MINISTRY OF EDUCATION AND TRAINING HANOI NATIONAL UNIVERSITY OF EDUCATION PHAM XUAN CUONG STUDY PROPERTIES AND MECHANISMS ADSORPTION HEAVY METAL IONS ON MATERIALS MADE FROM RED MUD Specialized: Theoretical chemistry and Physicochemical Code: 62.44.01.19 SUMMARIZED DISSERTATION CHEMISTRY HA NOI - 2016 2 THESIS WERE COMPLETED AT THE HANOI NATIONAL UNIVERSITY OF EDUCATION Instructors scientific studies: Associate Professor Doctor Nguyen Trung Minh Associate Professor Doctor Nguyen Ngoc Ha Counter Argument No.1: Prof.Dr Lam Ngọc Thiem Counter Argument No.2: Assoc Prof Dr Dang Xuan Thu Counter Argument No.3: Assoc Prof Dr Nguyen Anh Tuan The dissertation will be defended before the Council of State level thesis dots, at Hanoi National University of Education Date and Time: hours / ./ 2016 Can search This dissertation at: - Library of Hanoi National University of Education - National Library 3 REPORTED AND SCIENTIFIC WORKS RELATED [1] [2] [3] [4] [5] [6] [7] [8] [9] SCIENTIFIC JOURNALS Phạm Xuân Cường, Nguyễn Trung Minh, Phạm Việt Hà, Nguyễn Đức Chuy (2011), “Phương pháp hấp phụ cột nghiên cứu xử lý ô nhiễm kim loại nặng chì (Pb2+) hạt vật liệu chế tạo từ bùn đỏ-laterit đá ong” - Tạp chí Hóa học -Viện khoa học Công nghệ Việt Nam, T.49 số 5AB-2011 tr - 14 Phạm Việt Hà, Phạm Xuân Cường, Nguyễn Trung Minh, Nguyễn Đức Chuy (2011), “Xử lý Asen nước hạt hấp phụ chế tạo từ bùn đỏ” Tạp chí Hóa học-Viện khoa học Cơng nghệ Việt Nam, T.49 số 5AB-2011tr42 – 48 Phạm Xuân Cường, Nguyễn Trung Minh, Nguyễn Đức Chuy, Nguyễn Ngọc Hà (2013), “Nghiên tổng hợp khảo sát ảnh hưởng khối lượng hạt vật liệu chế tạo từ bùn đỏ đến khả hấp phụ kim loại nặng Asen - Tạp chí Xúc tác Hấp phụ T.2-N04-trang 52- 58 Phạm Xuân Cường, Nguyễn Trung Minh, Nguyễn Đức Chuy, (2013), “Xử lý ô nhiễm kim loại nặng Cadimi( Cd2+) hạt vật liệu chế tạo từ bùn đỏ theo phương pháp hấp phụ cột” - Tạp chí Xúc tác Hấp phụ T.2-N04-tr 46 – 51 Phạm Xuân Cường, Nguyễn Trung Minh, Nguyễn Ngọc Hà, Nguyễn Đức Chuy, (2013) ”Nghiên cứu lý thuyết chế hấp phụ ion Cu 2+ dung dịch nước tâm hấp phụ Geothite hạt vật liệu chế tạo từ bùn đỏ” Tạp chí Xúc tác Hấp phụ T.4-N01 2015-Trang 39-44 Phạm Xuân Cường, Nguyễn Trung Minh, Nguyễn Đức Chuy, Nguyễn Ngọc Hà (2013), “Application of particles made from material sludge in remediation oh heavy metal lead Pb2+”- International Conference on Sciences and Social Sciences 2013: Reaserch and Development for Sustainable Life Quality(ICSS 2013) tr 325 – 328 Phạm Xuân Cường, Nguyễn Trung Minh, Nguyễn Đức Chuy, Nguyễn Ngọc Hà (2014), “Theoretical study of adsorption mechanisms of heavy metal Copper Cu 2+ on seed materials made from red mud” –The International Conference on Sciences and Social Sciences 2014: Integrated Creative research for Local Development toward the ASEAN Economic Community (ICSS 2014) tr 128 – 132 Phạm Xuân Cường, Nguyễn Trung Minh, Nguyễn Đức Chuy, Nguyễn Ngọc Hà (2014) “Theoretical study of adsorption mechanisms of heavy metal Zinc (Zn +) on seed materials made from red mud”–The 6th International Science, Social Science, Engineering and Energy Conference (I-SEEC 2014) Phạm Xuân Cường, Nguyễn Trung Minh, Nguyễn Đức Chuy, Nguyễn Ngọc Hà (2014), “Theoretical study of adsorption mechanisms of heavy metal Cadmium (Cd2+) and arsenic on seed materials made from red mud”–The 6th International Science, Social Science, Engineering and Energy Conference (ISEEC 2014) Đề tài khoa học Phạm Xuân Cường (2013), Đề tài khoa học cấp tỉnh: “Điều tra, đánh giá trạng nhiễm bẩn kim loại nặng vùng đất trồng lúa khu vực cánh đồng Mường Thanh tỉnh Điện Biên, đề xuất giải pháp khắc phục” - năm 2013 4 INTRODUCTION Urgency of the theme Water pollution in the world in general and Vietnam in particular is a