Sorption of surfactants and personal care products in Indian soils

Sorption of three surfactants and personal care products in four types of commonly occurring Indian soils was extensively studied. The soils used in the study were red soil, clay soil, compost soil and sandy soil as classified by American Society for Testing and Materials (ASTM). The three surfactants used in the study were representative of cationic, non-ionic and anionic surfactant groups. The sorption of surfactants followed the descending order: sodium dodecyl sulphate (SDS) > trimethyl amine (TMA) > propylene glycol (PG). The maximum adsorption capacity (Q_max) was obtained in compost soil (28.6 mg/g for SDS; 9.4 mg/g for TMA and 4 mg/g for PG). The rate of adsorption was the maximum in compost soil followed by clay and red soils, and minimum for sandy soils. It is found that the Freundlich model fits the isotherm data better than the Langmuir model. Freundlich coefficient (K _f) increased as the organic content of soils increased. Desorption of target pollutants in tap water was 20–50% whereas acid desorbs 40–90% of target pollutants from soil matrix. It was also found that the adsorption and desorption were significantly affected by the presence of clay and organic matter. The results also indicate that surfactants and personal care products, especially TMA and PG, are highly mobile in sandy soil followed by red soil. Therefore, immobilization of target pollutants is most economical and effective in compost and clayey soils whereas for other type of soils the combination of physiochemical and biological process will be effective option for remediation.     

Adsorption of copper, nickel and lead ions from synthetic semiconductor industrial wastewater by palm shell activated carbon

Granular activated carbon produced from palm kernel shell was used as adsorbent to remove copper, nickel and lead ions from a synthesized industrial wastewater.Laboratory experimental investigation was carried out to identify the effect of pH and contact time on adsorption of lead, copper and nickel from the mixed metals solution. Equilibrium adsorption experiments at ambient room temperature were carried out and fitted to Langmuir and Freundlich models. Results showed that pH 5 was the most suitable, while the maximum adsorbent capacity was at a dosage of 1 g/L, recording a sorption capacity of 1.337 mg/g for lead, 1.581 mg/g for copper and 0.130 mg/g for nickel. The percentage metal removal approached equilibrium within 30 min for lead, 75 min for copper and nickel, with lead recording 100 %, copper 97 % and nickel 55 % removal, having a trend of Pb²⁺ > Cu²⁺ > Ni²⁺. Langmuir model had higher R² values of 0.977, 0.817 and 0.978 for copper, nickel and lead respectively, which fitted the equilibrium adsorption process more than Freundlich model for the three metals.     

Removal of lead(II) from aqueous stream by hydrophilic modified kapok fiber using the Fenton reaction

A hydrophilic kapok fiber was prepared by a chemical process of the Fenton reaction and used as an adsorbent to remove Pb(II) from aqueous solution. The effects of experimental parameters including pH, contact time, Pb(II) concentration, and coexisting heavy metals were estimated as well as evaluated. The optimum concentrations of FeSO₄ and H₂O₂ for the Fenton reaction-modified kapok fiber (FRKF) were 0.5 mol L^?1 and 1 mol L^?1, respectively. The adsorption kinetic models and isotherm equations of Langmuir and Freundlich were conducted to identify the most optimum adsorption rate and adsorption capacity of Pb(II) on FRKF. The FRKF displayed an excellent adsorption rate for Pb(II) in single metal solution with the maximum adsorption capacity of 94.41?±?7.56 mg g^?1 at pH 6.0. Moreover, the FRKE still maintained its adsorption advantage of Pb(II) in the mixed metal solution. The FRKF exhibited a considerable potential in removal of metal content in wastewater streams.     

Adsorption of anionic dye on magnesium hydroxide-coated pyrolytic bio-char and reuse by microwave irradiation

Magnesium hydroxide-coated pyrolytic bio-char composite was prepared by chemical precipitation, and the adsorption behavior of anionic dye (directly frozen yellow) onto magnesium hydroxide-coated pyrolytic bio-char was investigated in the batch mode. The Fourier transform infrared spectroscopy, X-ray diffraction spectroscopy and X-ray fluorescence spectroscopy of adsorbents were characterized. Adsorption studies were performed at different pH, salt concentration, contacting time and dye concentration. The pH value of the solution influenced the adsorption capacity significantly, and adsorption is favored of pH 6–8. Salt coexisted in solution increased slightly directly frozen yellow adsorption capacity. The isotherm data were analyzed by Langmuir and Freundlich isotherm model, and Langmuir model was better to predict the equilibrium data. Thermodynamic calculations showed that the adsorption was a spontaneous and endothermic process. Exhausted magnesium hydroxide-coated pyrolytic bio-char was treated by microwave irradiation, and yield of regeneration was 98 % in the case of microwave irradiated time 5 min at 320 W. The magnesium hydroxide-coated pyrolytic bio-char can be reused.     

