Order Kinetic Equation Research Articles

Adsorption of Non-Steroidal Anti-Inflammatory Drugs on Alginate-Carbon Composites-Equilibrium and Kinetics.

In this work, alginate–carbon composites with different active carbon content were synthesized and studied by various techniques. The obtained materials can be used as adsorbents in the processes of removing organic pollutants from water. In this study, the effect of the immobilization of activated carbon in calcium alginate was investigated. Textural properties were determined by measuring low-temperature nitrogen adsorption/desorption isotherms. The largest specific surface area was recorded for ALG_C8 and amounted to 995 m2/g. The morphology of alginate materials was determined on the basis of scanning electron microscopy. The adsorption properties were estimated based on the measurements of equilibrium and adsorption kinetics. The highest sorption capacities were 0.381 and 0.873 mmol/g for ibuprofen and diclofenac, respectively. The generalized Langmuir isotherm was used to analyze the equilibrium data. A number of equations and kinetic models were used to describe the adsorption rate data, including first (FOE) and second (SOE) order kinetic equations, 1,2-mixed-order kinetic equation (MOE), fractal-like MOE equation (f-MOE), multi-exponential equation (m-exp), in addition to diffusion models: intraparticle diffusion model (IDM) and pore diffusion model (PDM). Thermal stability was determined on the basis of data from thermal analysis in an atmosphere of synthetic air.

Studies on luminescence properties and photo-thermo transfer phenomena in fluorapatite

This study reports the structure, composition, photoluminescence (PL), thermoluminescence (TL), and optically stimulated luminescence (OSL) properties of the Brazilian natural fluorapatite. Also, the existence of photo-thermo transfer phenomena is investigated from TL/OSL emission mechanisms. X-ray diffraction (XRD) pattern reveals that the sample has a hexagonal system with a crystallite size of about 46 nm calculated using the Scherrer formula. The presence of several elements including the rare earths such as Ce, Nd, and Er are identified using total X-ray fluorescence (TXRF) spectroscopy results. Ce3+ ions are associated with the emission band at 371 nm when excited at 300 nm. Fluorapatite exhibits intense TL and OSL signals when irradiated with beta particles and shows linear dose-response from 1 up to 50 Gy. The TL glow curves are deconvoluted to six peaks centered at 99, 147, 188, 242, 329, and 431 °C using general order kinetic equation. The corresponding activation energies vary between 0.68 and 1.11 eV. An anomalous fading is noticed for the first TL peak, which decays completely in 6 h; the second TL glow peak decays about 59% within 12 h and other high temperature peaks are more stable. Continuous-wave OSL (CW-OSL) is constituted of three components, having decay times (τ) of 0.39, 5, and 64 s. The deconvoluted linearly modulated OSL (LM-OSL) has four peaks, with peak maxima (tm) at 2.85, 7.4, 27, and 130 s. Further, it is noticed the phenomenon of phototransferred TL (PTTL) at 30 °C, due to the optical transfer of electrons related to the traps of 329 and 431 °C peaks to the main peak at 242 °C. The temperature-induced PTTL using thermally assisted OSL (TA-OSL) at 170 °C with 400 s of blue stimulation depicted a transfer of trapped electrons from very deep traps (VDTs), located at temperatures higher than 500 °C, to the main peak. Here, the luminescence intensity increases with the beta dose.

Investigation on the adsorption desulfurization effect of carboxyl and phosphotungstic acid modified UiO-66

UiO-66 loading carboxyl and phosphotungstic acid has a good affinity to thiophene (TH). The synthesized catalyst, changed its original structure, which can increase its reactive site and enhance the interaction with thiophene (TH) in order to improve the adsorption performance. Then the structural changes were analyzed by XRD, FT-IR, SEM, BET, EDS and other characterization methods. Through static experiments of adsorption desulfurization, it is found that when the adsorption time is 240 min, the adsorption temperature is 30 ℃ and the oil-to-agent ratio is 100:1, the adsorption effect: UiO-66-(COOH)2 (UC2) > UiO-66, the highest adsorption capacity can reach 89.99 mg/g; while PTA@UiO-66 (PAU) can reach adsorption equilibrium at 210 min, it has better desulfurization performance than UiO-66. After being recycled for 5 times, the adsorption effect is only slightly decreased: the adsorption capacity of UC2 was still 78.02% of the initial adsorption capacity, while that of PAU was 76.07% of the initial adsorption capacity. According to the adsorption kinetics, the adsorption process of thiophene on the adsorbent UC2 is more consistent with W-M model, and the adsorption of PAU is more in line with the pseudo-first order kinetic equation. In addition, it also includes the process of intraparticle diffusion and liquid film diffusion.

