Optimization of electrocoagulation process for efficient removal of ciprofloxacin antibiotic using iron electrode; kinetic and isotherm studies of adsorption
TL;DR: In this paper, the authors focused on the removal of ciprofloxacin from hospital wastewater using electrocoagulation (EC) process by iron electrode and the kinetic and isotherms of adsorption were investigated.
About: This article is published in Journal of Molecular Liquids.The article was published on 2017-01-01 and is currently open access. It has received 130 citations till now. The article focuses on the topics: Adsorption & Langmuir adsorption model.
Summary (2 min read)
Jump to: [Introduction] – [Methods] – [Interview and measurements] – [Laboratory measurements] – [Statistical analysis] – [Undiagnosed and diagnosed diabetes] – [Diabetes mismanagement: old definition] – [Predictors of diabetes] – [Diabetes-related co-morbidities] and [Discussion]
Introduction
- The diabetes pandemic will increase from 175 million patients with diabetes in 2000 to 353 million in 2030.
- According to the national coronary artery disease (CAD) risk factors surveillance report, the overall prevalence of diabetes in Iran is estimated to be 8.7% in adults aged 15-64 years, of whom half (4.1%) were the newly diagnosed cases.
- It is not clear how many are at pre-diabetes stage and are prone to suffer from diabetes, or vice versa, with timely interventions, the disease can be prevented.
- 5 Using fasting plasma glucose (FPG) ≥7.2 mmol/L the criteria for poor management of diabetes, about 57% of individuals with diagnosed diabetes had high level of plasma glucose.
- The authors reported the age-sex standardized prevalence of diabetes at all stages including pre-diabetes (pre DM) and diabetes (DM).
Methods
- The Kerman Coronary Artery Disease Risk Factors.
- Study is a population based cohort study with repeated surveys.
- The methodology of KERCADR study has been explained in detail elsewhere.
- Only those who were able and provided written informed consent were recruited into the study.
- The study protocol was approved by the Ethical committee of Kerman University of Medical Sciences, Iran (Permission No. 88/110KA).
Interview and measurements
- All details of the measurement are presented elsewhere.
- Part of the questionnaire that the authors used in this study included demographic information, cigarette smoking (yes/no), opium addiction (no/occasional/ dependent), the level of physical activity (low/moderate/ high), and the level of depression and anxiety (related BECK questionnaires).
- Subjects who had no previous history of diabetes or anti-diabetic medication, but turned out to have FPG ≥7 mmol/L at the recruitment were considered as undiagnosed diabetic cases.
- In the old definition, uncontrolled diabetes was specified as HbA1c >53 mmol/mol (>7%) for all individuals.
- The authors found that diabetes and susceptibility in to diabetes was very common in Kerman.
Laboratory measurements
- All participants were asked not to eat for 12-14 h before coming to the clinic.
- Subjects who had FPG more than 5.6 mmol/L were recalled for another FPG test and HbA1c test (NYCOCARD Kit, Code 1042184, Austria).
- To measure serum lipid profiles, total cholesterol (KIMIA Kit, Code 890303, Iran) and triglycerides (KIMIA Kit, Code 890201, Iran) were also measured for all individuals.
Statistical analysis
- All statistical analyses were conducted under survey data analysis using STATAv.12 (StataCorp, 2011 College Station, TX, USA).
- For age-sex direct standardizations, the authors used Kerman population reported in census 2006.
- All prevalence rates were weighted according to the sampling weight (reciprocal of the probability of selection) and individual response rate.
- The data were presented as absolute and relative frequencies as well as 95% confidence intervals (95% CI).
- Univariate and multivariate logistic regression models were applied to determine the predictors of diabetes (both diagnosed and undiagnosed DM).
Undiagnosed and diagnosed diabetes
- There was nearly an equal prevalence of undiagnosed-DM in subpopulations regarding depression and physical activity.
- The prevalence of DM was diagnosed in 7.0% of occasional opium users, while it was 4.0% among dependent users.
- Seven percent of overweight and 7.6% of obese people had diagnosed-DM.
Diabetes mismanagement: old definition
- The uncontrolled-DM increased from 60% in young adults to 77.8% in elderly people.
- The frequency of uncontrolled-DM among people without and with (both insulin and non-insulin) treatment was 57.9% and 92.9%, respectively.
- The frequency of uncontrolled-DM varied from 76.1% among non opium users to 81.3% in dependent opium users.
- People with low physical activity had a higher frequency of uncontrolled-DM (79.4%), which decreased to 66.7% in people with high level of physical activity.
Predictors of diabetes
- In crude analysis, sex (male vs female), age, education, opium addiction, depression, increased BMI category, lower physical activity, and DM familial history turned to be potential significant predictors for DM (Table 3 ).
- While in the multivariate model, after removing confounding effects, it was shown that the odds diabetes increased significantly only by age group (AOR 5.0 to 18.2), depression (AOR 1.2), overweight and obesity (AOR 1.6, and 1.5), moderate and low physical activity, (AOR 1.5, and 1.4) and the positive familial history of DM (AOR 2.2).
- The other variables did not have a statistically significant association with diabetes.
Discussion
- In their analysis, the authors found one out of four individuals living in an urban area in Iran either had impaired glucose level (pre-diabetes) or diabetes.
- In several studies, it has been reported that the prevalence of diabetes (diagnosed and undiagnosed), impaired glucose tolerance (IGT) and impaired fasting glucose (IFG) increased by age [13] [14] [15] is not similar between men and women.
- Regarding the effect of cigarette smoking and opium consumption, the results of this study showed almost no statistically significant effects on control of diabetes or odds ratio of predictors of diabetes (Tables 2,3 ).
- In rural areas, Iran has a well-developed primary health-care system, having Behvarz workers responsible for population-based prevention and control services.
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TL;DR: In this article, the performance of the EC process with zinc and titanium electrodes for treating real printing wastewater through several experimental conditions was investigated through batch systems and the effects of the operating variables, including varying current densities (CDs), spacing between electrodes, electrolysis time, and varying electrode materials (titanium and zinc) on the efficiency of the removal of different parameters were studied.
Abstract: Electrocoagulation (EC) has numerous benefits over traditional coagulation. It is noteworthy that most researchers have studied EC using either iron electrodes or aluminum electrodes. The key objective of this study is to investigate the performance of the EC process with zinc and titanium electrodes for treating real printing wastewater through several experimental conditions. Experiments were done through batch systems. The effects of the operating variables, inclusive of varying current densities (CDs), spacing between electrodes, electrolysis time, and varying electrode materials (titanium and zinc) on the efficiency of the removal of different parameters were studied. Oil and grease, total dissolved solids (TDS), and chemical oxygen demand (COD) were among these parameters. The highest removal efficiency for COD after 90 min using a zinc electrode was approximately 50 % attained at 20 mA/cm2. For the titanium electrode, after 90 min, the highest removal efficiency for COD was 46 % attained at 15 mA/cm2. For the removal efficiency of TDS, the zinc electrode performance was better than that of the titanium electrode for every CD. After 90 min, the optimal TDS removal efficiencies were 9 % and 19 % for titanium and zinc electrodes, respectively. The titanium electrode offers the maximum efficiency of removal for oil and grease. The highest efficiencies of removal were attained at a separation distance of 4 cm. At a CD of 15 mA/cm2, the best COD elimination efficiencies using the titanium electrode at the separation distances of 6, 4, and 2 cm were 24 %, 47 %, and 30 %, respectively. At a CD of 15 mA/cm2, the best COD removal efficiencies using the zinc electrode at the separation distances of 6, 4, and 2 cm were 27 %, 41 %, and 38 %, respectively. In both the zinc and titanium electrodes, following the experiments, corrosion occurred in the anodes, which is evidence that the process of treatment took place. The EC performance was observed to be much better than that of conventional coagulation during the treatment of printing wastewater. Zinc and titanium electrodes demonstrated a good capability of removing pollutants when used in the EC process.
