scholarly journals RESEARCH INTO DYNAMICS OF ADSORPTION OF HEAVY METALS ON ACID-ACTIVATED BENTONITE

2021 ◽  
Vol 2 (39) ◽  
pp. 115-124
Author(s):  
D. Stetsenko ◽  
D. Yelatontsev
Keyword(s):  
Heavy Metals ◽  
Chemical Modification ◽  
Flow Rate ◽  
Protective Action ◽  
Acid Activation ◽  
Sorbent Layer ◽  
Layer Height ◽  
Modified Bentonite ◽  
Sorption Column ◽  
Sorption Time

Acid activation of bentonite clay is a common way to obtain porous adsorbents of organic and inorganic substances. Acid activation with preservation of the layered structure is the initial stage of chemical modification. Acid treatment of natural aluminosilicates is aimed at increasing their adsorption capacity and specific surface area. In industrial practice, water treatment of heavy metals is in most cases carried out bypassing the liquid through a fixed layer of backfill. Therefore, in this study, we studied the dynamics of adsorption with the definition of the main characteristics of the process: the speed of the working zone, the coefficient of protective action, the length of the working layer, the loss of protective action time, the duration of the sorption column before leakage. In addition, the establishment of the basic laws of this process can be used to determine the optimal parameters of the sorption material at a given initial characteristic — the length of the layer of the sorption column, the filtration rate. We have studied the possibilities of chemical modification of granular bentonite during acid-salt treatment. Through sorption columns with a height of 0.1; 0.2 and 0.3 m, filled with samples of modified bentonite, were passed model solutions of salts Fe2+, Mn2+, Cu2+ and Cd2+ with a concentration of cations of 0.01 g/dm3. The flow rate of the solution was 0.5; 1.0 and 1.5 m/h. Experimental data show that the optimal sorption values ​​are obtained for samples of modified bentonite: at the same height of the sorbent layer and flow rate, the duration of the layer before skipping in modified samples is 1.25—1.52 times higher than in unmodified ones. It is established that the sorption time before skipping mainly depends on the flow rate and the height of the sorbent layer. Thus, at a layer height of 0.3 m and the same rate of transmission of the solution, the sorption time is up to 3.5 times greater than at a layer height of 0.1 m for all investigated cations.

scholarly journals Simulation of a Breathing Apparatus on Chemically Bound Oxygen with a Circular Pendulum Circuit of the Air Duct Part

2021 ◽  
pp. 46-52
Author(s):  
S.G. Ekhilevskiy ◽  
◽  
O.V. Golubeva ◽  
E.P. Potapenko ◽  
◽  
...  
Keyword(s):  
Maximum Permissible Concentration ◽  
Protective Action ◽  
Dead Layer ◽  
Respiratory Protection ◽  
Sorbent Layer ◽  
Breathing Resistance ◽  
Breathing Apparatus ◽  
Short Period ◽  
The Dead ◽  
Made In

At present, the main prospects for improving the insulating means of respiratory protection are associated with the chemical method of oxygen reservation. The arguments in favor of this choice are the high packing density of oxygen and its self-regulating supply, depending on the physical activity of a person. The main schemes of the air duct part of breathing apparatus on chemically bound oxygen are circular and pendulum. The attempt is made in the article to combine the advantages of the circular (small harmful space) and pendulum (small volume of the dead layer) schemes of breathing apparatus on chemically bound oxygen. For these purposes, the formalism method was developed, which allows mathematically and with the help of a computer to simulate the dynamic sorption activity of the regenerative cartridge of a breathing apparatus with a hybrid (circular-pendulum) scheme of the air duct part. The increase in the protective action of the apparatus is determined due to the use of the resource of the dead sorbent layer in the result of the air flow reverse in the pendulum part of the regenerative cartridge. Feasibility of using a hybrid scheme in the self-rescuers with a short period of protective action is shown. The optimal length of the pendulum part is determined, at which the breathing resistance decreases, and the harmful space occupied by the air returning for inhalation without contact with the unreacted layers of the oxygen-containing product is not increased. Its weak dependence on the total length of the regenerative cartridge and the maximum permissible concentration of carbon dioxide in the air returning to inhalation is shown, which makes the circular pendulum scheme realizable in practice.