Kinetic Studies of Wastewater Purification Using Local Sand Samples in Erbil, Kurdistan

This research describes a straightforward procedure for extracting the pigment of Methylene Blue (MB) dye from aqueous solutions by utilizing a low-cost, safe, natural, and national source. Batch adsorption experiments were carried out to determine contact time, adsorbent dose, and the starting concentration of the adsorbate. For the analysis, a UV spectrophotometer was employed. Dye adsorption equilibrium was obtained after 120 minutes of contact time. Temkin, Langmuir, and Freundlich isotherm adsorption were used at solution concentrations of (3, 4, 6, and 8) mg/l. Adsorption data is used to predict the pseudo first and pseudo second order kinetic equations, Elovich kinetic models, and intra-particle diffusion using pseudo first and pseudo second order kinetic equations. The Langmuir adsorption model fits the MB adsorption data better than other isotherm models, with the MB capacity at 8 mg/l equal to 0.992 mg/g. The pseudo-second-order model and the adsorption kinetic data are satisfactorily related.

Efficient removal of methyl orange using magnesium oxide nanoparticles loaded onto activated carbon

ABSTRACT. In this work, an activated carbon composite made with magnesium oxide nanoparticles (MgONP-AC) was effectively utilized for methyl orange (MO) adsorption. The effect of pH (6-10), mass of MgONP-AC (0.1-0.3 g/L), initial MO concentration (10-30 mg/L), and temperature (283-323 K) on MO removal was investigated using a central rotatable composite experimental design based on the response surface technique (RSM) at an equilibrium agitation period of 60 min. The studies predicted the optimal MO removal of 98.99% at pH 7.68, MgONP-AC dosage of 0.24 g/L, and starting MO concentration of 15 mg/L, and temperature of 313 K. Furthermore, an artificial neural network (ANN) was utilized to simulate MO adsorption, and it properly predicted MO removal using mean squared error (MSE) and R2 for the testing data. The ANN predicts a maximum removal of 99.63% with ANN with R2 = 0.9926. The kinetic results suited the pseudo-second order kinetic equation, and the data from the equilibrium investigations corresponded well with the Langmuir isotherm (maximum uptake capacity qmax = 346 mg/g). Endothermic, spontaneous, and physical adsorption were discovered during the thermodynamic investigations.
 
 KEY WORDS: Adsorption, Artificial neural network, Experimental design, isotherms, Kinetics, Methyl orange, MgONP-AC
 
 Bull. Chem. Soc. Ethiop. 2022, 36(3), 531-544. 
 DOI: https://dx.doi.org/10.4314/bcse.v36i3.4

Theorithecal and experimental study on the thermodynamic parameters and adsorption of methylene blue on “Argania shells” in industrial waters

The present work consists in studying the kinetic, isothermal and thermodynamic properties related to the adsorption of Methylene Blue in industrial waters. The study proposes an package to study the adsorption on the side calculating the parameters: (Langmuir constant KL, Frendlich constant KF, the rate constants for a first order K1, pseudo-second order K2 and second order kinetic K3, and paramètres thermodynamiques) and plotting the trends, through a user-friendly graphical interface. This package aims to save time and avoid errors that may occur when processing experimental results. The experimental study of methylene blue adsorption on Argan shells was performed to verify the performance of this package. The experimental study of the adsorption of methylene blue on the shells of Argan was carried out to verify the performance of this set. It is found that the amount of adsorption of methylene blue on the shells of Argan is 90.96 mg / g for an estimated equilibrium time of 240 min. The correlation coefficient showed that the pseudo-second order kinetic equation best describes the adsorption kinetics. The experimental equilibrium data were analyzed, the Langmuir isotherm provided the best correlation. In addition, the determination of the thermodynamic parameters shows that the reaction is spontaneous and exothermic.

