scholarly journals An alternative low-cost adsorbent for gold recovery from cyanide-leached liquors: Adsorption isotherm and kinetic studies

2018 ◽  
Vol 37 (1-2) ◽  
pp. 3-23 ◽  
Author(s):  
Refiloe Tsolele ◽  
Fanyana Moses Mtunzi ◽  
Michael John Klink ◽  
Vusumzi Emmanuel Pakade
Keyword(s):  
Activated Carbons ◽  
Selective Adsorption ◽  
Low Cost ◽  
Kinetic Studies ◽  
Agitation Speed ◽  
Gold Recovery ◽  
Attractive Alternative ◽  
Solution Ph ◽  
Initial Concentration ◽  
Modified Activated Carbons

Pristine Macadamia nutshell-based activated carbons were chemically oxidized with different concentrations of H3PO4 and HNO3 to increase their surface adsorption properties and further explore if they could be an attractive alternative low-cost adsorbent for gold recovery from cyanide-leached liquors. The modified activated carbons were labeled MACN20, MACN40 and MACN55 to signify the materials prepared from 20%, 40% and 55% (v/v) HNO3, respectively. Similar nomenclature was followed for H3PO4-modified activated carbons. Brunauer-Emmet-Teller, scanning electron microscopy, thermogravimetric analysis, Fourier transform infrared spectroscopy, elemental analysis and X-ray diffraction spectroscopy were used to characterize the prepared activated carbons. The physical properties were attained through determining attrition, ash content, volatile matter and moisture content of all the activated carbons. Various parameters that affect selective adsorption such as the effect of initial concentration, time, agitation speed, interfering species and the dose of the adsorbent were investigated. Optimal parameters for gold ion adsorption were as follows: solution pH, 10; contact time, 6 h; agitation speed, 150 r/min; sorbent amount, 4 g and initial concentration, 5.5 mg/L. The observed selectivity order was not the same for all the adsorbents, but the adsorption of gold was found to be mostly influenced in the presence of nickel and least influenced by copper. MACN55 was found to be the most efficient adsorbent with 74% of gold adsorption from a real-world sample and displayed a similar performance to coconut-based activated carbons.

SURFACE ALTERATION OF ACTIVATED CARBON FOR DETOXIFICATION OF COPPER (II) FROM INDUSTRIAL EFFLUENTS

2013 ◽  
Vol 20 (02) ◽  
pp. 1350021
Author(s):  
SADAF BHUTTO ◽  
M. NASIRUDDIN KHAN
Keyword(s):  
Activated Carbons ◽  
Selective Adsorption ◽  
Low Cost ◽  
Industrial Effluents ◽  
Copper Adsorption ◽  
Adsorption Capacities ◽  
Surface Alteration ◽  
Equilibrium Data ◽  
Modified Activated Carbons ◽  
Acetic Acids

The low-cost modified activated carbons were prepared from Thar and Lakhra (Pakistan) coals by activation with sulfuric acid and further modified with citric, tartaric and acetic acids for the selective adsorption of Cu(II) from aqueous solution. The original carbon obtained from activated Thar and Lakhra coals at pH 3.0 displayed significant adsorption capacity for lead and insignificant capacity values (0.880 and 0.830 mg⋅g-1) for copper. However, after modification with citric, tartaric and acetic acid the copper adsorption capacities enhanced in the range of 5.56–21.85 and 6.05–44.61 times, respectively. The Langmuir, Freundlich and Temkin adsorption isotherms were used to elucidate the observed sorption phenomena. The isotherm equilibrium data was well fitted by the Langmuir and sufficiently fitted to the Freundlich models. The calculated thermodynamic parameters such as change in Gibbs free energy (ΔG°), enthalpy (ΔH°) and entropy (ΔS°) inferred that the investigated adsorption was spontaneous and endothermic in nature. Based on the results, it was concluded that the surface alteration with citric and tartaric acid, Thar and Lakhra activated carbons had significant potential for selective removal of copper(II) from industrial wastewater.

scholarly journals Oxytetracycline Adsorption from Aqueous Solutions on Commercial and High-Temperature Modified Activated Carbons

