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Sorption studies of Cu(II) on gooseberry fruit ( emblica of fi cinalis ) and its removal

from electroplating wastewater

Rifaqat Ali Khan Rao ? , Shaista Ikram

Environmental Research Laboratory, Department of Applied Chemistry, Faculty of Engineering and Technology, Aligarh Muslim University, Aligarh 202002 (U.P.) India

Article info

Article history:

Received 4 December 2010

Received in revised form 10 April 2011

Accepted 27 April 2011

Available online 28 May 2011

Keywords:

Sorption

Cu(II)

Equilibrium isotherms

Kinetics

Thermodynamics

Abstract

The sorption of Cu(II) onto waste residue left after extraction of juice from Indian gooseberry (Amla) fruit

(Emblica officinalis ) was studied. Equilibrium isotherms, kinetic data and thermodynamic parameters have been

evaluated. Equilibrium data agreed well with Langmuir, Freundlich, Temkin and Dubinin –Radushkevich (D–R)

isotherm models. The kinetic data followed pseudo-second-order model and it was found that intra-particle

diffusion was not the sole rate-controlling factor. Gibbs free energy showed spontaneous process for all

interactions. The breakthrough and exhaustive capacities were found to be 4.0 and 24.0 mg/g respectively.

Emblica officinalis was shown to be a promising sorbent for Cu(II) removal from aqueous solutions. The practical

utility of the sorbent has been demonstrated by achieving 97.60% removal of Cu(II) from electroplating

wastewater by column process.

? 2011 Elsevier B.V. All rights reserved.

1.Introduction

One of the cardinal demerits of rapid industrialization is the

manifold increase in industries ranging from metalfinishing, electro-

plating, plastics and polymer manufacturing, pigments, textile, pulp

and paper, mining etc. giving rise to air, soil and water pollution [1 –3] .

The uncontrolled discharge of ef fluent from these industrial units

pollutes different aquatic bodies posing serious health and environ-

mental problems [4]. Among the wide variety of toxic compounds

found in wastewater, heavy metals are of utmost signi ficance because

of their high toxicity at ultra trace concentrations and persistent

nature [5]. Due to their non-biodegradability they tend to accumulate

in the vital organs of living organisms causing various diseases and

long term disorders, as well as deleterious ecological effects [6]. Hence

there has been a continuous quest to develop novel process and

techniques over the years to remove these deleterious heavy metal

io n s p resen t in in du s tr ia l wa s te wa t er s . A p ra c ti c a l p ro b le m in

removing out these heavy metal ions from wastewater is their

appreciable solubility in aqueous systems and hence their removal by

ordinary physical and chemical means is very difficult and ineffective

[7].

There is a variety of conventional treatment techniques employed

o remove heavy metals from wastewaters before their final discharge

n to the envi ronm ent. Mos t notab le among the se are c hemic al

recipitation, evaporation, electro deposition, ion exchange, adsorp-

on, membrane separation, coagulation etc. [8]. However, these techniques suffer from either one drawback or the other. Some of

these techniques are either too costly or they are ineffective in terms

of removal of heavy metal ions present at low concentration. Among

all these enlisted conventional techniques, removal of heavy metal

ions by adsorption is found to be highly effective, inexpensive and

ease of operation [9]. The use of sorbent for removing and recovering

heavy metals from contaminated industrial effluents has emerged as a

potential alternative method to the conventional ones [10] . In recent

years, the process involving the removal of heavy metal ions by

passive binding with the dead or living biomass, emerges as one of the

potentially cost-effective techniques[11] . Sorption contains many

passive processes of accumulation such as sorption, ion exchange,

covalent bonding, complexation, chelation, and micro-precipitation

processes. Several studies have shown that the method is effective to

remove heavy metals from industrial wastewaters and could be

employed most effectively in concentration range below 100 mg/L

[12,13].

Cu(II) is one of the most common heavy metals which is essential

for hum an bei ngs, a ni mal s an d m ic ro -or g ani s ms but e xcessi ve of

C u ( I I ) produces many toxic and harmful effects on the living organism

[14] . Acute Cu(II) poisoning may lead to hemolysis, liver and kidney

damage, and influenza syndrome while its local effects give rise to

irritation of upper respiratory tract, gastrointestinal disturbance with

vomiting, and diarrhea and a form of contact dermatitis [15] .The

seriousness of the Cu(II) toxicity and its bioaccumulation property

have led the United States Environmental Protection Agency (USEPA)

to recommend a t hreshold conce ntrat ion l i mi t, de fi ned a s t he

m a x i m um c on ta m i n a n t l ev e l ( MC L ) o f 1. 3 m g /L[16] . C u( I I ) m a in ly