serious problem now by their enormous harm to the environmental quality and human health worldwide Heavy metals are often related to environmental pollution problems Most heavy metals such as Pb, Hg, Cd, As, Cu, Zn, Fe, Cr, Co, Mn, Se, Mo exist in water in the form of ions The use of natural materials, reuse of waste environmental friendliness to remove heavy metals in the water to acceptable levels has always been at the forefront in order to not harm the environment, ensuring that sustainable development while giving higher efficiency when used The theme of the thesis is the study found a new material from waste (sludge) in the alumina refining process and study the nature and mechanism of heavy metal ions adsorbed on the materials Materials from sludge particles has solved two difficult problem that's: - Handling of red mud waste source in the industry of mining and processing of bauxite - Creates a new low cost materials to meet environmental needs treatment is increasing Urgency of the thesis is shown from the urgency of the problem of environmental pollution treatment at present, especially in Vietnam in industrial zones, urban areas and villages The aim of the thesis Manufacture new adsorbent from waste sludge, industrial mining and processing of bauxite research nature and mechanism of adsorption of heavy metal ions Cd2+, Cu2+, Zn2+ and As(V) in the form of wastewater HAsO 42- by actual experiments combined with modern computational theory Subjects and scope of research 3.1 Subjects of research - The heavy metal ions Cd2+, Cu2+, Zn2+ and As(V) in the aquatic environment - Adsorbent materials derived from red mud Bao Loc, Lam Dong, Binh Yen laterite, Hanoi and liquid glass additives - The software supports calculation of modern quantum chemistry as Gaussian, SIESTA 5 3.2 Scope of research - Study the adsorption of heavy metal ions Cd 2+, Cu2+, Zn2+ and As(V) in water on materials made from red mud Bao Loc, Lam Dong province, laterite Binh Yen, Hanoi and parts Family molten glass within the laboratory - The theoretical study adsorption mechanisms of heavy metal ions above and As(V) by density-functional method The significance of science and practical subjects - Adsorbent beads made from waste sludge in industrial mining and processing bauxite pretty good adsorption of heavy metal ions such as Cd 2+, Cu2+, Zn2+ and As(V) in the aquatic environment The results of the thesis is the scientific basis for the calculation, selection of materials made from red mud in the treatment of heavy metals in water in some industries Find out the type of adsorbent efficiency of heavy metal ions Cd 2+, Cu2+, Zn2+ and As(V) in water, handle partial source of waste sludge in the extraction and processing of bauxite there was an urgent problem now and in the future when Vietnam is a large aluminum manufacturing centers in the world - Explain adsorption mechanism of heavy metal ions Cd 2+, Cu2+, Zn2+ and As(V) in water on geothite center - The contents of the thesis shows the close relationship and support between theoretical calculations and experimental A new feature of the thesis - Look at a new adsorbent system: Switch from hazardous waste, harmful to the environment (sludge) into a useful material (heavy metal adsorption) - From the results received, materials made from red mud is a material polycentric adsorption, likely adsorption of heavy metal ions Cd 2+, Cu2+, Zn2+ and As(V) in the environment country Adsorption of heavy metal ions on materials made from red mud just obey Freundlich isotherm Langmuir isotherm fit follow and comply with complex mechanisms to create surfaces The experimental value calculated ∆Go < and -∆H0 = 52 - 89 kJ/mol should adsorption process