Sequelae of carbide-related thermo-chemical injury: A retrospective analysis

Purpose

To describe the outcomes of eyes with calcium carbide (CaC2)-related thermo-chemical injury.

Methods

This study included 28 eyes of 23 patients who presented with calcium carbide-related ocular burns. Only patients with more than three months of follow-up were included. Group A included 16 eyes with Dua's Grade I-III burns, while Group B included 12 eyes with Grade IV-VI burns. Electronic medical records were reviewed to provide data on the etiology of burn, presenting clinical signs and visual acuity, sequelae, and surgical interventions performed, both in the acute and chronic phases.

Results

The overall mean age was 28.48 ± 11.8 years. Fifteen patients were injured while using carbide to create an explosion to scare away animals on farms. The median presenting BCVA (best-corrected visual acuity) in Group A (20/160) was significantly better than in Group B [(20/2000) (P = 0.002)]. Five eyes in Group A and one eye in Group B underwent medical management. There was no difference in the duration of follow-up for both groups (P = 0.24). The median final BCVA in Group A (20/32) was significantly better than in Group B [(20/200) (P = 0.02)]. Two eyes in Group A and nine eyes in Group B developed LSCD. Two eyes in Group B were phthisical at the last visit.

Conclusion

Calcium carbide-related ocular injuries can result in significant visual morbidity in young adults. Early presentation and management may improve outcomes. Prevention of these injuries by increasing awareness and increasing advocacy efforts is necessary.

Electrochemical CaC2-Mediated Conversion of Biochar to C2H2: High Carbon Efficiency and Low Contamination

The carbon to CaC2 route is promising to provide a sustainable elementary unit, C2H2, for the organic synthesis industry, but the traditional thermal reaction process suffers from low carbon efficiency, harmful gas contamination, high temperature operation, and risky CO management. We herein report a high carbon efficiency (ca. 100%) conversion of biochar to C2H2 through an electrolytic synthesis of solid CaC2 in molten CaCl2/KCl/CaO at 973 K. The main reactions are carbon reduction to CaC2 at the solid carbon cathode and oxygen evolution at an inert anode. Meanwhile, the electrolysis removes S and P from the solid cathode, avoiding the formation of CaS and Ca3P2 in CaC2 and consequently eliminating H2S and PH3 contamination in the finally produced C2H2.

Reducing options of ammonia volatilization and improving nitrogen use efficiency via organic and inorganic amendments in wheat (Triticum aestivum L.)

Background

This study investigates the effect of organic and inorganic supplements on the reduction of ammonia (NH3) volatilization, improvement in nitrogen use efficiency (NUE), and wheat yield.

Methods

A field experiment was conducted following a randomized block design with 10 treatments i.e., T1-without nitrogen (control), T2-recommended dose of nitrogen (RDN), T3-(N-(n-butyl) thiophosphoric triamide) (NBPT @ 0.5% w/w of RDN), T4-hydroquinone (HQ @ 0.3% w/w of RDN), T5-calcium carbide (CaC2 @ 1% w/w of RDN), T6-vesicular arbuscular mycorrhiza (VAM @ 10 kg ha-1), T7-(azotobacter @ 50 g kg-1 seeds), T8-(garlic powder @ 0.8% w/w of RDN), T9-(linseed oil @ 0.06% w/w of RDN), T10-(pongamia oil @ 0.06% w/w of RDN).

Results

The highest NH3 volatilization losses were observed in T2 at about 20.4 kg ha-1 per season. Significant reduction in NH3 volatilization losses were observed in T3 by 40%, T4 by 27%, and T8 by 17% when compared to the control treatment. Soil urease activity was found to be decreased in plots receiving amendments, T3, T4, and T5. The highest grain yield was observed in the T7 treated plot with 5.09 t ha-1, and straw yield of 9.44 t ha-1 in T4.

Conclusion

The shifting towards organic amendments is a feasible option to reduce NH3 volatilization from wheat cultivation and improves NUE.

Calcium carbide-induced derangement of hematopoiesis and organ toxicity ameliorated by cyanocobalamin in a mouse model

Background

Calcium carbide (CaC₂) is a chemical primarily used in the production of acetylene gas. The misuse of CaC₂ to induce fruit ripening is a global challenge with a potential adverse effects to human health. Additionally, CaC₂ is known to contain some reasonable amount of arsenic and phosphorous compounds that are toxic and pose a danger to human health when ingested. The current study sought to characterize CaC₂ toxicity and elucidate any protective effects by cyanocobalamin (vitamin B₁₂), a well-established antioxidant and anti-inflammatory bio-molecule. Female Swiss white mice were randomly assigned into three groups; the first group was the control, while the second group was administered with CaC₂. The third group received CaC₂ followed by administration of vitamin B12. The mice were sacrificed at 60 days post treatment, hematological, biochemical, glutathione assay, cytokine ELISA and standard histopathology was performed.

