Study properties and mechanisms adsorption heavy metal ions on materials made from red mud

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”.. P

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

THESIS WERE COMPLETED AT THE HANOI NATIONAL UNIVERSITY OF EDUCATION

Instructors scientific studies:

1 Associate Professor Doctor Nguyen Trung Minh

2 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

2

REPORTED AND SCIENTIFIC WORKS RELATED

SCIENTIFIC JOURNALS

[1] 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+) của hạt vật liệu chế tạo từ bùn đỏ-laterit đá ong” - Tạp chí Hóa học -Viện khoa học và Công nghệ Việt Nam, T.49 số 5AB-2011 tr 9 - 14.

[2] Phạm Việt Hà, Phạm Xuân Cường, Nguyễn Trung Minh, Nguyễn Đức Chuy

(2011), “Xử lý Asen trong nước bằng hạt hấp phụ chế tạo từ bùn đỏ” Tạp chí Hóa học-Viện khoa học và Công nghệ Việt Nam, T.49 số 5AB-2011tr42 – 48

[3] Phạm Xuân Cường, Nguyễn Trung Minh, Nguyễn Đức Chuy, Nguyễn Ngọc Hà

(2013), “Nghiên cứ tổng hợp và khảo sát ảnh hưởng của khối lượng hạt vật liệu chế tạo từ bùn đỏ đến khả năng hấp phụ các kim loại nặng và Asen - Tạp chí Xúc tác và Hấp phụ T.2-N 0 4-trang 52- 58.

[4] Phạm Xuân Cường, Nguyễn Trung Minh, Nguyễn Đức Chuy, (2013), “Xử lý ô

nhiễm kim loại nặng Cadimi( Cd 2+ ) bằng hạt vật liệu chế tạo từ bùn đỏ theo phương pháp hấp phụ cột” - Tạp chí Xúc tác và Hấp phụ T.2-N 0 4-tr 46 – 51

[5] Phạm Xuân Cường, Nguyễn Trung Minh, Nguyễn Ngọc Hà, Nguyễn Đức Chuy,

(2013) ”Nghiên cứu lý thuyết cơ chế hấp phụ ion Cu 2+ trong dung dịch nước trên tâm hấp phụ Geothite của hạt vật liệu chế tạo từ bùn đỏ” Tạp chí Xúc tác và Hấp phụ T.4-N 0 1 2015-Trang 39-44.

[6] 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 Pb 2+ ”- International Conference on Sciences and Social Sciences 2013: Reaserch and Development for Sustainable Life Quality(ICSS 2013) tr 325 – 328.

[7] 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 4 International Conference on Sciences and Social Sciences 2014: Integrated Creative research for Local Development toward the ASEAN Economic Community (ICSS 2014) tr 128 – 132 [8] Phạm Xuân Cường, Nguyễn Trung Minh, Nguyễn Đức Chuy, Nguyễn Ngọc Hà

(2014) “Theoretical study of adsorption mechanisms of heavy metal Zinc (Zn 2 + ) on seed materials made from red mud”–The 6 th International Science, Social Science, Engineering and Energy Conference (I-SEEC 2014).

[9] 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 SEEC 2014)

(I-Đề tài khoa học

Phạm Xuân Cường (2013), Đề tài khoa học cấp tỉnh: “Điều tra, đánh giá hiệntrạng nhiễm bẩn kim loại nặng trên vùng đất trồng lúa khu vực cánh đồngMường Thanh tỉnh Điện Biên, đề xuất các giải pháp khắc phục” - năm 2013

3

1 Urgency of the theme

Water pollution in the world in general and Vietnam in particular is aserious problem now by their enormous harm to the environmental quality andhuman health worldwide

Heavy metals are often related to environmental pollution problems Mostheavy metals such as Pb, Hg, Cd, As, Cu, Zn, Fe, Cr, Co, Mn, Se, Mo exist inwater in the form of ions The use of natural materials, reuse of wasteenvironmental friendliness to remove heavy metals in the water to acceptablelevels 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 ofheavy metal ions adsorbed on the materials Materials from sludge particles hassolved two difficult problem that's:

- Handling of red mud waste source in the industry of mining andprocessing 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 ofenvironmental pollution treatment at present, especially in Vietnam in industrialzones, urban areas and villages