is the adsorption of materials chemistry - Building a model using software Geothite supporting calculations, select the section FeOOH(101)-(1×1×3) to calculate the most efficient structure for the complex obtained [Cd(H2O)6]2+, [Cu(H2O)6]2+, [Zn(H2O)6]2+ HAsO42- interact with the surface Hydrated-FOOH(101)-(1×1×3) with the adsorption energy values -ΔE = 419-519 kJ/mol Great energy to the reaction occurred, as well as the variation in complex structures 6 - Incorporates between practical experiments with theoretical calculations to study thoroughly the nature and mechanisms of heavy metal ions adsorbed on the materials made from red mud Determination of adsorption mechanism [Cd(H2O)6]2+, [Cu(H2O)6]2+, [Zn(H2O)6]2+ HAsO42- on Goethite center of county BVNQ adsorption, BOS complexing Hydrated- style FOOH(101)-(1×1×3) via hydrogen bonds - Contribute to add an adsorbent material from the waste sludge of industrial exploitation and processing of bauxite, to handle the heavy metal ions in water The layout of the thesis The thesis consists of 119 pages, including Opening: pages, Chapter I: Overview document: 21 pages Chapter II: The method and empirical research: 16 pages Chapter III: Findings and discussion: 76 pages Catalog articles and scientific works: pages References pages and 68 references and abroad II CONTENT THESIS Chapter 1: OVERVIEW DOCUMENT The review has introduced the basic knowledge and research results related to the thesis: In the process of refining alumina, the ore is insoluble in alkaline are settling, washed and removed from the chain This residue is commonly known as red mud The aqueous phase of alkaline red mud corrosive to materials, may penetrate the soil affect crops entering aquifers causing water pollution Heavy metal is the concept to denote metal atoms high toxicity and often for life Heavy metals Hg, Cd, Pb, As, Sb, Cr, Cu, Zn, Mn, are not involved or less involved in biochemical processes of the organism and often accumulate in the body them Therefore, they are harmful elements with creatures In experiments to evaluate the absorption capacity of the material particles made from red mud through adsorption capacity (q), q is a function of many variables q=f(T, P, C ) When T = const, then q = φ (C) is called adsorption isotherm equation Now there are many adsorption isotherm equation, but app adsorption liquid phase adsorption material use one or isothermal qi = qm (K.Ci ) + K Ci Langmuir or Freundlich isotherm 7 (qm: maximum capacity monolayer adsorption, K: constant, Pi, Ci is the pressure or the concentration of adsorbed) Special attention overview introduction to quantum chemistry, is a science application of quantum mechanics to solve the problem of the chemical Thus the method of quantum chemistry and computational software to become an effective tool in the study, examined the molecular structure and mechanism of many chemical reactions in different conditions which is sometimes very difficult to perform experiments or can not be performed That shows the importance of theoretical studies using computational software modern quantum chemistry as programming language Pythonw, Gaussian, GaussView, Chemcraft, Siesta, Notepad ++ CHAPTER METHODS AND EMPIRICAL RESEARCH 2.1 The research methodology Applying the method of statistical analysis to layout mathematical experiments, sampling, data processing and evaluation results ensure objective requirements and accuracy allows for the support of some software Excel The thesis method using an atomic absorption spectroscopy (AAS) to analyze the content of elements; SEM and TEM methods (scanning electron microscopy and transmitted) to determine the size and the center geothite and their distribution