1MOE Key Laboratory of Space Applied Physics and Chemistry, Shaanxi Key Laboratory of Macromolecular Science & Technology, School of Science, Northwestern Polytechnical University, Xi’an, 710072, PR China
Received date: April 12, 2017; Accepted date: April 18, 2017; Published date: April 25, 2017
Citation: Batool S, Idrees M (2017) Adsorption of Copper (II) by Using Farmyard and Poultry Manure Biochar’s: Efficiency and Mechanism. J Anal Bioanal Tech 8: 361. doi: 10.4172/2155-9872.1000361
Copyright: © 2017 Batool S, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
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Biochar has recently become an attractive adsorbent for the removal of toxic metals from aqueous media. In this study, the adsorption efficiency of biochars derived from farmyard and poultry manure for the removal of Cu2+ from water was evaluated. The porosity, surface structure, internal morphology, thermal stability, and functional groups of the biochars were analysed using different analytical techniques such as scanning electron microscopy, X-ray photon spectroscopy (XPS), thermogravimetry, and Fourier transmission infrared spectroscopy. Kinetics and isotherm data were acquired in batch adsorption mode. The isotherm sorption data correlated well (R2 >0.98) with the Freundlich model describing multilayer orption of Cu2+ on heterogeneous biochars. The maximum Cu2+ sorption was estimated as 44.50 mg/g for farmyard manure-derived biochar and 43.68 mg/g for poultry manure-derived biochar. The sorption data fit the pseudo-second order kinetics equation best, indicating chemical interaction between Cu2+ and the negatively charged surface of biochar. The thermodynamic parameters indicated that the reaction was exothermic and spontaneous. Post-adsorption analysis of the biochars by XPS suggested the formation of CuO and carbonate dihydroxide. The outcomes of the present study indicated that manure-derived biochars could be valuable green sorbents for removing Cu2+ from contaminated aqueous media.
Cu2+; Derived-biochar; Adsorption; Kinetics; Isothermal
Copper considered as most essential nutrient in minute concentration while it’s toxic beyond certain limit cause hazardous health effects. Its daily prerequisite for grown person is 2 mg. It is indispensable heavy metal for human beings and it’s used in surplus causes Wilson’s disease, adulterates the environmental ecosystem and exerts damaging effects on the living beings, intake in excess also causes gastrointestinal diseases, severe head ach, kidney damage, hair loss, blood pressure, hypoglycemia, capillary damage, nausea and CNS irritation which causes depression and hypertension [1-3]. In fact, metals sorb on the surface of different particulate matter present on the earth and engender free metal ions, which form complexes, these complexes are soluble in aqueous media and enter into food chains and become cause of different diseases .
Wastewater which contains heavy metals present in different industries e.g. pigments, electroplating, heavy metal finishing its dangerous for all living beings on earth’s ecosystem . Different conventional methods redox reactions, filtration, ion exchange for heavy metals removal from aqueous media has been applied. However all these techniques are expensive to implement when concentration exceeds in range 1 mg L-1 to 100 mg L-1 [6-8]. On large scale adsorption is one of the versatile, cheap and easy handling method for the treatment of contaminated water. However, disadvantages and huge cost of bio sorbent developed an alternative low cost adsorbent for remediation of heavy metals from aqueous media. Bio sorbents (biochars) have mobile potential to fulfill the need of amputation of heavy metals from polluted water.
Biochar cost has been increased the interest to find a cheap effective adsorbent material to remediate the heavy metals from aqueous solution and recently got attention due to its proven applications to manage the environmental issues . Biochars are most effective adsorbents for the removal of trace heavy metals from aqueous media [10-13]. Also, it has ability to alter the pH, electrical conductivity and cation exchange ability of the adsorbate . Biochar fined grinned material reveals porosity produced by pyrolysis .
