رضا درویشی چشمه سلطانی

Waste separation and recycling have become crucial in managing waste materials, especially with the involvement of parents and student groups. As such, a study was conducted to investigate the predictors of waste separation behavior in elementary school students of Khorram Abad, based on the theory of planned behavior.

This is an analytical cross-sectional study that was carried out on 200 primary school students in Khorram Abad during the academic year of 2020. The sampling was done in a multi-stage manner from eight elementary schools in the city. The study collected information through a reliable and valid questionnaire that included knowledge (nine questions) and theory of planned behavior (26 questions). Statistical analysis was conducted using Mann-Witney and linear regression.

The age of the students and their mothers had a mean of 10.22±0.84 and 36.44±5.43, respectively. There was no significant difference between the level of knowledge and constructs of the TPB and behavior among male and female students. The average waste separation behavior was observed to be 2.37±0.70 (out of 4). Using the regression model of perceived behavioral control and the age of students, it was found that 18% had the highest power to predict the behavior of waste separation in students.

After analyzing the data, it was concluded that although students had a good understanding and attitude towards waste separation, their performance was still inadequate. To improve this, it is crucial to conduct a thorough needs assessment to identify any obstacles preventing proper waste separation behavior. These findings should be prioritized and emphasized in educational materials and programs.

Waste separation education is very important for students because of the important role of this group in attracting parental involvement. Therefore, this study was conducted to investigate the effect of educational intervention based on the theory of planned behavior on the promotion of waste separation at source behavior among the primary school students in Khorramabad City, Iran.

This randomized controlled interventional study was conducted during the academic year of 2020-2021 among the primary school students in the city of Khorramabad. Eight schools were selected in a multi-stage method and the sample size was estimated at a total of 200 people, taking into account at least 100 samples in each group (test and control). Then, the educational intervention was performed based on the results of needs assessment for the experimental group during one month and in the form of three sessions of 60-minute training. The data were collected 2 months after the intervention and were analyzed using SPSS software by using independent t-test, paired t-test, and chi-square test.

Before the educational intervention, except for the score of awareness variable, all variables were not significantly different between the two groups; however, after the intervention, the two groups had significant differences regarding all of the studies variables (P < 0.050). The performance of the intervention group before training was 2.34 ± 0.73, which increased significantly to 3.11 ± 0.45 after training (P < 0.001).

Educational intervention based on the theory of planned behavior by promoting attitudes and evaluating the behavioral consequences of students in the field of waste separation behavior at source eventually improved the behavior of students; it is suggested that this educational method be implemented in other schools as well.

Contamination of water resources is one of the most important health and environmental concerns related to textile wastewater. In the present study, sodium alginate natural polymer was implemented as adsorbent for the adsorption of an organic dye (Basic Red 46) in aquatic phase. As a novel approach, adsorption process was enhanced using ultrasonic irradiation.

In this study, at first, sodium alginate polymeric adsorbent was synthesized. Then, the enhanced adsorption process of the dye was performed in a discontinuous flow experimental reactor located inside an ultrasonic bath. The effects of parameters such as initial pH, reaction time, dye concentration and adsorption content on the enhanced adsorption of the target pollutant were investigated. Residual concentration of the dye in the solution was measured using a UV-visible spectrophotometer at 530 nm.

The results showed that adsorption alone was responsible for the decolorization efficiency of 20.8%, while ultrasound-assisted adsorption of organic dye resulted in the enhanced removal efficiency of 63.2%. Increasing initial concentration of the dye from 3 to 10 mg/L led to decreasing the removal efficiency from 83.1 to 42.9%, respectively. With increasing adsorbent dosage from 0.3 to 0.7 g/L, the removal efficiency increased from 41.9 to 67.3%, respectively. Increasing the amount of adsorbent to 1.0 g/L resulted in the remarkable reduction in the removal of organic dye. The adsorption data obeyed the Langmuir model with the maximum adsorption capacity of 9.2 mg/g.

It can be indicated that the ultrasound can be applied as an efficient physical agent for the enhanced adsorption of organic dyes onto natural polymeric compounds like calcium alginate.

The aim of this investigation was to synthesize ZnO nanoparticles and compare their photocatalytic activity with its commercial form in terms of photocatalytic oxidation of methylene blue dye in aqueous environment.
In this study, ZnO nanoparticles were prepared using hydrogen peroxide treatment and were immobilized on glass surface using thermal immobilization. The prepared glasses were placed inside the reactor. Finally, the photocatalytic degradation of methylene blue in the reactor was investigated using different parameters.
Findings: The results of the study showed that the photocatalytic process with the synthesized catalyst (96.35%) had higher efficiency compared to the commercial catalyst (82.87%) in terms of degradation of 5 mg/l methylene blue within 120 minutes. Subsequently, using the synthesized catalyst, at distances of 2, 3.5, and 5 cm between the UV lamps and glass plates containing immobilized ZnO nanoparticles, the dye removal rates were 96.35%, 63.34%, and 45.31%, respectively.
According to the findings, it can be concluded that synthesized ZnO nanoparticles can be applied as an efficient catalyst in photocatalytic processes.