2 The aim of the thesis

Manufacture new adsorbent from waste sludge, industrial mining andprocessing of bauxite research nature and mechanism of adsorption of heavymetal ions Cd2+, Cu2+, Zn2+ and As(V) in the form of wastewater HAsO42- byactual experiments combined with modern computational theory

3 Subjects and scope of research

3.2 Scope of research

- Study the adsorption of heavy metal ions Cd2+, Cu2+, Zn2+ and As(V) inwater on materials made from red mud Bao Loc, Lam Dong province, lateriteBinh Yen, Hanoi and parts Family molten glass within the laboratory

- The theoretical study adsorption mechanisms of heavy metal ions aboveand As(V) by density-functional method

4 The significance of science and practical subjects

- Adsorbent beads made from waste sludge in industrial mining andprocessing bauxite pretty good adsorption of heavy metal ions such as Cd2+,

Cu2+, Zn2+ and As(V) in the aquatic environment The results of the thesis is thescientific basis for the calculation, selection of materials made from red mud inthe treatment of heavy metals in water in some industries

Find out the type of adsorbent efficiency of heavy metal ions Cd2+, Cu2+,

Zn2+ and As(V) in water, handle partial source of waste sludge in the extractionand processing of bauxite there was an urgent problem now and in the futurewhen Vietnam is a large aluminum manufacturing centers in the world

- Explain adsorption mechanism of heavy metal ions Cd2+, Cu2+, Zn2+ andAs(V) in water on geothite center

- The contents of the thesis shows the close relationship and supportbetween theoretical calculations and experimental

5 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 materialpolycentric adsorption, likely adsorption of heavy metal ions Cd2+, Cu2+, Zn2+

and As(V) in the environment country Adsorption of heavy metal ions onmaterials made from red mud just obey Freundlich isotherm Langmuir isothermfit follow and comply with complex mechanisms to create surfaces Theexperimental value calculated Go < 0 and -H0 = 52 - 89 kJ/mol shouldadsorption process is the adsorption of materials chemistry

- Building a model using software Geothite supporting calculations, selectthe section FeOOH(101)-(1×1×3) to calculate the most efficient structure forthe complex obtained [Cd(H2O)6]2+, [Cu(H2O)6]2+, [Zn(H2O)6]2+ và HAsO42- interactwith the surface Hydrated-FOOH(101)-(1×1×3) with the adsorption energyvalues -~E = 419-519 kJ/mol Great energy to the reaction occurred, as well asthe variation in complex structures

- Incorporates between practical experiments with theoretical calculations

to study thoroughly the nature and mechanisms of heavy metal ions adsorbed

qi = qm (K.Ci )

1 + K Ci

on the materials made from red mud Determination of adsorption mechanism

[Cd(H2O)6]2+, [Cu(H2O)6]2+, [Zn(H2O)6]2+ và HAsO42- on Goethite center of countyBVNQ adsorption, BOS complexing Hydrated- style FOOH(101)-(1×1×3) viahydrogen bonds

- Contribute to add an adsorbent material from the waste sludge ofindustrial exploitation and processing of bauxite, to handle the heavy metal ions

in water

6 The layout of the thesis

The thesis consists of 119 pages, including Opening: 5 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 andscientific works: 3 pages References 7 pages and 68 references and abroad

II CONTENT THESIS

Chapter 1: OVERVIEW DOCUMENT

The review has introduced the basic knowledge and research results related

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 particlesmade from red mud through adsorption capacity (q), q is a function of manyvariables q=f(T, P, C ) When T = const, then q = φ (C) is called adsorptionisotherm equation Now there are many adsorption isotherm equation, but appadsorption liquid phase adsorption material use one or isothermal

Langmuir or Freundlich isotherm

(qm: maximum capacity monolayer adsorption, K: constant, Pi, Ci is thepressure or the concentration of adsorbed)

Special attention overview introduction to quantum chemistry, is a scienceapplication of quantum mechanics to solve the problem of the chemical Thusthe method of quantum chemistry and computational software to become an

effective tool in the study, examined the molecular structure and mechanism ofmany chemical reactions in different conditions which is sometimes verydifficult to perform experiments or can not be performed That shows theimportance of theoretical studies using computational software modernquantum chemistry as programming language Pythonw, Gaussian, GaussView,Chemcraft, Siesta, Notepad ++