on the seed material; X-ray diffraction method (XRD) to study the mineral composition in particle form study materials, their size in the sample content; density-functional method (DFT) to investigate the electron structure of geothite and after adsorption systems; thereby determining the adsorption energy and adsorption mechanisms, thereby contributing to explain the experimental results 2.2 The experiment Red mud Bao Loc, Lam Dong, Binh Yen laterite, Hanoi and liquid crystal additives are mixed according to the ratios, squeezing granulation 2,5 mm diameter and heated at a temperature of 350 0C and time hours, collected seeds materials BVNQ, BOS To test the absorption capacity of the sample series BVNQ, BOS, we have conducted experiments with group ions adsorbed heavy metals copper (Cu), zinc (Zn), cadmium (Cd) and arsenic (V) in aqueous solution Influence of particle mass BVNQ materials, BOS to KLN ion adsorption capacity Effect of pH on the absorption capacity of seed material KLN BVNQ, BOS, Effect of concentration on adsorption capacity KLN KLN, Influence of time to adsorb 8 heavy metal, Determination of animal reactions BVNQ materials, BOS temperature 35°C (308K) 45°C (318K) These experiments are adsorbed metal single batch Model Building Centre adsorbed by calculating the parameters structure, the kind of energy to find structurally adsorbed ion Cu 2+, Zn2+, As(III), Cd2+ surface Geothite software Chemcraft, GaussView and SIESTA CHAPTER 3: RESEARCH RESULTS AND DISCUSSION 3.1 The composition, structure and physicochemical properties of the adsorbent particles - Grains BVNQ made of weathered basalt mixed red mud Bao Loc, Lam Dong, with 15% of molten glass and heated to 350 °C, the preheating time hours - Grains BOS is made from a mixture of 45% laterite Binh Yen, Hanoi + 45% red mud Bao Loc, Lam Dong, with 10% of molten glass and heated to 350 °C, the preheating time hours Table 3.1: Results measured BET specific surface area of the material particles material Surface The pore volume STT Pore size average Å particles area m /g cm2/g BVNQ 105.3 0.3611 137.11 BOS 59.01 0.005448 203.54 He surface area and Pore size average are two important factors determining the absorption capacity of the material, from Table 3.1, notice that the material particles BVNQ and BOS have specific surface and the average pore size large easy adsorbed heavy metals Determine the mineral composition of the material particles and BOS BVNQ XRD method results in components with 35% -37% Geothite, 21% -23% Kaollinte in grains BOS, 7% -9% Geothite, Kaollinte 16% -18% in grains BVNQ Results TEM and SEM analysis for rod-shaped goethite, tidbits of materials and BOS BVNQ Including part-FESEM EDS spectrum analysis showed there geothite Fe atoms and composition Kaolinite mainly Al atoms Adsorption would be interested Through spectroscopic analysis EDS-FESEM showed that Al and Fe are two main components of particulate materials BVNQ and BOS The results of empirical research and theory, mechanism of ion adsorption heavy metals and arsenic particles of material particles BVNQ, BOS 9 3.2 The results of experimental studies of heavy metal ion adsorption of arsenic particles and materials BVNQ, BOS 3.2.1 Experimental results Cd2+ ion adsorption in aqueous solution of seed BVNQ, BOS SEM Figure analysis and EDS-FESEM for county BVNQ materials, BOS after conducting experiments with concentrations of Cd adsorption initially 105,5 mg/L Laboratory results determined ion adsorption capacity of the county BVNQ Cd2+, BOS showed adsorption capacity Qe and% of particles adsorbed large BVNQ materials (1.077 mg/g, 61.43%), BOS (1,086 mg/g , 61,98%), adsorption capacity Cd2+ ions in aqueous high EDS