Adsorption characteristics of heavy metals in soil zones developed on spilite

Various soil zones such as Bw, C1, and C3 are developed on spilite. Montmorillonite, vermiculite and chlorite is moderately occurred in the C1 and C3 soil zones, in contrast montmorillonite and vermiculite are absent in Bw soils whereas illite and sesquioxide are relatively increased. The high cation exchange capacity (CEC) of montmorillonite and vermiculte and moderate CEC of chlorite and illite resulted in the high adsorption of heavy metals. The adsorption of the heavy metals on spilite soil zones was studied at different concentrations and pH levels. Heavy metals like lead, cadmium, and copper were selected for adsorption studies considering their contribution as toxic metals in the environment. The initial solute concentrations ranged from 7.0 × 10⁻³ to 1.0 × 10² mg/L. The sorption behavior of Cd²⁺, Pb²⁺, and Cu²⁺ on soil zones of spilite was investigated using the batch equilibrium technique at 25°C. The characteristics of the adsorption process were investigated using Scatchard plot analysis (q/C vs. q) by the batch equilibrium technique at 25°C. In the adsorption of heavy metals, deviation from linearity in the plot of q/C versus q was observed, indicating the presence of multi-model interaction and non-Langmuirean behavior. When the Scatchard plot showed a deviation from linearity, greater emphasis was placed on the analysis of the adsorption data in terms of the Freundlich model, in order to construct the adsorption isotherms of the metal(s) at particular concentration(s) in solutions. The adsorption behavior of these metal ions on spilite soil zones is expressed by the Freundlich isotherms. Adsorption constants and correlation coefficients for the Cd, Pb, and Cu on spilite soil zones were calculated from Freundlich plots.     

苏州城市河道底泥对磷酸盐的吸附与释放特征

为了探讨苏州古城区河道底泥对磷酸盐的吸附-释放特征,文中分别从改变上覆水的pH值、底泥吸附-释放动力学和等温吸附实验三个方面进行了研究。结果表明:(1)随着上覆水pH值的增大,苏州河道底泥对磷的吸附量逐渐减小;(2)底泥对磷的吸附过程是一个复合动力学过程,通常包括快吸附和慢吸附两个过程。底泥对磷的快速吸附在2h内快速进行,之后为慢吸附过程,到6h左右,基本达到一种动态吸附平衡;底泥对磷释放的动力学过程也包括快释放和慢释放过程。底泥释放磷在1·5h内快速进行,之后进入慢释放过程,磷酸盐含量基本稳定,达到释放平衡;(3)底泥具有较大的吸附磷的能力。随着上覆水的磷酸盐浓度增高,底泥吸附磷酸盐的量也增加。上覆水与底泥的比值越大,底泥对磷的吸附率越小。     

Phosphorus adsorption characteristics at the sediment–water interface and relationship with sediment properties in FUSHI reservoir, China

This study was designed to survey the reservoir sediment properties, assess the phosphorus (P) sorption isotherm, and analyze the relationship between sediment properties and sorption parameters. Physicochemical analysis indicated that sediment from the FUSHI reservoir in Zhejiang Province, China, has similar physical and chemical properties and has been contaminated by P. Sorption isotherm experiments showed that the sorption process could be described by Langmuir and Freundlich models. The parameters of Q _max (Phosphorus sorption maximum) and K (Freundlich adsorption isotherm constant) ranged from 618.98 to 825.70?mg?kg^?1 and 114.18 to 170.74?l?kg^?1, respectively. EPC₀ (zero P equilibrium concentration) ranged from 0.14 to 0.24?mg?l^?1, more than the total P concentration in the water of the reservoir. Thus, the reservoir sediment releases P into the water and acts as a ??P resource??. The clay, Fe_o, Al_t, and Fe_t?+?Al_t content were the main active components in P sorption. Q _max had a highly significant positive relationship with some properties and could be estimated by a combination of these.     

