LANGMUIR ISOTHERM MODEL Langmuir adsorption isotherm originally developed to describe gas–solid-phase adsorption onto activated carbon, has traditionally been used to quantify and contrast the performance of different bio-sorbents [134]. In its formulation, this empirical model assumes monolayer adsorption (the adsorbed layer is one molecule in thickness) with adsorption can only occur at a finite (fixed) number of definite localized sites, that are identical and equivalent with no lateral interaction and steric hindrance between the adsorbed molecules, even on adjacent sites [135]. In its derivation, Langmuir isotherm refers to homogeneous adsorption, which each molecule possess constant enthalpies and sorption activation energy (all sites …show more content…
Adsorption behavior of these metal ions on the resin was studied by varying the parameters such as pH (2–6), adsorbent dose (0–4.0 g/L), contact time (0–240 min), and metal ions concentration (20–300 mg/L). Adsorption percentage was increased by increasing each of these parameters. The isotherm models such as Langmuir, Freundlich, Temkin, and Dubinin–Radushkevich were used to describe adsorption equilibrium [146]. The batch experiments were conducted to evaluate the removal of heavy metals from aqueous solutions by fly ash under various conditions of initial metal concentration, pH and fly ash dosage and contact time. The adsorption data was described by the Langmuir, Freundlich and BET adsorption Isotherm model [147]. The equilibrium sorption of the phosphoric acid modified rice husk was studied. The Physico-chemical properties of the modified rice husk were determined. The equilibrium sorption data were fitted into Langmuir, Freundlich, Temkin and Dubinin–Radushkevich (DRK) isotherms. Of the four adsorption isotherm, the R2 value of Langmuir isotherm model was the highest [148]. The efficiency of removal was slightly changed by replacing an aqueous solution by saline water or wastewater containing the same copper concentration. Adsorption kinetic data were tested using pseudo-first order, pseudo-second order, Bangham's equation and intra-particle diffusion models. Kinetic studies showed that the adsorption followed a pseudo-second order reaction. Studies revealed that intra-particle diffusion played an important role in the mechanism of copper (II) adsorption. The equilibrium data were analyzed using Langmuir, Freundlich, Tempkin, Dubinin-Radushkevich, Redlich-Peterson and Koble-Corrigan isotherm models at different doses of GA and CGA [149]. The sorption of
As the solution pH can influence the stability of NaClO-NH3 blend and the elimination of SO2, NOx, the impact of the pH of NaClO-NH3 blend solution on the instantaneous removal as well as the duration time was investigated, and the final pH after reaction was also detected and shown in Fig. 5. It can be seen that the variation of solution pH has a negligible effect on the desulfurization, but the elevated pH has a great promotion on the NOx removal, the efficiencies are significantly increased from 36% to 99% for NO2 in the pH range of 5–12 and from 19% to 65% for NO when the pH is between 5 and 10, after where, both of them are constant. Hence, the optimal pH of the NaClO-NH3 solution for the
This paper will employ a close visual analysis of the White-Ground Lekythos, which is attributed to the Reed Painter circa 450-400 B.C.E. on ceramic with paint.
...ppm of DDT. Effective degradation was achieved with an inoculum pre-exposed to DDT for 72 hours. In the presence of auxiliary carbon sources citrate and rice straw hydrolysate, the degradation was inhibited. In the presence of yeast extract, peptone, and glycerol and tryptone soya broth, there was a complete disappearance of DDT. The optimum conditions for degradation are mesophilic temperatures, (30-40 degrees Celsius) and a near neutral pH. (Science Direct-Aerobic Degradation of DDT by Serratia Marcescens).
Chromatography has been developed over the past century and has an important contribution in many areas of modern science. However the main original work of M.S.Tswett was published in a book Chromatographic Adsorption Analysis.
where So = initial supersaturation. Therefore by keeping the surface area constant in metastable supersaturated solutions, the rate constant (k) can be derived. This can be utilized in the Langmuir adsorption isotherm to compare inhibitory activities of added substances . In whole urine, calcium oxalate crystallization can be directly measured by adding specific quantities of oxalate seed crystals and measuring changes of 14C in the supernatant fraction (Gill et al.
Sediment transport model plays an important part in the aquatic system as aquatic systems display slow recovery rates due to the continued presence of toxic substances. In a water column, toxic substances accumulate in the bottom sediments of aquatic systems. Depending on the chemical properties and hydraulic characteristics, sorption to biotic and abiotic suspended matter may occur, resulting in chemical settling from the water column and accumulating among bottom sediment. In addition, the effects of industrial contamination on aquatic life are a continuing concern of local, state, and federal agencies throughout the United States.
