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Removal of heavy metals by bioadsorbents is one of the effective and inexpensive methods for water and wastewater treatment. The aim of this study was to investigate the ability of tea pulp in order to remove Cu2+ and Pb2+ metals in two states of adsorption (single element and two elements) from aqueous solutions.

Experiments were performed on synthetic and real samples at ambient temperature. The effect of solution pH, adsorbent dose, contact time, and initial concentration on single and competitive removal of copper metals and lead was studied. Adsorption kinetics and adsorption isotherms were analyzed by pseudo-second-order kinetic equations, Elovich model and intraparticle diffusion, Freundlich and Langmuir equations, respectively.

The maximum adsorption capacity for copper and lead was observed at pH = 5-8 and pH = 4-8, respectively. Maximum adsorption capacity for copper and lead by tea pulp in single-element solution (single) was 37.17 and 48.54 mg/g and in two-element solution (competitive), was 28.41 and 43.47 mg/g, respectively. The adsorption reaction of heavy metals by tea pulp followed the Longmuir isotherm and pseudo-second-order kinetic models.

Tea pulp as an inexpensive bioadsorbent is able to remove about one-third of the copper, and approximately, half of lead from aqueous solutions, so its use in the treatment of aqueous solutions will be beneficial.

Urban and industrial development has increased the concentration of heavy metals in various environments, and also, increased their amount in dust fall particles. The aim of this study was to determine and assess the risk of heavy metals in air dust fall particles.

Sampling of air dust fall particles was performed using the British model Dust Fall Jar devices. Heavy metals concentrations in the samples were determined using an atomic absorption spectrometer device. Then, the risk assessment of heavy metals in air dust fall was calculated by three indicators including enrichment factor (EF), geo-accumulation index (Igeo), and integrated pollution index (IPI). Data were analyzed using descriptive statistics and Excel 2016 software.

Zn was the most abundant heavy metal. The results of EF index showed that the highest degree of enrichment of dust fall particles with heavy metals is related to Ag and the lowest one is related to Cr. Also, the changes of Mean of both Igeo and IP indicators were as Ag > Pb > Zn > Cd > Cu > Co > Cr.

According to the results, it can be concluded that Cr metal is originated from the earth and other metals are of man-made origin and are mainly due to the emissions of vehicles and industries. Also, on average, the samples had very low pollution in relation to all metals. Although the amount of pollution caused by heavy metals has not exceeded the allowable limits, but considering industrial development programs in the region, continuous measures to control air pollution caused by industries, are absolutely necessary.

The presence of medicines in the environment is considered as a serious threat to the human health. The entrance of these substances into the water sources causes soil pollution, which eventually leads to the environmental pollution and it creates some problems for the public health. Also, increasing antibiotic resistant bacteria has attracted the attention of researchers to the use of natural resources such as marine products, for producing new antibiotics. The aim of this study was to evaluate antimicrobial activities of powdered cuttlebone against Klebsiella oxytoca, Staphylococcus aureus, and Aspergillus flavus.
At first, cuttlebones were washed, dried, and powdered. Then, the powdered cuttlebone was characterized. In the next step, its antimicrobial activities were evaluated using agar well diffusion technique, and minimum inhibitory concentration (MIC) was calculated.
The powdered cuttlebone was found to be effective against K. oxytoca (24 mm, MIC: 10-1 mg/mL), but no antimicrobial response was found against S. aureus. Also, the powdered cuttlebone antifungal activity and MIC against A. flavus were recorded 23 mm and 10-1 mg/mL, respectively.
The obtained results suggest antimicrobial activities of powdered cuttlebone, which are concentration dependent. Furthermore, cuttlebone can be used as an accessible natural source to provide novel, low cost, and safe antimicrobial agents.

The presence of antibiotics such as metronidazole in wastewater even at low concentrations requires searching for a suitable process such as advanced oxidation process (AOP) to reduce the level of pollutants to a standard level in water.
In this study, zinc oxide (ZnO) nanoparticles were synthesized by thermal method using zinc sulfate (ZnSO4) as a precursor, then, stabilized on stone and was used as a catalyst, in order to degrade metronidazole by photocalytic process. Effective factors on the removal efficiency of metronidazole including the initial metronidazole concentration, contact time, pH, and 0.9 gL-1 ZnO stabilized on the stone surface were investigated.
The X-ray diffraction (XRD) studies showed that the synthesized nanomaterials have hexagonal Wurtzite structure. Also, scanning electron microscopy (SEM) analysis revealed that the average crystalline size of the synthesized ZnO particles was in the range of 1.9-3.2 nm. The spectra represented a sharp absorption edge at 390 nm for ZnO nanoparticles corresponding to band gap of 3.168 eV. The BET-BJH specific surface area of the synthesized ZnO nanoparticles was 25.504 m2/g. The EDS spectrum of ZnO nanoparticles showed four peaks, which were identified as Zn and O. The maximum removal efficiency was 98.36% for the synthetic solution under a specific condition (pH = 11, reaction time = 90 minutes, ZnO concentration = 0.9 gL-1, and the initial concentration of metronidazole = 10 mgL-1). The photocatalytic degradation was found to follow pseudo-first-order degradation kinetics.
Therefore, the ZnO nanoparticles synthesized by thermal decomposition are suitable and effective photocatalytic materials for degradation of pharmaceutical contaminants.

Sulfur dioxide gas is known to include pollutants that are harmful to human health and the environment. Therefore, due to the increase of industrial activities, SO2 gas pollution control is very important. The purpose of this study was to investigate the efficiency of sulfur dioxide removal by iron oxide nanoparticles deposited on clinoptilolite zeolite. Two materials, natural clinoptilolite and clinoptilolite containing iron oxide nanoparticles, were used as adsorbents of SO2. Both materials were characterized via scanning electron microscopy imaging, infrared spectroscopy, and N2 porosimetry, along with the determination of the thermodynamic properties and kinetics of SO2 adsorption. Therefore, breakthrough experiments were carried out at different temperatures and with different contact times. Sulfur dioxide adsorption of a real sample was considered for both adsorbents. The adsorption efficiency of SO2 in the synthetic and actual sample was obtained at 80.3% and 66.7%, respectively, under optimum conditions (temperature of 25°C and duration of 28.5 minutes) by modified zeolite with iron oxide nanoparticles. The removal percentage average of SO2 was also obtained in the synthetic and actual sample at 43.8% and 31.3%, respectively, by zeolite in optimum conditions (temperature of 25°C and contact time of 20.5 minutes). The adsorption of SO2 with both adsorbents followed the pseudo-second-order equation and the adsorption process was an exothermic and spontaneous process. The addition of these iron oxide nanoparticles had a positive impact on the surface area and on SO2 capacity.