Lead removal from wastewater using fluted pumpkin seed shell activated carbon: Adsorption modeling and kinetics

Activated carbon produced from fluted pumpkin (Telfairia occidentalis) seed shell was utilized for the removal of lead (II) ion from simulated wastewater. Adsorption tests were carried out in series of batch adsorption experiments. Several kinetic models (Bhattacharya-Venkobacher, Elovich, pseudo first and second order, intra-particle and film diffusion) were tasted for conformity to the experimental data obtained. The Langmuir and Freundlich adsorption models were also used to test the data. The amount of lead (II) ion adsorbed at equilibrium from a 200 mg/L solute concentration was 14.286 mg/g. The experimental data conform very well to the pseudo-second order equation where equilibrium adsorption capacities increased with increasing initial lead (II) concentration. The rate of the adsorption process was controlled by the film (boundary layer) diffusion as the film diffusion co-efficient values obtained from data analysis were of the order of 10 ⁶cm²/s. From the plots, the linear regression coefficient (R²) of the Langmuir model was higher than that of the Freundlich: the adsorption isotherm obeyed the Langmuir model better than the Freundlich model.     

Adsorption of copper (II) on mesoporous silica: the effect of nano-scale confinement

Nano-scale spatial confinement can alter chemistry at mineral–water interfaces. These nano-scale confinement effects can lead to anomalous fate and transport behavior of aqueous metal species. When a fluid resides in a nanoporous environments (pore size under 100 nm), the observed density, surface tension, and dielectric constant diverge from those measured in the bulk. To evaluate the impact of nano-scale confinement on the adsorption of copper (Cu²⁺), we performed batch adsorption studies using mesoporous silica. Mesoporous silica with the narrow distribution of pore diameters (SBA-15; 8, 6, and 4 nm pore diameters) was chosen since the silanol functional groups are typical to surface environments. Batch adsorption isotherms were fit with adsorption models (Langmuir, Freundlich, and Dubinin–Radushkevich) and adsorption kinetic data were fit to a pseudo-first-order reaction model. We found that with decreasing pore size, the maximum surface area-normalized uptake of Cu²⁺ increased. The pseudo-first-order kinetic model demonstrates that the adsorption is faster as the pore size decreases from 8 to 4 nm. We attribute these effects to the deviations in fundamental water properties as pore diameter decreases. In particular, these effects are most notable in SBA-15 with a 4-nm pore where the changes in water properties may be responsible for the enhanced Cu mobility, and therefore, faster Cu adsorption kinetics.     

Modification of PPTA-based polymeric waste and adsorption properties for metal ions

Novel composite adsorbents PPTA-AOx were synthesized by grafting polyacrylonitrile onto poly(p-phenylene terephthalamide) (PPTA) followed by converting the acrylonitrile into the amidoxime (AO) groups. Their structures were characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, elemental analysis, transmission electron microscopy, etc. Scanning electron microscopy analysis and pore structure analysis manifested that PPTA-AOx adsorbents are all composed of nanoparticles aggregation. The as-synthesized PPTA-AOx adsorbents showed good adsorption capacity for Hg²⁺ with a maximum adsorption capacity of 2.50 mmol g^?1. The pseudo-second-order model can reasonably describe the adsorption kinetics of the three adsorbents for Hg²⁺. Langmuir model provided better fit for the isothermal adsorption of Hg²⁺ on PPTA-AO₁ and PPTA-AO₂, while the Freundlich model was better for PPTA-AO₃. The adsorption process might involve both chemisorption and physisorption. According to the calculated thermodynamic parameters, it can be concluded that the adsorption is an endothermic, spontaneous and entropy-driven process.     