scholarly journals Batch and continuous fixed bed adsorption of heavy metals removal using activated charcoal from neem (Azadirachta indica) leaf powder

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Himanshu Patel
Keyword(s):  
Heavy Metals ◽  
Flow Rate ◽  
Activated Charcoal ◽  
Batch Adsorption ◽  
Order Kinetic ◽  
Column Study ◽  
Initial Concentration ◽  
Bed Height ◽  
Leaf Powder ◽  
Batch Treatment

Abstract The present investigate was intended for adsorption of heavy metals i.e. Pb, Cu, Cr, Zn, Ni and Cd onto activated charcoal prepared from neem leaf powder (AC-NLP) using batch and column studies. Batch adsorption was performed using different variables like adsorbent dose, temperature and contact duration. Thermodynamic analysis of batch treatment concluded that adsorption is thermodynamically feasible and endothermic. This adsorption followed the Pseudo second-order kinetic model derived from correlation coefficient values of chemical kinetic studies. For column study, interpretation of breakthrough curves and parameters were conducted by varying flow rate, initial concentration and bed height; and reveal that optimum conditions were lower flow rate (5 mL/min) and lower initial concentration (5 mg/L) and higher bed height (20 cm). Comparisons of batch and column study through isotherm models were evaluated and column study is more preferred than batch treatment. Maximum Thomas adsorption capacity was achieved upto 205.6, 185.8, 154.5, 133.3, 120.6, 110.9 mg/g for Pb, Cu, Cd, Zn, Ni and Cr respectively. This removal pattern is elucidated by metal ionic properties. Various adsorbing agents such as acids and bases were utilized for adsorption–desorption of AC-NLP.

Application of Biopolymer-Based Adsorbents in Removal of Heavy Metals

2014 ◽  
Vol 1048 ◽  
pp. 373-377 ◽  
Author(s):  
Min Xiao ◽  
Jian Can Hu ◽  
Wen Li Liu ◽  
Feng Ming Nie
Keyword(s):  
Heavy Metals ◽  
Heavy Metal ◽  
Chemical Modification ◽  
Metal Pollution ◽  
Heavy Metal Pollution ◽  
Graft Copolymerization ◽  
Removal Of Heavy Metals ◽  
Chelating Ability ◽  
Chemical Conditions ◽  
Chitin And Chitosan

Heavy metal pollution has raised a lot of concerns because of its bioaccumulation and non-degradability. A variety of methods have been applied in removal of heavy metals. This paper focused on the method of biosorption using biopolymer-based adsorbents in removing heavy metals from waster water. Cellulose and chitin/chitosan are abundant in supply and contain reactive functional groups. Cellulose-based adsorbents prepared from direct chemical modification or graft copolymerization are proved to show chelating ability to bind heavy metals. Chitin-and chitosan-based adsorbents have improved mechanical strength and better resistance to chemical conditions after physical or chemical modification. The regeneration and reusability of biopolymer-based adsorbents were also discussed in this paper.

scholarly journals A Review on Removal of Heavy Metal Ions from Waste Water using Natural/ Modified Bentonite

2018 ◽  
Vol 144 ◽  
pp. 02021 ◽  
Author(s):  
Prathiksha P. Prabhu ◽  
Balakrishna Prabhu
Keyword(s):  
Waste Water ◽  
Heavy Metals ◽  
Heavy Metal Ions ◽  
Well Being ◽  
Potential Effect ◽  
Inorganic Contaminants ◽  
Inorganic Pollutants ◽  
Environment Friendly ◽  
Modified Bentonite ◽  
Removal Of Heavy Metals