or ig in a te s f r om d ye in g , p a p e r, p e tr ol eu m , c op p er / b ra s s - pl a t in g a n d copp er-ammonium r ayon indus tr ial wastewaters. S amples of wastewater co llected from co pper c lean ing, co pper plating an d

metal p ro cessing industries, have s hown Cu(II ) c oncentrations up t o

100 –120 mg/L which are a bout 1 00 to 200 times gr e a t er than its MC L

[15] . H ence there is a dire need to develop econo mic a ll y feasible and

effective sorbent wh ich c an remo ve Cu(II) thus s aving the life o f

people engaged i n these abov e mentioned industries. Removal o f

heavy metal io ns from the a qu eou s streams b y a gricultural wa ste

ma terials i s a n i nn ovative a nd promising technology . The effi ciency

of the wa ste material depends upon t he capacity, affi nity, and

specifi c it y , i nc l udi n g i t s p h y si co - c hem i ca l n atu re . In r e cen t ye a r s,

bio log ica l mat e ria ls i ncludin g ag ri cult ural and i ndust ri a l so li d

wastes are b ein g used as sor bents for the removal o f heavy metals

[17] . This paper describes the sor ption abil ity o f I ndian go o seberry

( A ml a) frui t ( abb re v i a ted a s EO ) f or t he removal o f C u (I I) f rom

aqueous s olu tio n.

2.Materials and methods

2.1. Sorbent

EO belongs to the familyPhyllanthaceae . The tree is medium sized

reaching 8 –18 m in height and found natively in India. Amla fruit is

used as valuable ingredient in various Ayurvedic medicines in India

and abroad. It contains on an average, moisture 81.8%, protein 0.5%, fat

0.1%, minerals 0.5%, fibers 3.4% and carbohydrates 13.7% per 100 g of

edible part. Its minerals and vitamin contents include calcium, iron,

phosphorous, carotene, thiamine, riboflavin, niacin and vitamin C. The

fruit juice of EO can be extracted and used in many pharmaceutical

industries for the formulation of various drugs. The waste material left

after extraction was used to explore its sorption properties.

2.2. Treatment of sorbent

The waste material left after extraction of juice from EO was

collected from local medicine manufacturing unit at Aligarh. The

biomass was rinsed with water and dried in an oven at 60 °C. The

dried mass was sieved to obtain particle size of 100–300 μm. The

biomass was washed several times again with double distilled water

(DDW), and subsequently dried again in an oven at 60 °C and then

stored in an airtight container in order to avoid moisture and used as

such for the sorption studies.

2.3. Sorbate solution

Stock solution of Cu(II) was prepared (1000 mg/L) by dissolving

the desired quantity of copper nitrate trihydrate (AR grade) in DDW.

The stock solution was diluted to obtain desired Cu(II) concentration.

Solutions of other metal ions were prepared by dissolving their

chlorides or nitrates.

2.4. Determination of active sites

Active sites present on the surface of the sorbent were determined

by acid–base titration method [18] at room temperature (30 °C).

2.5. Sorption studies

Sorption studies were carried out by batch process. 0.5 g sorbent

was placed in a conical flask in which 50 mL solution of metal ion of

desired concentration was added and the mixture was shaken in

shaker. The mixture was then filtered and fi nal concentration of metal

ion was determined in the filtrate by atomic adsorption spectropho-

tometer (AAS) (GBC 902). The amount of metal ions sorbed was

calculated by subtracting final concentration from initial concentra-

tion. All the experiments were carried out in triplicate and mean

concentration was calculated by averaging them. The percent sorptionof sorbate and equilibrium sorption capacity (q

e

), were calculated

using the following relationships.

% Sorption = C

o

– C

e

eT= C

o

×100 e1T

Sorption capacity q

e

eT mg= g eT=Co

–C

e

eT×V= W e2T

whe re , Co

is in it ia l c on c ent ra t ion of so rb at e ( mg/ L ) , C

e

is th e

equilibrium sorbate concentration (mg/L), V is the volume of the

solution (L) and W is the mass of the sorbent (g).

2.6. Effect of pH

The experiment was performed by taking 100 mL of Cu(II) solution

in a beaker and the desired pH of solution was adjusted by adding

either 0.1 N HCl or NaOH solutions. 50 mL of this solution was taken in

a conical flask and treated with 0.5 g of sorbent and after equilibrium,

the final concentration of Cu(II) was determined.

2.7. Effect of contact time

A series of 250 mL conical fl asks, each having 0.5 g sorbent and

50 mL solution (of known metal concentration) were shaken in

temperature controlled shaker incubator at 120 rpm and at the pre

determined intervals (1, 2, 3, 5, 10, 15, 30, 60, 120, 1440 min). The

solution from the speci fi edflask was taken out and the concentration

of Cu(II) was determined by AAS. The amount of Cu(II) sorbed in each

case was then determined as described earlier.