无机盐与表面活性剂对菲在黄土上吸附/解吸行为的联合影响

以NaCl和MgCl₂、十二烷基苯磺酸钠(SDBS)分别作为无机盐、表面活性剂的代表, 研究两者共存对菲在黄土中吸附/解吸行为联合影响的特点及其形成机制.结果表明, NaCl(≥0.1 mol/L)、MgCl₂或SDBS的单独介入, 可缩短吸附平衡时间、增加吸附容量等, 即对吸附具促进作用, 随着介入浓度的升高, 促进作用越明显, 促进能力为MgCl₂＞SDBS＞NaCl; 不改变吸附模式, 仍较好地符合F型与H型.NaCl与MgCl₂同时介入, 对菲吸附的影响仍表现为促进作用, 呈现相加作用的特点, 且随着MgCl₂浓度的升高, 促进作用更明显.NaCl(或及MgCl₂)与SDBS的同时介入对吸附的联合影响, 总体上表现为相加作用, 但还呈拮抗作用的特点, 尤其MgCl₂浓度较高时.NaCl或(及)MgCl₂的存在, 或与SDBS共存时, 与纯水相比, 菲的解吸速度较快、解吸率较高、平衡时间较短, 且无滞后效应.可见, 无机盐与表面活性剂同时适量介入, 以强化菲等污染地下水系统的修复功效具一定的可行性.      

Adsorption of hydroxamate siderophores and EDTA on goethite in the presence of the surfactant sodium dodecyl sulfate

Siderophore-promoted iron acquisition by microorganisms usually occurs in the presence of other organic molecules, including biosurfactants. We have investigated the influence of the anionic surfactant sodium dodecyl sulfate (SDS) on the adsorption of the siderophores DFOB (cationic) and DFOD (neutral) and the ligand EDTA (anionic) onto goethite (α-FeOOH) at pH 6. We also studied the adsorption of the corresponding 1:1 Fe(III)-ligand complexes, which are products of the dissolution process. Adsorption of the two free siderophores increased in a similar fashion with increasing SDS concentration, despite their difference in molecule charge. In contrast, SDS had little effect on the adsorption of EDTA. Adsorption of the Fe-DFOB and Fe-DFOD complexes also increased with increasing SDS concentrations, while adsorption of Fe-EDTA decreased. Our results suggest that hydrophobic interactions between adsorbed surfactants and siderophores are more important than electrostatic interactions. However, for strongly hydrophilic molecules, such as EDTA and its iron complex, the influence of SDS on their adsorption seems to depend on their tendency to form inner-sphere or outer-sphere surface complexes. Our results demonstrate that surfactants have a strong influence on the adsorption of siderophores to Fe oxides, which has important implications for siderophore-promoted dissolution of iron oxides and biological iron acquisition.     

Surfactant-enhanced remediation of contaminated soil: a review

Extracting aqueous solutions with or without additives are employed to solubilize contaminants in soil. Since water solubility is the controlling removing mechanism, additives are used to enhance efficiencies. These additives can reduce the time to treat a site compared to the use of water alone. Additives must be of low toxicity and biodegradable. The research in this area has focussed mainly on halogenated volatile organic compounds (VOCs) and is still quite limited for metal removal. Additives include surfactants, organic and inorganic acids, sodium hydroxide, which can dissolve organic soil matter, water-soluble solvents such as methanol, displacement of cations with nontoxic ones, complexing agents such as EDTA, acids in combination with complexing agents or oxidizing/reducing agents. Cationic, anionic and nonionic surfactants are particularly used for soil washing or flushing. They contain both hydrophobic and hydrophilic portions, making them ideal for solubilization of hydrophobic compounds. Numerous studies have indicated that surfactants enhance recoveries of non-aqueous phase liquids (NAPLs). There have also been indications that pretreatment of soil with surfactant washing to solubilize hydrophobic compounds such as PAHs enhances biodegradation of these contaminants. A few in situ field studies have been performed with surfactants. Large-scale treatment has been done mostly for organic removal. Soil pH, soil type, cation exchange capacity (CEC), particle size, permeabilities and contaminants all affect removal efficiencies. High clay and organic matter contents are particularly detrimental. Understanding the chemistry of the binding of the contaminant and the hydrogeology of the site are very important. Once the water is pumped from the soil, it must be extracted and then treated to remove the hydrocarbons and metals. Several technologies exist such as sodium hydroxide or sodium sulfide precipitation, ion exchange, activated carbon adsorption, ultrafiltration, reverse osmosis, electrodialysis and biological processes. Recycling of the surfactants is desired to decrease treatment costs.

This paper will provide an overview of the laboratory research, field demonstration and full-scale application of surfactants for the remediation of contaminated soil. The majority of pilot scale in situ flushing tests, particularly in the United States, have involved the use of surfactants and co-solvents. There are only a few full-scale projects however. Recent laboratory scale efforts by the authors concerning the use of biosurfactants, biologically produced surfactants, to enhance the removal of copper, cadmium and zinc from contaminated soils and sediments are discussed. Three types of biosurfactants were evaluated for their effectiveness. They included a lipopeptide called surfactin from Bacillus subtilis, a rhamnolipid from Pseudomonas aeruginosa and a sophorolipid from Torulopsis bombicola. The results indicated the feasibility of removing the metals with the anionic biosurfactants even though the exchangeable fractions were not significant.     