Literature indicate that biochar is newly introduced scientific term which means “carbon containing product” it is produced at different temperatures in the absences or short availability of oxygen, origin of biochar is from Amazone region [16,17]. For Biochar production, waste material of animals and plants has been widely used, waste biomass used for biochar production because of cost- effectiveness as compared to other types of biomass . For the production of biochars the useful pyrolysis methods adopted, which generally increases or decreases its properties depends on residence time, heating rate and temperature. Pyrolysis conditions, residence time and heating rate generally affect the biochar adsorption capacity . FTIR analysis of biochar showed that in pyrolysis high temperature affects the functional chemistry of biochar, the C ratio increases due to high temperature and decreases the O and H ratio. Poultry manure biochar doesn’t undergo de-polymerization due to lignocelluloses compounds . Cr (III) adsorption occurs on those adsorbents which have organic functional groups . FTIR analysis showed that poultry manure and farmyard manure both has organic functional groups C, O and H. The physicochemical properties of biochar are affected by temperature. No doubt biochar is a green environmental sorbent. For safe and beneficial removal of animal litter, sewage sludge and plants waste from surface of earth we can convert this material in to biochar, it is an effective step to safe environment. Biochar is a very effective tool for the management of environment .
The newest report is based on impending features of derived biochar towards aqua-copper adsorption. The competence of copper adsorption was checked at different parameters by applying thermodynamics, isothermal and kinetic adsorption. Cu2+ adsorption was evidenced by post FTIR and XPS adsorption analysis.
Raw poultry manure and farmyard manure were acquired from PMAS Arid Agriculture University’s farm houses and agricultural land. First raw materials were dried in drying oven. Then biomass crushed and sieved through metal sieving tubes of different particular size. Both manures biomass of separately heated under limited supply of oxygen at 450°C to 650°C. For the estimation of mass product, biochar was finally obtained, which contained maximum C ratio as compare to other elements. This green bio-adsorbent remediate contaminant from aqueous environment efficiently due to its characteristics. Table 1 indicated summary of different sorbent’s capacity for adsorption of Cu+2 [13,22-30]. The` surface functional groups play important role, on extent of sorption and desorption ability of adsorbent and adsorbate .
|1||Cr (II) Stock Solution||1000 ppm|
|2||pH||2, 4 ,6|
|3||Concentration||0.4, 0.8, 1.6, 3, 6 and 10 ppm|
|4||Contact Time||1, 2, 3, 4, 5 and 6 hours|
Table 1: Parameters of batch adsorption study.
Preparation of stock solution
Distilled water was self-contaminated with salt of CuSO4 .5H2O for the preparation of 1000 mL stock solution. 3.92 g of copper sulphate were dissolved in 1000 ml deionized water as a stock solution and then from that stock solution, equipped further stock solutions of different concentration 2, 4, 8, 15, 30 and 50 mg/L.
All experiments were accompanied in 50 mL polyethylene bottle by adding 0.25 g adsorbent (biochar) each. Different factorial parameters (pH, concentration, temperature and contact time) were took into consideration for standard adsorption. All samples were incubated in shaker incubator at 180 rpm for 24 h. Samples were filtered by Whatman filter paper 42 and tested on atomic absorption spectrophotometer (AAS). Fresh 1 M NaOH and 1 N H2SO4 solutions were used to adjust hydrogen ion concentration. All factorial set up for enhanced Cu2+ described in Table 2.
|pH||C (%)||H (%)||N (%)||O (%)||Ash (%)||Surface area (m2 g-1)|
Table 2: Basic features of poultry manure biochar (PM-BC) and farmyard manure biochar (FYM-BC).
The amount of Cu+2 adsorbed were determined by (Eq.1) following formula. For the estimation of multilayer, monolayer formation and calculated R2 value on the biochars in isothermal study, Freundlich (Eq.3) and Langmuir isotherms (Eq.4)  were applied respectively, while (Eq.2) were used for metal percent removal.
Qe=(Ci - Ce) V/m (1)
(Ci–Ce) / Ci × 100 (2)
Ln qe=ln KF +1/n ln Ce (4)
Ci (mg.L-1), Ce (mg.L-1), V and m (g) referred to initial concentration, Numbers Parameters equilibrium concentration, volume and mass of the adsorbent. ‘b’ is Langmuir constant .
To predict the chemical kinetics rate in different decades’ pseudo first order (Eq.5), pseudo second order (Eq.6) and power function (Eq.7) models were applied for Cu+2 contaminants which pollute the natural environment; it elaborates the chemisorption phenomenon which is linked with outer most shell exchange of electrons between biochar and metal .
Log (qe−qt)=log qe− k1t/2.303 (5)
t/qt=1/k2q2 e+t/qe (6)
log q=log a+b log t (7)
Qe for adsorbed Cu+2 ions amount and qt also adsorbed amount of metal ions at equilibrium at time t (h) . K1 and K2 constants for pseudo first and pseudo second order [35,36], a and b are the rate constant .
