فهرست مطالب seyed gholamreza moussavi

With industrial development and population growth, the emerging contaminants enter into the natural water resources. Therefore, in this study Adsorption potential of NH4Cl-induced activated carbon (NAC) was investigated to remove antibiotic sulfanilamide from contaminated water.

Materials & Methods:

The effect of operational conditions including solution pH, NAC concentration, sulfanilamide initial concentration and contact time were studied.

NAC and SAC had specific surface area of 1029, 1024 and mean pore volume of 2.64, 2.23nm, respectively. With increasing the NAC concentration to 1 g/L, sulfanilamide adsorption efficiency increased to 84.4% within 40 min. Then the adsorption slightly increased with the increase in the contact time to 120 min and reached to its maximum adsorption of 99.2%. The maximum adsorption percentage of sulfanilamide onto SAC under similar conditions reached to 49.2%. The kinetics analysis showed that experimental adsorption data for both NAC and SAC were best fitted to the pseudo-second-order model. The maximum adsorption capacity of sulfanilamide onto NAC and SAC, calculated by the Langmuir model, was 238.1 and 87/7 mg/g, respectively.

Generally, these results showed that NAC was an efficient adsorbent with high removal efficiency for eliminating the antibiotics from the contaminated water streams

Hexavalent chromium (VI) is a very strong oxidizing agent that, despite its many uses in various industries, duration of the exposure can lead to lung cancer, deep wounds (in the hands, arm, tongue and palate), nasal septum perforation, burning and inflammation in the nose, lung and upper respiratory tract, asthma, contact dermatitis, damage to the kidneys and liver, and skin allergy. This study aimed to determine the activated carbon efficiency in chromium adsorption (VI) from air flow and its effective parameters.
Material and In this experimental study, chromium mists were generated by a nebulizer (3A model, Italy). Performance of activated carbon in the Cr (VI) adsorption and its influencing factors such as air flow rate (1 and 3L/min), the initial Cr concentration (0.05, 0.15, 1 and 10 mg/m3) and bed depth (2.5, 5 and 10 cm) were investigated. Yoon-Nelson and Thomas models were used to predict performance of adsorbent column and correlation test was used to determine accordance between the model and actual data.
Activated carbon adsorption capacity increased with increasing of bed depth but decreased with increasing of flow rate and inlet concentration. The results showed that the Yoon-Nelson and Thomas models with a correlation coefficient above 0.9953 matched with the experimental data.
The results indicated that activated carbon has a high efficiency in Cr (VI) adsorption, so that its efficiency at flow rate of 3 L/m, depth of 5 cm and concentration of 20 TLV and TLV was 85.42 and 71.83 percent respectively.

Objectives Type of adsorbent is the most important parameter to adsorb volatile organic compounds (VOCs) from the air stream. Application of a selective adsorbent could lead to the higher efficiency and lower costs in the adsorption processes. The current study aimed at investigating the efficiency of manganese oxide impregnated on GAC support (MnO/GAC) to remove toluene from air stream. The efficiency of MnO/GAC and GAC absorbents for toluene removal were compared at the same experimental conditions.
Methods The MnO/GAC preparation method was Sol-gel. Retention time (0.5, 1, 1.5, 2, and 4 seconds), inlet toluene concentration (100, 200, 300, and 400 part per million, by volume) and the temperature of the air stream (25, 50, 75, and 100˚C) were examined as the main functional parameters in the adsorption process.
Results Breakthrough time of MnO/GAC adsorbent in comparison to that of the plain GAC increased 6% to 11% at the retention time of 0.5 to 4 seconds. Adsorption capacity of GAC and MnO/GAC increased 67.9% and 61.1% by increasing inlet toluene concentration from 100 to 400 ppmv, respectively. Breakthrough time of GAC and MnO/GAC decreased 57.9% and 59.6% by increasing inlet toluene concentration from 100 to 400 ppmv, respectively. Breakthrough time of GAC decreased from 41 to 26 hours by increasing the temperature of the air stream from 25˚C to 100˚C. Direct air temperature increase affected the MnO/GAC efficiency for toluene adsorption and the breakthrough time increased from 46 to 57 hours.
Conclusion Results of the current study showed that MnO/GAC could be applied as a good substitution for GAC in the adsorption of VOCs from air streams.