Effects of salinity on NH4 + adsorption capacity, nitrification, and denitrification in Danish estuarine sediments

The regulatory effect of salinity on nitrogen dynamics in estuarine sediments was investigated in the Randers Fjord estuary, Denmark, using sediment slurries and intact sediment cores and applying ¹⁵N-isotope techniques. Sediment was sampled at three representative stations varying in salinity, and all experiments were run at 0‰, 10‰, 20‰, and 30‰. The sediment NH₄ ⁺ adsorption capacity decreased markedly at all stations when salinity was increased from 0‰ to 10‰; further increase showed little effect. In situ nitrification and denitrification also decreased with increasing salinities, with the most pronounced reduction of approximately 50% being observed when the salinity was raised from 0‰ to 10‰. The salinity-induced reduction in NH₄ ⁺ adsorption capacity and stimulation of NH₄ ⁺ efflux has previously been argued to cause a reduction in nitrification activity since the nitrifying bacteria become limited by NH₄ ⁺ availability at higher salinities. However, using a potential nitrification assay where NH₄ ⁺ was added in excess, it was demonstrated that potential nitrification activity also decreased with increasing salinity, indicating that the inhibitory salinity effect may also be a physiological effect on the microorganisms. This hypothesis was supported by the finding that denitrification based on NO₃ ⁻ from the overlying water (D_w), which is independent of the nitrification process, and hence NH₄ ⁺ availability, also decreased with increasing salinity. We conclude that changes in salinity have a significant effect on nitrogen dynamics in estuarine sediments, which must be considered when nitrogen transformations are measured and evaluated.     

Adsorption behaviors of Cd^2＋ on Fe2O3/MnO2 and the effects of coexisting ions under alkaline conditions

This study describes the adsorption features of cadmium on Fe2O3 and MnO2 in alkaline saline conditions. The adsorption reached equilibrium in 6 hours under alkaline conditions. The absorption of cadmium on Fe2O3 and MnO2 was consistent with Freundlich absorption isotherms, and the corresponding adsorption capacities were 16.3 and 16.7 mg·g-1, respectively. Moreover, the adsorption quantity of cadmium on Fe2O3 and MnO2 rose with increasing pH from acidic to neutral, and reached the maximum at pH= 9. The coexisting chlorides reduced the adsorption capacity of Fe2O3 and MnO2. The influence intensities of different cations follow the order of CaCl2>>KCl>NaCl. However, the influence of sodium salts on the capacities of Fe2O3 and MnO2 to adsorb cadmium appeared more complicated: the relatively low concentrations of sodium salts could reduce the adsorption capacity; with increasing concentrations of sodium salts, e.g. NaCl and NaNO3. The adsorption capacity decreased continually. Moreover, due to the competition adsorption and precipitation effects, the adsorption capabilities of Na2CO3, NaH2PO4 and Na2HSO4 could also be reduced and cadmium concentrations in the solution were reduced as well.     

Removal of bisphenol A from aqueous solution using cetylpyridinium bromide (CPB)-modified natural zeolites as adsorbents

Surfactant-modified natural zeolites (SMNZs) with different coverage types were prepared by loading cetylpyridinium bromide onto the surface of natural zeolites. The resulting SMNZs were characterized and used as adsorbents to remove bisphenol A (BPA) from aqueous solution. The monolayer and bilayer SMNZs were effective for removing BPA from aqueous solution. The BPA adsorption capacity for the monolayer SMNZ increased slightly with increasing pH from 4 to 9, but decreased significantly with increasing pH from 9 to 11. The BPA adsorption capacity for the bilayer SMNZ was relatively high at pH 9–10, but decreased with decreasing pH from 9 to 4 or increasing pH from 10 to 11. The equilibrium adsorption data of BPA on the monolayer and bilayer SMNZs under the experimental condition could be well described by the Langmuir and Freundlich isotherm models. The adsorption kinetics of BPA on the monolayer and bilayer SMNZs followed a pseudo-second-order model. The adsorption of BPA on the monolayer and bilayer SMNZs took place in three different stages: a fast external surface adsorption, a gradual adsorption controlled by both the external mass transfer and the intra-particle diffusion, and a final equilibrium stage. The adsorption of BPA on the monolayer and bilayer SMNZs is spontaneous and exothermic. The mechanisms for BPA adsorption onto the monolayer SMNZ at pH 4–11 include the hydrophobic interaction and hydrogen bonding. The mechanisms for BPA adsorption onto the bilayer SMNZ at pH 4–8 include the organic partitioning and hydrogen bonding. The mechanisms for BPA adsorption onto the bilayer SMNZ at pH 8–11 include the organic partitioning, hydrogen bonding and electrostatic attraction.     