CHAPTER 2 METHODS AND EMPIRICAL RESEARCH 2.1 The research methodology

Applying the method of statistical analysis to layout mathematicalexperiments, sampling, data processing and evaluation results ensure objectiverequirements and accuracy allows for the support of some software Excel Thethesis method using an atomic absorption spectroscopy (AAS) to analyze thecontent of elements; SEM and TEM methods (scanning electron microscopyand transmitted) to determine the size and the center geothite and theirdistribution on the seed material; X-ray diffraction method (XRD) to study themineral composition in particle form study materials, their size in the samplecontent; density-functional method (DFT) to investigate the electron structure

of geothite and after adsorption systems; thereby determining the adsorptionenergy and adsorption mechanisms, thereby contributing to explain theexperimental results

2.2 The experiment

Red mud Bao Loc, Lam Dong, Binh Yen laterite, Hanoi and liquid crystaladditives are mixed according to the ratios, squeezing granulation 2,5 mmdiameter and heated at a temperature of 350 0C and time 3 hours, collected 2seeds materials BVNQ, BOS

To test the absorption capacity of the sample series BVNQ, BOS, we haveconducted experiments with group 3 ions adsorbed heavy metals copper (Cu),zinc (Zn), cadmium (Cd) and arsenic (V) in aqueous solution Influence ofparticle mass BVNQ materials, BOS to KLN ion adsorption capacity Effect of

pH on the absorption capacity of seed material KLN BVNQ, BOS, Effect ofconcentration on adsorption capacity KLN KLN, Influence of time to adsorbheavy metal, Determination of animal reactions BVNQ materials, BOStemperature 35C (308K) và 45C (318K) These experiments are adsorbedmetal single batch

Model Building Centre adsorbed by calculating the parameters structure,the kind of energy to find structurally adsorbed ion Cu2+, 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 preheatingtime 3 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 3 hours

Table 3.1: Results measured BET specific surface area of the material particles STT particles material area m Surface 2 /g

The pore volume cm 2 /g Pore size average Å

He surface area and Pore size average are two important factorsdetermining the absorption capacity of the material, from Table 3.1, notice thatthe material particles BVNQ and BOS have specific surface and the averagepore size large easy adsorbed heavy metals

Determine the mineral composition of the material particles and BOSBVNQ XRD method results in components with 35% -37% Geothite, 21% -23% Kaollinte in grains BOS, 7% -9% Geothite, Kaollinte 16% -18% in grainsBVNQ Results TEM and SEM analysis for rod-shaped goethite, tidbits ofmaterials and BOS BVNQ Including part-FESEM EDS spectrum analysisshowed there geothite Fe atoms and composition Kaolinite mainly Al atomsAdsorption would be interested Through spectroscopic analysis EDS-FESEMshowed that Al and Fe are two main components of particulate materials BVNQand BOS

The results of empirical research and theory, mechanism of ion adsorptionheavy metals and arsenic particles of material particles BVNQ, BOS

3.2 The results of experimental studies of heavy metal ion adsorption

of arsenic particles and materials BVNQ, BOS

3.2.1 Experimental results Cd 2+ ion adsorption in aqueous solution of seed BVNQ, BOS

SEM Figure analysis and EDS-FESEM for county BVNQ materials, BOSafter conducting experiments with concentrations of Cd adsorption initially105,5 mg/L Laboratory results determined ion adsorption capacity of the

county BVNQ Cd2+, BOS showed adsorption capacity Qe and% of particlesadsorbed 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-FESEMresults also showed the presence of trace elements with an atomic Cd is ~ 6% inmaterials 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 Cd 2+

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 Cd2+ of material increasesand did not change much in proportion 60 g/L even when the material volumeincreased BOS Cd2+ adsorption capacity of the material has increased

3.2.1.2 Effect of pH on the absorption capacity Cd 2+ of seed material BVNQ, BOS

pH increases, the ability to handle Cd2+ of material BVNQ also increased,county BOS notice pH = 6 is economical and best suited but not at this pH, theprocessing performance of metal ions is also highest This is also consistentbecause in fact, most of the waste water pH ~ 6 feature So we choose pH = 6for subsequent experiments

3.2.1.3 Effect of Cd 2+ ion concentration to ion adsorption capacity Cd 2+

Figure 3.1 : Freundlich isotherm adsorption Cd 2+ BVNQ county and BOS

Thus the particles adsorbed on BVNQ Cd2 +, BOS in concentrationsstudied almost obey Freundlich adsorption isotherm Based on the data (Figure3.1) 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 Cd 2+ county BVNQ and BOS