Energies ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3481
Author(s):  
Joanna Lach ◽  
Agnieszka Ociepa-Kubicka ◽  
Maciej Mrowiec
Keyword(s):  
Activated Carbon ◽  
Aqueous Solutions ◽  
Activated Carbons ◽  
Electricity Consumption ◽  
Solution Ph ◽  
Carbon Modification ◽  
Modification Method ◽  
Flow Through ◽  
Proposed Modification ◽  
Modified Activated Carbons

The aim of the work was to evaluate the possibility of using commercial and modified activated carbons for the removal of oxytetracycline from aqueous solutions. The kinetics and statics of adsorption as well as the effect of the activated carbon dose and solution pH on the efficiency of the oxytetracycline adsorption were analyzed. Based on the study of oxytetracycline adsorption isotherms, the activated carbons were ranked in the following order: F-300 > WG-12 > Picabiol > ROW08 > WACC 8 × 30 > F-100 > WAZ 0.6–2.4. The most effective activated carbons were characterized by large specific surfaces. The best matching results were obtained for: Redlich–Peterson, Thot and Jovanovic models, and lower for the most frequently used Freundlich and Langmuir models. The adsorption proceeded better from solutions with pH = 6 than with pH = 3 and 10. Two ways of modifying activated carbon were also assessed. A proprietary method of activated carbon modification was proposed. It uses the heating of activated carbon as a result of current flow through its bed. Both carbons modified at 400 °C in the rotary kiln and on the proprietary SEOW (Joule-heat) modification stand enabled to obtain adsorbents with higher and comparable monolayer capacities. The advantage of the proposed modification method is low electricity consumption.

scholarly journals Possibility of Removing Phosphates from Activated Charbon Made from Date Kernels

2021 ◽  
Vol 06 (03) ◽  
Author(s):  
Nora Seghairi ◽  
Keyword(s):  
Activated Carbon ◽  
Natural Waters ◽  
Activated Carbons ◽  
Kinetic Studies ◽  
Phosphate Adsorption ◽  
Initial Concentration ◽  
Adsorbent Dosage ◽  
Isotherm Study ◽  
Freundlich Isotherms ◽  
Batch Tests

Phosphates in natural waters and whatever their origin, promote the formation of algae, reduce dissolved oxygen and reduce biodiversity in aquatic ecosystems. At high doses, phosphate salts can cause health problems. The objective of our study was to develop a simple, efficient and environmentally friendly sorption depollution technique on available and inexpensive media. We have studied the adsorption of phosphate on activated carbons prepared from date kernels. Batch tests were carried out in order to study different operating parameters such as the effect of contact time, pH, initial phosphate concentration and adsorbent dosage and adsorption kinetic. The sorption equilibrium was analyzed by Langmuir, Freundlich isotherms model. Results show that the phosphate adsorption was reversible and the quantity adsorbed reached its maximum value (14.49 mg/g) after 40 minutes. It was also found that phosphate uptake was affected by variation of pH, initial concentration of phosphate and activated carbon dosage. The adsorption improved with an acidic pH (pH = 6), initial concentration and adsorbent dosage. The results of kinetic studies revealed that adsorption phosphate on activated carbon based on date kernels (Biocar) and the intra-particle diffusion involved in the adsorption mechanism. Also, isotherm study showed that Langmuir isotherm best fit the data and the adsorption was a physical type.

scholarly journals Brilliant Green and Acid Orange 74 Dyes Removal from Water by Pinus roxburghii Leaves in Naturally Benign Way: An Application of Green Chemistry

2019 ◽  
Vol 2019 ◽  
pp. 1-10 ◽  
Author(s):  
Rabia Rehman ◽  
Sara Jan Muhammad ◽  
Muhammad Arshad
Keyword(s):  
Brilliant Green ◽  
Low Cost ◽  
Kinetic Studies ◽  
Agitation Speed ◽  
Pinus Roxburghii ◽  
Acid Orange ◽  
Pseudo Second Order ◽  
Optimized Conditions ◽  
Adsorbent Dose ◽  
Dyes Removal