纳米材料对水体中PFCs的去除行为及机制

全氟化合物（Perfluorinated Compounds,PFCs）是一类含有强极性碳氟键的阴离子表面活性剂.由于PFCs的高稳定性、高生物累积性和潜在毒性,其在水环境中的广泛存在已经对人类的生命健康造成了极大的威胁.近年来,研究者不断寻找有效的材料和处理技术去除水体中的PFCs.纳米材料因其特殊的结构和效应,比一般材料有更高的反应活性.总结了如碳纳米管、改性粘土矿物、纳米二氧化钛、氧化铟、氧化镓等新型纳米材料在物理吸附、光化学及电化学法去除PFCs中的应用,并比较了上述各材料去除PFCs的优缺点及各自的去除机制,分析了目前纳米材料去除水体中PFCs存在的主要问题并展望了今后的发展趋势.      

Effects of cations and anions on iron and manganese sorption and desorption capacity in calcareous soils from Iran

This study investigated the effect of cations and anions on the sorption and desorption of iron (Fe) and manganese (Mn) in six surface calcareous soil samples from Western Iran. Six 10 mM electrolyte background solutions were used in the study, i.e., KCl, KNO₃, KH₂PO₄, Ca(NO₃)₂, NaNO₃, and NH₄NO₃. NH₄NO₃ and NaNO₃ increased the soil retention of Fe and Mn, whereas Ca(NO₃)₂ decreased the soil retention of Fe and Mn. Iron and Mn sorption was decreased by NO₃ ^? compared with H₂PO₄ ^? or Cl^?. The Freundlich equation adequately described Fe and Mn adsorption, with all background electrolytes. The Freundlich distribution coefficient (K _F) decreased in the order H₂PO₄ ^? > Cl^? > NO₃ ^? for Mn and H₂PO₄ ^? > NO₃ ^? > Cl^? for Fe. The highest sorption reversibility was for Fe and Mn in competition with a Ca²⁺ background, indicating the high mobility of these two cations. A MINTEQ speciation solubility model showed that Fe and Mn speciation was considerably affected by the electrolyte background used. Saturation indices indicated that all ion background solutions were saturated with respect to siderite and vivianite at low and high Fe concentrations. All ion background solutions were saturated with respect to MnCO_3(am), MnHPO₄, and rhodochrosite at low and high Mn concentrations. The hysteresis indices (HI) obtained for the different ion backgrounds were regressed on soil properties indicating that silt, clay, sand, and electrical conductivity (EC) were the most important soil properties influencing Fe adsorption, while cation exchange capacity (CEC), organic matter (OM), and Mn-DTPA affected Mn adsorption in these soils.     

Utilization of ochre as an adsorbent to remove Pb(II) and Cu(II) from contaminated aqueous media

The ability of ochre to remove Pb(II) and Cu(II) from aqueous media has been studied by batch sorption studies varying the contact time, initial metal concentration, initial solution pH and temperature to understand the adsorption behaviour of these metals through adsorption kinetics and isotherms. The pH of the solution and the temperature controlled the adsorption of metal ions by ochre and rapid uptake occurred in the first 30 min of reaction. The kinetics of adsorption followed a pseudo-second-order rate equation (R ² > 0.99) and the isotherms are well described by the Freundlich model. Adsorption of metals onto ochre is endothermic in nature. Between the two metals, Pb(II) showed more preference towards the exchangeable sites on ochre than Cu(II). This study indicates that ochre is a very effective adsorbent in removing Pb(II) and Cu(II) from the aqueous environment with an adsorptive capacity of 0.996 and 0.628 mg g^?1 and removal efficiency of 99.68 and 62.80 %, respectively.