2.8. Effect of concentration and temperature

The effect of concentration on sorption of Cu(II) was investigated

with initial Cu(II) concentrations of 10, 20, 30, 40, 50, 80, 100, and

150 mg/L. The experiments were performed by adding 50 mL solution of each concentration to eight different 250 mLflasks each containing

0.5 g of sorbent. Theflasks were shaken at 120 rpm and 30 °C for 3 h

and the final concentration of Cu(II) was determined by AAS. The

same experiment was repeated at 40 and 50 °C.

Fig. 1. A. Emblica of ficinalis (native). B. Cu (II) adsorbed Emblica of fi cinalis .

Fig. 2. IR spectra of Emblica of ficinalis : (a) before sorption; (b) after Cu(II) sorption.

2.9. Determination of point of zero charge

The pH at point of zero charge (pHpzc) of the sorbent was

determined by the solid addition method[19] . To a series of 250 mL

Stoppard conical fl asks, 40 mL of 0.01 N KNO3was transferred. Theinitial pH (pHi) values of the solutions were roughly adjusted between 2 and 10 by adding either 0.1 N HCl or NaOH solution. The total volume of the solution in each flask was made 50 mL by adding KNO3solution of the same strength. The pHiof the solution was thenaccurately noted and 0.5 g of sorbent was added to eachflask, and theflask was securely capped immediately. The suspensions were then manually shaken and allowed to equilibrate for 24 h with intermittentmanual shaking. Thefinal pH (pHf) values of the supernatant liquidwere no t ed. The difference betwe en the init ial and fi nal pH( ΔpH = pHi ?pHf) was plotted against pHi. The point of intersectionof the resulting curve with the abscissa, at which ΔpH = 0, gave the pH PZC. The same experiment was repeated with DDW.

2.10. Quality assurance and quality control

To make sure that no metal ions were released to the solution from

the sorbent, an equilibrium test was performed using sorbent EO in

DDW. For assuring quality in the sorption studies DDW blank was

included in the experiment. To ensure accuracy after each set of five

samples, a standard was run to ensure that drift had not occurred.

The samples were analyzed in triplicate by AAS. Average of the

values obtained gives mean concentration of the sample. In order to

compare quantitatively the applicability of different models in fitt in g to

data, the percent deviation (P), was calculated. It is generally accepted

that when P value is less than 5, the fit is considered to be excellent [20] .

2.11. Breakthrough capacity

0.5 g of sorbent was taken in a glass column (0.6 cm internal

diameter) with glass wool support. 500 m L of Cu(II) solution of 50 m g/L

initial concentration (Co) was then passed through the column with a

flow rate of 1 mL/min. The effluent was collected initially in 10 mL and

then 50 mL fractions and the concentration of Cu(II) (Ce) was then

determined in each fraction with the help of AAS. The breakthrough

curve was obtained by plotting Ce/Co

versus volume of the effluent.

2.12. Desorption studies

Desorption studies were carried out by batch as well as column

process. In batch process desorption of Cu(II) was carried out by

treating 0.5 g of sorbent with 50 mL of Cu(II) solution (50 mg/L) in a

conical flask. The solution was fi ltered after 24 h and filtrate was

analyzed for Cu(II). The sorbent was then washed several times with

DDW to remove any excess of Cu(II). It was then treated with 50 mL of

0.1 N HCl solutions and then fi ltered after 24 h. The fi ltrate was

analyzed for Cu(II) desorbed. The same procedure was repeated with

different desorbing solutions like sodium chloride, acetic acid, sodium

sulfate, sodium hydroxide and EDTA.

Desorption studies by column process were carried out as follows.

The exhausted column (from breakthrough capacity) was washed

several times with DDW to remove excess of Cu(II) ions from the

column, then 0.1 N HCl solution was passed through the column with a

flow rate of 1 mL/min. The Cu(II) ions eluted were collected in 10 mL

fractions and the amount of Cu(II) ions desorbed in each fraction was

determined by AAS.

2.1

3. Treatment of electroplating wastewater

Electroplating wastewater was collected from a local electroplating

plant in Aligarh city. The pH of the wastewater was noted. It wasfilt er ed to remove suspended matter and diluted and then analyzed for various

parameters. Heavy metal was determined by AAS. 50 mL of the diluted

wastewater was treated with 0.5 g sorbent by batch as well as column

process. In column process wastewater was passed through the column

with a flow rate of 1 mL/min. The effluent collected was again analyzed

and amount of metal ions removed were determined.