Biochar thermal properties were analyzed by thermo gravimetric analyzer (TGA, NETZSCH STA449F3) on heating rate 10°C /min under Argon flow presence at temperature range 40°C to 1000°C. For sample holder Alumina crucibles were taken into consideration. Biochar surface characteristics were determined by scanning electron spectroscopy (SEM, WASINCA X-ACT, 58794), Oxford Instruments, China while sorbents functionalities were identified by Fourier transform infrared instrument named (Perkin Elmer, USA). SS-100 X-ray photoelectron spectra (SS-100) used to determine metal and their binding energies fixation on the surface. Elemental composition of biochars was analyzed by Elemental Analyzer (LECO-CHNS 932, USA). Surface area was determined by MICORMERITICS INSTRUMENT Co., Norcross, GA, USA BET (Brunauer- Emmett- Teller). Atomic adsorption spectrometer (AAS) model An Analyst 300 Perkin- Elmer which contained copper cathode lamp and air acetylene flame was used for the detection of quantity of metal in the solution.
Thermodynamic parameters and Gibbs energy were evolved in order to determine reaction type, spontaneity and adsorption process on both farmyard manure and poultry manure biochar. LnKe values were estimated from Figure 9 and Table 3 Gibbs free energy was checked out by following equation used [38,39].
ΔGº = -RT ln Ke (8)
ΔGº=ΔHº–T ΔSº (9)
Ln Ke=ΔSº/ R−ΔHº/ RT (10)
|Pseudo-second-order model||Power function|
Table 3: Kinetic models for evaluation of rate-constants.
where (ΔHº kJ/mol) and (ΔSº J/mol K) indicate enthalpy and entropy, respectively, R and T represents general gas constant (8.314 J/ mol K) and temperature in (Eq.10).
Characterization of adsorbent
When studied the basic properties of adsorbents through analysis of different instruments got following results PH of PM-BC was 7.8 and FYM-BC 8.2 which were determined by PH meter model name Mettler Toledo Delta 320 suggested that FYM BC was more basic then PMBC. CHN Elemental analyzer made by Perkin Elmer gave results in Table 2 which showed that FYM-BC (47.47%) contained more C% age then PM-BC (42.43%) and other components H, N, O and ash% age also mentioned in Table 2. Surface Area Analyzer instrument named Gemini VII 2390 Series- Micrometrics also showed results that PM-BC had 8.61 m2g-1 and FYM-BC 10.11 m2g-1 Figure 1.
FTIR pre-adsorption analysis: Functional groups on the poultry manure have close relationship with the chemical properties of heavy metals. In Figure 2b peaks at 3377.92 cm-1 and 2955.68 showed O-H, C-H stretching, indicated hydrogen bonded functional groups alcohol, phenols and alkane respectively. Other peaks at 1582.8 cm -1 ,1432.27 cm-1 (C-C stretching in ring form) indicated aromatic functional groups,1090 cm-1 and 1031.77 cm-1 indication of C-N stretching and detection of aliphatic amines. Sharp peak at 789.49 cm-1 showed =C-H bending and predict alkenes.
In Figure 2a Farmyard manure exhibited broad peak at 3399 cm-1(O-H stretching) and other medium peaks at 2955.06 cm-1 (C-H stretching), 2831.93 (H-C=O, C-H) and 2510.86 (O-H) predict following groups hydroxyl groups, alkanes, aldehydes, carboxylic acids. Small peaks at 1592.80 cm-1 and 1418.06 cm-1 showed C-C stretching with aromatic functional groups another peak at 1031.77 cm-1 C-O stretching with following functional groups alcohols, carboxylic acids, esters and ethers.
Scanning electron microscopy (SEM) analysis showed in Figure 1 the morphological structure of (a) PM and (b) FYM, both bio chars has porous biomass and larger surface area, poultry manure showed pores of different shapes with irregular sizes and heterogeneous structure, so above data suggested that both bio chars has greater potential to adsorb metal.
