Дэлгэрэнгүй мэдээлэл

Abstract The widespread presence of antibiotic metronidazole (MNZ) in the environment and its associated harmful effects require effective treatment methods. In this study, a novel, environmental-friendly and metal-free dual-cathode electro-Fenton system was developed to explore the degradation process of MNZ. KOH-activated graphite felt (AGF) served as one of the double cathodes and was mainly utilized to reduce O2 to generate H2O2, while boron (B) and nitrogen (N) co-doped graphite felt (BN-GF) cathode was mainly utilized to activate the in-situ generated H2O2 to form active species to degrade MNZ. The system exhibited excellent catalytic degradation performance (99.9%) and extremely high-rate constant (0.12352 min-1) for MNZ removal at a wide pH range under a low current density. The system also had a wide range of environmental adaptability (satisfactory treatment of various antibiotics in various practical water substrates), good stability and reusability, and significant biotoxicity reduction, etc.. Mechanism analysis showed that •O2- and 1O2 played a primary role in the degradation of MNZ in this system. These results suggest that the environmental-friendly and metal-free dual-cathode electro-Fenton system may provide a promising route for the degradation/removal of organic contaminants.

Electro-reduction of nitrate (NO3–) to ammonia is a promising method to transform the environmental contaminant NO3– to value-added ammonia. Since diverse end-products might be formed and a convenient material preparation process is preferable, it is of great importance to facilely synthesize a high-performance electro- catalyst towards ammonia generation with high selectivity. Herein, a coral-like nitrogen (N) and sulfur (S) co- doped carbon-encapsulated FeS2 composite material (FeS2@NSC) was successfully fabricated for effective electro-reduction of high-concentration of NO3– to ammonia through a simple one-step pyrolysis method. The FeS2@NSC-400 material exhibited remarkable electrocatalytic NH3 production performance with the NH3 yield of 4428.35 μg h− 1 cm− 2 and NH3 Faraday efficiency of 84.75 % at − 1.4 V vs. Ag/AgCl, which outperforms many of the reported electrocatalysts. The unique small cluster coral-like core–shell structure, N, S co-doping and the interaction between inner FeS2 and the outer carbon layer greatly enhanced the electrical conductivity and stability of the material and the adsorption of NO3– and intermediate products, thereby facilitating the electrocatalytic performance of nitrate-to-ammonia. The FeS2@NSC material induced the electrocatalytic reduction of NO3– mainly through direct electron transfer instead of the indirect atomic H* mediation, and the main reduction product NH3 was speculated to derive from the pathway of NO3–* → NO2–* → NO* → HNO* → H2NO* → H2NOH* → NH3.

The widespread occurrence of organic antibiotic pollution in the environment and the associated harmful effects necessitate effective treatment method. Heterogeneous electro-Fenton (hetero-EF) has been regarded as one of the most promising techniques towards organic pollutant removal. However, the preparation of efficient cathode still remains challenging. Herein, a novel metal-organic framework (MOF)-derived Fe/Ni@C marigold-like nanosheets were fabricated successfully for the degradation of oxytetracycline (OTC) by serving as the hetero- EF cathode. The FeNi3@C (Fe/Ni molar ratio of 1:3) based hetero-EF system exhibited 8.2 times faster OTC removal rate than that of anodic oxidation and possessed many advantages such as excellent OTC degradation efficiency (95.4% within 90 min), broad environmental adaptability (satisfactory treatment performance for multiple antibiotics under various actual water matrixes), good stability and reusability, and significant toxicity reduction. The superior hetero-EF catalytic performance was mainly attributed to: 1) porous carbon and Ni existence were both conducive to the in-situ generation of H2O2 from dissolved O2; 2) the synergistic effects of bimetals together with electron transfer from the cathode promoted the regeneration of ≡FeII/NiII , thereby accelerating the production of reactive oxygen species; 3) the unique nanosheet structure derived from the precursor two-dimensional Fe–Ni MOFs enhanced the accessibility of active sites. This work presented a promising hetero-EF cathode for the electrocatalytic treatment of antibiotic-containing wastewaters.

