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Showing 4 results for Adsorbent
Application of Rice Husk Biochar to Desalinate Irrigation Water
R. Rostamian, M. Heidarpour, S.f. Mousavi, M. Afyuni,
Volume 19, Issue 71 (6-2015)
Abstract

In recent years, use of carbon-based adsorbents has increased in pollution reduction from aqueous solutions. Biochar is a carbon-rich porous material, with low costs, and environmentally friendly, which is prepared by pyrolysis of biomass. In this study, potential of rice husk biochar to desalinate irrigation water with EC of 5, 15 and 25 dS/m was investigated. The effect of pyrolysis temperatures of 400 (RHB4), 600 (RHB6) and 800 (RHB8) on selected physicochemical characteristics and their desalination power was considered. The results showed that pyrolysis temperature has a significant effect on biochar properties. RHB6 with 301.1 mg g-1 desalination capacity was more efficient than the other biochars. This adsorbent had maximum surface area (211 m2 g-1) and total pore volume (0.114 cm3 g-1). The results of this study could open new horizons to manage the agricultural wastes and simultaneously reduce the cost of irrigation water.


Optimization of the Mixing Scheme of the Porous Concrete to Reduce Urban Runoff
M. Javaheri Tehrani, S. F. Mousavi, J. Abedi Koupai, H. Karami,
Volume 24, Issue 2 (7-2020)
Abstract
In the last few decades, the use of porous concrete to cover the sidewalks and pavements as an interface to collect the urban runoff has been increased. This system is economically more efficient than other runoff-pollution reduction methods. To design a runoff control system and reduce its pollution, it is necessary to determine the hydraulic and dynamic properties of the porous concrete (with and without additives). In this research, the effects of cement type (2 and 5), water to cement ratio (0.35, 0.45 and 0.55), fine grains percent (0, 10 and 20%), the type of additive (pumice, industrial pumice, perlite and zeolite), and the added additive percent (5, 10, 15 and 20%) on the physical properties of the porous concrete (porosity, hydraulic conductivity and compressive strength), each with three replications,  were  investigated using robust design. Qualitek-4 software was also used to discuss the results. The results showed that to obtain the highest porosity in the mixing scheme of the porous concrete, no fine grains, cement type 2 and 15% industrial pumice should be used, and water to cement ratio should be 0.35. Also, the water to cement ratio of 0.55, 0% fine grains, type 2 cement and 15% industrial pumice resulted in the highest value of hydraulic conductivity in the porous concrete. Finally, the water to cement ratio of 0.55, 20% fine grains, type 2 cement and 5% zeolite led to the maximum compressive strength. In general, it was not possible to reach a logical conclusion in this research with the least costs without employing the robust design.

Use of Modified Nano Particles of Beech Leaves for Nitrate Removal from Aqueous Solutions in the Column System
T. Dehgan, M. A. Gholami Sefidkouhi, M. Khoshravesh, N. Samadani Langroudi,
Volume 25, Issue 1 (5-2021)
Abstract
In this research, the nitrate removal by beech leaves was investigated in batch and column systems. The batch experiment was performed to address the effect of pH, contact time, adsorbent dosage and initial nitrate ion concentration on the nitrate removal. The results showed that with an increase in pH, the removal efficiency and adsorption capacity were decreased and nitrate removal by millimeter and nano adsorbent beech leaves reached equilibrium 120 and 90 minutes after experiment, respectively. With an increase in the nitrate concentration, the removal efficiency was decreased from 59.2% to 39.7% and 82.1% to 69.9% for millimeter and the nanoparticles of Beech leaves, respectively. In fixed-bed column adsorption experiments, the flow rates of 5, 8 and 11 ml/min and the nitrate concentration of 15, 50 and 120 mg/L were studied. The results showed with an increase in the nitrate concentration from 15 to 120 mg/L, the saturation time was decreased from 240 to 150 and 360 to 270 minutes for millimeter and nanoparticles of Beech leaves, respectively. Thomas, Dose-response and Yoon-Nelson models were fitted to the results of the continuous experiments. The Thomas model fitted the experimental data with high accuracy. Compared to the adsorbents, nano-adsorbent had more adsorption capacity in the batch and column systems. 

Production of Cyanobacterial Microscale Adsorbent by Hydrothermal Method for Pre-concentration of Cadmium from Water
T. Mohammadi Arian, G. Rahimi, R. Khavari Farid,
Volume 29, Issue 1 (4-2025)
Abstract
Heavy metal pollution is considered a serious risk to the environment and human health due to its toxicity and indestructibility. Measuring and monitoring little concentration (even lower than the detection limit of the device) in the case of dangerous and biostable pollutants such as cadmium in natural water samples is a necessity. Solid-phase extraction using carbon adsorbents is the most efficient and common method of pre-concentration of heavy metals from environmental samples. The carbon adsorbent used in solid phase extraction must have favorable physical and chemical characteristics, along with low cost and biocompatibility. In this research, Aphanocapsa cyanobacterial cells were used as a cheap precursor to make a microscale absorbent using the hydrothermal method. The qualitative and absorption characteristics of this adsorbent were evaluated using instrumental analysis tests and chemical tests based on cadmium. The absorbent is made in the form of relatively spherical particles (with a size of less than 10 micrometers) with a rough surface and a specific surface area of 382.02 square meters per gram. The efficiency of cadmium absorption of absorbent was in a wide range of pH (3 to 8) and more than 90% due to the buffering effect. The absorbent surface was rich in oxygen and nitrogen functional groups, such as hydroxyl, isothiocyanate, and carbonyl. The cadmium absorption isotherm was the best fit with the Freundlich nonlinear model, and the cadmium absorption rate was the best fit with the pseudo-second-order nonlinear model. The calculation variables related to the Freundlich model, including the inverse of the absorption intensity, showed that the adsorbent has a great tendency to absorb low concentrations of cadmium. Cadmium had the most and least competition for absorption on the adsorbent with alkali metal cations and heavy metal cations, respectively. The resistance of the adsorbent against the increase of ionic strength and the concentration of competing cations was equal to 4 and 20 mg/liter, respectively. The washing efficiency of the adsorbent loaded in the adsorbent-to-solution ratio (1:1000), at a normal concentration of 0.3 and a volume of 160 microliters of detergent (nitric acid), reached its maximum value. According to the findings of this research, the carbon adsorbent originating from the cyanobacterium Aphanocapsa can be an efficient adsorbent to use in the solid phase extraction of cadmium to reduce environmental pollution due to its unique properties.

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