dose, batch and column studies, initial concentration of metal ions, equilibrium time and PH of the solution were also presented. Furthermore, it also highlights the use of Langmuir adsorption isotherm and Freundlich isotherm modelstore determine the maximum capacity of biosorbents and effect of the physical and chemical properties on the adsorption capacity of the adsorbent. But the industrial application of those materials is still a dare; as such more studies are needed to transfer the process to pilot-plant scale.

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Received on 27.01.2016 Modified on 14.02.2016

Asian J. Research Chem. 9(2): Feb., 2016; Page 70-76

DOI: 10.5958/0974-4150.2016.00013.4

INTRODUCTION: