DSpace at VNU: Sugarcane bagasse treated with hydrous ferric oxide as a potential adsorbent for the removal of As(V) from aqueous solutions

Food Chemistry 138 (2013) 133–138 Contents lists available at SciVerse ScienceDirect Food Chemistry journal homepage: www.elsevier.com/locate/foodchem Sugarcane bagasse treated with hydrous ferric oxide as a potential adsorbent for the removal of As(V) from aqueous solutions E Pehlivan a,⇑,1, H.T Tran b, W.K.I Ouédraogo c, C Schmidt d, D Zachmann d, M Bahadir d a Department of Chemical Engineering, Selcuk University, Campus, 42079 Konya, Turkey Hanoi University of Science, Hanoi, Vietnam c Laboratoire de Chimie Organique: Structure et Réactivité, UFR-SEA, Université de Ouagadougou, 03 BP 7021 Ouagadougou 03, Burkina Faso d Institute of Environmental and Sustainable Chemistry, Technische Universitaet Braunschweig, Germany b a r t i c l e i n f o Article history: Received 16 January 2012 Received in revised form September 2012 Accepted 24 September 2012 Available online November 2012 Keywords: Sugarcane bagasse Adsorption Arsenic Iron oxide-based adsorbent a b s t r a c t The mechanism of As(V) removal from aqueous solutions by means of hydrated ferric oxide (HFO)-treated sugarcane bagasse (SCB-HFO) (Saccharum officinarum L.) was investigated Effects of different parameters, such as pH value, initial arsenic concentration, adsorbent dosage, contact time and ionic strength, on the As(V) adsorption were studied The adsorption capacity of SCB-HFO for As(V) was found to be 22.1 mg/g under optimum conditions of pH 4, contact time h and temperature 22 °C Initial As(V) concentration influenced the removal efficiency of SCB-HFO The desorption of As(V) from the adsorbent was 17% when using 30% HCl and 85% with M NaOH solution FTIR analyses evidenced two potential binding sites associated with carboxyl and hydroxyl groups which are responsible for As(V) removal Adsorption, surface precipitation, ion exchange and complexation can be suggested as mechanisms for the As(V) removal from the solution phase onto the surface of SCB-HFO Ó 2012 Elsevier Ltd All rights reserved Introduction Among various elemental species, arsenic is near the top of the toxic list Arsenic enters water bodies through both natural erosion processes and anthropogenic activities High levels of arsenic in drinking water are a crucial problem in many countries, e.g Mexico, Bangladesh, Vietnam, and Argentina (Farias et al., 2003; Fazal & Kawaci, 2001) Arsenic is released into the environment while using pesticides, treating wood, producing glass and electronic devices, manufacturing copper and other metals, as well as producing fertilisers Arsenic ions occur in surface and ground waters in both organic and inorganic species, the inorganic forms being the predominant ones, e.g arsenite (H2AsO3À and arsenate (H2AsO4À) (Fazal & Kawaci, 2001) While arsenic is toxic to plants and animals, inorganic arsenic species are strong carcinogens to humans (Ng, 2005) Usually, arsenic is taken up and accumulated in the human body through drinking water, the food chain, and inhalation of polluted air The human toxicity of arsenic ranges from skin lesions to cancer of the brain, liver, kidney, and stomach Arsenic intake causes disturbance of nervous system functions and can lead to death (Boddu, ⇑ Corresponding author Tel.: +90 332 2232127; fax: +90 332 2410635 E-mail address: erolpehlivan@gmail.com (E Pehlivan) Present address: Department of Chemical Engineering, Selcuk University, Konya 42079, Turkey 0308-8146/$ - see front matter Ó 2012 Elsevier Ltd All rights reserved http://dx.doi.org/10.1016/j.foodchem.2012.09.110 Abburib, Talbottc, Smitha, & Haasch, 2008) Because of these effects, the World Health Organisation (WHO) and the United State Environmental Protection Agency (USEPA) reduced the arsenic standard concentration in drinking water from 50 to 10 mg/l (Environmental Protect Agency, 1999) If this