Аж үйлдвэрлэлийн хурдацтай хөгжил, уул уурхай, үйлдвэрлэл, техник технологиуд тасралтгүй хөгжихийн хэрээр тэдгээрийн хэрэглээ, хэрэгцээ, шаардлагууд улам нэмэгдэж байдаг. Үүний үр дүнд бидний хүрээлэн буй орчин болох агаар, ус, хөрсөнд хорт бодисууд хуримтлагдаж улмаар байгаль орчин, хүн, мал амьтны эрүүл мэндэд ноцтой сөрөг нөлөө үзүүлж байгаа нь манай орны хувьд тулгамдаж буй асуудлууд юм. Тиймээс энэхүү судалгааны ажлаар байгалийн нөөцийг эдийн засгийн эргэлтэд оруулах, байгалийн гаралтай хүний эрүүл мэндэд хоргүй шингээгч материалын сонголтод цеолит нь ион солилцооны өндөр идэвх, сүвэрхэг шинж чанараар төгс тохирсон эрдэс бөгөөд энэ шинж чанар дээр үндэслэн хямд, үр ашиг өндөртэй шингээгч композит материал гарган авч, тасралтгүй урсгалтай баганан шингээлт явуулах замаар хар тугалгаар бохирдсон усан уусмалаас хар тугалгыг бууруулах туршилтыг гүйцэтгэлээ. Байгалийн цеолитыг натрийн алгинат полимер материалтай хольж бөмбөлөг хэлбэрийн шингээгч материал гарган авсан. Гарган авсан композит материалаар баганан шингээлтийг явуулан шингээлтэд нөлөөлөх баганын голлох параметрүүд болох баганын эзлэхүүн, шингээгч материалын хэмжээ, бохирдсон уусмалын анхны концентраци, уусмалын эзлэхүүн зарцуулалтыг нөлөөг судаллаа. Цеолитын найрлага болон хар тугалганы концентрацийн өөрчлөлтийг багажийн шинжилгээ (XRD, XRF, AAC)  хийсэн. Баганын эзлэхүүнийг 2.5 см3 - 5 см3 болгож ихэсгэх үед  шингээлтийн эхний цэг дэх анхны уусмалын концентраци болон шингээлтийн дараах концентрацийн (C/C0)  харьцаа 3 дахин ихэссэж хар тугалганы бохирдлыг 60%, 88%-иар тус тус бууруулсан.  Баганын эзлэхүүн тогтмол 5.0 см3 байх үед эзлэхүүн зарцуулалтыг 2.5 мл/мин - 6.25 мл/мин болгон хувьсгахад шингээлт 4 дахин багассаж хар тугалганы бохирдлыг 96%, 42%-иар тус тус бууруулсан байна. Баганан шингээлтийн үеийн нийт уусмалын эзлэхүүн 200 мл, эзлэхүүн зарцуулалт 6.25  мл/мин байх үед уусмалын анхны концентрацийг хувьсган туршилтыг явуулахад эхний цэгийн C/C0   харьцаа  уусмалын концентраци ихсэх тусам дагаад ихсэж байсан. Төгсгөлийн цэгт өөрчлөлт ажиглагдаагүй. Баганын эзлэхүүн болон уусмалын анхны концентрацийг ихэсгэхэд гаргаж авсан композит материалын шингээлт  нэмэгдсэн бол эзлэхүүн зарцуулалтыг нэмэгдүүлэхэд шингээлт буурч байна. Улмаар гарган авсан композит материал нь хар тугалганы уусмалын концентрациас хамааран 40-60% бууруулж байгаа нь ижил төстэй материалуудаас багтаамж өндөртэй хар тугалганы бохирдолыг бууруулахад үр нөлөөтэй байгааг тодорхойлсон.

