Removal of salicylic acid as an emerging contaminant by a polar nano-dendritic adsorbent from aqueous media.

A polar nano-dendritic adsorbent containing amine groups (SAPAMAA) was synthesized onto the nanoparticles of SiO2Al2O3 and its uptake of salicylic acid (SA) from the synthetic and real water was investigated. The synthesized nanomaterials were fully studied by nuclear magnetic resonance spectrum (1H NMR and 13C NMR), Fourier transform infrared spectroscopy (FT-IR), zeta potential (ζ), inductively coupled plasma atomic emission spectroscopy (ICP-AES), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Brunauer-Emmett-Teller (BET) and elemental analysis. Various parameters such as the effect of the contact time, adsorbent dosage, initial SA concentrations, effect of solution's temperature, interfering ions, the hydrophobicity of the nanoadsorbent and initial pH were assessed. The contact time to approach equilibrium for higher adsorption was 15min (252.8mgg-1). The isotherms could be fitted by Sips model (with the average relative error of 6.6) and the kinetic data could be characterized by pseudo-second-order rate equation (with the average relative error of 13.0), implying chemical adsorption as the ratelimiting step of uptake process which was supported by the experimental data from the effect of interfering ions, zeta potential, and altering of the adsorbent's hydrophobicity. The uptake capacities decreased with temperature increasing, and showed that the uptake of SA was chemically exothermic in nature between 15 and 80°C. In addition, the spent SAPAMAA could be regenerated by the removal of adsorbed SA with NaOH and ethanol to regain the original SAPAMAA, the regenerated SAPAMAA also exhibited the high adsorption capacity after 10 runs. Moreover, SAPAMAA could also be applied to uptake SA from a real water (Anzali lagoon water). We envisage that the prepared nano-dendritic with remarkable characteristics such as environmentally friendly, low-cost, easy preparation in large quantity, high mechanical and chemical stability will play a significant role in developing a new generation of emerging contaminants adsorbent.

Adsorption of methyl orange and salicylic acid on a nano-transition metal composite: Kinetics, thermodynamic and electrochemical studies.

In this work synthesis of Mn-nanoparticles (MnNPs) supported on the Schiff base modified nano-sized SiO2Al2O3 mixed-oxides (Si/Al) and its implementation as an adsorbent for the removal of organic pollutions such as methyl orange (MO) and salicylic acid (SA) was investigated. Si/Al were functionalized by grafting Schiff base ligand and in the next step, MnNPs were prepared over the modified nano sol-gel Si/Al. Structures and adsorption characteristics of the obtained organometallic-modified SiO2/Al2O3 mixed oxide were studied by several methods such as elemental analysis, diffuse reflectance UV-vis spectroscopy, FT-IR spectroscopy, nitrogen adsorption/desorption, scanning electron microscope (SEM), transmission electron microscope (TEM), energy dispersive X-ray (EDX), inductively coupled plasma (ICP-AES), Electron Paramagnetic Resonance (EPR), electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). EPR data of the immobilized manganese ions resulted that the transition state of active sites in the nano-adsorbent are in the form of Mn(II) ions at the surface. The adsorption properties of heterogeneous Mn(II) ions showed that this nano-adsorbent has very good potential to remove MO and SA ions from aqueous solution. The removal efficiency of the SAPAS@MnNPs towards MO reached out to 89.3 and 29.1% and for SA approached to 54.6 and 18.9% at 150 and 500mg/dm(3) initial organic pollution concentrations, respectively. To investigate the adsorption kinetic of Mn(II) ions onto the nano-sized support, pseudo first and pseudo second order kinetics, and the Freundlich, Langmuir and Langmuir-Freundlich isotherm models have also been applied to the equilibrium adsorption data. The contact time to obtain equilibrium for maximum adsorption capacity was 45min. The adsorption process was spontaneous and endothermic in nature and it was well explained with pseudo-second-order kinetic model. No remarkable loss of removal capacity even after 8th times regeneration was obtained, implying that the immobilized MnNPs has high solidity through the regeneration process. Finally, the mechanism of the MO adsorption process as a model has been studied by the CV, EIS and FTIR techniques. The electrochemical results showed that the oxidation of Mn(II) was easier and took place at lower potentials in the presence of MO, where the electron density at SAPAS@MnNP is higher, consequently reduction of Mn(III) to Mn(II) is more favored. These results suggest that the surface of SAPAS@MnNP was interacted and complexed by MO therefore accelerates electron transfer rate of the reaction related to Mn(II)/Mn(III) redox couple.