Docbrown.info,. 'Gcse 1. Introduction To The Extraction Of Metals Method Related To The Activity Of Reactivity Series Of Metals Igcse O Level KS4 Science Chemistry Revision Notes Revising'. N.p., 2015. Web. 24 Apr. 2015.
Contemporary 20th century choreographer Paul Taylor used the components of dance -space, time and energy to explore the struggle of an individual versus the conformity of the masses in his dance Esplanade. In addition, Taylor intertwined the principles of contrast, repetition, and resolution throughout Esplanade to portray the emotion, which accompanied this isolation. This esplanade (a long, open, level area usually by the sea) represented the journey of an independent women’s movement against the societal norm of heterosexual couples within the masses.
Figure-9: Adsorption of Carbon dioxide on carbon made from orange peel powder (7g) for 10, 12 and 14 LPH
Lead is a naturally occurring metal used in various industrial goods from pipes, paints, and well linings. Lead is a greyish heavy metal that is harmful if swallowed or breathed in. Lead can be handled without gloves, but should be limited and a thorough hand cleaning is needed afterwards 1. Lead originates from the Greek word “Protos”, which means first 2. Lead is known to be introduced into groundwater by contact with old lead pipes, runoff of lead based paint, leaded gasoline leakage, and automobile air emissions 3. Lead poisoning can greatly affect people such as “brain and nervous system damage, and particularly mental development impairment in children; reproductive system interference including effects such as premature infant and low births; circulatory system damage such as O2 absorption decrease and increase in blood pressure; and kidneys malfunctioning” (Kinder, 1997) 4. Lead contamination can be found anywhere lead is used or refined. As it is a naturally occurring metal, lead tends to seep into the ground easily with the assistance of water and its abundant use in manufacturing. Lead is transported into the system mainly by leeching by contact into the water source by older lead pipes, fittings, and various lead lined containers 5. Currently there is no other viable way to remove lead contamination from groundwater other than to pump and treat either in mass quantities or through reverse osmosis, distillation, or carbon filters 6. The main course of action and most reliable is to remove the source of the lead from contact with water 7.
E-wastes are including many dangerous chemicals, such as, cadmium, beryllium, and mercury. Therefore, when we disposal the e-waste in the wrong way, these toxics have a high risk of air pollution, soil contamination and absorb into the water. For instance, in Guiyu villages (China), has the highest dioxin in the world, which can cause cancer. In the villages, seven out of ten children have a numerous lead in their body because of the water is polluted (Levin, 2010). Furthermore, according to Lincoln University (New Zealand), these toxic from e-waste can come through the “soil-crop-food-pathway”. These toxics are not able to disintegrate, they exist in the environment for the long time and the risk of exposure will be increased (McAllister, n.d.). Moreover, in several countries, to provide the family income; some people need to work with the e-waste every day (Honorine, 2010). Thus, e-wastes are not only the economical problem. They are also affect the environment and human
For hundreds, even thousands of years, human beings have mined for metals and stones, and with the advent of greater technology as well as greater needs, the demands for these resources continue to grow. While these resources benefit our lives in many ways, the effects of mining can be detrimental, and one such effect is the topic of this essay, acid mine drainage (A.M.D.). The causes of A.M.D. will be discussed, along with some of the physical and biological problems associated with it. Some prevention and remediation treatments will also be considered.
The first step of water treatment process is the coagulation process of water. Hendricks (2011), defined coagulation as the reaction between a chemical and particles to form microfloc. During the process of coagulation occur, the coagulant is added to the untreated water. The function of coagulant is to remove the unwanted substance and dirt in the water by sticking it together to form a floc (Smethurst, 1997). Generally, a liquid aluminium sulfate or known as alum is used as a coagulant because of their ability to form multi charged polynuclear complexes with enhanced adsorption characteristic (Miller, 2010). Other than that, pH of the system also affects the coagulation of the ...
Phytoextraction is the uptake and storage of pollutants in the plants stem or leaves. Some plants, called hyperaccumulators, draw pollutants through the roots. After the pollutants accumulate in the stem and leaves the plants are harvested. Then plants can be either burned or sold. Even if the plants cannot be used, incineration and disposal of the plants is still cheaper than traditional remediation methods. As a comparison, it is estimated a site containing 5000 tons of contaminated soil will produce only 20-30 tons of ash (Black, 1995). This method is particularly useful when remediating metals. Some metals are also being recycled from the ash.
Water pollutants are of different types such as oxygen demanding wastes, disease causing agents, synthetic organic compounds, plant nutrients, inorganic chemicals and minerals, oils, thermal discharge and radioactive wastes. Of all these water pollutants, heavy metals and synthetic organic compounds cause majority of water pollution. Industries like paper and pulp, tanneries, textiles and coke ovens, pha...