spectrum-FESEM results also showed the presence of trace elements with an atomic Cd is ~ 6% in materials BVNQ, BOS 2% in the county after the adsorption experiments 3.2.1.1 Influence of particle mass BVNQ materials, BOS to ion adsorption capacity Cd2+ Conducting experiments at Research Department, Institute of Geology Institute of Science and Technology Vietnam earned results: When the volume of materials BVNQ increased adsorption capacity Cd 2+ of material increases and did not change much in proportion 60 g/L even when the material volume increased BOS Cd2+ adsorption capacity of the material has increased 3.2.1.2 Effect of pH on the absorption capacity Cd2+of seed material BVNQ, BOS pH increases, the ability to handle Cd 2+ of material BVNQ also increased, county BOS notice pH = is economical and best suited but not at this pH, the processing performance of metal ions is also highest This is also consistent because in fact, most of the waste water pH ~ feature So we choose pH = for subsequent experiments 3.2.1.3 Effect of Cd2+ ion concentration to ion adsorption capacity Cd2+ Figure 3.1 : Freundlich isotherm adsorption Cd2+ BVNQ county and BOS Thus the particles adsorbed on BVNQ Cd2 +, BOS in concentrations 10 10 studied almost obey Freundlich adsorption isotherm Based on the data (Figure 3.1) may establish adsorption isotherm equation for the sample BVNQ-Cd, BOS-Cd BVNQ-Cd: q = 0,089C1.0308 với n = 0,97 ( q = mg/mg; Ce = mg/L) BOS-Cd: q = 0,199C0.8306 với n = 1,2 ( q = mg/mg; Ce = mg/L) The figures that are calculated on a linear Langmuir equation to determine qmax and KL Figure 3.2: Langmuir isotherm adsorption of Cd2+ county BVNQ and BOS From Figure 3.2 can determine the value of KL Qmax and Cd 2+ adsorption process on county BVNQ and BOS BVNQ: qmax = 21,88 mg/g; KL = 0,052 L/g BOS: qmax = 21,55 mg/g; KL = 0,11 L/g Thus the results from Figure 3.2 it can be concluded that the Cd 2+ ion adsorption in aqueous solution on material particles BVNQ and BOS obey Langmuir isotherm equation is quite good with regression coefficient R = 0,9661(BVNQ) and R2 = 0,9919 (BOS) Langmuir isotherm equation of material particles: q Cd + BVNQ: q BVNQ Cd + BOS = 21,88 = 21,55 0,052.CeCd 2+ + 0,052.CeCd 0,11.CeCd 2+ 2+ Cd + + 0,11.Ce BOS: Thus, the maximum adsorption capacity (monolayer) of Cd2+ on the material BOS higher than BVNQ From these results we see adsorption Cd2+ on materials BVNQ and BOS again just follow the equation isotherm Freundlich (surface adsorption heterogeneous) and simultaneously comply isotherm Langmuir (with a hypothetical surface homogenous adsorption), this can be explained as follows: - Material particles BVNQ, BOS is a material with complex geometry, surface chemistry have heterogeneous (max adsorption center FeOH, AlOH, SiOH ) so the heavy metal ions adsorbed on the particle BVNQ , BOS often 14 14 Cu2+ on materials BVNQ and BOS again just follow the equation isotherm Freundlich (surface adsorption heterogeneous) and simultaneously comply isotherm Langmuir (with a hypothetical surface homogenous adsorption), the data and results of the thesis is also quite consistent with the situation of a few recent research study published 3.2.2.4 Influence of time to adsorb Cu2+ When time increases the likelihood county BOS BVNQ and Cu 2+ adsorption increased adsorption capacity Cu 2+ has stabilized after 24 hours, then with increasing adsorption time on the adsorption capacity increases also not much So choose the time to handle adsorption Cu 2+ is 24h for the next survey 3.2.2.5 Determination of the material reaction BVNQ, BOS temperature 35°C (308 K) 45°C (318 K) Surveying the effect of temperature on the adsorption of heavy metal ions Cu2+ conditions: concentration