Removal of methyl orange on modified ostrich bone waste--a novel organic-inorganic biocomposite.

The synthesis and growth behavior of the chemically modified ostrich bone wastes as bioadsorbents for the removal of methyl orange from aqueous solutions have been investigated. The ostrich bone wastes were treated with cetyltrimethylammonium bromide (CTABr) and sodium dodecyl benzene sulfonate (SDBS). The synthesized biomaterials were characterized by several physicochemical techniques. The modified ostrich bone with CTABr was found to be effective as adsorbent for the removal of methyl orange (MO) from aqueous solutions. The effect of the experimental conditions on the adsorption behavior was studied by varying the contact time, initial MO concentration, temperature, initial pH, chemical modification process, and amount of adsorbent. The contact time to attain equilibrium for maximum adsorption (90%) was found to be 50 min. The adsorption kinetics of MO has been studied in terms of pseudo-first- and -second-order kinetics, and the Freundlich, Langmuir and Langmuir-Freundlich isotherm models have also been applied to the equilibrium adsorption data. The adsorption process was spontaneous and endothermic in nature and followed pseudo-second-order kinetic model.

Synthesis and adsorption characteristics of an heterogenized manganese nanoadsorbent towards methyl orange.

Heterogeneous Mn nanoparticles (5-30 nm diameter) is found to be a nanomaterial for the rapid removal of large quantities of toxic dye (methyl orange) from aqueous solution, with wide ranging potential applications. The synthesized materials were characterized with different methods such as FT-IR spectroscopy, CHN elemental analysis, BET, SEM, TEM, ICP-OES and EPR. The contact time to obtain equilibrium for maximum adsorption of methyl orange was 20 min. EPR of Mn ions evidenced that most of the covalently bond active sites of the nano-adsorbent are in the form of Mn(III) ions at the surface. The heterogeneous Mn(III)-Cl ions were found to be effective adsorbent for the removal of methyl orange from solution. The adsorption of methyl orange ions has been studied in terms of pseudo-first-order and pseudo-second-order kinetics, and the Freundlich, Langmuir and Langmuir-Freundlich isotherm models have also been applied to the equilibrium adsorption data. The adsorption process was spontaneous and endothermic in nature and followed pseudo-second-order kinetic model.

Kinetic and thermodynamic investigations of Pb(II) and Cd(II) adsorption on nanoscale organo-functionalized SiO2-Al2O3.

This paper reports the preparation of three new Schiff base ligands modified SiO2-Al2O3 mixed oxide adsorbents, and their use for removal of Pb(II) and Cd(II) from aqueous solutions. Equilibrium and kinetic models for Pb(II) and Cd(II) sorption were applied by considering the effect of the contact time, initial Pb(II) and Cd(II) concentrations, effect of temperature, and initial pH. The contact time to attain equilibrium for maximum adsorption was 120 min. These heterogeneous Schiff base ligands were found to be effective adsorbents for the removal of heavy metal ions from solution, with Si/Al-pr-NH-et-N=pyridine-2-carbaldehyde having a high adsorption capacity for Pb(II) and Cd(II) ions from aqueous solution. The adsorption of heavy metal ions has been studied in terms of pseudo-first- and -second-order kinetics, and the Freundlich, Langmuir and Langmuir-Freundlich isotherms models have also been used to the equilibrium adsorption data. The adsorption kinetics followed the mechanism of the pseudo-second-order equation for all systems studied, confirming chemical sorption as the rate-limiting step of adsorption mechanisms and not involving mass transfer in solution, which were confirmed by techniques of DS UV-vis and FT-IR. The thermodynamic parameters (ΔG, ΔH and ΔS) indicated that the adsorption of Pb(II) and Cd(II) ions were feasible, spontaneous and endothermic between 25 and 80°C.

