The Effect of Activated Carbon Using on Aroma and pH Values in Yogurt Fermentation

Yogurt is a known food item all over the world. Consuming yogurt can be quite difficult for people with lactose intolerance at times. In addition to its active carbon adsorbent feature, it is a lactose chelate. It is aimed to use yoghurt prepared by using activated carbon for nutritional purposes. For this purpose, aroma and pH changes in yogurt made with activated carbon compared to classical yogurt production were studied. It was determined that the active carbon usage method used in the study did not cause any aroma change in yoghurt, however, it increased the pH. This result makes us think that lactose cannot be used by yogurt microorganisms and that yogurt with activated carbon may be an alternative for lactose intolerant people who want to consume yogurt.

Beta-Cyclodextrin-Decorated Magnetic Activated Carbon as a Sorbent for Extraction and Enrichment of Steroid Hormones (Estrone, β-Estradiol, Hydrocortisone and Progesterone) for Liquid Chromatographic Analysis

A β-cyclodextrin-decorated magnetic activated carbon adsorbent was prepared and characterized using various analytical techniques (X-ray diffraction (XRD), scanning electron microscopy–electron diffraction spectroscopy (SEM-EDS) and transmission electron microscopy (TEM)), and the adsorbent was used in the development of a magnetic solid-phase microextraction (MSPE) method for the preconcentration of estrone, β-estradiol, hydrocortisone and progesterone in wastewater and river water samples. This method was optimized using the central composite design in order to determine the experimental parameters affecting the extraction procedure. The quantification of hormones was achieved using high-performance liquid chromatography equipped with a photodiode array detector (HPLC-DAD). Under optimum conditions, the linearity ranged from 0.04 to 300 µg L−1 with a correlation of determinations of 0.9969–0.9991. The limits of detection and quantification were between 0.01–0.03 and 0.033–0.1 µg L−1, with intraday and interday precisions at 1.1–3.4 and 3.2–4.2. The equilibrium data were best described by the Langmuir isotherm model, and high adsorption capacities (217–294 mg g−1) were obtained. The developed procedure demonstrated high potential as an effective technique for use in wastewater samples without significant interferences, and the adsorbent could be reused up to eight times.

Heat and Mass Transfer in an Adsorbed Natural Gas Storage System Filled with Monolithic Carbon Adsorbent during Circulating Gas Charging

Adsorbed natural gas (ANG) technology is a promising alternative to traditional compressed (CNG) and liquefied (LNG) natural gas systems. Nevertheless, the energy efficiency and storage capacity of an ANG system strongly depends on the thermal management of its inner volume because of significant heat effects occurring during adsorption/desorption processes. In the present work, a prototype of a circulating charging system for an ANG storage tank filled with a monolithic nanoporous carbon adsorbent was studied experimentally under isobaric conditions (0.5–3.5 MPa) at a constant volumetric flow rate (8–18 m3/h) or flow mode (Reynolds number at the adsorber inlet from 100,000 to 220,000). The study of the thermal state of the monolithic adsorbent layer and internal heat exchange processes during the circulating charging of an adsorbed natural gas storage system was carried out. The correlation between the gas flow mode, the dynamic gas flow temperature, and the heat transfer coefficient between the gas and adsorbent was determined. A one-dimensional mathematical model of the circulating low-temperature charging process was developed, the results of which correspond to the experimental measurements.

Application of carbon monolith based on exfoliated graphite for sorption and subsequent chromatographic determination of volatile organic compounds in soil air

The possibility of using a new graphene-based carbon monolith for searching new oil deposits or branches adjacent to the already registered oilfields by areal geochemical survey is demonstrated. The material has been developed at the Faculty of Chemistry of M. V. Lomonosov Moscow State University. Sorption of volatile organic compounds (VOCs) from soil air at the oilfield was carried out using two sorbents (carbon adsorbent and Tenax-TA traditionally used for such analyses) with subsequent determination by gas chromatography with mass spectrometric detection and thermal desorption as a way of sample injection (TD/GC/MS). The new material absorbs more hydrocarbons (n-alkanes and monoaromatics) in the range from C8 to C16 than Tenax-TA, the intensities of the chromatographic peaks of the compounds also being higher. The phenomenon of irreversible sorption from carbon materials is observed for VOCs from C17 and more. However, the concentration of such substances in the soil air is rather low due to the low pressure of saturated vapors of these compounds under normal conditions. Hence, the chromatogram of carbon monolith reflects the macro-characteristics of this oil deposit better than Tenax-TA. To increase the sensitivity of the determination, a preliminary optimization of thermal desorption conditions was carried out. The values of the helium flow rate through the sorbent sample and the desorption time of the compounds are chosen to get the largest peak area. The regeneration of sorbent samples is carried out to provide the possibility of their reusage. Tenax-TA decomposes at lower temperatures compared to carbon sorbent and thus cannot be purified completely unlike the new monolith. The graphene-based sorbent is reusable and much cheaper in the manufacture than imported polymer Tenax-TA since it is made of domestic materials.