In X-ray photoelectron spectroscopy (XPS) photons of specific energy excite the electronic states of sample atoms. In Figure 3 plotted graph between intensity and binding energy, combined graph of PM and FYM showed their sharp peaks at 282 eV and 538 eV indicated the presences of C and O respectively. PM showed another minor peak at 110 eV which indicated the presences of Si element. TGA curves in Figure 4 of FYM BC and PM BC showed the thermal stability analysis of weight loss with respect to time indicated temperature at X-axis and weight loss at Y-axis. Both biochars contained a lot of C component when they were heated carbon changed into CO2 and weight loss occurred. Results showed that PM loses more weight than FYM BC. In Figure 4 FYM lose 16% weight between 650 to 740°C and in the same figure part (b) PM started weight loss between 40°C to 1000°C and 35% weight loss observed. Through pyrolysis pores would persuaded on the surface of Biochar by evaporation of gases which also increase surface area of adsorbent .
Copper adsorption experiment
Parameters effect: pH is essential parameter in heavy metal adsorption. It affects the surface charge, degree of ionization and speciation of metal ion in the solution . Effect of pH on Cu+2 adsorption was observed by changing pH concentration shown in Figure 5a. Effective competition between binding sites for Cu2+ and proton occurs and maximum adsorption confirmed at pH 2. Comparatively, poultry manure indicated maximum efficiency of adsorption followed by farmyard manure in ranging 2-6 pH. The reason for maximum adsorption is due to electrostatic interaction between the Cu2+ ions and biochar surface. Moreover, the biochar surface functionalities explained well in following portion based on FT-IR analysis. At pH, these groups reacted and dissociates with Cu2+ and form stable complexes while unstable complexes observed at pH greater than this. Higher hydrogen ion concentration leads Cu2+ desorption occurs due to precipitation in the form of sulphate, hydroxide. So, gradual increase in pH gives Cu2+ enhanced adsorption, while higher pH does not attain equilibrium.
Figure 5b indicated adsorption of Cu2+ increases with contact time. Contact time is the agitation of biochar with aqueous solution as a result equilibrium attained. Contact time was adjusted 1 to 6 hours with difference in one hour at two different adjusted temperatures. Figure 5b reflected that higher adsorption is achieved at the initial contact time. However, decreasing trend observed after the maximum equilibrium achieved after 3 h. Poultry manure biochar efficiently adsorbed higher Cu2+ compared of farmyard manure due to its effective binding surface with Cu2+ metals in aqueous solution during the first three hours. Maximum removal capacity depends on higher affinity between biochar and metal.
Metal adsorption on biochar surface extremely depends on the metal ions in the solution. In Figure 5c maximum equilibrium attained at 50 mg/L, maximum adsorption capacity of PM-BC was 49.02 mg.L- 1 and FYM-BC was 48.99 mg.L-1. Pores of biochars completely filled due to higher concentration. Maximum adsorption gradient between adsorbent and adsorbate became cause of mass transfer. Efficiency (98.04%) observed at maximum concentration due to effectiveness of both derived biochars. Results achieved at 298 K, 308 K and 318 K expose that high temperature favored high energy molecules. Figure 5d revealed maximum Cu+2 adsorption at 318 K due to interaction of molecules with the biochar surface.
Kinetic study: Adsorption Kinetics describe the solute uptake rate. Chemical kinetics gives information about reaction rate, the path through which reaction take place and time in which equilibrium established. These isotherms were time dependent . Related linear graphs in Figure 6 and statistical parameters in Table 3 showed progressively well fitness of pseudo second order model which were based on value of regression correlation R2 and also indicated that high temperature favors the adsorption phenomenon compared to power function.
Isothermal study: The distribution of solute between liquid phase and solid phase had determined by several isotherms. Adsorption isotherms for Cu2+ were mathematically represented by Langmuir (Eq.3) and Freundlich (Eq.4). The data were evaluated by both isotherms. The plotted graph between lnqe and lnce in Figure 7 for Freundlich isotherm justified well multilayer adsorption due to higher regression correlation value R2. In Langmuir model Figure 8 Drew against (Ce/qe) and Ce, prsented weak R2 values for Cu2+ adsorption and rejected . KF stands for Freundlich capacity constant and n stands for adsorption intensity and values of intercept and slope gave us the values of KF and n. KF stands for Freundlich capacity and n for adsorption intensity. The constants b (energy adsorption) and q max (max. adsorption capacity) obtained from slope and intercept  shown in Table 4.
|Langmuir model||Freundlich model|
Table 4: Langmuir and Freundlich isotherms constants for Cu2+ on poultry and farmyard manure derived biochar.