Green synthesis of Ag nanoparticles using elm pod polysaccharide for catalysis and bacteriostasis

The green synthesis of silver nanoparticles (Ag NPs) for catalysis and biological applications has gained great interest. Natural elm pods are a type of food that possesses anti-inflammatory and pain-relieving effects. In this study, elm pod polysaccharide (EPP) was extracted from elm pods using hot water extraction for the first time. Biocompatible EPP-stabilized silver nanoparticles (EPP-Agn NPs) were prepared by using a green synthesis method. The EPP-Ag25 NPs had a hydrodynamic size of 40.9 nm and a highly negative surface charge of −27.4 mV. Furthermore, EPP-Ag25 NPs exhibited high catalytic activity for the reduction of 4-nitrophenol, and the catalytic reaction followed a pseudo-first order kinetic equation. More importantly, the inhibition rate of EPP-Ag25 NPs on Escherichia coli was 71 % when samples were treated with an 808 nm laser. Besides, EPP-Agn NPs effectively inhibited the proliferation of tumor cells irradiated by an 808 nm laser. The improved performance of EPP-Agn NPs was due to the good stability of EPP. Taken together, EPP-Agn NPs had good stability, catalytic activity, antibacterial and antitumor ability under laser irradiation. EPP is a good stabilizer for many nanoparticles which have broad applications in the field of catalysis and biomedicine in the future.

ВПЛИВ КАВІТАЦІЙНИХ ЯВИЩ НА ПРОЦЕСИ РУЙНУВАННЯ ОРГАНІЧНИХ ТА БІОЛОГІЧНИХ ЗАБРУДНЕНЬ У ВОДІ

The regularities of cavitation treatment of food and chemical industries wastewater from organic and biological contaminants in the presence of gases of different nature were studied. The optimal temperature range 313K - 318 K for cavitation wastewater treatment was established. It is shown that the process of cavitation destruction of organic compounds can be described by a first - order kinetic equation. The efficiency of gas bubbling in the cavitation zone in order to intensify the simultaneous destruction of microbiological and organic contaminants in industrial wastewater was confirmed.

Marine Biomass-Supported Nano Zero-Valent Iron for Cr(VI) Removal: A Response Surface Methodology Study.

Heavy metal ions such as Cr(VI) pose great hazards to the environment, which requests materials and methods for decontamination. Nano zero-valent iron (nZVI) has emerged as a promising candidate for Cr(VI) removal. Herein, harnessing the merits of marine biomass, a heterogeneous water treatment system for the decontamination of Cr(VI) is developed based on the in situ immobilization of nZVI on the seashell powder (SP)-derived porous support. A response surface methodology (RSM) study involving three independent factors is designed and conducted to direct material synthesis and reaction design for products with optimal performances. Under optimal synthetic conditions, the nZVI-loaded seashell powder (SP@nZVI), which is characterized in detail by scanning electron microscope (SEM), X-ray diffraction (XRD), and Fourier-transform infrared spectroscopy (FTIR), results in a 79% increase in the removal efficiency of Cr(VI) compared to free nZVI. Mechanism studies show that the removal of Cr(VI) by SP@nZVI conforms to the Langmuir adsorption model with a quasi-second order kinetic equation, in which redox reactions between nZVI and Cr(VI) occurred at the SP surface. The results of this work are expected to benefit the reuse of bioresource waste in developing environmental remediation materials.

Release kinetics of Zn from soil and growing media mixtures in a laboratory study

Aim: To assess the zinc release from soils and various soilless growing media mixtures comprising different organic manures mixed at various proportions and to understand the kinetic behaviour of Zn release. Methodology: An incubation study was conducted to examine the time dependent release of zinc from soil and different growing media mixtures of Cocopeat (CP), Vermicompost (VC), Farm Yard Manure (FYM), Pressmud (PM), Vermiculite (VL) and Composted coco peat (CCP) by adding various levels of ZnSO4 (0, 12.5, 25, 37.5 and 50 kg ha-1) for 60 days. The Zn release at required time interval was quantified in soil and growing media mixtures. Results: Higher zinc release was recorded with growing media mixture of Cocopeat + Vermicompost + Pressmud (1:1:1) as compared to other mixtures. The release was linear up to 30 days and dropped at 45 days then increased. Fitting of various kinetic equations for better understanding of zinc release satisfactorily accounted (R2, 0.975 to 0.998, at p ≤0.05) by the zero order kinetic equation. Higher half-life time for Zn release (t1/2) was noticed with Soil + FYM and Cocopeat + Vermicompost + Pressmud mixtures, which confirmed their suitability. A significant negative correlation between pH, C:N ratio with Zn availability as well as linear decrease in organic carbon content prompted zinc release. Interpretation: Based on the amount of zinc released and grouping through principal component analysis with hierarchical clustering, a mixture of Cocopeat +Vermicompost +Pressmud at 1:1:1 was the best growing media mixture. Higher initial zinc availability and half-life time (t1/2) for zinc release makes it more efficient and best growing media mixture to sustain Zn supply to crops for a longer period of time.