Энэхүү судалгааны ажлаар байгалийн нөөцийг эдийн засгийн эргэлтэд оруулах, байгалийн гаралтай хүний эрүүл мэндэд хоргүй шингээгч материалын сонголтод цеолит нь ион солилцооны өндөр идэвх, сүвэрхэг шинж чанараар төгс тохирсон эрдэс бөгөөд энэ шинж чанар дээр үндэслэн хямд, үр ашиг өндөртэй шингээгч композит материал гарган авч, тасралтгүй урсгалтай баганан шингээлт явуулах замаар хар тугалгаар бохирдсон усан уусмалын бохирдлыг бууруулах туршилтыг гүйцэтгэлээ. Байгалийн цеолитод механик боловсруулалтыг гариган бөмбөлөгт тээрмийг ашиглан гүйцэтгэж, натрийн алгинат полимер материалтай бөмбөлөг хэлбэрийн шингээгч материал гарган авсан. Гарган авсан композит материалаар баганан шингээлтийг явуулан шингээлтэд нөлөөлөх баганын голлох параметрүүд болох баганын эзлэхүүн, шингээгч материалын хэмжээ, бохирдсон уусмалын анхны концентраци, уусмалын эзлэхүүн зарцуулалтыг нөлөөг судаллаа. Цеолитын найрлага болон хар тугалганы концентрацийн өөрчлөлтийг багажийн шинжилгээ (XRD, XRF, AAC)  хийсэн. Баганын эзлэхүүнийг 2.5 см3 -5 см3 болгож ихэсгэх үед  шингээлтийн эхний цэг дэх анхны уусмалын концентраци болон шингээлтийн дараах концентрацийн (C/C0)  харьцаа 3 дахин ихэссэн.  Баганын эзлэхүүн тогтмол 5.0 см3 байх үед эзлэхүүн зарцуулалтыг 2.5 мл/мин - 6.25 мл/мин болгон хувьсгахад шингээлт 4 дахин багассан байна. Баганан шингээлтийн үеийн нийт уусмалын эзлэхүүн 200 мл, эзлэхүүн зарцуулалт 6.25  мл/мин байх үед уусмалын анхны концентрацийг хувьсган туршилтыг явуулахад эхний цэгийн C/C0   харьцаа  уусмалын концентраци ихсэх тусам дагаад ихсэж байсан. Төгсгөлийн цэгт өөрчлөлт ажиглагдаагүй. Баганын эзлэхүүн болон уусмалын анхны концентрацийг ихэсгэхэд гаргаж авсан композит материалын шингээлт  нэмэгдсэн бол эзлэхүүн зарцуулалтыг нэмэгдүүлэхэд шингээлт буурч байна. Улмаар гарган авсан композит материалын шингээлтийн багтаамжийг тооцоход уусмалын концентрациас хамааран 40-60 мг/гр гэж гарсан нь ижил төстэй материалуудаас багтаамж өндөртэй байгааг тодорхойлсон.

Oxidation of copper concentrate changes the phase of copper and iron, and the content of copper decreases. This has a significant negative impact on the economy. Therefore, we aimed to study the interactions between the factors affecting oxidation (temperature and humidity). Artificial oxidation in laboratory conditions was carried out in a «Temperature Humidity Chamber» at temperatures of 10°C, 30°C, 50°C, and humidity was adjusted to 10 %, 30 %, and 60 %,

The resistance of infectious bacteria to antibiotics and other drugs has become a significant threat to the health and development of humans due to its high medical costs, prolonged hospital stays, and increased mortality rates1,2. In this line, utilizing zeolites is one of the most promising materials as a drug delivery system to improve antibiotic efficiency and develop new pro-drugs with reduced side effects3,4 . For that purpose, we previously reported that Mongolian natural zeolite (MNZ) has a high potential capability for drug delivery systems. We performed chemical and thermal treatment, subsequently, ion exchange to improve the availability of the human body to ensure zeolite compatibility with access to medical purposes. We studied adsorption kinetic, isotherm, and release studies of ceftriaxone on surfactant modified Mongolian natural zeolite from Tsagaan Tsav deposit, Dornogovi province. In the present work, we evaluated the in vitro antibacterial activities of MNZ, hexadecyltrimethylammonium (HDTMA) modified zeolite (MNZ-HDTMA), and ceftriaxone (CFT) loaded, modified zeolite (CFT/MNZ-HDTMA), which were examined by using the minimum inhibitory concentration method against gram-positive (Staphylococcus aureus and Streptococcus pyogenes) and gram-negative (Escherichia coli and Salmonella enteritidis) bacteria. CFT/MNZ-HDTMA has a high antibacterial activity against gram-negative bacteria, especially Escherichia coli bacteria, and generally was inactive against Staphylococcus aureus. CFT/MNZHDTMA has been shown to be a lower effect against Streptococcus pyogenes and Salmonella enteritidis than Escherichia coli bacteria. This result shows a similar antibacterial effect with raw CFT. Overall, MNZ can act as an effective adsorbent with a higher potential for drug delivery.