The pollution of water due to various toxic components especially heavy metals are causing an adverse effect on the flora and fauna and also have a potential effect on the human well-being. Due to this there is an immediate requirement to find various techniques for the removal of lethal toxins in wastewater. Amongst all of the existing methods, adsorption is one of the most effective and efficient technique for the elimination of contaminants such as heavy metals from wastewater. The increasing number of research publications on adsorption of heavy metals using modified bentonite leads to the fact that there has been a surging importance in the production of a variety of economical adsorbents for water treatment. Outcome from the latest advances in using bentonites and modified bentonite shows the adaptable nature of the clay and its environment friendly nature. The present review shows the removal of heavy metals using modified bentonite. The main purpose of this review is to describe the flexible way of natural bentonite and modified bentonite and its ability to absorb array of inorganic pollutants, which are present in the waste water. It is apparent from the review that modified bentonite have displayed high removal potential for certain kind of inorganic contaminants from wastewater.

Environmental Impact of Sewage Sludge Co-Gasification With Coal

2006 ◽  
Author(s):  
M. Helena Lopes ◽  
Filomena Pinto ◽  
A. Teresa Crujeira ◽  
Rui Andre´ ◽  
Ma´rio Dias ◽  
...  
Keyword(s):  
Heavy Metals ◽  
Sewage Sludge ◽  
Environmental Impact ◽  
Adverse Effects ◽  
Flow Rate ◽  
Significant Influence ◽  
Equivalence Ratio ◽  
Poor Quality ◽  
Air Flow Rate ◽  
Analytical Detection

The aim of this work is to study the minimization of the environmental impact associated with the gasification of sewage sludge. Co-gasification of a poor quality coal with dried sewage sludge was undertaken on a lab-scale gasifier. The presence of sewage sludge in co-gasification with coal led to higher energy conversions and the gas produced had greater hydrocarbons content. Both temperature and air flow rate were increased with the objective of giving rise to higher energy conversion, thus producing more gas, maximizing hydrogen formation and lowering hydrocarbons, char and tar contents. Due to the adverse effects of the presence of N, S and Cl pollutant precursors leading to the presence of highly corrosive compounds in the syngas, their conversion was evaluated. The increase of sewage sludge content in the feedstock was found to enhance the production of NH3, but working at higher temperatures and with greater Equivalence Ratio (ER) promoted the destruction of NH3. Production of H2S was similar for sewage sludge and coal and seemed to have been decreased by the presence of large quantities of ashes containing Ca and Fe. Temperature had no significant influence on H2S, but higher ER lowered H2S in the syngas. HCl was low and did not varied significantly for the conditions studied. The bed char residues were characterized and their leachability behaviour was evaluated. Heavy metals supplied with the fuel were mostly retained in solid residues, Pb and Hg being the most volatiles at 850°C. However, leachability of these metals was found to be below the analytical detection levels and only small quantities of SO42− and Cl− were released. The bed char residues were found to have variable concentrations of residual C, hence they could be used either as fuels to provide energy for gasification reactions or as sorbents to capture volatile heavy metals.

scholarly journals Packed Bed Biosorption of Lead and Copper Ions Using Sugarcane Bagasse

2016 ◽  
Vol 16 (1) ◽  
pp. 23 ◽  
Author(s):  
Norwin Dale F Duga ◽  
Pauline Edrickke A Imperial ◽  
Allan N Soriano ◽  
Aileen D Nieva
Keyword(s):  
Heavy Metals ◽  
Adsorption Capacity ◽  
Sugarcane Bagasse ◽  
Flow Rate ◽  
Copper Ions ◽  
Continuous System ◽  
Packed Bed ◽  
Packed Bed Column ◽  
Varying Parameters ◽  
Bed Height