Removal of Fe2+ and Mn2+ from Polluted Groundwater by Insoluble Humic Acid/Tourmaline Composite Particles.

Insoluble humic acid/tourmaline composite particles (IHA/TM) were prepared by combining inorganic tourmaline (TM) with the natural organic polymer humic acid (HA) and carbonizing them at 330 °C to study the removal characteristics and mechanism of Fe2+ and Mn2+. The results showed that the optimal ratio of TM to IHA is 2:3. When the temperature of the IHA/TM composite particles was 35 °C and the pH was 6, the adsorption of Fe2+ and Mn2+ by IHA/TM reached equilibrium at 240 min. The optimum dose of the adsorbent was 10 g/L, and the equilibrium adsorption capacities of Fe2+ and Mn2+ were 5.645 mg/g and 3.574 mg/g, respectively. The process of IHA/TM adsorption of Fe2+ and Mn2+ in water was spontaneous, endothermic and sustainable, and cooling was not conducive to adsorption. The pseudo-second order kinetic equation can well reflect the adsorption mechanism of IHA/TM on Fe2+ and Mn2+, and the Langmuir adsorption model better describes the isothermal adsorption behaviour. The material characterisation and adsorption experiments indicate that surface coordination and chemical precipitation are the main mechanisms of Fe2+ and Mn2+ removal by IHA/TM.

Removal of Copper(II) in the Presence of Sodium Dodecylobenzene Sulfonate from Acidic Effluents Using Adsorption on Ion Exchangers and Micellar-Enhanced Ultrafiltration Methods.

The selective removal of Cu(II) in the presence of sodium dodecylobenzene sulfonate from acidic effluents was made using the adsorption and micellar-enhanced ultrafiltration methods. Lewatit MonoPlus TP220 showed the best adsorption behavior in the systems containing Cu(II) in the presence of ABSNa50 surfactant compared to the other adsorbents (removal efficiency ≈ 100%, sorption capacity ≈ 10 mg/g). The kinetics followed the pseudo-second order kinetic equation. The Langmuir adsorption capacities were 110 mg/g (the system with ABSNa50 above CMC) and 130.38 mg/g (the system with ABSNa50 below CMC). The working ion exchange capacities were Cw = 0.0216 g/mL and Cw = 0.0135 g/mL. The copper removal by the micellar-enhanced ultrafiltration method was 76.46% (0.1 mol/L HCl).

Feasible synthesis of coal fly ash based porous composites with multiscale pore structure and its application in Congo red adsorption

Facing the great challenge that the increasing solid waste fly ash is difficult to treat and utilize properly, this paper reports a class of novel low–cost fly ash porous materials with high interconnected porosity fabricated by a facile foaming process. On this basis, composites with multiscale pore structures from the nanometer to macroscopic scale were designed and constructed by decorating layered double hydroxide (LDH) onto the inner channel surface. Such porous materials with 3D through–hole structures showed high interconnected porosity (up to 77.61%), suitable compressive strength (up to 23.79 MPa) and significant water permeation flux (549.86 m3∙m−2∙h−1 at 0.1 MPa). Moreover, the adsorption effect of dosage, initial concentration, pH, temperature and contact time on Congo red (CR) from simulated wastewater was investigated. The composites exhibited a good adsorption efficiency of ∼100% and adsorption capacities of 45.79 mg/g. The adsorption kinetic can be explained well by the pseudosecond–order kinetic equation and isotherm adsorption followed Langmuir isotherm model. This suggests that low–cost and eco–friendly fly ash composites have potential applications in industrial–scale wastewater treatment. This work also provides a general strategy to design and utilize fly ash porous materials for filtration and adsorption.