concentration is exceeded in surface and ground waters in many countries, it is essential to develop effective methods for the removal of arsenic ions from the water supply Arsenic removal, using low-cost adsorbents, such as lignocellulosic materials and agricultural by-products has been under investigation since the last decade Agricultural by-products are of particular interest since these materials are produced in great amounts and are easily available worldwide In Vietnam, sugarcane industries produce large amounts of SCB that could be applied for arsenic removal from water streams It was reported that the main components of SCB are cellulose (46.0%), hemicellulose (24.5%), lignin (19.95%), fat and waxes (3.5%), ash (2.4%), silica (2.0%), and others (1.7%) (Sene, Converti, Felipe, & Zilli, 2002) The polysaccharides found in sugarcane bagasse are biopolymers with many hydroxyl and/or phenolic groups that can be chemically modified to form new compounds with various properties (Navarro, Sump, Fujii, & Matsumura, 1996) The arsenic removal from water streams could be achieved by using various techniques (Fe-electro-coagulation/ co-precipitation, coagulation–microfiltration, oxidation/precipitation, coagulation/precipitation, reverse osmosis, filtration, nanofiltration, ion-exchange) and different adsorbents (cellulose beads loaded with iron oxyhydroxide, iron-oxide coated sand, granular 134 E Pehlivan et al / Food Chemistry 138 (2013) 133–138 ferric hydroxide, activated carbon, fly ash, zeolites, Calix[4]arenegrafted magnetite nanoparticles) have been used for the removal of arsenic (Guo & Chen, 2005; Gupta, Basu, & De, 2007; Leupin & Hug, 2005; Singh & Pant, 2004; Badruzzaman, Westerhoff, & Knappe, 2004; Mondal, Balomajumder, & Mohanty, 2007; Sayin et al., 2010) Some of these new techniques are rather expensive for limited size water treatment systems situated in rural residential districts and they are in the developmental stages; consequently, innovative cost-effective treatment processes are urgently needed Adsorption is considered as an economical and effective technique for arsenic removal because of its lower cost, and availability of suitable adsorbents and their regeneration Although the adsorption capacity of agricultural by-products is usually less than those of synthetic adsorbents, these materials could be an inexpensive alternative for water treatment plants In order to enhance their adsorption capacity, these materials are modified with various organic compounds having different functional groups The SCB contain biopolymers, mainly of polysaccharides with hydroxyl, carboxyl and/or phenolic groups that can be chemically modified to form new compounds with different properties With this investigation, we aimed at combining the beneficial effects of both the polysaccharides and iron oxyhydroxides, such as SCBHFO, to form a new adsorbent for the removal of As(V) ion from aqueous solutions and compare their performance with other adsorbents for the same purpose The influences of physical–chemical key parameters, e.g pH, the initial concentration of arsenic, the amount of adsorbent, contact time, the point of zero charge (pHzpc) and ionic strength, were investigated in this study Materials and methods 2.1 The preparation of sugarcane bagasse SCB SCB, obtained from a suburb of Hanoi, Vietnam, was powdered in a ball mill (BLB Braunschweig) and sieved in a sieving machine (Retsch, West of Germany) The sample having the sieve fraction of 125–200 lm was washed thoroughly with deionised water, and dried in an aerated oven at 60 °C for 24 h The air-dried and powdered SCB (50 g) was hydrolysed by using 1.15 M H2SO4 (w/w of dry material, at 80 °C for 30 min) for removing starch, proteins and sugars Thereafter, the low molecular weight lignin compounds were removed by stirring the solid for 24 h at room temperature in 0.1 M NaOH solution (ratio SCB/sodium hydroxide is 5) After thorough