The purpose of this study was to use low cost and easily accessible biosorbent for batch-scale elimination of brilliant green and acid orange 74 dyes from aqueous solution. Pinus roxburghii leaves were utilized to study their dye-eliminating capacities. The adsorbent was characterized by FTIR, TGA, DTA, and SEM. The optimized conditions for brilliant green and acid orange 74 dye elimination were adsorbent dose, 1.2 and 1.8 g; contact time, 30 and 45 min; pH, 2 and 1; temperature, 50°C and 60°C; and agitation speed, 125 rpm and 50 rpm for BG and AO-74, respectively. Adsorption records well fitted Langmuir isotherm. Possibility of the procedure was shown by negative values of the thermodynamic parameter ∆G° for both dyes. Kinetic studies showed that adsorption of BG and AO-74 dyes from watery solution by PR leaves followed pseudo-second-order kinetics.

scholarly journals Methylene Blue removal from aqueous solutions by activated carbon prepared from N. microphyllum (AC-NM): RSM analysis, isotherms and kinetic studies

2017 ◽  
Vol 19 (4) ◽  
pp. 697-705 ◽  
Keyword(s):  
Methylene Blue ◽  
Activated Carbon ◽  
Low Cost ◽  
Kinetic Studies ◽  
P Value ◽  
Water And Wastewater Treatment ◽  
Freundlich Model ◽  
Initial Concentration ◽  
Layer Adsorption ◽  
Water And Wastewater

This study was conducted to remove Methylene Blue (MB) from aqueous solution using activated carbon prepared from N. microphyllum (AC-NM) as a new, cheap, and non-toxic. Design of experiments based on Response Surface Methodology (RSM) conducted to investigate the effect of variables namely; initial dye concentration, pH, contact time and absorbent dosage. An empirical model was developed applying ANOVA analysis. The interaction effects of all factors and their optimization have been carried out using RSM. Dye removal efficiency increased to more than 90% with increasing pH and initial concentration of dye from 3 to 11 and 10 to 210 mg/L, respectively under 1.1 to 1.4 g/L of absorbent dosage. Among factors, initial concentration of MB known as an important factor with P- value <0.0001. The experimental data are fitted with Freundlich model based on multi layer adsorption states (R2=0.99). The adsorption kinetics well described by second order model with R2 = 0.98. This novel absorbent has different advantages such as low cost, high ability to absorb pollutants and easily available that can be suggested for water and wastewater treatment.

Study of Pb2+, Cd2+ and Ni2+adsorption onto activated carbons prepared from glycyrrhiza residue by KOH or H3PO4 activation

2015 ◽  
Vol 72 (3) ◽  
pp. 451-462 ◽  
Author(s):  
Chunfang Ma ◽  
Wei Fan ◽  
Jinbao Zhang ◽  
Yang Shi ◽  
Ningchuan Feng
Keyword(s):  
Activated Carbons ◽  
Ph Value ◽  
Raw Materials ◽  
Chemical Properties ◽  
Kinetic Studies ◽  
Physical Structure ◽  
Micropore Volume ◽  
Solution Ph ◽  
Analytical Instruments ◽  
H3po4 Activation

The activated carbons (ACs) were prepared from glycyrrhiza residue by KOH or H3PO4 activation and were used for removing Pb2+, Cd2+ and Ni2+ from simulated wastewater. The changes of the physical structure and chemical properties of the glycyrrhiza residue before and after activation were characterized by using a variety of analytical instruments and methods. Kinetics and equilibrium isotherms were obtained and the effects of solution pH value and adsorbent dosage were studied in batch experiments. The results indicated that after activation, the surface structure of glycyrrhiza residue changes and surface area, micropore volume also increase accordingly. Kinetic studies showed that the adsorption followed a pseudo-second-order reaction. The Freundlich model fitted the equilibrium data better than the Langmuir isotherm. According to the Langmuir equation, the maximum adsorption capacities of ACs prepared from glycyrrhiza residue by KOH and H3PO4 activation for Pb2+, Cd2+ and Ni2+ are 2.170 mmol/g, 2.617 mmol/g, 3.741 mmol/g and 2.654 mmol/g, 3.095 mmol/g, 3.076 mmol/g, respectively, which are much higher than ACs prepared from other raw materials.