Bagasse, a waste material from sugarcane has been studied as a biosorbent for removing heavy metals, Pb2+ and Cu2+, in a continuous system using a packed bed column. This study was undertaken to determine the influence of varying the bed height and flow rate on the breakthrough and saturation time. Thomas, Adams-Bohart and Yoon-Nelson models were used to assess the effects of varying parameters and both Thomas and Yoon-Nelson models were found to be satisfactory to describe the column data obtained in the experiment. Moreover, lead ions are adsorbed more efficiently with an adsorption capacity of 4.54 mg/g compared to copper ions with 3.98 mg/g at the most feasible parameters having a flow rate of 100 mL/min and a bed height of 30 cm

scholarly journals Optimization of Carob Shells Biomass Activation by Nitric Acid for Heavy Metals Sequestration from Contaminated Water

2021 ◽  
Vol 12 (5) ◽  
pp. 5941-5952
Keyword(s):  
Heavy Metals ◽  
Nitric Acid ◽  
Removal Efficiency ◽  
Energy Demand ◽  
Aqueous Media ◽  
Experimental Result ◽  
Acid Activation ◽  
Activation Temperature ◽  
Cobalt Ions ◽  
Preparation Conditions

This study reports the use of agro-waste (carob shells) as a precursor for the synthesis of activated carbon by nitric acid activation. The prepared adsorbent was used for the removal of cadmium and cobalt ions from aqueous media. In order to optimize the preparation conditions for the high removal efficiency of heavy metals, the Box-Behnken design was used to correlate activation agent ratio g(HNO3)/g(carbon), reaction time, and activation temperature to the removal efficiency of metals. The experimental result shows that the rise in activation temperature strongly decreases the removal of both metals. This result suggests a low energy demand for the activation of carob shells by HNO3. The sample prepared at optimum conditions was characterized by DRX, SEM, FTIR, and surface groups titrations in order to obtain information on its structural, morphological, and surface properties. It has also been found that equilibrium data are well correlated to the Langmuir model with adsorption capacities of 125.52 and 69.01 mg/g, respectively, for Cd(II) and Co(II).

scholarly journals ADSORPTION OF ORGANIC DYES ON METALLURGICAL SLAG OF Fe-Ni ALLOY PRODUCTION

2020 ◽  
Vol 63 (8) ◽  
pp. 103-108 ◽  
Author(s):  
Elina B. Khobotova ◽  
Inna V. Hraivoronska ◽  
Marina I. Ihnatenko ◽  
Iuliya S. Kaliuzhna
Keyword(s):  
Organic Dyes ◽  
Chemical Activation ◽  
Local Treatment ◽  
Methyl Violet ◽  
Metallurgical Slag ◽  
Maximum Efficiency ◽  
Acid Activation ◽  
Sorbent Layer ◽  
Static Mode ◽  
Ni Alloy

The optimal parameters of organic dyes adsorption on the metallurgical slag of the Fe-Ni alloy production of the Pobuzhsky Ferronickel Plant, Ukraine: pH, the mass ratio “dye: slag adsorbent”, the type of chemical activation depending on the mode of the adsorption process were determined. Sorption of organic dyes (methylene blue MB, Congo red and methyl violet MV) by slag was studied spectrophotometrically. It is shown that after acid and alkaline activation the surface adsorption centers are formed on the surface of the slag: hydroxyl and silanol groups, whose dissociation causes a negative charge of the particles surface. The most appropriate ratio is “MB : slag” = 1 mg/g, at which the adsorption value a=0.92 mg/g is recorded at a treatment efficiency of 92 %. The maximum efficiency of MB adsorption by slag based on diopside was recorded in the pH range of 4.8- 10.4. The dependence of the type of chemical activation of slag with basic mineral – diopside on the sorption mode of organic dyes was determined. Slag acid activation is advisable in the static mode of MV sorption; alkaline – under conditions of MV dynamic sorption with a low rate of solution passage through the sorbent layer. Diopside-based slag is expedient to use as an adsorbent of organic dyes at the level of their low concentrations at the local treatment of wastewater generated during the certain technological operations.

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