2.14. Regeneration and recycling studies

0.5 g of sorbent was taken in a glass column (0.6 cm diameter)

with glass wool support. 50 mL of Cu(II) solution of 50 mg/L initial

concentration (Co) was then passed through the column w ith aflow

rate of 1 mL/min.The ef fluent was collected and the amount of Cu(II)

was then determined as usual. The sorbent was washed several times

with DDW to remove any excess of Cu(II) ions and then 50 mL of 0.1 N

HCl was passed with the same flow rate. The ef fluent was collected in

10 mL fraction and amount of Cu(II) desorbed in each fraction was

then determined. The sorbent was then washed several times with

DDW to remove any excess of HCl and again treated with 50 mL Cu(II)

solution. The same procedure was repeated several times.

3. Results and discussion

3.1. Characterization of sorbent

3.1.1. Scanning electron microscope (SEM) analysis

The SEM was used to examine the surface of the sorbent before and after sorption of Cu(II). The surface of the sorbent appeared to be

irregular and porous. The pores were prominent on the surface of

sorbent before sorption ( Fig. 1 A). After sorption of Cu(II) the pores

werefilled showing adherence of Cu(II) on the surface ( Fig. 1B).

3.1.2. Fourier transform infrared (FTIR) spectroscopy

The FTIR spectra of native and Cu(II) sorbed EO shown in Fig. 2a

and b indicated the presence of several functional groups. The peak 3438 cm? 1 in native sorbent indicates the presence of OH groups. The

peak at 2922 cm? 1

may be due to the carboxylic stretching bonds

[21] . The peak at 1643 cm? 1

may be attributed to C=C and C=O

where as peaks in the region 1506 and 1452 cm? 1

represent OH

bonds. The broad peak at 1038 cm? 1

may be attributed to the C ―OH

stretching vibrations. It has been observed that the peak of ionizable

functional groups was slightly reduced or distorted in the Cu(II)

sorbed sample of EO ( Fig. 2b) showing that Cu(II) was sorbed at these

functional groups.

3.3. Effect of contact time and initial concentration

Sorption of Cu(II) on EO at various initial concentrations was carried out at different intervals of time. The maximum uptake of Cu(II)

at equilibrium was found to be 1.7, 3.1 and 5.8 mg/g at 20, 40 and

80 mg/L initial Cu(II) concentrations respectively. The extent of

sorption increased rapidly in the initial stages and then became slow

at later stages till the equilibrium was attained. Equilibrium time for

sorption of Cu(II) at concentrations 20, 40 and 80 mg/L was found

to be 15, 30 and 60 min. showing that equilibrium time depends

upon the initial concentration of Cu(II) (Fig. 3). The increase in initial

concentration of Cu(II) ions resulted an increase in the sorption

capacity. This is a usual phenomenon observed on various sorbents

since transfer of metal ions from bulk to the surface of the sorbent

increases with increase in concentration of metal ions. This is the basic

p rop er ty of th e s or ben t t o be u tiliz ed f or t he re mo va l o f me ta l i on s f ro m

solution.

3.4. Effect of pH

Fig. 4 indicates that sorption of Cu(II) on EO was strongly pH

dependent. The%sorption was minimum (48%) at pH 2 and reached to

maximum when pH was increased to 3. The sorption of Cu(II) with

respect to pH can be explained by considering the surface charge on

the sorbent and the speciation of Cu(II). The minimum sorption at pH

2 (excess of H+ions) was due to the fact that the surface of sorbent

became positively charged because H+ ions compete with Cu(II) ions

and did not favor the sorption of positively charged Cu2+

because of

the electrostatic repulsion. The sorption of H+

ions resulted in the

protonation of various functional groups present on the surface of the

sorbent decreasing the negatively charged surface sites. However,

when pH was increased to 3, the acidic sites were deprotonated and

attractions of positively charged Cu(II) ions increased. Cu(II) exists as

Cu2+ at pH 3 hence it can be concluded that maximum amount of

copper was sorbed in the form of Cu2+

ions up to pH 3. Above pH 3

sorption increased very slowly due to the formation of other Cu(II)

species like Cu(OH)+

(pH 4 –5) and Cu(OH)2 (pH N 6)[22] . The pH of

the solution also infl uenced the surface charge of the sorbent. The

pH pzc of EO in DDW was found to be 6 (Fig. 5) showing that surface is

positively charged below pH 6. Therefore, at high pH value (above 6) Cu(II) species mainly present as Cu(OH)+and Cu(OH)2

were sorbed (due to micro precipitation). The shifting of pH pzc towards lower pH va lu e (Fi g. 5) in presence of electrolyte (0.01 N KNO3) indicated that

sorption of Cu(II) ions was specific [23] . The effect of electrolyte on the

sorption of Cu(II) is also shown in Fig. 4. The sorption of Cu(II) decreased

appreciably in presence of electrolyte (0.1 N KNO3)atpHN 3.