Recently, various porous materials especially zeolites are employed in drug delivery applications that affect the drug loading efficacy and the release rate of drug molecules due to their pore size, size distribution, stable uniform porous structure, surface area, volume, and well-defined surface properties. The polarity of the drug molecules and the nature of the zeolite surface play an important role in the adsorption efficiency. The application of a quaternary ammonium cationic surfactant on minerals such as zeolites causes the change of the clay surface that have an excellent hydrophobicity and great efficiency for adsorption. Zeolite surface charged negatively and when modifying the zeolite surface changes from hydrophilic to hydrophobic and from negatively to positively charged, due to the adsorption of organic molecules onto its external surface and into the interlayer spacing. In this study we investigated the adsorption isotherm, kinetic and thermodynamic parameters of cephalosporin on cationic surfactant modified zeolite. The characterization of zeolite used for drug adsorption indicates that the natural zeolite used in this study was classified into clinoptilolite that accepted to use in a biomedical field. Adsorption isotherm, kinetic and thermodynamic functions were carried out using batch method as a function of the initial concentration of antibiotic and temperature. The kinetic and isotherm studies of the cephalosporin adsorption were best fitted by the pseudo second order kinetic model (R2=0.9996) with monolayer adsorption capacity 12.3609 mg/g and Langmuir (R2=0.9950) isotherm model. The activation energy (Ea) of cephalosporin adsorption onto cationic surfactant modified zeolite indicated that this antibiotic is more strongly adsorbed onto surfactant modified zeolite. Thermodynamic parameters, such as Gibbs free energy, the enthalpy, and the entropy change of adsorption onto cationic surfactant modified Mongolian zeolite have also been evaluated and it has been found that the adsorption process was spontaneous, feasible, and exothermic. In conclusion, the result of this study suggested that surfactant modified natural zeolite may be an effective and promising adsorbent for cephalosporin from aqueous solution.

Энэхүү судалгааны ажлаар байгалийн цеолит болон гулуронатын полимер ашиглан усан орчноос хүнд металыг шингээх чадвартай композит материал гарган авах тохиромжтой нөхцөлийг тогтоолоо. Цеолит нь сүвэрхэг бүтэцтэй, хөнгөнцагаант суурь болон катион, усны молекулуудыг агуулсан эрдэс бөгөөд шингээгч материалд өргөн хэрэглэгддэг нэгдэл юм. Тасралттай шингээлтийн процессын үед нунтаг цеолит нь шингээлтийг сайтар явуулах боловч, тасралтгүй баганан шингээлтийн үед нунтаг материал нь усыг нэвтрүүлэх чадваргүй байдаг. Иймээс мөхлөг хэлбэрийн (packed bed) баганан шингээлтэнд тохирох жижиг үрэл хэлбэрийн композит материалыг гарган авах, улмаар усан орчинд хичнээн удсан ч буцаж тэлэхгүй байх материалыг гарган авах нь бидний судалгааны ажлын гол зорилго болсон билээ. Тасралтгүй урсгалтай аргаар явагдах баганан процессын үед композит материалаар тэлэлтгүй ус нэвтрүүлэх хурд нь тогтмол байх нь шингээлтийн баганын чухал үзүүлэлт болно. Иймээс мөхлөг хэлбэрийн үрлэн шингээгч материалыг гарган авахдаа усан орчинд тэлэлт өгөхгүй байх тохиромжтой нөхцлийг тогтоон, амжилттай гарган авлаа. Цеолит агуулсан композит материалыг гарган авахад Na-альгинатын полимерын концентрацийг 1-2\% байхад тохиромжтой болох нь харагдлаа. Түүнчлэн $CaCl_2$-ын уусмалтай харьцуулахад $BaCl_2$-ийн уусмалаар бэлтгэсэн композит үрэл нь тэлэлтийн харьцаа багатай байгаа нь уусмал дотор хангалттай хэмжээний $Ba$ атом байхад тогтвортой композит үрэл үүсэж болохыг харуулж байна. $BaCl_2$ - ийн 10% - ийн үед гарган авсан материал нь тэлэлтийн харьцаа 1 орчим байлаа.