washing, the adsorbent was dried in an oven at 50 °C and stored in a desiccator prior to further experiments 2.2 The modification of SCB with ferric nitrate Fe(NO3)3 to SCB-HFO Ten grams of pretreated SCB were mixed for 48 h with 300 ml of 0.05 M ferric nitrate Fe(NO3)3 in a l beaker Aliquots of M NaOH were added dropwise into the beaker under continuous stirring, keeping the pH between 2.8 and 3.5 After 48 h of the covering process, the suspension was filtered and washed with de-ionised water several times until neutral pH was obtained Coated adsorbent SCB-HFO was dried in an oven at 50 °C Furthermore, it was stored at room temperature until used 2.3 Preparation of standards and reagents Reagents used were purchased from Merck (Darmstadt, Germany) and were of analytical grade MgSO4Á7H2O (Fluka, Seelze, Germany), Na3PO4Á12H2O (Sigma–Aldrich, Seelze, Germany) and NaNO3 (Merck) were used for studying the effects of ionic strength As(V) stock solution was purchased from Merck Iron Nitrate (Fe(NO3)3) was used for modification of the adsorbent All glassware was cleaned with diluted nitric acid and rinsed with deionised water Standard acid (0.1 M HCl) and base (0.1 M NaOH) solutions were used for the pH adjustment of the solution The AAS standard solution of 1000 mg/l As(V) was prepared by transferring the contents of a Titrisol ampule with As2O5 in H2O (Merck, Germany) into a l volumetric flask, which was filled up to the mark at 20 °C according the instructions by Merck The working solutions of different concentrations were prepared by diluting the stock solution immediately before starting the batch studies The As analyses were performed with a Hitachi Atomic Absorption Spectrophotometer (HG-AAS, Series Z-2000; Hitachi Corporation, Japan) which was connected to a hydride formation system (model HFS-3; Hitachi) For hydride generation, the following solutions were used: (i) 1.2 M HCl (p.a., Merck); (ii) NaBH4– NaOH-solution: solute 10 g NaBH4 (p.a., Fluka) in l of H2O (Seralpure) by adding g of NaOH (p.a., Merck); the solution was prepared immediately before use; (iii) KI-solution as a reduction agent; 20% (w/v; reduction to As(III)) All standards, reference solutions, and sample solutions were adjusted to 0.24 M HCl and 2% KI The reduction agent was added at least 30 before analysis In general, a 5-point calibration was run before starting the analyses (0–20 lg/l) For monitoring of a possible signal drift, reference solutions of and 10 lg/l were used As levels were measured every 5–7 samples For generation of hydride, HCl (1.2 M) and NaBH4-solution were pumped into the reaction chamber in the hydride formation system; sample and standard solutions were added The flow rates of HCl and NaBH4 were 8–10 ml/min for sample and standard 12 ml/min A 12 cm quartz cuvette was mounted above the standard burner flame zone that ran with air (0.5 MPa) and C2H2 (1.2 l/min) Argon was used as carrier gas with a flow rate of 0.3 l/min for constant transfer of As-hydride from the reaction cell to the cuvette The 193.7 nm emission line of the Ashollow-cathode lamp was used Due to the long transport distances for reaction solutions and hydride gas, the absorption signals should be followed thoroughly; with pre-integration times of at least 120 s for rinsing memory effects and to yield a constant common analytical signal An integration time of s is standard Under these conditions, the instrumental detection limit was 0.2 lg/l As a reducing agent, ml of 30% HCl and ml of 20% (w/v) KI were added to 20 ml of the standard or sample As(V) solution and left for about 15 for conversion of As(V) to As(III) ions 2.4 Batch adsorption experiments The defined amounts of SCB-HFO were added in 50 ml of aqueous As(V) solutions of different concentrations and shaken, using a rotary shaker (Retsch, Germany), at 120 rpm for certain time intervals (15 min–24 h) Supernatant was filtered through a cellulose acetate filter (pore size 0.2 