Thermodynamic parameter: There are three thermodynamic parameters which are useful for the calculation of Gibb’s free energy. ΔGº calculated from (Eq.9). Thermodynamic study in Table 5 elaborated that both biochars contained negative values of ΔHº, which is unblemished indication of exothermic reaction. Poultry manure, which was more effective then farmyard manure, gave positive ΔSº showed reaction was perfectly irreversible. After calculating negative ΔG° value concluded that reaction was spontaneous.
|ΔG0 (kJ mol-1)||ΔH0 (kJ mol-1)||ΔS0 (J mol-1 K-1)|
Table 5: Thermodynamic parameters of Cu2+onto derived biochars.
Adsorption mechanism: When studied post adsorption spectra of Cu+2 on FYM in Figure 2c it presented that 798.48 cm-1 peak at right side shifted to 786.78 cm-1 it lost its sharpness and became broad Cu+2 ions interact with alkanes and selective oxidation of alkanes occurred. Another sharp peak at 1031.71 cm-1 shifted towards1049 cm-1 and by reduction of Cu+2 ions with C-N formation of cuprocyanide indicated. Organo-copper compounds produced when 1418.06 cm-1 peak shifted towards 1422.65 cm-1 became more intense and broad. Peaks between 1500 cm-1 to 3000 cm-1 disappeared and a medium broad peak appeared, due to adsorption of metal ions of Cu+2 different complexes (organocuprates) formed in this region on the surface of biochar. On left side of FYM post adsorption spectra broad and intense peak appeared after shifting of 3377.92 cm-1 peak toward 3396.48 cm-1 indicated the formation of copper hydroxides complex.
In Figure 2d post adsorption of Cu+2 loaded PM BC studied which indicated that sharp and medium heighted peak 789.49 cm-1 shifted towards 800 cm-1 and Cu-CH3-CH4 formed. Sharp intense peak at 1031.77 cm-1 and 1090.30 cm-1 merged and a broad peak of 1095.31 cm-1 appeared which indicated the reduction of Cu+2 ions formation of cupric cyanide complex medium peak in pre-adsorption spectra of PM at 1432.27 cm-1 shifted to 1600 cm-1. Broad intense peak appeared at 3390.48 cm-1 by merging of two peaks 2955.68 cm-1 and 3377.92 cm-1. Post-adsorption spectra of XPS (Figure 3b) revealed that Cu+2 with 2p electronic configuration gave following information after reaction with functional groups on the surface of BCs. Cu2+ metal when adsorbed on the surface of PM, its binding energy shifted 933 eV to 933.4 e V for CuO and peak of Cu (II) Carbonate dihydroxide appeared at 934.7 eV binding energy.
Present work focused on the water treatment by low cost effective, eco-friendly biochar. The conclusion through the series of experiment was predicted. Both biochar is efficient removal agent. However, comparatively derived biochar poultry manure confirm maximum removal capacity followed by farmyard manure. Electrostatically Cu2+ adsorption on derived biochars observed by stable copper sulphate complexes formation with carboxyl and hydroxyl groups, organic fractions, large oxygen groups and surface morphological characteristics on surfaces of derived biochars. This high efficiency demonstrated best characteristics of biochars. Cu2+ adsorption was predisposed by pH, contact time, concentration and temperature. Lineraized Freundlich equation well fitted and exposed maximum Cu2+ adsorption capacity by both biochars, while pseudo second order demonstrated well kinetic study. The inveterate Cu2+ adsorption mechanism was predictable by post-analysis of derived biochars, which strongly reflected spontaneity, physical and exothermic behavior (Table 6).
|Adsorbent||Quantity adsorbed (mg/g)||Reference|
|Green macro alga||5.57|||
|Granular beet pulp||21.16|||
|BS swine manure||21.94|||
Table 6: Efficiency of different adsorbents for sorption of Cu2+.
The author would like to thank and grateful to the Laboratory of Soil Science and Soil Water Conservation, PMAS Arid Agriculture University, Rawalpindi,Pakistan and Northwestern Polytechnical University, Xi’an 710072 P.R. China for providing research opportunities, analysis and characterization of the sorbents.