The dyestuff manufacturing and textile industries consume a high volume of water and produce a great amount of wastewater containing various toxic substances. This study was conducted to evaluate the possibility of using activated carbon prepared from milk vetch wood for removing methylene blue dye from synthetic wastewater.
This research was carried out in laboratory scale with using of 100 ml volume of batch photoreactor and in chemistry laboratory of Ilam university of medical sciences (summer 2013). Activated carbon was prepared using chemical-thermal method. The effect of pH, contact time, dye concentration and adsorbent dosage on the adsorption of methylene blue dye as model organic dye was studied and kinetic and isotherm of the adsorption process was investigated. The dye concentrations were measured via spectrophotometer (665 nm wavelength).
Findings: The results showed that activated carbon prepared from milk vetch has high potential to remove dye molecules. The MB absorption capacity rates were 38.66, 40 and 48.5 mg/g respectively at pH of 3, 7 and 11 for the initial dye concentration of 50 mg/L and 0.1 g/0.1L absorbent mass at 30 minute. Also dye absorption rates were 40, 69.66, and 78.04 mg/g on absorbent respectively for 50, 100, and 150 mg/l dye concentration, at pH of 7, 1 g/0.1L absorbent mass, and 30 minutes time. Adsorption data followed Langmuir isotherm model (R2=0.99).
Discussion & Based on the obtained results, activated carbon prepared from milk vetch can be considered as an efficient adsorbent for removing dye from aqueous phase.

The presence of organic dyes, discharged by textile industries, in aqueous environments can cause detrimental effects on aquatic life and subsequently human health. Therefore, the decolorization of aquatic environments is mandatory to protect the environment. For this reason, in the present study, nano-sized diatomite was immobilized within calcium alginate as a nanocomposite adsorbent for removing organic azo dye (Direct blue 15) from aqueous solutions.
First of all, Iranian diatomite was grinded in a planetary ball mill equipped with tungsten carbide cup for 20 h to achieve nanoparticles of the diatomite. For the immobilization of nanostructured diatomite, a 2% sodium alginate solution was used. Scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infra-red (FT-IR) spectroscopy were used to characterize immobilized nano-diatomite. Fifty milliliter Erlenmeyer flasks were used as batch flow mode experimental reactors. Working solutions were prepared by the dilution of stock solution (1 g/L) to desired concentrations. The effect of different operational parameters including contact time, initial pH, adsorbent dosage and initial dye concentration along with kinetic and isotherm of the adsorption were evaluated. After each experiment, the residual concentration of the dyes was measured spectrophotometrically.
As results, the adsorption of organic dye increased with increasing contact time and adsorbent dosage, while increasing initial dye concentrations resulted in decreasing the adsorption. The adsorption of DB-15 was favored at basic PH. The immobilization of diatomite led to enhancing the adsorption of DB-15 compared to diatomite alone. According to the obtained correlation coefficient, the adsorption of DB-15 obeyed pseudo-second order kinetic model and Langmuir isotherm model. The maximum adsorption capacity of diatomite/alginate nanocomposite for the adsorption of DB-15 were found about 33.22 mg/g.
The results of this study showed that the diatomite/alginate nanocomposite can be used effectively for treating colored effluents containing azo dyes. Because of its high efficiency, availability of diatomite mines in our country, it can be used as an economic adsorbent for the decolorization of textile effluents.

The main objective of the present study was to investigate Cd(II) adsorption by immobilized silica nanopowder within calcium alginate and to determine the isotherm, kinetics, and thermodynamics of the adsorption process. Batch flow mode reactors were used to investigate the effects of initial pH, contact time and metal ion concentration on Cd(II) adsorption. The optimal contact time and initial pH for Cd(II) adsorption were found to be 120 min and 4.0, respectively. Increasing Cd(II) ion concentration from 10 to 1000 mg/L led to increasing adsorbed Cd(II) ions from 5.71 to 100.65 mg/g. The results showed that the Langmuir isotherm model was the best model to describe the experimental data (R2=0.997). The maximum adsorption capacity (qm) for Cd(II) adsorption onto the adsorbent was estimated to be 72.99 mg/g. Based on the mean free energy of adsorption (E) obtained from Dubinin-Radushkevich (D–R) isotherm model, Cd(II) adsorption onto immobilized silica nanopowder follows a chemical mechanism (E=8.451 kJ/mol). The kinetic study indicated that the pseudo-second order model was a more suitable model than the pseudo-first order one for describing Cd(II) adsorption (R2=0.999). Additionally, the negative ∆Hº and ΔGº values demonstrated an exothermic and spontaneous Cd(II) adsorption onto immobilized silica nanopowder.