Microencapsulation technology has been used in a variety of fields including materials such as buildings, walls, industrial, medicine, and cosmetics. One of the most active research on microencapsulation is microstructure formation. Important properties of microcapsules such as releasing rate of active agent are depending on their microstructure. Same as the strength of bridges, skyscrapers, and buildings is characterized by their geometry, and the strength of microcapsules is also influenced by their microstructure. The effect of trioctylamine on the morphology of polystyrene microcapsules was investigated. The influence of trioctylamine was on both the inner and outer morphology of microcapsules. On outer morphology, two types which are smooth and crown were observed. Three types of inner morphology of microcapsules were classified. The inner morphologies are evenly spaced, clustered, and randomly spaced. The morphologies of the crown and evenly spaced were small in size.

Lead contamination was removal from aqueous solution by continuous flow column adsorption with composite material of Na-alginate and natural zeolite. The optimum conditions for the breakthrough curve were found depending on the parameters of the column such as the dimensions of the column, the amount of adsorbent material, the initial concentration of the contaminated solution, and the volume consumption of the solution. The adsorption breakthrough curve was obtained in the experimental condition, where the ratio of initial concentration of the aquas solution and the column volume was 3:8 and the total volume of the solution and the column volume ratio (VF/VR) was in the range of 1000 – 1300. According to the results of the breakthrough curve observed under the above optimal conditions, the adsorption capacity was 70.5 mg/g, which is higher than other similar studies conducted with high concentration solutions.

Дэлхий дахины хувьд хүрээлэн буй орчны хүнд металын бохирдол жил ирэх тусам өсөн нэмэгдсээр байна. Манай улсын хувьд бохирдсон хөрс, хаягдал усанд металоксианион ихээр агуулагддаг ба үүнийг хэрхэн цэвэршүүлэх талаар судалгаа хийх хэрэгтэй. Сүүлийн жилүүдэд анион шингээх чадвар бүхий шаварлаг материал болох үелсэн давхар гидроксид (ҮДГ) ихээр судлагдаж байгаа. Энэ материал нь нэмэх цэнэгээр хүрээлэгдсэн брусит төрлийн үет бүтэцтэй ба үе хоорондоо сул холбоотой учир органик болон орнганик бус анионыг шингээх боломжийг бий болгодог. Хөрсний хүнд металлууд нь органик бохирдуулагч болон бусад бохирдуулагч бодисуудыг бодвол задарч саармагжих, цэвэрших процесст ордоггүй, хөрсөнд удаан хугацаагаар хуримтлагдаж дан ганц хөрсийг бохирдуулаад зогсохгүй агаар, усыг бохирдуулах нөхцлийг бүрдүүлдэг. Энэхүү судалгаагаар Улаанбаатар хотын ХУД-ийн 20 дугаар хороонд байрлах УСУГ-ын харьяа “Харгиа” ус цэвэрлэх байгууламжийн эргэн тойрны бохирдолтой хөрс болон хотоос зайдуу байрлах хүнд металлаар бохирдоогүй цэвэр хөрсийг сонгон авч хөрсөн дэх хромын агуулгыг бууруулах судалгааг хийж гүйцэтгэсэн болно. Түүнчлэн Mg/Al үелсэн давхар гидроксид материалаа хам тунадасжуулах аргаар гарган авч SEM, XRD, FTIR зэрэг багажуудаар шинжилгээ хийсэн ба үр дүнгээс харахад 20-30 нм зузаантай гидроталцит талст бүтэцтэй үелсэн давхар гидроксид болох нь батлагдсан. Судалгааны туршилтын үр дүнг тооцоход ҮДГ ашиглаагүй 1-р туршилтад хромын агуулга 2435.61 мг/кг байсан бол, ҮДГ тусгаарлагч ашигласан туршилт 2, 3, 4-т 2154.56 мг/кг, 1956.94 мг/кг, 1292.99 мг/кг 5-т 611,23 мг/кг болж буурсан байна. Үүнээс харахад хромын бохирдлыг 5-р туршилтаар 74 хувь хүртэл бууруулах боломжтой, үр дүнтэй, байгаль орчинд ээлтэй, эдийн засагт хэмнэлттэй арга гэдэг нь харагдаж байна.