lm) and analysed for As(V), using a HG-AAS The mass balance of As(V) adsorbed per mass unit of the SCB-HFO (mg/g) was calculated by the following (Eq (1)) (Altun & Pehlivan, 2012): Q e ẳ C i C e ịV=W 1ị where Ci and Ce are the initial and equilibrium As(V) concentrations in mg/l, respectively V is volume of the As(V) solution in ml, and W is the weight of adsorbent in mg The effect of initial pH (2–10) on the As(V) uptake by SCB-HFO was studied by using 50 ml of mg/l As(V) solution and g/l of adsorbent dosage at 23 °C To study the effect of initial As(V) concentration, 10, 20, 30, 50, 75, 100, 200 and 300 mg As/l, g adsorbent/l, pH 4, and a temperature 23 °C were applied The effects of contact time (15 min–24 h) and adsorbent amount (0.1–0.25 g) were studied with an initial As(V) concentration of mg/l, pH and temperature 23 °C E Pehlivan et al / Food Chemistry 138 (2013) 133–138 135 Results and discussion 3.2 The influence of pH on As(V) sorption 3.1 FT-IR analysis Solution pH normally has a large impact on adsorption performance (Arief, Trilestari, Sunarso, Indraswati, & Ismadji, 2008) The effect of pH on As(V) adsorption was investigated using different kinds of adsorbents and it produced similar results (Rahaman, Basu, & Islam, 2008) Fig 2b shows the relationships between pH value and sorption yield of As(V) It was indicated that most of the As(V) ions were bound to the adsorbent at an initial pH range of 2–4 Therefore, there is more adsorption under acidic conditions as well as in the near neutral region, i.e at pH 2–6; even more than 30% sorption is still observed up to pH 10 The sorption yield reached a maximum value of 98% at pH for As(V) ions Many investigations were conducted on the adsorption of soluble arsenic species from adsorbent surfaces The electrostatic force is one important factor in the adsorption mechanisms In the aqueous solution, the As(V) species predominate as a single negatively charged anion (H2AsO4À) at pH 3–6 and a double negatively charged form (HAsO42À) at pH up to 11, which can be adsorbed on the SCB-HFO by substituting hydroxyl In natural waters, the electrostatic force between the negatively charged As(V) species and the usually positively charged iron oxyhydroxide surface is much stronger, resulting in a better adsorption of As(V) If the arsenic concentration decreases, the electrostatic force for the sorption is not strong enough to remove arsenic for meeting the acceptable limit values in drinking water (Vaclavikova, Matik, Jakabsky, & Hredzak, 2005) SCB is a cellulose matrix, which has different binding sites, including carboxyl (–COOH) and hydroxyl (–OH) groups All infrared spectra of raw and treated materials were recorded using an ATR technique at 4000–520 cmÀ1 and 32 scans with a BRUKER FT-IR Tensor 27 The broad and strong band at 3343 cmÀ1 is due to the hydroxyl group (–OH) and the absorption band at 2897 cmÀ1 due to the alkyl groups of the biomass Absorption at 1729 cmÀ1 was attributed to stretching vibration of the carboxyl group The bands observed at 1034 cmÀ1 were assigned to C–O stretching of alcohols and carboxylic acids (Fig 1a) Fig 1b shows the SEM analysis of samples SCB and SCB-HFO The surface charge of sorbent was characterised by measuring the zeta potential for the treated adsorbent that indicates the surface charge of a particle at a certain distance from the surface of shear plane For materials that undergo acid base reactions, the surface charge depends on pH The sorption of the As(V) is expected to be favoured at a pH less than pHzpc (zpc: zero point charge) of the adsorbents (Kamala et al., 2005) SCB-HFO has ironoxyhydroxide groups, which are positively charged at pH smaller than (Fig 2a) For that reason, the adsorption experiments were performed at pH The reactivity of HFO coated on SCB is similar to iron oxide surface sites and the active form of this adsorbent is the hydrolysed surface species „FeOH, which behaves like