of Cu2+ 50 mg/L pH = 6, adsorption time 24 hours at the temperature: the temperature 35°C (308 K) and 45°C (318 K) Table 3.3 Results calculated reaction temperature heat 35°C (308 K) and 45° C (318 K) beads of materials BVNQ, BOS ∆H0 ∆S0 (kJ/mol) (kJ/mol) (kJ/mol) (kJ/molK) BVNQ -63,66 -0,192 -4,253 -2,324 BOS -60,54 -0,183 -3,960 -2,123 Comment: - For seed BVNQ: Value ∆Ho< 0, ∆So< 0, ∆Go< and increases with increasing temperature ∆Go shows Cu2+ adsorption of materials is exothermic and self happen, value /∆H0/= 63,66 kJ/mol so the process of adsorption of Cu2+ material is chemically adsorbed - For seed BOS: Value ∆Ho< 0, ∆So< 0, ∆Go< and increases with increasing temperature ∆Go shows Cu2+ adsorption of materials is exothermic and self happen, value /∆H0/= 60,54 kJ/mol so the process of adsorption of Cu2+ material is chemically adsorbed 3.2.3 Experimental results Zn2+ ion adsorption in aqueous solution of seed BVNQ, BOS SEM Figure analysis and EDS-FESEM for county BVNQ materials, BOS after conducting Zn2+ adsorption experiments with initial concentrations 70,02 mg/L Laboratory results determined ion adsorption capacity of the county 15 15 BVNQ Zn2+, BOS showed adsorption capacity adsorbent Qe and % of particles larger BVNQ materials (1,140 mg/g, 65,20 %), BOS (1,563 mg/g , 89,35 %), adsorption capacity Zn2+ ion in aqueous high Results EDS-FESEM spectral analysis also showed the presence of elemental Zn with an atomic fraction is ~ 3% in BVNQ materials, 30% of the particles after the end BOS adsorption experiments 3.2.3.1 Influence of particle mass BVNQ materials, BOS to ion adsorption capacity Zn2+ Conducting experiments at Research Department, Institute of Geology Institute of Science and Technology of Vietnam obtained results: the quantity of material BVNQ and BOS increased adsorption capacity Zn 2+ of materials increased, however in proportion material volume/volume of liquid absorbed is 40 g/L, we achieved the highest percentage adsorption 3.2.3.2 Effect of pH on the absorption capacity of seed material Zn 2+ BVNQ, BOS pH increases, the ability to handle Zn2+ of material BVNQ, BOS also increased but we found that when pH = for efficiently handling high but in fact, most of the waste water has pH ~ So we choose pH = for subsequent experiments 3.2.3.3 Effect of Zn2+ ion concentration to ion adsorption capacity Zn2+ From the experimental results found that the Zn2+ ions adsorbed on the particle BVNQ, BOS obey Freundlich isotherm and Langmuir isotherm quite good Freundlich equation BVNQ - Zn: y = = 0,7169x – 1,1182 R² = 0,9671 Freundlich equation BOS - Zn: y = 0,7528x – 1,0213 R² = 0,9567 Thus the particles adsorbed on BVNQ Zn2+, BOS in concentrations studied almost obey Freundlich adsorption isotherm Based on the Figure data can establish adsorption isotherm equation for BVNQ-Zn sample, BOS-Zn BVNQ-Zn: q = 0,076C0.7169 với n = 1,39 ( q = mg/mg; Ce = mg/L) BOS-Zn: q = 0,095C0.7528 với n = 1,32 ( q = mg/mg; Ce = mg/L) The value Langmuir, qmax(mg/mg), and KL (L/g) is calculated as follows: BVNQ: qmax = 20,04 mg/g; KL = 0,0046 L/g BOS: qmax = 28,09 mg/g; KL = 0,0024 L/g Langmuir isotherm equation of material particles: q BVNQ: Zn + BVNQ = 20,04 0,0046.Ce Zn 2+ + 0,0046.Ce Zn 2+ 16 16 q Zn2 + BOS = 28,09 0,0024.Ce Zn 2+ + 0,0024.Ce Zn 2+ BOS: Thus, the maximum adsorption capacity (monolayer) of Zn2+ on the 2+ 2+ Zn Zn material BVNQ higher than BOS qmax (BOS) >1,4 qmax ( BVNQ) From these results we see adsorption Zn2+ on materials BVNQ and BOS again just follow the equation isotherm Freundlich (surface adsorption heterogeneous) and simultaneously comply isotherm Langmuir (with a hypothetical surface homogenous adsorption 3.2.3.4 Influence of time to adsorb