3.5. Sorption isotherms

The data obtained from studies were tested for their applicability

to the isotherm models namely Langmuir, Freundlich, Temkin and

Dubinin–Radushkevich (D–R) isotherm. The dependence of 1/qe on

1/Ce with varying concentration of Cu(II) ions at different tempera-

ture was observed to be linear indicating the applicability of the

Langmuir isotherm. The values of Langmuir isothermconstants b and

qm were calculated from the slope and intercept of the linear plots of

1/Ce vs. 1/qe [24]. The values of dimensionless constant separation

factor (RL) were plotted at different initial Cu(II) concentrations and

temperatures (Fig. 6). RL values were found to be in the range 0–1in

all experimental systems, which con?rmed the favorable uptake of

Cu(II). The monolayer sorption capacity (qm) of EO was compared

with various agricultural byproducts studied earlier [15,25–35].EO

represented higher Cu(II) sorption capacity than 11 from 14 sorbents,

re?ecting a promising future for EO utilization in Cu(II) removal from

aqueous solution. The values of Freundlich isotherm constants Kf and

n were calculated from the intercept and slope of the freundlich plots

at different temperatures. When ‘n’approached zero, the surface site

heterogeneity increased. The values of nN1(Table 2) at all temperatures

indicated favorable sorption of Cu(II) [36]. The values of Temkin

constants A and B related to sorption potential and heat of sorption

respectively were calculated from the slope and intercept of the plot of

qe versus lnCe. To distinguish between the physical and chemical

sorption, Dubinin–Radushkevich (D–R) isotherm based on the hetero-

geneous nature of the sorbent surface was applied. The values of qm

(maximum sorption capacity) and constant βwere calculated from the

intercept and slope of the D–R linear plots of lnqm vs. ε 2

(Polanyi potential). The constant βgave an idea about the mean free energy (E)

(kJ/mol) of sorption molecule of the sorbate when it was transferred to

the surface of the solid from in?nity and can be calculated using the

following relationship [37].

E=1= 2βeT1= 2e3T

The fitting procedure was performed using R software version 2.10.1 (2009-12-14). The fitness of the data, correlation coef ficients (R2), error analysis (residual standard error (RSE)) and P-values were calculated. The values of constants obtained from different models werefitted and corresponding q e values were calculated from each model (qecal ). The values of q e found experimentally (q exp) were compared with ecalusing chi-square test (χ2). The chi-square test values were calculated from the following relation

χ& =∑q eexp –q ecal hi2 = qe cal e4T

The sum of square error (SSE) values were calculated using the following relation

SSE = ∑q eexp –q ecal 2 = N 1 = 2 e5T

where, N is the number of observations. The lower the value ofχ2 and

SSE the better is the fit. It was clear fromTable 2that r 2

values for all the

isotherms were higher (except D –R isotherm at 50 °C), indicating the

applicability of these isotherms. However, Langmuir and Temkin

isotherms were better obeyed by the system as indicated by their

le ast χ2 and SSE values. These data also indicated that Freundlich

isotherm was obeyed at 40 °C. D–R isotherm was obeyed at 30 and 40 °C

but at 50 °C the data become insigni ficant because of the higher P-value

(P-value N 0.05).

3.6. Sorption kinetics

In order to further explore the sorption mechanism of Cu(II) and

rate controlling steps, a kinetic investigation was conducted. Pseudo-

first-order, Pseudo-second-order and intra-particle diffusion kinetic

models have been used for testing experimental data. The Pseudo-

first-order rate equation of Lagergren [38] was widely used for the

sorption of liquid/solid system on the basis of solid capacity. The linear

form of Lagergren equation is generally expressed as

log q e–qt

eT=?K1

= 2: 303 eT×teT+ logq e e6T

wh er e , qe ( mg/g) a nd q t (m g/g) ar e th e sorption c apa ci ties at eq uilibriu m

an d a t tim e t ( min) res pectively. K1(min?1) is the rate constant of

Pseudo- first-order sorption process. The values of k1 we re determin ed

by plotting log(qe–qt)versustandlistedin Table 3. The values of qe

calculated from the model (qecal) differed from t he experimen tal values

(qeexp) implying that the sorption process did not follow the Pseudo-

first-order sorption rate equation.Pseudo-second-order sorption rate equation [39] may be ex- pressed as

t =qt=1= K2q2e +1= qeeT×t e7T

K2(g/mg/min) is the pseudo-second-order sorption rate constant.