an amphoteric site with a point of zero charge 5.8 (Fig 2a) Fig 1a FT-IR spectrum of raw SCB (black) and SCB-HFO (red) (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.) Fig 1b SEM of SCB (left) and SCB-HFO (right) 136 E Pehlivan et al / Food Chemistry 138 (2013) 133–138 Different situations in the adsorption of As(III) and As(V) can be expressed by their respective speciations in aqueous medium As(III) is present as an anion above pH (and the experimental data between pH and 8); it is thus reasonable to accept that the neutral form, H3AsO3, interacts with the adsorbent (Dupont, Jolly, & Aplincourt, 2007) When pH increases from to 10, the As(V) biosorption decreased because of the decrease of electrostatic interactions between the positively charged surface groups („FeOH2+) and the anionic As(V) species which prevents the formation of surface complexes (Dupont et al., 2007) Physical forces, e.g van der Waals and London forces, might slightly overlap the adsorption processes 3.3 The determination of Fe(III) amount loaded onto SCB The amount of Fe(III) (in hydrated ferric oxide) loaded onto SCB was determined after acid digestion In order to avoid uncontrolled reactions, 0.1 g of SCB-HFO was kept for 24 h at room temperature in aquatic conditions The digestion was completed by raising the temperature to 90 °C until the sample became dry; 10 ml of M HCl were added to the solution, and stirred several times After 12 h, ml of digested solution were drawn off and diluted to 10 ml The concentration of Fe(III) in the solution was analysed by GF-AAS Fig 2a The pH point zero of charge (pHpzc) of SCB-HFO 120 As(V) 100 % Sorption 80 3.4 Adsorption isotherm models 60 40 20 0 10 12 Ce Ce ẳ ỵ qe As As K b pH Fig 2b Sorption of As(V) on SCB-HFO as a function of pH (50 ppm As(V) in 50 ml of solution at different pH values; temperature 22 ± °C) Another possible reaction mechanism assumes that hydroxyl groups coordinate with As(V) ions (Boddu et al., 2008) At elevated pH, As(V) sorption was decreased due to the competition of the OH-groups bound to the matrix surface with the free hydroxyl ions Under alkaline conditions, the surface of SCB-HFO will become negatively charged, causing a repulsive force versus the anionic species of As(V), resulting in a decreasing sorption efficiency (Rahaman et al., 2008) The formation of surface complexes between positively charged surface groups „FeOH2+ and negatively charged As(V) ions can be described according to the following equilibrium (2 and 3) (Sherman & Randall, 2003): 2 FeOHỵ2 ỵ H2 AsO4 Ă ẵ FeOị2 AsOOHị ỵ H3 O ỵ H2 O  ỵ H2 AsO4 ỵ Ă ẵ Fe Oị2 AsOOHị þ H3 O ð3Þ In this situation, arsenate adsorption on the adsorbent can occur through non-specific coulombic interactions (outer-sphere adsorption) and formation of monodentate (2) and bidentate (3) surface complexes In another case, ligand exchange on the surface (inner-sphere adsorption) might happen during the following equilibrium (4 and 5) (Jeon, Baek, Park, Oh, & Lee, 2009):  FeOHỵ2 ỵ H2 AsO4 Ă  Fe O AsO3 H2 ỵ H2 O 4ị  FeOH ỵ H2 AsO2 Ă  Fe2 O2 AsO2 H ỵ 2OH ð5Þ ð4Þ where As (mol gÀ1) and Kb (l molÀ1) are the coefficients, qe is the weight of adsorbate which was adsorbed per unit mass of adsorbent, and Ce is the analyte concentration in aqueous phase at equilibrium.Freundlich equation: x 1=n ị ẳ kC e m 5ị where 1/n is the adsorption intensity, k is the adsorption yield, x/m is the mass of adsorbate adsorbed per unit mass of adsorbent and Ce is the element concentration at equilibrium in the aqueous phase The modified formula of this equation was obtained as follows (Eq (6)): log ỵ 2ị FeOHỵ2 Two well established equilibrium models, after Langmuir and Freundlich, were applied for the adsorption study The Freundlich model assumes a heterogeneous sorbent surface and different binding energies for the active sites (Altun & Pehlivan, 2007) The Langmuir isotherm is frequently used for the adsorption of metal ions