Zn2+ When time increases, the ability BVNQ and BOS adsorbed particles Zn2+ increases, the absorption capacity has stabilized Zn2+ after 24 hours, then with increasing adsorption time on the adsorption capacity increases also not much So pick adsorption time to handle the Zn2+ 24h for the next survey 3.2.3.5 Determination of the material reaction BVNQ, BOS temperature 35°C (308K) 45°C (318K) Surveying the effect of temperature on the adsorption of heavy metal ions 2+ Zn conditions: concentration of Zn2+ 50 mg/L pH = 6, adsorption time 24 hours at the temperature: the temperature 35 °C (308 K) 45°C (318 K) Table 3.4 Results calculated reaction temperature heat 35°C (308 K) and 45 °C (318 K) beads of materials BVNQ, BOS ∆H0 ∆S0 (kJ/mol) (kJ/molK (kJ/mol) (kJ/mol) ) BVNQ 63,26 0,211 -1,768 -3,879 BOS 73,64 0,247 -2,559 -5,033 Comment: - For seed BVNQ: Value ∆Ho> 0, ∆So> 0, ∆Go< and increases with increasing temperature ∆Go shows Zn2+ adsorption of materials is endothermic and self happen, value /∆H0/= 63,26 kJ/mol so the process of adsorption of Zn2+ material is chemically adsorbed - For seed BOS: Value ∆Ho> 0, ∆So> 0, ∆Go< and increases with increasing temperature ∆Go shows Zn2+ adsorption of materials is endothermic and self happen, value /∆H0/= 73,64 kJ/mol so the process of adsorption of Zn2+ material is chemically adsorbed 3.2.4 Experimental results ion adsorption of As(V) in aqueous solution of seed BVNQ, BOS 17 17 SEM Figure analysis and EDS-FESEM for county BVNQ materials, BOS after conducting experiments adsorption of As(V) with an initial concentration of mg/L Laboratory results determined ion adsorption capacity of As (V) of particles BVNQ, BOS showed adsorption capacity adsorbent Qe and% of particles larger BVNQ materials (0,197 mg/g, 98.50%), BOS (0188mg/g, 94,00%), ion adsorption capacity of As(V) in aqueous high Results EDSFESEM spectral analysis also showed the presence of elements of As(V) with an atomic fraction is ~ 2% in materials BVNQ, BOS 2% in the county after the adsorption experiments 3.2.4.1 Influence of particle mass BVNQ adsorption, absorption capacity BOS to As(V) Conducting experiments at Research Department, Institute of Geology Institute of Science and Technology of Vietnam obtained results: the quantity of material and BOS BVNQ increased adsorption capacity of As(V) of the material tangKhi rate volume reached 20 g/L, the adsorption percentage change is negligible 3.2.4.2 Effect of pH on adsorption capacity of As(V) of the material particles BVNQ, BOS Through the survey results of pH affects the ability particles adsorbed BVNQ and BOS As shows, with a pH in the range of 4-5 the adsorption capacity of As (V) above, when pH increases, the absorption capacity As(V) decrease 3.2.4.3 Effect of concentration of As(V) to the adsorption capacity of As(V) of particles BVNQ, BOS From the experimental results found that the As(V) ions adsorbed on the particle BVNQ, BOS obey Freundlich isotherm and Langmuir isotherm quite good Freundlich equation BVNQ - As(V): y = = 0,3998x - 0,1894 R² = 0,9814 Freundlich equation BOS - As(V): y = 0,583x – 0,7313 R² = 0,9749 or BVNQ- As(V): q = 0.646C0.3998 với n = 2.50 ( q = mg/mg; Ce = mg/L) or BOS- As(V): q = 0,185C0.583 với n = 1,71 ( q = mg/mg; Ce = mg/L) Thus the adsorption of As(V) on county BVNQ, BOS in concentrations studied almost obey Freundlich adsorption isotherm The value Langmuir, qmax (mg/mg), and KL (L/g) is calculated as follows: BVNQ: qmax = 1,33 mg/g; KL = 2,73 L/g BOS: qmax = 0,91 mg/g; KL = 0,33 L/g Langmuir isotherm equation of material particles: 18 18 BVNQ: q q As As 2,73.Ce As BVNQ = 1,33 + 2,73.Ce As 0,33.Ce As BOS = 0,91 + 0,33.Ce As BOS: In this study, the maximum adsorption capacity