28 citations
TL;DR: In this article, the authors investigated the effects of the process parameters (such as the electrolyte solution concentration, graphite dosage, applied current strength, and air flow rate) on the concentration of hydroxyl radicals.
Abstract: A novel and simple apparatus for the continuous generation of hydroxyl radicals has been constructed for the first time. In this paper, we focused on the investigation into the kinetic study of hydroxyl radical formation in the preparation process. The effects of the process parameters (such as the electrolyte solution concentration, graphite dosage, the applied current strength, and air flow rate) on the concentration of hydroxyl radicals were investigated in detail. The concentration of hydroxyl radicals first increased with the concentration of sodium dodecyl benzene sulfonate electrolyte solution, graphite dosage, applied current strength, and air flow rate, and then decreased. The concentration of ·OH and time well fit a third-order model of {C(·OH) = B1 × t + B2 × t2 + B3 × t3 + intercept}. The highest concentration of hydroxyl radicals was 7.98 × 10−3 mol L−1 under the following conditions: sodium dodecyl benzene sulfonate concentration 10.0% (w/v), graphite dosage 5.0 g, applied current strength 10 mA, and air flow rate 1.0 L h−1. Our hydroxyl radical generation method can achieve the preparation of higher-concentration hydroxyl radicals continuously without using strong acid reagents. Moreover, our method has low energy consumption by using milliampere-level current. It is a green and efficient method for the generation of hydroxyl radicals. The kinetic study of hydroxyl radical generation can quantitatively predict the concentration changes with process parameters and provide a good prediction of hydroxyl radical generation, which is crucially important in industrial applications.
27 citations
TL;DR: In this paper, a novel application of artificial neural networks (ANN) combined with Taguchi orthogonal experimental design methodology (27 runs, 3 levels, 6 factors) was introduced for modeling and optimization of a new alternating pulse current electrocoagulation-flotation (APC-ECF) process for the removal of humic acid (HA) from aqueous media.
27 citations
TL;DR: A versatile synthesis of poly(styrene-block-acrylic acid) diblock copolymer/Fe3O4 magnetic nanocomposite was achieved for environmental applications, and particularly for the removal of antibiotic compounds, which resulted in the maximum removal efficiency of ciprofloxacin.
Abstract: There are different ways for antibiotics to enter the aquatic environment, with wastewater treatment plants (WWTP) considered to be one of the main points of entrance. Even treated wastewater effluent can contain antibiotics, since WWTP cannot eliminate the presence of antibiotics. Therefore, adsorption can be a sustainable option, compared to other tertiary treatments. In this direction, a versatile synthesis of poly(styrene-block-acrylic acid) diblock copolymer/Fe3O4 magnetic nanocomposite (abbreviated as P(St-b-AAc)/Fe3O4)) was achieved for environmental applications, and particularly for the removal of antibiotic compounds. For this reason, the synthesis of the P(St-b-AAc) diblock copolymer was conducted with a reversible addition fragmentation transfer (RAFT) method. Monodisperse superparamagnetic nanocomposite with carboxylic acid groups of acrylic acid was adsorbed on the surface of Fe3O4 nanoparticles. The nanocomposites were characterized with scanning electron microscopy (SEM), X-ray diffraction (XRD) and vibrating sample magnetometer (VSM) analysis. Then, the nanoparticles were applied to remove ciprofloxacin (antibiotic drug compound) from aqueous solutions. The effects of various parameters, such as initial drug concentration, solution pH, adsorbent dosage, and contact time on the process were extensively studied. Operational parameters and their efficacy in the removal of Ciprofloxacin were studied. Kinetic and adsorption isothermal studies were also carried out. The maximum removal efficiency of ciprofloxacin (97.5%) was found at an initial concentration of 5 mg/L, pH 7, adsorbent’s dosage 2 mg/L, contact time equal to 37.5 min. The initial concentration of antibiotic and the dose of the adsorbent presented the highest impact on efficiency. The adsorption of ciprofloxacin was better fitted to Langmuir isotherm (R2 = 0.9995), while the kinetics were better fitted to second-order kinetic equation (R2 = 0.9973).
27 citations
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