from aqueous solutions (Langmuir, 1918) The general form of the Langmuir model is given below (4):Langmuir equation x m ẳ log k ỵ log C e n ð6Þ Table shows that the values of Kf and n were 1.55 Â 10À6 and 0.18 for As(V) adsorption However, R2 was calculated for Freundlich as 0.79, that is much lower than 0.99 for the Langmuir isotherm It was shown that the Langmuir model described the adsorption of the As(V) onto SCB-HFO better than did the Freundlich model It could be concluded that the Langmuir isotherm model better fits the equilibrium data Fig 3a shows that the non-linear relationship between the amount of As(V) ion adsorbed on SCB-HFO depends on the arsenic concentration The maximum sorption capacity (As) of adsorbent was found to be 22.1 mg/g for As(V) The Kb value was found to be 0.45 for As(V) sorption 137 E Pehlivan et al / Food Chemistry 138 (2013) 133–138 Table Langmuir and Freundlich isotherm constants 14 Freundlich isotherm parameters 2 12 As (mg/g) Kb R Kf (mg/g) n R 22.1 0.45 0.99 1.55 Â 10À6 0.18 0.79 As(V) uptake (mg/g) Langmuir isotherm parameters 25 10 As(V) uptake (mg/g) 20 0 0.05 15 0.1 0.15 0.2 0.25 0.3 Adsorbent amount (g) Fig 3b Sorption of As(V) on SCB-HFO as a function of adsorbent amount (50 ppm As(V) in 50 ml of solution at pH 4; adsorbent amount 0.1–0.25 g; temperature 22 ± °C 10 Table The relationship of desorption and pH values 50 100 150 200 250 300 350 As(V) concentration (ppm) Leaching agent pH Desorption (%) HCl (30%) NaOH (1 M) 1.5 12 14 17 54 85 Fig 3a Sorption isotherm of As(V) on SC-HFO as a function of initial As (V) concentration (10–300 ppm As(V); 50 ml; 0.2 g adsorbent; pH 4; 22 ± °C; contact time h) Iron compounds are reported to be effective for the removal of As(V) ions Several Fe(III) oxides/oxyhydroxides, e.g amorphous hydrous ferric oxide HFO (FeOOH), poorly crystalline hydrous ferric oxide–ferrihydride (Wilkie & Hering, 1996), goethite (a-FeOOH) and akaganeite (b-FeOOH), were investigated for removing As(V) from aqueous solutions Other sorbents, based on iron oxides/oxyhydroxides, e.g iron oxide-coated polymeric minerals (Katsoyiannis & Zouboulis, 2002), iron-hydroxide-coated alumina (Hlavay & Polyak, 2005), and natural iron ores (Zhang, Singh, Paling, & Delides, 2004) were also investigated A comparison of the removal capacities, for As(V), of different sorbents materials is given in Table showing that the SCB-HFO presented in this study had a medium sorption capacity compared with others 3.5 The effect of adsorbent dose on sorption of As(V) by SCB-HFO The effect of adsorbent amount on As(V) sorption was studied with the initial As(V) ion concentration of 50 ppm at 22 ± °C and pH The amount of SCB-HFO changed from 0.1–0.25 g It was indicated that the equilibrium concentration in the dissolved phase decreased when increasing the amount of adsorbent (Fig 3b) The optimum amount of SCB-HFO was found to be 0.25 g/50 ml of As(V) solution When the dosage was increased, the number of surface sites in the structure of the adsorbent lattice increased This shows that the main factors governing the adsorption of arsenic species are the electrostatic interaction between ironoxyhydroxide sites of the adsorbent and the anionic arsenic species Hence, facilitating the binding of arsenate resulted from both electrostatic interactions and hydrogen bonding 3.6 Desorption efficiency The desorption of the adsorbed As(V) from SCB-HFO was studied by eluting with 30% HCl and M NaOH (each 20 ml) The results were given in Table The desorption of As(V), using 30% HCl, was 17%, whereas the highest recovery of 85% was reached with M NaOH pH of the solution phase was adjusted by adding HCl and NaOH solutions The results showed that the adsorbent can be successfully reused upon treatment with 0.1 M NaOH solution, which may be referred to the displacement of As(V) bound to the adsorbent with OHÀ ions Table Arsenic removal capacities of different sorbents Adsorbent Qmax (mmol gÀ1) pH References Akaganeite Akaganeite Goethite 1.79 0.93 0.330 7.5 3.5 5.0 Deliyanni, Bakoyannakis, Zouboulis, and Matis (2003) Vaclavikova et al (2005) Hydrous ferric oxide HFO Fe(III) loaded resin 1.340 0.800 4.0 1.7 Fe-hydroxide coated alumina Coconut-shell carbon Peat-based carbon Magnetite 0.210 0.430 0.070 0.350 6.6–7.2 5.0 5.0 6.5 (Rau, Gonzalo, & Valiente, 2003) Hlavay and Polyak (2005) Lorenzen, van Deventer, & Landi (1995) Lorenzen, van Deventer, & Landi (1995) Javier, Maria, de Joan, Miquel, and Lara (2007) SCB-HFO 0.300 4.0 Present study (Matis, Lehmann, & Zouboulis, 1999) Wilkie and Hering (1996) 138 E Pehlivan et al / Food Chemistry 138 (2013) 133–138 3.7 The effects of the ionic strength (competing anions) on As(V) removal The ionic strength of the solution might compete with the As(V) removal, in particular in the case of other co-occurring multiple charged anions Therefore, the removal of 50 ppm As(V) in 50 ml, through 0.2 g of SCB-HFO, was investigated in parallel in the presence and absence of PO43À (50 ppm), NO3À (50 ppm), and SO42À (250 ppm) The pH of the solutions was adjusted to 4.0 and the samples were agitated for h at 200 rpm The results confirmed that As(V) removal was suppressed by PO43À ions The adsorption capacity for As(V) was decreased by 6.5%, but the other anions did not affect the adsorption process Conclusion The occurrence of arsenic in water is of major concern in many countries The threshold values of arsenic in drinking water have been set by public authorities, worldwide, at 10 lg lÀ1 In this study, a novel adsorbent from sugarcane bagasse, as a low-cost agro-waste, was developed, through treatment with iron(III)oxyhydroxide (SCB-HFO), that seems to have promising properties for the removal of As(V) from aqueous solutions The main factors determining the adsorption of As(V) on this sorbent are electrostatic interactions, ligand exchange, and chelation between positively charged surface groups „FeOH2+ and negatively charged As(V) ions The adsorption capacity of SCB-HFO was found to be 22.1 mg/g for As(V) under optimum conditions of h agitation at pH 4, and 22 °C As(V) ions could be desorbed successfully from SCB-HFO by using M NaOH and the absorbent was thus regenerated Among typical anions in surface waters, only phosphate (50 ppm) suppressed As(V) removal by the adsorbent whereas nitrate and sulfate did not affect the sorption process The presented findings suggest that SCB-HFO is an inexpensive adsorbent for As(V) removal from aqueous solutions Acknowledgements This investigation was performed at the Guest Chair within the project ‘‘Exceed-Excellence Center for Development CooperationSustainable Water Management in Developing Countries’’ at the Technische Universitaet Braunschweig, Prof Pehlivan being the visiting professor, and Ms Tran and Mr Ouédraogo are the international exchange staff members The Exceed Project is granted by the German Federal Ministry for Economic Cooperation and Development (BMZ) and German Academic Exchange Service (DAAD); their financial support is gratefully acknowledged References Altun, T., & Pehlivan, E (2007) Removal of copper(II) ions from aqueous solutions by walnut- hazelnut- and 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removal from contaminated water by natural iron ores Minerals Engineering, 17, 517–524  ... surface charge of sorbent was characterised by measuring the zeta potential for the treated adsorbent that indicates the surface charge of a particle at a certain distance from the surface of. .. polysaccharides and iron oxyhydroxides, such as SCBHFO, to form a new adsorbent for the removal of As( V) ion from aqueous solutions and compare their performance with other adsorbents for the same... data Fig 3a shows that the non-linear relationship between the amount of As( V) ion adsorbed on SCB-HFO depends on the arsenic concentration The maximum sorption capacity (As) of adsorbent was