Pengaruh Konsentrasi Aktivator Asam Fosfat (H3PO4) pada Pembuatan Karbon Aktif dari Sabut Kelapa terhadap Adsorpsi Logam Kromium

Chromium is one of the hazardous heavy metal contained in the industrial wastewater. It can be reduced by various methods, such as adsorption. The purpose of this study was initialized an activated carbon from coconut fiber by various phosphoric acid (H₃PO₄) activator concentration (0,1M; 0,5M; 1M; 1,5M; 2M) and variation of contact time (30; 60; 90; 120; 150; 180 minutes) to obtain optimum adsorption capacity of chromium. Analysis of the activated coconut fiber carbon by SAA obtained a surface area of 53,39 m²/g. The potassium chromate (K₂CrO₄) solution was adsorbed by the adsorbent and then analyzed by a UV-VIS Spectrophotometer to measure the chromium content. This study proved that chromium adsorption by activated coconut fiber carbon was increased by the time until reaching optimum condition. Enhancement of adsorption capacity was directly proportional as the more concentrated phosphoric acid activator. Maximum adsorption capacity obtained was 3,464 mg/g and the optimum condition was at contact time of 150 minutes with the phosphoric acid activator concentration of 2M.

Effect of Interaction between 17β-Estradiol, 2-Methoxyestradiol and 16α-Hydroxyestrone with Chromium (VI) on Ovary Cancer Line SKOV-3: Preliminary Study

Ovarian cancer is the leading cause of death from gynecologic malignancies. Some estrogens, as well as xenoestrogens, such as chromium (VI) (Cr(VI)), are indicated as important pathogenic agents. The objective of this study was to evaluate the role of estradiol and some its metabolites upon exposure to the metalloestrogen Cr(VI) in an in vitro model. The changes in cell viability of malignant ovarian cancer cells (SKOV-3 resistant to cisplatin) exposed to 17β-estradiol (E2) and its two metabolites, 2-methoxyestradiol (2-MeOE2) and 16α-hydroxyestrone (16α-OHE1), upon exposure to potassium chromate (VI) and its interactions were examined. The single and mixed models of action, during short and long times of incubation with estrogens, were applied. The different effects (synergism and antagonism) of estrogens on cell viability in the presence of Cr(VI) was observed. E2 and 16α-OHE1 caused a synergistic effect after exposure to Cr(VI). 2-MeOE2 showed an antagonistic effect on Cr(VI). The examined estrogens could be ranked according to the most protective effect or least toxicity in the order: 2-MeOE2 > E2 > 16α-OHE1. Early pre-incubation (24 h or 7 days) of cells with estrogens caused mostly an antagonistic effect—protective against the toxic action of Cr(VI). The beneficial action of estrogens on the toxic effect of Cr(VI), in the context of the risk of ovarian cancer, seems to be important and further studies are needed.

The Common Ice Plant (Mesembryanthemum crystallinum L.)–Phytoremediation Potential for Cadmium and Chromate-Contaminated Soils

The common ice plant (Mesembryanthemum crystallinum L.) is a widely studied model due to its tolerance to numerous biotic and abiotic stresses. In this study, carried out in model pots, the plants were treated with variant doses of Cd(II) and Cr(VI) and proved resistant to extreme levels of these heavy metals. Initial toxicity symptoms were observed upon final concentrations of 818 mg Cd kg−1 soil d.w., and 1699 mg Cr kg−1 applied as potassium chromate. Biometric analyses revealed that none of the Cr(VI) doses affected dry weight of the plant organs thus maintaining the shoot-to-root ratio. The Cd and Cr hypertolerance strategies were divergent and resulted in different accumulation patterns. For the case of Cd(II), an excluder-like mechanism was developed to prevent the plant from toxicity. For chromate, high accumulation potential together with Cr(VI) root-to-shoot translocation at sublethal concentrations was revealed (up to 6152 mg Cr kg−1 shoot at 4248 mg Cr kg−1 soil). It is concluded that M. crystallinum reveals considerable phytoremediation capabilities due to unique growth potential in contaminated substrates and is suitable for bioreclamation of degraded soils. The plant is especially applicable for efficient phytoextraction of chromate-contamination, whereas for Cd-affected areas it may have a phytostabilizing effect.

Study the efficiency of tobacco extracts as corrosion inhibitor for steel pipes buried in organic and clay soil

This research includes an experimental study of tobacco extract to be used as natural corrosion inhibitors by applying it on steel pipe (Steel 355) buried in soil, by selecting a suitable extract. Two types of soil were studied (organic soil and clay soil). The steel pipes treated with tobacco extract were buried for a period of (five months), and the effectiveness of tobacco extract on pipes’ corrosion is studied. The results showed the effectiveness of the tobacco extract as an inhibitor of corrosion، as well as it is better than its standard counterparts in both studied soils (organic and clay). The inhibitory activity of both (tobacco extract and potassium chromate) was recorded in organic soil for the first month as (71.42and 58.9%) respectively. The inhibitory effectiveness was found in clay soil of both (tobacco extract، potassium chromate) for the first month as (67.65 and 54.05%)، respectively. The results of this study also showed a better inhibitory effect of the extract of tobacco in organic soil than in the clay soil during the study period (five months)، where the inhibitory effect of the tobacco extract was for the fifth month in both organic soil and clay soil (38.55 and 34.99%) respectively.

Mitotic Studies and Genotoxic Assessment of Edible Nigerian Aroids to Selected Oilfield Chemicals

The genotoxic potentials of two water-based oilfield chemicals on edible aroids were investigated. Five accessions of Colocasia eculenta and three accessions of Xanthosoma maffafa were exposed to graded concentrations of sodium azide and potassium chromate; while the accessions without any chemical additive were used as controls. Results revealed that the peak periods of cell division were recorded between 12:00 noon to 4:00 pm in both the treated and control accessions. Metaphase cells increased after prophase cells and continued mostly between 10.00 am and 4.00 pm. Variations observed with the treatments included: shifts of metaphase peaks, high percentages of prophase cells, high intensity of cytoplasmic staining and induction of micronuclei among others. Sodium azide was observed to be a stronger genotoxic substance than potassium chromate. Accession NCe 001 had the highest survival rate while NCe 002 recorded the least rate of survival. Statistical evidence revealed that the difference in various mitotic stages and time of harvest between different accessions and treatments was significant at both 5% and 1%. The study provides useful information that would be used to promote cytogenetic researches as well as the exploitation and improvement of this neglected and underexploited economic plant.