Comparison of the efficacy of gentamicin for 5 days plus doxycycline for 8 weeks versus streptomycin for 2 weeks plus doxycycline for 45 days in the treatment of human brucellosis: a randomized clinical trial.

OBJECTIVES: To compare the efficacy of gentamicin for 5 days plus doxycycline for 8 weeks with streptomycin for 2 weeks plus doxycycline for 45 days in the treatment of human brucellosis. METHODS: In each arm of the study, 82 patients older than 10 years randomly received 5 mg/kg gentamicin once daily for 5 days plus 100 mg of doxycycline twice daily for 8 weeks or 1 g of streptomycin intramuscularly for 2 weeks plus the same dose of doxycycline for 45 days. Therapeutic failure and relapse in these two treatment groups were compared. This study was registered in the Iranian Registry of Clinical Trials (www.irct.ir) with registration number ID: IRCT138708191441N1. RESULTS: The clinical manifestations in these two groups were similar. Therapeutic failure was seen in two (2.4%) patients in the gentamicin/doxycycline group and in four (4.9%) patients in the streptomycin/doxycycline group [relative risk (RR) = 0.5, 95% confidence interval (CI) 0.09-2.66, P = 0.68]. Relapse was seen in two (2.4%) cases in the gentamicin/doxycycline group and in five (6.1%) cases in the streptomycin/doxycycline group (RR = 0.4, 95% CI 0.08-2, P = 0.44). The efficacy with the gentamicin/doxycycline regimen was 95.12% and that with the streptomycin/doxycycline regimen was 89% (RR = 1.07, 95% CI 0.98-1.17, P = 0.25). Cox regression analyses showed no differences among the two treatment groups for patients who had relapse or therapeutic failure and those who had not regarding baseline covariates such as sex, duration of disease before diagnosis, positive blood culture and focal disease. CONCLUSIONS: The results show that the efficacy of gentamicin for 5 days plus doxycycline for 8 weeks is not superior to that of streptomycin for 2 weeks plus doxycycline for 45 days.

Epidemiological features and clinical manifestations in 469 adult patients with brucellosis in Babol, Northern Iran.

The epidemiological features and clinical manifestations of adult cases of brucellosis admitted to the Department of Infectious Diseases, Babol Medical University, Iran from 1997 to 2002 were investigated. Of 469 cases, 267 (56.9%) were males. The mean age of cases was 36.9 +/- 15 years. Most (60.8%) were from rural areas. Two thirds of cases (306, 66.3%) presented during spring or summer. Fresh cheese (22.4%), animal husbandry (11.3%), laboratory worker (8.1%) and veterinary profession (1.5%) were the main risk factors. Forty-five families (9.6%) had two cases. Sweating, fever, and arthralgia were the most frequent clinical symptoms. Complications were documented in 105 males (39.5%) and 41 females (20.3%, P=0.0001). Peripheral arthritis was seen in 24 (9%) males and 19 (9.4%) females, with knees and hips being the most common sites of infection. Sacroiliitis and spondylitis were seen in 28 (6%) and 32 (6.8%) cases respectively with spondylitis more common in males (P=0.023). Epididymo-orchitis was seen in 29 (10.9%) males. There were three cases each of endocarditis (0.6%) and neurological complications (0.6%). Most patients with brucellosis did not have any of the known risk factors for brucellosis. Thus consumption of unsafe dairy products could be the main route of infection. The disease manifested with a diversity of clinical manifestations and complications. Complications were more frequent in males than females.