Adsorptive removal of dichlorophenoxyacetic acid (2,4-D) using novel nanoparticles based on cationic surfactant-coated titania nanoparticles.

A novel nanomaterial based on cationic surfactant-coated TiO2 nanoparticle (CCTN) was systematically fabricated in this work. Synthesized titania nanoparticles were thoroughly characterized by XRD, FT-IR, HR-TEM, TEM-EDX, SEM with EDX mapping, BET, and ζ potential measurements. The adsorption of cationic surfactant, cetyltrimethylammonium bromide (CTAB), on TiO2 was studied under various pH and ionic strength conditions. Adsorption of CTAB on TiO2 increased with ionic strength increment in the presence of hemimicelle monolayer structure, indicating that nonelectrostatic and electrostatic forces control CTAB uptake. CTAB adsorption isotherms on TiO2 were according to a two-step model. Potential application in pesticide removal of 2,4-dichorophenoxy acetic acid (2,4-D) using CCTN was also studied. Optimum parameters for 2,4-D treatment through adsorption technique were pH 5, adsorption time of 120 min, and CCTN dosage of 10 mg·mL-1. Very low 2,4-D removal efficiency using TiO2 without CTAB coating was found to be approximately 28.5% whereas the removal efficiency was up to about 90% by using CCTN under optimum conditions, and the maximum adsorption capacity of 12.79 mg·g-1 was found. Adsorption isotherms of 2,4-D on CCTN were more suitable with the Langmuir model than Freundlich. Adsorption mechanisms of 2,4-D on CCTN were mainly governed by Columbic attraction based on isotherms and surface charge changes.

Epidemiological study of chronic obstructive pulmonary disease in COPD Hanoi-Vietnam

This was the cross-sectional epidemiological survey of a general population sample of 2001 men and women whose age >35 years old living in the Khuong Mai precinct, Thanh Xuan district, Ha Noi, Viet Nam. Data on respiratory symptoms, diseases, and risk factors were collected through standardized interview questionnaires. Lung function tests were performed using spirometer analyser ST 300, Japan. Subjects whose FEV1NC value was <70% underwent a bronchodilator test with inhalation of 400mcg of Salbutamol. Results. The prevalence of COPD was 1.53%, 4.15% in smokers, 3.47 in ex-smokers, 0.39 % in non-smokers. The prevalence was 2.73% in men and 0.36% in women. The prevalence of COPD was significantly higher in the male group as smoking habit and tobacco consumption was greater. There was no previous diagnosis of COPD in 94.1 % of cases. 64.7% with mild COPD, 17.6 % of patients with moderate COPD and 17.6% of patients with severe COPD. The prevalence of stage 0 of COPD was 3.9%.