of As(V) on BVNQ was 1,33 mg/g equivalent to 0,006 mmol/g and above BOS is 0,91 mg/g equivalent to 0,004 mmol/g On the other hand the value and significance of the constant n in Freundlich equation are not really clear, but based on the results of the research, could remark that the adsorption of As(V) on BVNQ and BOS favorable for the value n > But n the greater the adsorption affinity between adsorption and ion center absorbed decreases, resulting in adsorption of As(V) n = 2,5 of the subject, BVNQ and nBOS = 1,71 particles with an adsorbed BVNQ A(V) higher than BOS 3.5.4 Influence of time to adsorb As(V) Through survey results influence of time shows, as time increases, the ability to adsorb particles BOS BVNQ and As(V) increases, the absorption capacity of As(V) achieved stable after 24 hours, then the increase adsorption time on adsorption capacity increases also not much So, time to treatment adsorption of As(V) is 24 hours for the next survey 3.5.5 Determination of the material reaction BVNQ, BOS temperature 35°C (308 K) 45°C (318K) Surveying the effect of temperature on the adsorption of As(V) in the following conditions: concentration of Zn2+ 2mg/L pH = 6, adsorption time 24 hours at the temperature: the temperature 35°C (308K) 45°C (318K) we obtain the following result table: Table 3.5 Results calculated reaction temperature heat 35°C (308K) and 45°C (318K) beads of materials BVNQ, BOS ∆H0 ∆S0 (kJ/mol) (kJ/mol) (kJ/mol) (kJ/molK) BVNQ -59.84 -0.188 -1.985 -0.107 BOS 52.63 0.174 -0.960 -2.701 Comment: 19 19 - For seed BVNQ: Value ∆Ho< 0, ∆So< 0, ∆Go< and increases with increasing temperature ∆Go shows the adsorption of As(V) of the material is endothermic and takes place spontaneously the value /∆Ho/ = 59,84 kJ/mol, so adsorption of As(V) of the material is chemically adsorbed - For county BOS: Value ∆Ho> 0, ∆So> 0, ∆Go< and the giam ∆Go when temperature rise shows the course of adsorption of As (V) of the material is endothermic and takes place spontaneously the value /∆Ho/ = 52,63 kJ/mol, so adsorption of As(V) of the material is chemically adsorbed 3.2.5 Synthesis and discussion of the results of empirical research Table 3.6: Summary of research findings adsorption isotherm of ion Cd2+, Cu2+, Zn2+ As(V) on BVNQ, BOS Cd2+ Materia l BVNQ n 0,97 qmax 21,88 BOS 1,2 21,55 Cu2+ KL 0,05 0,11 Zn2+ n 1,12 qmax KL 27,86 0,0035 0,94 26,73 0,002 n 1,3 1,3 qmax 20,04 KL 0,004 28,09 0,0024 As(V) n 2,5 1,7 qmax 1,33 KL 2,73 0,91 0,33 20 20 From the data on capacity adsorbed Langmuir, found capacity adsorption maxima (qmax) of BVNQ larger BOS in case adsorbed metal ions Cd2+, Cu2+, As(V) but qmax again smaller than in the case of Zn 2+ ion adsorption which can predict that although both BVNQ and BOS are many adsorption center BVNQ however there was an increase over BOS adsorption center And coverage of the absorbed substances very small compared to the particle surface BVNQ, BOS is therefore adsorbed monolayer Based on the results of isothermal Freundlich might remark that both county BVNQ, BOS adsorbed ions Cd2+, Cu2+, Zn2+ As(V) is n small and largely n> or approximately equal to due which adsorption occurs smoothly On the other hand based on the R value (the constant in the equation Langmuir) found that different metal ions will adsorb on different center (by value different KL) Thus the adsorption of ions Cd2+, Cu2+, Zn2+ As(V) on BVNQ, BOS criteria fit both model Langmuir and Freundlich should be able to understand that the adsorption of ions Cd2+, Cu2+, Zn2+ As(V) on BVNQ, BOS obey the Langmuir and Freundlich model is reasonable and quite coincide with reality Heat the reaction of materials BVNQ, BOSS 35 0C temperature (308K) and 450C (318K) Counts ∆Go