Most microcapsule preparation methods produce a population of microcapsules in a bulk solution. To control the micro- capsule preparation or obtain an optimal preparation condition, the mechanism of the microcapsule preparation should be investigated. The mechanism is estimated via structure reformation during the preparation process because diameter and wall thickness are drastically altered in the solution. Considering microcapsule applications, some important proper- ties, such as the mechanical properties of microcapsules and release rate of the encapsulated product, depend on the microcapsule structure. In this study, polystyrene microcapsules containing saline water droplets were prepared via the solvent evaporation method from a solid-in-oil-in-water (S/O/W) emulsion system. The microcapsules exhibited a specific structural distribution, which comprised monocore, multicore, and solidcore structures. The structural distribu- tion was altered by the preparation condition. The monocore structure was absolutely dominant owing to the increase in the amount of calcium chloride added in the organic phase. The salt concentration is not the sole controlling factor of the microcapsule structure, as the surfactant and dispersion exerted a significant impact on the microcapsule structure. The structural distribution was automatically analyzed by a machine learning algorithm (MLA). The decision-making time for the microcapsules preparation was shortened by the accelerated structure determination, and the accuracy was improved by increasing the number of counting particles.

Polystyrene microcapsules were prepared by using the solvent evaporation method from S/O/W emulsion which contains fine particles of CaCl2 in the organic phase. The microcapsules were fractionated by their size and permeability of the wall using settling difference in methanol. Further, phase change materials that have two different wet-ability characters were successfully impregnated. The hydrophobic compound was easily impregnated to microcapsules which have hydrophobic wall material. Meanwhile, the hydrophilic compound, which is salt hydrate, was not impregnated to the same microcapsules via direct impregnation but the salt hydrate was successfully impregnated by the volatile exchange impregnation method. Simple thermal properties of the prepared phase change material microcapsules were examined by TGA and DSC methods.

Mongolia has a rich source of natural zeolite that is expected to be developed in the biomedical field. Nowadays, modified zeolites have been trying to use as a drug carrier and they can form controlled release drug delivery systems connected with their low toxicity, high porosity, good capacity and other unique characteristics. Natural zeolites are studied to investigate their ability to release drugs that can improve the bioavailability of the drug by preventing its premature degradation, maintaining its concentration within the therapeutic range, and ultimately reducing the potential side effects.

In order to apply microcapsules as a functional material of cement composites, such as self-healing and heat-transfer-controlling materials, the effect of the addition of microcapsules on the mechanical properties of cement mortar was investigated. Polystyrene microcapsules containing CaCl2 aqueous solution as a microencapsulation substance with monocore and multicore structures were successfully prepared from solid-in-oil-in-water (S/O/W) emulsion by the solvent evaporation method. The compressive strengths of the mortars with and without the microcapsules were measured at various curing times. The compressive strength of the mortar without microcapsules increased with curing time. The compressive strength of the mortar with the microcapsules was lower than that without microcapsules and increased with time. The decrease in the compressive strength increased with the amount of the microcapsules added in the mortar. The self-healing effect of cracked mortar by CaCl2, which would be supplied from the microcapsules due to outer mechanical force making cracks in the mortar and on the microcapsules was not clearly shown in this experiment. However, permeation and leakage of Cl− ion to the surrounding mortar from the microcapsules was observed by mapping analysis of SEM-EDX.