Performance of sesame straw cellulose, hemicellulose, and lignin biochars as adsorbents in removing benzo(a)pyrene from edible oil

The safety problems related to the occurrence of benzo(a)pyrene in edible oil have been a major threat to human health, and now significant attention has been to remove benzo(a)pyrene. So in this work, cellulose, hemicellulose, and lignin biochars were prepared, and then were used to remove benzo(a)pyrene from contaminated oil. Based on the nitrogen adsorption/desorption isotherms and the scanning election micrographs, the modified biochars had a huge specific surface area of 983.50-1915.55 m2/g and a well-developed porous structure. The modified biochars showed higher removal rate for benzo(a)pyrene than unmodified biochars. The highest adsorption (95.79%) of benzo(a)pyrene was achieved using the modified lignin biochar, which was therefore selected for evaluation of adsorptive capacity. The ability of the modified lignin biochar to adsorb benzo(a)pyrene was consistent with the pseudo-second order kinetic equation indicating mainly chemisorption, and it fit the Freundlich isotherm (R2 > 0.999), thereby revealing the occurrence of multilayer adsorption. The effect of π-π conjugation interaction and pore-filling together promoted the high adsorption performance of the modified lignin biochar. This work demonstrates that the modified lignin biochar could be a promising adsorbent for the removal of benzo(a)pyrene from edible oils.

An in situ grown amorphous ZrO2 layer on zeolite for enhanced phosphate adsorption.

Zeolite supported amorphous metal oxide nanolayers with high specific surface area, abundant adsorption sites, and excellent reusability hold a bright prospect in the efficient removal of contaminants, yet it is proven to be still challenging to precisely regulate and control their synthesis. Herein, we reported a facile synthetic strategy for rational design and achieving the uniform and firm in situ growth of an amorphous ZrO2 layer decorated on the surface of zeolite (ZEO@AZ) for enhanced phosphate adsorption. The Langmuir isotherm model and pseudo-second order kinetic equation well described the adsorption process towards phosphate solution, and the synthetized ZEO@AZ exhibited an excellent maximum adsorption amount of 24.98 mgP g−1. Furthermore, the adsorption of phosphates on ZEO@AZ was confirmed to be chemisorption, endothermic and spontaneous. This approach for fabricating amorphous metal oxide nanolayers on a robust matrix may provide a new route for constructing composites with superb phosphate adsorption performance.

Carboxylate-functionalized hollow polymer particles modified polyurethane foam for facile and selective removal of cationic dye

As an efficient technique for treatment of dye contaminated water, adsorption process has drawn wide research attention. However, conventional sorbents are mainly powdery and difficult to separate, which severely limited their practical application. Herein, a series of polyurethane foam (PUF) modified with carboxylate-functionalized hollow polymer particles (HPPs-COO-) were specially designed and synthesized. Combining the advantages of both open-cell foams and functional HPPs, the as-prepared HPPs-COO-/PUF can be utilized as advanced adsorbents towards cationic dyes (i. e., methylene blue b-MB). Batch adsorption experiments were performed to evaluate and optimize various parameters affecting the adsorption performance of HPPs-COO-/PUF, including the content (mass ratio) of HPPs-COO-, initial b-MB concentration, and solution pH. The experimental data demonstrated that the adsorption isotherm results fitted well with Langmuir model, possessing maximum sorption capacity of 125 mg/g at pH = 10 (25 °C). Furthermore, the adsorption process was better described by the pseudo-second order kinetic equation. Besides, the HPPs-COO-/PUF exhibit a remarkable pH-sensitive sorption capacity. When the pH value changed from 10.0 to 2.0, the sorption capacity of HPPs-COO-/PUF dropped sharply from 115.6 mg/g to 26 mg/g. Hence, regeneration of b-MB containing HPPs-COO-/PUF can be effectively realized. The recovered HPPs-COO-/PUF show > 90% b-MB removal efficiency during five adsorption–desorption processes, demonstrating excellent recyclability. With advantages of facile preparation, high adsorption capacity, and outstanding reusability, the HPPs-COO-/PUF showed great potential for dye wastewater treatment.