Experimental study of the thermal management process at low-temperature circulating charging of an adsorbed natural gas storage system

Adsorbed natural gas (ANG) technology is a promising alternative to traditional compressed (CNG) and liquefied (LNG) natural gas systems. Nevertheless, energy efficiency and storage capacity of ANG system strongly depends on thermal management of its inner volume because of significant heat effects occurring during adsorption/desorption processes. At the same time low-temperature charging of ANG system provides its higher storage capacity as well as increased fire and explosion safety due to lower operating pressure and “bound-state” of gas molecules with the surface of adsorbent. In present work, a prototype of low-temperature circulating charging system for ANG storage tank filled with shaped microporous carbon adsorbent was studied experimentally in wide ranges of pressures (0.5-3.5 MPa) and gas flow rates (8-18 m3/h).

Outlook on the Carbon-Based Materials for Heavy Metal Removal

Carbon-based materials, including graphene (GR), carbon nanotubes (CNTs), activated carbon, and biochar, are the most common materials often applied to separate heavy metals from the water stream. A key feature of carbon adsorbent is the functional group of its adjustable surfaces. Both GR and CNTs exhibit the most favorable materials and may be the right choice in the future because of their excellent nature and unique structure. In order to commercialize the use of carbon absorbent in the removal of heavy metals, the mechanism of adsorption of carbon on heavy metals must be fully understood. In view of the good properties of carbon-based materials, a detailed study of their characteristics and synthesis, and modifications should be highlighted. Therefore, this article will discuss the properties, modifications, and use of carbon-based materials as adsorbents for various hazardous metal ions.

KINETIC STUDIES OF Cu ADSORPTION FROM SASIRANGAN LIQUID WASTE USING RICE HUSK ACTIVATED CARBON

The industry of sasirangan – traditional fabric of Banjar Tribe – has been one of prime commodities of South Kalimantan. The coloring process in sasirangan production used a lot of chemical elements containing heavy metals and its waste potentially pollute the environment. One of the heavy metal waste contained is copper (Cu) which is toxic to aquatic organisms and humans. The treatment for sasirangan liquid waste can be done by adsorption process using activated carbon as adsorbent. This study aims to determine the appropriate kinetic model for adsorption of Cu metal from sasirangan liquid waste using activated carbon adsorbent made from rice husks.The process was conducted by batch system with chemical and physical activation. Chemical activation was done by soaking the activated carbon of rice husk with HCl solution for 24 hours. While physical activation was carried out by burning in a furnace at 500̊C for 2 hours. The adsorption treatment was given on sasirangan waste samples with variations on contact time (30, 60 and 120 minutes). The results of kinetics study showed that the adsorption process of Cu from sasirangan liquid waste onto rice husk activated carbon adsorbent followed first-order reaction kinetics with a correlation coefficient value (R2) of 0.96 and adsorption rate constant (k1) of 0.0044 min-1.

Utilization of Macadamia Nutshell Residue for the Synthesis of Magnetic Activated Carbon toward Zinc (II) Ion Removal

In this study, macadamia nutshell residue, a prevalent leftover and green agricultural waste in Vietnam, was utilized to prepare a magnetic activated carbon adsorbent. The obtained material was characterized by its surface functionalities, elemental composition, crystalline structure, and magnetic properties. The characterization results revealed that the composite comprised Fe3O4 nanoparticles attached to the carbon matrix. The saturation magnetization (Ms) of the composite was found to be 38.2 emu g−1, indicating a convenient separation of the solid adsorbent from aqueous media using an external magnetic field. The feasibility of removing zinc (II) ion from an aqueous solution of the activated carbon/Fe3O4 (AC/Fe3O4) composite was examined. The adsorption kinetics were best explained by the Elovich model and the pseudo-second-order model. The adsorption capacity at equilibrium and the initial rate of Zn2+ adsorption determined by the pseudo-second-order model were 22.73 mg g−1 and 4.18 mg g−1 min−1, respectively. The implications of this study are that a low-cost, green, and magnetically separable material prepared by a large-scale available solid waste can be a promising adsorbent for the elimination of heavy metals.