Plots of t/qtversus t for all experimental concentrations gave straight

lines ( Fig. 7), and values of qeand K2 were calculated from the slope

and intercept respectively. The initial sorption rate, h (mg/g/min) is

expressed as [40] .

h=K2q2ee8T

The values of qe,h,K2and r2 are listed in Table 3. The values of

correlation c oef fi ci en ts (r2)werefound tobe verycloseto 1con firming the applicability of the Pseudo-second-order equation. Inaddition, the qe exp

values were very close to qe cal from the model

indicating the better applicability of this model. It can also be seen

from Table 3 that with an increase in initial metal concentration, the

rate constant of sorption (K2) decreased. A similar observation was also reported by earlier researchers[41] .The kinetic data were analyzed using intra-particle diffusion

model to elucidate the diffusion mechanism[42] .

qt=Kid×t1= 2+I e9T

where Kid(mg/g/min) is the intra-particle diffusion rate constant and I

(mg/g) is another constant that gives an idea about the thickness of a

boundary layer, qt is the amount of Cu(II) sorbed (mg/g) at time t (min).

Pl ots of qt ve rs us t 1/ 2 are shown in Fig. 8for different concentrations. The

deviation in the plots from origin for all concentrations indicated that

pore diffusion was not the only sole rate-controlling factor but some

other processes likefilm diffusion were also involved in the sorption

Process.

3.7. Sorption thermodynamics

Temperatures used in this study were 30, 40 and 50 °C. The

equilibrium constant at different temperatures can be calculated with

the following relation.

Kc=CAc=Cee10T

Kc is the equilibrium constant. C

Ac(mg/L) is the amount of Cu(II)sorbed on solid at equilibrium and Ce (mg/L) is the equilibrium concentration of Cu(II) in the solution, respectively. The values of free

energy change (ΔG°) at different temperatures were calculated from

the following relation

ΔG°=?RTlnKce11T

where R is gas constant and T is absolute temperature. van't Hoff

equation was applied to calculate the enthalpy change (ΔH°) and

entropy change ( ΔS°).

lnKc =ΔS°= R –ΔH °=R×1= T eT e12T

ΔS°and ΔH°can be calculated from the intercept and slope of the

linear plot of lnKc

versus 1/T. These values are reported in Table 4. The

negative value of ΔG°indicated the spontaneous nature of the

sorption.ΔG°value was more negative with increase in temperature.

The positive value of ΔH°implied that the sorption phenomenon was

endothermic. The positive value of ΔS°suggested increased random-

ness at adsorbate –adsorbent interface. The magnitude of Ea indicated

that the sorption is chemical in nature.

3.8. Sorption mechanism

In order to investigate themechanism of Cu(II) sorption by EO, the

release of alkali metals (Na+ and K+) and alkaline earthmetal (Ca2+)

present in the sorbent was determined. The released concentrations

of Na+,K+ and Ca2+ during the sorption process were calculated by

subtracting their amount released by washing with DDW (used as

control) from the amount released during acidi?cation of EO with

0.1 N HCl. The total amount of cations released were 0.07 meq/g

(comprise of Ca2+ and Na+ ions) while no K+ was released in either

case. It has been suggested that the total cationic contents can be

considered as ameasure of the approximate cation-exchange capacity

(CEC) of the sorbent [43].

The amount of Na+,K+ and Ca2+ released during the sorption of

Cu(II) was also determined in the supernatant liquid (Table 5). These

results showed that 0.0634 meq of Cu(II) was sorbed and a sum of

0.042 meq Na+ and Ca2+ were released indicating that 0.042 meq

removal of Cu(II) (66.25%) per g of sorbent was by ion-exchange

mechanism with Na+ and Ca2+ therefore it may be concluded that

sorption of Cu(II) occurred mainly through ion-exchange mechanism

involving replacement of Na+ and Ca2+ ions. A similar type of

mechanism has been suggested for mango peel waste [44]. The involvement of ion-exchange process during the sorption of Cu(II)

was also con?rmed by Cu(II) desorption with 0.1 N HCl. About 80% Cu(II) was released by means of exchange of H+ ions.

3.9. Breakthrough capacity

The breakthrough curve (Fig. 9) showed that 40 mL of Cu(II) solution (corresponding to 2.0 mg Cu(II)) could be passed through the column (containing 0.5 g sorbent) without detecting Cu(II) in the

ef?uent. The breakthrough and exhaustive capacities were deter- mined as 4 and 24 mg/g, respectively.

3.10. Desorption studies

In order to make the sorption process more economical, it is important to desorb metal ions from the spent sorbent. Desorption studies were carried out by batch process using NaCl, CH3COOH, EDTA, Na2SO4 and HCl solutions. Desorption of Cu(II) with NaCl, CH3COOH or Na2SO4 was negligible showing that Cu(II) was strongly sorbed. However, N80% desorption could be achieved with 0.1 N HCl. Desorption by column process was carried out by passing 0.1 N HCl through the column saturated with Cu(II) ions (from breakthrough capacity experiment) containing 1.83 mg sorbed Cu(II). Fig. 10 showed that desorption of Cu(II) was rapid and 1.41 mg of Cu(II) (77%) was desorbed within 30 mL of ef?uent.