MOFs-derived magnetic hierarchically porous CoFe2O4-Co3O4 nanocomposite for interfacial radicals-induced catalysis to degrade chloramphenicol: Structure, performance and degradation pathway

Bimetallic organic frameworks derived bimetallic oxides as novel heterogeneous catalysts have been admitted to enhance catalytic capacity to great extent for peroxymonosulfate (PMS) activation. Herein, a magnetic hierarchically porous CoFe2O4-Co3O4 nanocomposite derived from heterometallic MIL-100 was one-step synthesized via manipulation of Fe/Co ratio and used to degrade chloramphenicol (CAP) in water. The structure of CoFe2O4-Co3O4 nanocomposite was evaluated by various characterization modes. The catalytic activity of CoFe2O4-Co3O4 nanocomposite was evaluated according to removal efficiency of CAP. Furthermore, the interfacial activation mechanism was deduced by a series of analysis. The results revealed CoFe2O4-Co3O4 nanocomposite was sphere-like nanoparticles with hierarchically micro/mesoporous structure. The nanocomposites had well-performed degradation efficiency toward 200 mL CAP of initial concentration of 10 mg/L (100% within 60 min). All of degradation followed the pseudo-first order kinetic reaction equation (kobs = 0.091 min−1). The whole degradation relied on interfacial radical generation via synergistic catalysis and sulfate radical (SO4•−) as well as hydroxyl radical (HO•) were ascertained as main reactive oxygen species (ROS). The possible degradation pathways involving dehydration, hydroxylation, substitution, oxidation, ring opening were proposed accordingly. This paper paid much attention to synergistic catalytic activity of Fe/Co and interfacial electron-transfer mechanism between CoFe2O4-Co3O4 nanocomposite and PMS, shedding a light on in-depth exploration of MOFs-derivates induced heterogeneous catalysis.

Residue dissipation and dietary risk assessment of cyazofamid and its metabolite CCIM in garlic, garlic bolt and garlic sprout

ABSTRACT The residue and dissipation dynamics of cyazofamid and its main metabolite 4-chloro-5-p-tolylimidazole-2-carbonitrile (CCIM) in garlic, garlic bolt and garlic sprouts were investigated by QuEChERS high-performance liquid chromatography–tandem mass spectrometry method. Field experiments were conducted in 6 sites for one year. The dietary intake risk of cyazofamid was assessed. At different levels, the results showed that the average recoveries of cyazofamid were 89.8%–1005% in garlic, 84.6%–109.4% in garlic bolt and 88.6%–108.5% in garlic sprout, recoveries of CCIM were 84.6%–104.2% in garlic, 84.6%–108.9% in garlic bolt and 85.3%–109.2% in garlic sprout, respectively, with relative standard deviation less than 10.1%. The limits of quantitation were all 0.01 mg/kg. The dissipation dynamics of cyazofamid and CCIM in garlic plant matrices fitted the first order kinetic equation, and the half-lives were 3.5–6.1 d and 0.9–3.9 d, respectively. The dietary intake risk assessment showed that the dietary exposure risk index of cyazofamid in garlic, garlic bolt and garlic sprout were less than 100%, which indicated that the dietary exposure risk was at an acceptable level.

Removal of methylene blue from aqueous solutions by internal microelectrolysis on the Fe-Cu materials

Fe-Cu material is made by chemical plating method. Materials Fe-Cu is used removal of methylene blue from aqueous solution by internal microelectrolysis. The results show that with optimal conditions for methylene blue decomposition is pH of 4, contact time of 120 minutes, material weight of 1.67 g/L, shaking rate of 300 revolutions per minute (rpm), methylene blue removal efficiency is 93.63 %, with the initial concentration is 245.11 mg/L. The process of decomposition of methylene blue by Fe-Cu material follows the assumed second order kinetic equation with reaction rate constant k = 0.0023 min-1. L.mg-1, The results show that materials Fe-Cu can be applied to remove methylene blue from aqueous solution by internal microelectrolysis

Adhesion evaluation of the Rhodococcus opacus strain on an apatite surface

Adsorption of microorganisms and/or their different components onto a mineral surface would modify the surface characteristics of the mineral. Thus, this investigation evaluated the adsorption capacity of the Rhodococcus opacus strain onto an apatite surface. Zeta potential and contact angle measurements of the mineral showed dislocations of the values after interaction with the microorganism. The maximum adsorption density reached was 24.10 mg of bacterial cells per gram of mineral using a biomass concentration of 400 mg/L. The experimental data were linearly fitted by the Freundlich model and the adsorption density as a function of time was linearly fitted by the pseudo-second order kinetic equation. The results showed that the bacterial strain has affinity for the apatite surface and ability to make it hydrophobic.