scholarly journals Effect of Solution pH on the Adsorption of Paracetamol on Chemically Modified Activated Carbons

Molecules ◽  
2017 ◽  
Vol 22 (7) ◽  
pp. 1032 ◽  
Author(s):  
Valentina Bernal ◽  
Alessandro Erto ◽  
Liliana Giraldo ◽  
Juan Moreno-Piraján
Keyword(s):  
Activated Carbons ◽  
Solution Ph ◽  
Chemically Modified ◽  
Modified Activated Carbons

Isotherms and kinetic studies on adsorption of Hg(II) ions onto Ziziphus spina-christi L. from aqueous solutions

2016 ◽  
Vol 5 (2) ◽  
Author(s):  
Ali Hashem ◽  
Alaauddin Al-Anwar ◽  
Negma M. Nagy ◽  
Doaa M. Hussein ◽  
Sara Eisa
Keyword(s):  
Experimental Data ◽  
Aqueous Solutions ◽  
Low Cost ◽  
Kinetic Studies ◽  
Plant Residue ◽  
Batch Adsorption ◽  
Pseudo First Order Reaction ◽  
Solution Ph ◽  
Equilibrium Data ◽  
Pseudo Second Order

AbstractL. (ZscL) is a plant residue that has been used as adsorbent for the removal of Hg(II) ions from an aqueous solution. The ability of ZscL to adsorb Hg(II) ions was investigated by using the batch adsorption procedure. It was characterized by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) to support the adsorption of Hg(II) ions. The effects of various parameters on the adsorption process, such as contact time, adsorbent concentration, solution pH and initial concentrations of metal ions were studied to optimize the conditions for maximum adsorption. Experimental equilibrium data were fitted to the Freundlich, Langmuir, Dubinin-Radushkevich, Halsey and Temkin (two parameter models), Redlich-Peterson, Sips, Khan, Hill, Radke-Prausnitz, Langmuir-Freundlich and Toth (three parameter models), Fritz-Schlunder and Baudu (four parameter models) and Fritz-Schlunder (five parameter model) at 30°C by using nonlinear regression analysis. The examination of error analysis methods showed that the Halsey model provides the best fit for experimental data compared with the other isotherms. Various kinetic models have been applied to the experimental data to predict the adsorption kinetics. It was found that pseudo-second-order rate was better obeyed than pseudo-first-order reaction, supporting that the chemisorption process was involved. The obtained results show that ZscL can be used as an effective and natural low-cost adsorbent for the removal of Hg(II) ions from aqueous solutions.

Novel Sorbents and their Sorptive Properties for Mercury Emissions Control of Coal-Fired Flue Gas

2015 ◽  
Vol 1088 ◽  
pp. 332-336 ◽  
Author(s):  
Na Huang ◽  
Yan Bin Zhu ◽  
Dan Jie Meng
Keyword(s):  
Activated Carbon ◽  
Power Plants ◽  
Activated Carbons ◽  
Low Cost ◽  
Waste Product ◽  
Elemental Mercury ◽  
Primary Objective ◽  
Mercury Emissions ◽  
Mercury Control ◽  
Modified Activated Carbons

Mercury is a striking pollutant and mercury emissions from coal-fired power plants are under environmental regulation. The primary objective of mercury abatement in coal-fired power plants is to remove elemental mercury. Sorbent injection is one of the major commercially available technologies for mercury control from coal fired power plants and activated carbon is the most commonly employed sorbent. Modified activated carbons have been found to exhibit high mercury emission reduction efficiency. Noble metal and metal oxides also showed excellent mercury adsorption capacity. Fly ash, a waste product from coal-fired solid wastes, may be an excellent adsorbent owing to its low cost and abundance. There is no consistent evidence for the adsorption mechanism of mercury on modified activated carbon; a popular view is that the sorption mechanism is combination of physisorption and chemisorption.

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