For the microcapsules preparation process, the mechanism is estimated by structure reformation during the preparation process since diameter and wall thickness drastically changed. Microstructures are recently studied by machine learning techniques. The Hough transformation algorithm is used by other researchers for the preparation of the microcapsules but it is difficult to determine the mechanism by using only a diameter change of the microcapsules. Therefore, one additional way to establish the mechanism is the analysis of the formation of the microcapsule structure. In this study, The Hough transformation algorithm was used for the image segmentation, the simple feature extractions were checked and the support vector machine and the k-nearest neighbors algorithm were used as classifiers in order to analyze the structure of the microcapsules which were prepared by solvent evaporation method from a solid in oil in water, S/O/W, emulsion system. The structural distribution was analyzed by the developed detection method. The microcapsules had a specific structural distribution which are monocore, multicore, and other aggregated structures. The structural distribution was changed by the preparation condition. The monocore structure was dominant by increasing in the amount of water soluble solid particles added in the organic phase.

Natural zeolite beads were prepared by encapsulating mesoporous zeolite into alginate beads via egg box method and its adsorption properties of Pb(II) ions were investigated in aqueous solution. Crystallinity and size reduction of natural zeolite were enhanced by mechanic modification of the ball milling process. FTIR and SEM-EDS analyses confirmed that mechanically modified zeolite particles were incorporated into alginate hydrogel. The highest adsorption amount of zeolite alginate beads was 87.47 mg/g after 20 h adsorption process. SEM-EDS result confirmed that the adsorption process has occurred on the surface of zeolite alginate beads. Adsorption kinetic data were fitted with Langmuir adsorption isotherm which showed that Pb2+ cation adsorbed into monolayers of adsorbent material. Moreover, we observed that calcium ion released after the Pb2+ adsorption process in the feed solution. Therefore, the adsorption mechanism of zeolite alginate beads explained by complex mechanisms including surface sorption and ion exchange of Pb2+ and Ca2+ in beads.

Electrokinetic (EK) remediation used to remove organic and inorganic compounds by using an electric potential. The purpose of this study was to reduce Cu, Mo and As contents from contaminated industrial soil using the EK remediation. Materials and Methods: The soil samples were collected at 0-100 cm depth in industrial area, Erdenet mine, Mongolia. The Cu (7312 mg kg–1), Mo (176 mg kg–1) and As (114 mg kg–1) content in topsoil sample was exceeded the toxic level of Mongolian National Soil Quality Standards (500, 20, 30 mg kg–1, respectively). The heavy metals removal from contaminated soil by EK remediation was studied via comparing electrolyte solution (de-ionized water and 0.1 M NaCl), voltage (10-20 V) and time (108-200 h). Results: Based on results, the maximum removal of Cu was 90% of initial concentration occurred near the anode, in the condition of 0.1 M NaCl electrolyte solution, 15 V constant voltage and 156 h. Besides, the contents of Mo and As in anode and cathode were removed almost 89 and 79%, respectively. Conclusion: This study showed that EK remediation is a viable, environmentally friendly method for treatment of the copper contaminated soil.

Давсыг ашиглан бас мөс хайлуулах бодис гарган авах судалгааны үр дүнгээр илтгэл хэлэлцүүлсэн