From Figure 3.2 can determine the value of KL Qmax and Cd2+ adsorptionprocess 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 Cd2+ ionadsorption in aqueous solution on material particles BVNQ and BOS obeyLangmuir isotherm equation is quite good with regression coefficient R2 =0,9661(BVNQ) and R2 = 0,9919 (BOS)

Langmuir isotherm equation of material particles:

BVNQ:

2 2

Ce q

2 BOS

0,11

21,55

1 0,11.Ce

Cd Cd

Cd

Ce q

- 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 oftenfollow Freundlich equation

- On the other hand the heavy metal ions adsorbed on the particle BVNQ,BOS also has the following characteristics:

+ The adsorbed particles without peer interaction because the distancebetween the center quite far apart: Cd2+ adsorption amount accounts for only

s S   and sBOS /S BET  1,85.100 / 59,01 3,14% 

total surface area, so if they are evenly distributed, the adsorbed particles arevery far apart

+ Materials BVNQ and BOS have more adsorption center and havedifferent energy, but Adsorption center is far away from each other, so they areless affected together (both in terms of energy and space language project,shielding geometry)

+ Because the surface coverage of the absorbed substances very smallcompared with the inherent surface of adsorbent ( 1) Hence the monolayeradsorption layer (not packed)

Thus, the adsorption Cd2+ on seed BVNQ, BOS criteria matching modelLangmuir, it can be concluded that the adsorption Cd2+ on seed BVNQ, BOSfollow both models Langmuir and Freundlich was reasonable and quitecoincide with reality

3.2.1.4 Influence of time to adsorb Cd 2+

Survey results influence the time to see, as time increases, the ability tosort Cd2+ increased, capable of Cd2+ has stabilized after 24 hours, then withincreasing time adsorbed on the adsorption capacity increased not lot Sochoose the time to handle adsorption Cd2+ is 24h for the next survey

3.2.1.5 Determination of the material reaction BVNQ, BOS in temperature 35C (308K) và 45C (318K)

Surveying the effect of temperature on the adsorption of heavy metal ions

Cd2+ in terms of: Cd2+ concentration of 50 mg/L pH = 6, adsorption time 24hours at the temperature: the temperature 35 C (308K) và 45 C (318K).Thermodynamic values, Ho, So, Go be determined through the followingequation: ∆G= ∆H -T∆S

LnKd = - ∆H + ∆S

Table 3.2 Results calculated thermal reaction at temperatures 35C (308K)

and45C (318K) of material particles BVNQ, BOS

Comment:

- For seed BVNQ: Value Ho< 0, So< 0, Go< 0 and increases withincreasing temperature Go shows Cd2+ adsorption of materials is exothermicand self happen, value /H0/= 89,57 kJ/mol, so the process of adsorption of

Cd2+ material is chemically adsorbed

- For county BOS: Value Ho< 0, So< 0, Go< 0 and increases withincreasing temperature Go shows Cd2+ adsorption of materials is exothermicand self happen, value /H0/= 61,89 (kJ/mol), so the process of adsorption of

Cd2+ material is chemically adsorbed

3.2.2 Experimental results Cu 2+ ion adsorption in aqueous solution of seed BVNQ, BOS

SEM Figure analysis and EDS-FESEM for county BVNQ materials, BOSafter conducting the Cu2+ adsorption experiments with initial concentration was69.82mg / l Laboratory results determined ion adsorption capacity of thecounty BVNQ Cu2+, BOS showed adsorption capacity adsorbent Qe and% ofparticles larger BVNQ materials (1.403 mg/g, 81,60%), BOS (1,627 mg/g,94,55 %), the ability to adsorb ions in aqueous Cu2+ high Results EDS-FESEMspectrum analyzer indicates the presence of elemental Cu with an atom fraction

is ~ 7% in materials BVNQ, BOS 3% in the county after the adsorptionexperiments

3.2.2.1 Influence of particle mass BVNQ materials, BOS to ion adsorption capacity Cu 2+

Conducting experiments at Research Department, Institute of Geology Institute of Science and Technology of Vietnam obtained results: the quantity

-of material and BOS BVNQ increase Cu2+ adsorption capacity of the materialincreases However in percentage weight of material/substance volumetricadsorption solution is 40 g/L, we achieved the highest percentage adsorption