One of the major disadvantages of zinc oxide in aqueous solution is the light unstability of this catalyst due to the light corrosion which causes substantial reduction of photocatalytic activity of zinc oxide and application of it for environment purification. In this study, the performance of photocatalytic of UV/Silica-ZnO was compared in dye and COD removal by UV/ZnO. This study was conducted in the lab scale. The various percentages of silica nanoparticles in the combination of zinc oxides nanoparticles were fixed onto the glass by UV/Silica-ZnO process and were examined at optimum condition in the UV/ZnO process. XRD patterns of zinc oxide nanoparticles alone and accomplished by silica were conducted. X-ray diffraction, confirm that there is no impurity in nanoparticles. The different percentages of silica (5, 10 and 15%) were tested in combination with zinc oxide nanoparticles. The findings showed that the value of dye and COD removal with contact time of 90 min and 10% silica loading in UV/Silica-ZnO process were 100 % and 81%, respectively and UV/ZnO process were 66% and 44% respectively. According to the obtained results, 10% of silica, in combination with zinc oxide nanoparticles, was the best percentage. Thus, UV/Silica-ZnO process can be used as an effective method for removing dye from textile waste waters.

Electrocoagulation is one of the technologies which have been considered by many researchers in recent years. This process has many advantages including high efficiency, no need to chemical addition, low sludge production, capability of process control, easy to operation and maintenance. Bipolar electrodes system is one of the electrocoagulation techniques which can be used for increasing the process efficiency and better distribution of the electric current. The aim of this study was to remove hexavalent chromium from aqueous solution by electrocoagulation technique. Response surface methodology (RSM) was used to optimize the parameters involving in the process, and the effect of current density, initial chromium concentration and pH on the process were investigated. At optimal conditions, for the highest chromium removal (>90%), the optimum initial chromium, reaction time, current density and pH were found to be 117 mg/L, 50 min, 11.75 mA cm-2 and 4.5, respectively. It can be stated that electrocoagulation is an efficient technique for separation and removing high chromium concentration from aqueous solutions.

Effluents containing synthetic dyes are hazardous to ecological systems and public health. Methylene blue is an important chemical aromatic dye which commonly used in textile industries. Due to being aromatic، it is often toxic، carcinogenic and mutagenic. The goal of this study was to investigate the efficiency of ZnO nano particles photocatalytic process for decolorization of methylene blue by UV irradiation from synthetic textile wastewater.

In this study methylene blue photocatalytic decomposition using Ultraviolet (UV) irradiation and zinc oxide nano particles having less than 50 nm in diameter was surveyed. A batch-through Plexiglass reactor having two compartment used to conduct the experiments. Wastewater was flowed to the compartment which contains of nano ZnO stabilized glasses. UV lamps were installed at another compartment. The variables of the study included: exposure time، color concentration، light intensity، and lamp distance to the catalyst surface.

ZnO nano particles characteristics were determined by Scanning Electron Microscope (SEM) and X-ray diffraction (XRD) analysis. Images showed that stabilizes nano particles on glass، their porosity remains in the optimal level. Optimium values for exposure time 120 minutes، color concentration 25 mg/l، light intensity 3950 μW/cm2، and distance to the catalyst surface 1 cm were achieved. At the optimal condition، methylene blue decolorization and COD removal was achieved 92. 2% and 75% respectively

Regarding the conducted experiments، the results of this studyshowed that ZnO/UV photocatalytic process has a significant efficiency in dye decolorization and COD removal. This method could be applied in the full scales.

One of the most important environmental problems is water and soil contamination with heavy metal ions. In this direction, the aim of this investigation was biosorptive removal of Cr (VI) using calcium alginate and determination of isotherm and kinetic of biosorption. Using batch system, biosorption capacity of calcium alginate for removal of Cr(VI) ions was investigated as function of pH, shaking time and Cr(VI) ions concentration. For determination of active bands and biosorbent characteristic, Fourier Transform Infrared (FT-IR) and Scanning Electron Microscopy (SEM) analysis were carried out respectively. Regarding the FT-IR analysis, It was shown that C=O and O–H groups played a significant role in Cr (VI) biosorption onto alginate calcium. The optimum pH was obtained at pH value of 4.0. Suitable fitness between the experimental data and studied isotherm was obtained (R2>0.9). Maximum biosorption capacity of calcium alginate was 84.75 mg/g. The mean free energy of Cr(VI) biosorption (E) was calculated 9.129 kJ/mol. Moreover, the pseudo-second order kinetic model was found to be suitable than the pseudo-first order kinetic model to correlate the experimental data (R2>0.97) and equilibrium was achieved within 120 min. It can be stated that biosorption of Cr (VI) onto calcium alginate occurs through a chemical mechanism. Also, according to maximum biosorption capacity, it can be stated that calcium alginate is an effective and efficient biosorbent.