3.11. Removal of Cu(II) from electroplating wastewater

The applicability of the sorbent was demonstrated by removing

Cu(II) from electroplating wastewater. The analysis of electroplating wastewater is shown in Table 6. The results reported in Table 7 showed that 65% removal of Cu(II) can be achieved by batch process and 97.60% by column process.

3.12. Regeneration studies

For potential practical application, it is important to examine the possibility of desorbing the metal ions from the sorbent for its reuse [44]. 0.1 N HCl was used in this study as a regenerating agent. The results showed slight increase in the sorption of Cu(II) from 98 to 100% in the fourth cycle (Fig. 11). This increase in the sorptionmay be due to the activation of some more surface active sites present on the sorbent surface when it came in contactwith 0.1 N HCl during elution. The recovery of Cu(II) was decreased from 99 to 56.77% in seventh consecutive cycle (Fig. 11). These results showed promising regen- eration potential of the EO. This property of EO may be utilized by small scale commercial units to remove Cu(II) from their discharging

ef?uents in an economical and ef?cient way.

4. Conclusions

The experimental data showed maximum sorption of Cu(II) at

pH 4. Addition of electrolyte in the solution hindered the sorption of

Cu(II) to some extent. The addition of electrolyte also affected the pHpzc. A shift in the pHpzc towards lower pH value indicated speci?c

sorption of Cu(II) ions. The positive value of ΔH°indicated that

sorption increases with increase in temperature. Higher value of E

showed that sorption is endothermic and chemical in nature. The

sorption kinetics followed the pseudo-second-order kineticmodel. On

the basis of intra-particle diffusion values it is concluded that intra-

particle diffusion is not the only rate controlling factor. The Langmuir

and Temkin models yielded a much better ?t than Freundlich model.

The maximum monolayer sorption capacity was found to be 5.2, 5.7,

and 9.5 mg/g at 30, 40, and 50 °C respectively. The RL values showed

favorable sorption of Cu(II). 97.60% removal of Cu(II) is possible from

electroplating wastewater at pH 4.2 by column process. Regeneration

studies showed that EO can be effectively utilized for the removal of

Cu(II) ion up to seven cycles.

Acknowledgements

Authors thank the Chairman, Department of Applied Chemistry,

Z.H. College of Engineering and Technology, AligarhMuslimUniversity,

Aligarh (India), for providing research facilities.

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常见的国际品牌英文名称

常见的国际品牌英文名称 Belle百丽女鞋,单词是"美女"的意思,很不错的鞋名 Badger贝吉獾,来自美国的一个保养品牌,badger本来就是獾的意 思,翻译很到位,也很可爱 Biotherm碧欧泉,化妆品牌,应该是”生物热量”的意思 Burberry巴宝莉,香水卖得挺好,它的单词是"雨衣",看来它家的风衣应该是防水的才对得起这个名字 Con verse匡威,运动品牌,单词是”颠倒"的意思,大概想说匡威的出现颠覆了运动的某个理念之类的 Colgate高露洁牙膏,col是关隘的意思,gate是门,大概是把牙齿缝比做了关隘,高露洁这个门可以保护牙齿的意思吧 Canon佳能,canon这个单词就是”真作”的意思,佳能是经典真作哦Carrefour家乐福超市,是个法语词,本身的意思是"交叉路”,也有集市的意思,难怪是个超市了 Clinique倩碧,雅斯兰黛旗下的化妆品牌,来自发文,意思是”医学诊所" Esprit埃斯普利特,服饰品牌,是个法语词,"才气"的意思,个人也觉得Esprit家的衣服有才气 Eland衣恋,韩国的服饰品牌,不过它竟然是”大羚羊”的意思 Ford福特汽车,单词是"涉水"的意思,看来是制造者觉得福特汽车可以 跋山涉水那么厉害吧 Microsoft微软,就是"微小的软件",越尖端的软件造出来形状一定