Mongolian natural zeolite has ability to adsorb heavy metal from water and it has been studied before. In those studies zeolite was mostly used in powder state. The aim of this study is to synthesize cryogel composite containing natural zeolite for adsorbent material of cation and anions. Embedding powder zeolite into cryogel reduces the agglomeration of powder sample, which makes it more convenient to use in adsorption process. Zeolite-cryogel composite was synthesized by cryoconcentration methods1-2 with 2 different reagent ratio. In the composite from the first method, zeolite was uniformly dispersed but it was not porous, while the composite from the second method was porous, zeolite particles were dispersed evenly through the cryogel column. Also, it was stable in the flow of the water. FT-IR analysis showed that the polymerization of cryogel and it matched with previous studies.3 SEM-EDX analysis showed that composite has macroporous structure and zeolite particles were embedded in the wall of cryogel. We used zeolite-cryogel composite for adsorption of arsenic in reactor and it adsorbed 1.669 mg/g in acidic solution. Powder zeolite is embedded into cryogel composite successfully and it adsorbed anionic arsenic from water. In further study, adsorption mechanism and optimal conditions of zeolite-cryogel on cation and anion will be investigated.

Zeolite alginate beads were developed by immobilizing mechanically modified and natural nanoporous zeolite into sodium alginate. Natural zeolite sample is determined as Clinoptilolite type of zeolite with BET average pore size of 8.3 nm. The developed beads used for adsorption of Pb(II) from aqueous solution. Alginate bead containing natural raw zeolite and mechanically modified natural zeolites were compared in terms of Pb(II) adsorption capacity. Prior to adsorption, natural zeolite was milled by planetary ball mill with 200 rpm speed and 3 mm zircon balls in range of 0-15 minutes. Adsorption experiment was conducted in batch reactor with 100-500 ppm initial concentration of Pb(II). Experiment result showed that modified zeolite was given higher adsorption amount than natural raw zeolite. After modification process, increase of peak intensity was observed in XRD analysis. This result may explain that ball-milling process increased purity of zeolite by removing natural impurity of sample. It tends to increase adsorption amount of Pb(II). Adsorption efficiency of zeolite alginate beads was all above 50% in pH range of 2 to 6 and highest removal efficiency was 94% at pH=3. The highest adsorption amount of Pb(II) was 87.37 mg/g with initial concentration of 500 ppm. Natural zeolite sample modified by ball milling process with 10 minutes in 200 rpm speed was given highest adsorption amount. This result showed that alginate beads with modified natural zeolite can be effective adsorbent for Pb(II) in various pH range.

монгол орны баруун бүсийн эрдэс түүхий эдийг ашиглан цеменкер тын клинкер гаргах кинетикийн судалгааны үр дүнгээр илтгэл хэлэлцүүлсэн

Mongolian natural zeolite from Tsagaan tsav had shown the ability of ion adsorption such as As or Pb from aqueous solution. In previous works, the zeolite mineral was used as powder in the batch process. However, it is not possible to use powder material for flow processes. Therefore, in this study, Arsenic adsorption ability of polymer embedded modified zeolite was investigated in two types of adsorption reactor. Modification of natural zeolite with magnesium oxide was carried out prior to polymer synthesis. SEM-EDX analysis result showed that the modification was successful. Zeolite polymer was synthesized by two different methods. Product of second method was high porous and zeolite particles were immobilized throughout the polymer. Adsorption in continuous column reactor was more effective than batch reactor. The adsorption amount was increased with time.

In order to investigate copper, arsenic, lead and zinc contamination in topsoil of the Erdenet copper mining area in Mongolia, soil samples collected from the surrounding area were examined for trace element concentrations, geochemical fractions, and phase distributions. Fifteen locations (residential area; mine industrial area; control area; tailings dam) were sampled during all four seasons. Of the 19 trace elements determined, the highest concentrations of Cu (1443–4866 mg kg−1), As (26–52 mg kg−1), and Mo (24–49 mg kg−1) in soils from the mine industrial area exceeded the corresponding values listed in the National Standard of Mongolia. Soil samples were fractionated into five phases: exchangeable, carbonate bound, Fe/Mn oxide bound, organic matter bound, and residual. Copper was largely associated with the organic/sulphide fraction, and As, Pb and Zn were associated mainly with the residual and Fe/Mn oxide fractions. Significantly high enrichment factor (EF) and geoaccumulation index (Igeo) values confirmed that Cu and As in the soil from the mine industrial area reach serious levels and their sources may be related to anthropogenic activities such as mining.

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