Catechol, a phenolic compound, is carcinogenic and toxic and enters the environment through industrial waste. The main objective of this paper was to evaluate the performance of the ozone in the removal of catechol from water. Catechol concentration was determined using a high-pressure gas chromatography (HPLC). Concentration of ozone and chemical oxygen demand (COD) was measured using standard methods. Efficiency of ozonation process in catechol degradation at optimum conditions (pH 10, catechol concentration 100 mg/L, ozone dosage 2.1 mg/min and reaction time 20 min) was 100%. Ozonation process can be used alone if the catechol concentration is less than 100 mg/L. Also, due to the synergistic effect of ozonation process with biological processes, this process can be used as pre-treatment if the catechol concentration is less than 1000 mg/L. The ozonation can be regarded as the only treatment and pretreatment process for the degradation of organic chemical compounds that are toxic and resistant to biodegradation.

UV/O3 is among the advanced oxidation processes and is used to break down volatile organic compounds. This study was designed to examine the efficiency of the UV/O3 process in the removal of benzene from the airflow and to study the effects of such factors as relative humidity، ozone dosage، and exposure time on the efficiency of this method Methods and Materials: The present study is of the experimental type and was performed on a laboratory scale. The laboratory equipment consisted of an air pump، an injection pump، mixing chamber، rotameter، an ozone generator، a 15-Watt UV-C lamp، and a humidity generating system (consisting of an impinger and a heater). 80 ppm of benzene was exposed to the combined UV/O3 process under varying conditions of different humidity levels، different ozone dosages، and different exposure times. The different concentrations of benzene before and after exposure to the afore-mentioned process were measured and compared. The data was analyzed using descriptive and inferential statistics and three-way ANOVA

The findings showed that all three factors of relative humidity، ozone dosage، and exposure time affected the efficiency of the UV/O3 process. Increasing the relative humidity enhanced the efficiency of the system in removing benzene up to %60. Additionally، increasing ozone dosage and exposure time led to augmentation of the benzene removal in the UV/O3 process

Given the ease of use and possibility of performing the reaction under the normal conditions of the environment، the UV/O3 method can be used as an effective method in removing benzene from the airflow. Altering variables such as relative humidity، ozone dosage، and exposure time can enhance the efficiency of the system

Benzene is one of the most widely used volatile organic compounds showing severely adverse effects on human health. Removing benzene from the airflow or controlling its amounts، is one of the issues put to discussion in the field of environmental engineering. The objective of this study was to examine the efficacy of the Ultraviolet-C (UV-C) radiations on removing benzene from the airflow under conditions of varying humidity and reaction time in the UV/O3 process.

This was an experimental study which was performed on a laboratory scale. The testing and measurement system included an air pump، an injection pump، a mixing chamber، a rotameter، an ozone generator، a heater، an impinger، and a steel reactor with 45 cm long، and with a net volume of 1. 35 L in which a 15-watt UV-C lamp with a wavelength of 254 nm was placed. Different concentrations of benzene were continuously exposed to the UV/O3 process under varying conditions of reaction time and humidity. The concentrations of benzene before and after exposure to the treatment process were measured taking aforementioned factors into account. The data were analyzed using descriptive and inferential statistics and three-way ANOVA test.

The results demonstrated that increasing the humidity levels up to 60% led to an increase in the efficacy of UV-C in the removal of benzene، while this efficacy decreased at humidity levels above 60%. Additionally، the findings indicated that increasing the reaction time can lead to the highest benzene removal rates in the presence of humidity (13. 2%، P < 0. 001).

Given the improvement in the efficacy of benzene removal as a result of the simultaneous use of UV and humidity، and the effects of increased reaction times in a process involving the simultaneous use of the UV rays and relative humidity، it can be concluded that the use of UV-C rays in an airflow containing humidity levels of 50% to 60% can have a positive potentiating effect on the efficacy.