越微小,就好像CPU越做越小一样,看来微软的野心倒是不小。 Nike耐克,运动品牌,"胜利女神"之意,确实它做到了最初的期望Puma彪马,运动品牌,从它的商标就知道了,一只大美洲狮 Peak匹克,运动品牌,单词是"山峰"的意思 Reebok锐步,运动品牌,单词意思是”南非的短角羚羊”,应该跑得快吧Rejoice飘柔洗发水,单词是"使人欢喜"的意思,制造商希望人们用了飘柔头发很顺很快乐哦 Safeguard舒肤佳香皂,单词是"保护、安全保卫",难怪舒肤佳要说保护家人健康 Siemens西门子家电,其实siemens就是个电学单位,中文译名就叫西门子,欧姆的倒数 STACCAT(思加图,百丽旗下的一个女鞋品牌,单词是"断音、断唱",有点莫名。 Opera娥佩兰,一个化妆品牌,opera是歌剧的意思 ONLY服饰品牌,only有”唯一"的意思,大概想表示自己设计独到吧Oracle美国的一个数据库生产公司,也是网络计算机的倡导者之一,oracle是”神的口谕”,一个典型的GRE单词 Whisper护舒宝,这个女孩子都知道啦,单词意思是"低声私语",咱女孩子自己的事情,确实是得低声细语的 Tissot天梭表,单词意思是"船舷的护索"

化学专业英语(修订版)翻译

01 THE ELEMENTS AND THE PERIODIC TABLE 01 元素和元素周期表 The number of protons in the nucleus of an atom is referred to as the atomic number, or proton number, Z. The number of electrons in an electrically neutral atom is also equal to the atomic number, Z. The total mass of an atom is determined very nearly by the total number of protons and neutrons in its nucleus. This total is called the mass number, A. The number of neutrons in an atom, the neutron number, is given by the quantity A-Z. 质子的数量在一个原子的核被称为原子序数,或质子数、周淑金、电子的数量在一个电中性原子也等于原子序数松山机场的总质量的原子做出很近的总数的质子和中子在它的核心。这个总数被称为大量胡逸舟、中子的数量在一个原子,中子数,给出了a - z的数量。 The term element refers to, a pure substance with atoms all of a single kind. T o the chemist the "kind" of atom is specified by its atomic number, since this is the property that determines its chemical behavior. At present all the atoms from Z = 1 to Z = 107 are known; there are 107 chemical elements. Each chemical element has been given a name and a distinctive symbol. For most elements the symbol is simply the abbreviated form of the English name consisting of one or two letters, for example: 这个术语是指元素,一个纯物质与原子组成一个单一的善良。在药房“客气”原子的原子数来确定它,因为它的性质是决定其化学行为。目前所有原子和Z = 1 a到Z = 107是知道的;有107种化学元素。每一种化学元素起了一个名字和独特的象征。对于大多数元素都仅仅是一个象征的英文名称缩写形式,一个或两个字母组成,例如: oxygen==O nitrogen == N neon==Ne magnesium == Mg

英文知名品牌与广告语翻译

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应用化学专业英语翻译完整篇

1 Unit5元素周期表 As our picture of the atom becomes more detailed 随着我们对原子的描述越来越详尽,我们发现我们陷入了进退两难之境。有超过100多中元素要处理,我们怎么能记的住所有的信息?有一种方法就是使用元素周期表。这个周期表包含元素的所有信息。它记录了元素中所含的质子数和电子数,它能让我们算出大多数元素的同位素的中子数。它甚至有各个元素原子的电子怎么排列。最神奇的是,周期表是在人们不知道原子中存在质子、中子和电子的情况下发明的。Not long after Dalton presented his model for atom( )在道尔顿提出他的原子模型(原子是是一个不可分割的粒子,其质量决定了它的身份)不久,化学家门开始根据原子的质量将原子列表。在制定像这些元素表时候,他们观察到在元素中的格局分布。例如,人们可以清楚的看到在具体间隔的元素有着相似的性质。在当时知道的大约60种元素中,第二个和第九个表现出相似的性质,第三个和第十个,第四个和第十一个等都具有相似的性质。 In 1869,Dmitri Ivanovich Mendeleev,a Russian chemist, 在1869年,Dmitri Ivanovich Mendeleev ,一个俄罗斯的化学家,发表了他的元素周期表。Mendeleev通过考虑原子重量和元素的某些特性的周期性准备了他的周期表。这些元素的排列顺序先是按原子质量的增加,,一些情况中, Mendeleev把稍微重写的元素放在轻的那个前面.他这样做只是为了同一列中的元素能具有相似的性质.例如,他把碲(原子质量为128)防在碘(原子质量为127)前面因为碲性质上和硫磺和硒相似, 而碘和氯和溴相似. Mendeleev left a number of gaps in his table.Instead of Mendeleev在他的周期表中留下了一些空白。他非但没有将那些空白看成是缺憾,反而大胆的预测还存在着仍未被发现的元素。更进一步,他甚至预测出那些一些缺失元素的性质出来。在接下来的几年里,随着新元素的发现,里面的许多空格都被填满。这些性质也和Mendeleev所预测的极为接近。这巨大创新的预计值导致了Mendeleev的周期表为人们所接