3.2.2.2 Effect of pH on the absorption capacity of seed material Cu 2+

BVNQ, BOS

pH increases, the ability to handle Cu2+ of material BVNQ, BOS alsoincreased but we found that when pH = 6 is capable of handling Cu2+ tends tosaturation (ie graphs horizontally), so to adsorption Cu2+ ions of the material,the optimal pH = 6

3.2.2.3 Effect of Cu 2+ ion concentration to ion adsorption capacity Cu 2+

From the experimental results found that the Cu2+ ions adsorbed on the particleBVNQ, BOS obey Freundlich isotherm and Langmuir isotherm quite good

Freundlich equation BVNQ - Cu: y = 0,8921x – 1,0509 R² = 0,9851Freundlich equation BOS - Cu: y = 1,0551x – 1,5584 R² = 0,9773Thus the particles adsorbed on BVNQ Cu2+, BOS in concentrations studiedalmost obey Freundlich adsorption isotherm Can set the adsorption isothermequation for samples BVNQ-Cu, BOS-Cu

BVNQ-Cu: q = 0,088C0,8921 với n = 1,12 ( q = mg/mg; Ce = mg/L)

BOS-Cu: q = 0,027C1,0551 với n = 0,94 ( q = mg/mg; Ce = mg/L)

The value Langmuir, qmax (mg/mg), and KL (L/g) is calculated as follows:BVNQ: qmax = 27,86 mg/g; KL = 0,0035 L/g.

BOS: qmax = 26,73 mg/g; KL = 0,002 L/g

Langmuir isotherm equation of material particles:

BVNQ:

2 2

Ce q

2 BOS

0,002

26,73

1 0,002.Ce

Cu Cu

Cu

Ce q

q  BVNQ >1,04

2 maxCu (BOS)

it pointed out after activation of adsorbed Cu2+

Adsorption center BVNQ more BOS From these results we see adsorption

Cu2+ on materials BVNQ and BOS again just follow the equation isothermFreundlich (surface adsorption heterogeneous) and simultaneously complyisotherm Langmuir (with a hypothetical surface homogenous adsorption), thedata and results of the thesis is also quite consistent with the situation of a fewrecent research study published

3.2.2.4 Influence of time to adsorb Cu 2+

When time increases the likelihood county BOS BVNQ and Cu2+

adsorption increased adsorption capacity Cu2+ has stabilized after 24 hours,then with increasing adsorption time on the adsorption capacity increases alsonot much So choose the time to handle adsorption Cu2+ is 24h for the nextsurvey

3.2.2.5 Determination of the material reaction BVNQ, BOS temperature

35C (308 K) và 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 24hours 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

- For seed BVNQ: Value Ho< 0, So< 0, Go< 0 and increases withincreasing temperature Go shows Cu2+ adsorption of materials is exothermicand 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< 0 and increases withincreasing temperature Go shows Cu2+ adsorption of materials is exothermicand self happen, value /H0/= 60,54 kJ/mol so the process of adsorption of Cu2+

material is chemically adsorbed

3.2.3 Experimental results Zn 2+ ion adsorption in aqueous solution of seed BVNQ, BOS

SEM Figure analysis and EDS-FESEM for county BVNQ materials, BOSafter conducting Zn2+ adsorption experiments with initial concentrations 70,02mg/L Laboratory results determined ion adsorption capacity of the countyBVNQ Zn2+, BOS showed adsorption capacity adsorbent Qe and % of particleslarger 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 spectralanalysis also showed the presence of elemental Zn with an atomic fraction is ~3% in BVNQ materials, 30% of the particles after the end BOS adsorptionexperiments

3.2.3.1 Influence of particle mass BVNQ materials, BOS to ion adsorption capacity Zn 2+

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 Zn2+ of materialsincreased, 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 alsoincreased but we found that when pH = 7 for efficiently handling high but infact, most of the waste water has pH ~ 6 So we choose pH = 6 for subsequentexperiments

3.2.3.3 Effect of Zn 2+ ion concentration to ion adsorption capacity Zn 2+

From the experimental results found that the Zn2+ ions adsorbed on the particleBVNQ, BOS obey Freundlich isotherm and Langmuir isotherm quite good

Freundlich equation BVNQ - Zn: y = = 0,7169x – 1,1182 R² = 0,9671Freundlich equation BOS - Zn: y = 0,7528x – 1,0213 R² = 0,9567Thus the particles adsorbed on BVNQ Zn2+, BOS in concentrations studied