Results

CaC₂ administration did not significantly alter the mice body weight. CaC₂ administration resulted in a significant decrease in packed cell volume (PCV), hemoglobin (Hb), red blood cells (RBCs) and RBC indices; indicative of CaC₂-driven normochromic microcytic anaemia. Further analysis showed CaC₂-driven leukopenia. Evidently, vitamin B₁₂ blocked CaC₂-driven suppression of PCV, Hb, RBCs and WBCs. Monocytes and neutrophils were significantly up-regulated by CaC₂. CaC₂-induced elevation of aspartate aminotransferase (AST), alanine aminotransferase (ALT) and bilirubin signaled significant liver damage. Notably, vitamin B₁₂ stabilized AST, ALT and bilirubin in the presence of CaC_2, an indication of a protective effect. Histopathological analysis depicted that vitamin B₁₂ ameliorated CaC₂-driven liver and kidney injury. CaC₂ resulted in the depletion of glutathione (GSH) levels in the liver; while in the brain, kidney and lungs, the GSH levels were elevated. CaC₂ administration resulted in elevation of pro-inflammatory cytokines TNF-α and IFN-γ. Vitamin B₁₂ assuaged the CaC₂-induced elevation of these pro-inflammatory cytokines.

Conclusions

These findings demonstrate for the first time that oral supplementation with vitamin B₁₂ can protect mice against CaC₂-mediated toxicity, inflammation and oxidative stress. The findings provide vital tools for forensic and diagnostic indicators for harmful CaC₂ exposure; while providing useful insights into how vitamin B₁₂ can be explored further as an adjunct therapy for CaC₂ toxicity.

Alkynyl functionalized MoS2 mesoporous materials with superb adsorptivity for heavy metal ions

Effective elimination of heavy metal ions from water is an arduous task for their toxic effects to aquatic ecosystem and human health. Herein, a novel alkynyl functionalized molybdenum disulfide (C-MoS₂) is fabricated via mechanochemical method with well interlayered spacing, meso porosity, and high surface area (~211 m²g^-1). Mineral MoS₂ was first peeled mechanically and oxidized in situ to MoS_2-xO_x, and then reduced by ball milling with CaC₂ to form the C-MoS₂ composite. The as-obtained C-MoS₂ shows extraordinary adsorptivity for heavy metal ions, viz. 1194 mg-Hg g^-1 (Hg(NO₃)₂ solution, pH= 5, 303.15 K, equilibrium Hg(II) concentration Ce= 36.9 μg·g^-1, ionic strength I= 17.2 mmolL^-1), and 442.3 mg-Pbg^-1 (Pb(NO₃)₂ solution, pH= 5, 303.15 K, equilibrium Pb(II) concentration Ce= 46.9μgg^-1, I= 5.8 mmolL^-1), respectively, along with excellent recyclability, representing one of the best sorbents till now. The adsorption isotherms of Hg(II) followed the Langmuir model and the adsorption kinetics followed the pseudo-second-order model. The adsorption is an endothermic and entropy driven spontaneous process. The excellent adsorption performance of C-MoS₂ is attributed to its very high S-content, availability, and soft acid-base interaction with mercury and lead anions. The C-MoS₂ is an advanced sorbent for Hg(II) and Pb(II) with excellent adsorption performance and recyclability.

Toilet chemical additives and their effect on faecal sludge characteristics

This study investigated the effects of two mostly improvised chemical additives, calcium carbide and lambda super 2.5 EC (LSEC), on the physico–chemical and microbial characteristics of faecal sludge from toilets. The quality of faecal sludge was assessed before and after application of the chemical additives in an experimental setup of ten different treatment units including a control, and treatment replicates. The initial characteristic of the faecal sludge was slightly acidic with high content of slowly degradable organic matter. The experimental control without additives after 30 days showed reduction in BOD₅, COD, helminth eggs and sludge mass by a maximum of 30%, 34.7%, 99.8% and 55% respectively. Similarly, calcium carbide additive reduced the BOD₅, COD, helminth eggs and the mass of the faecal sludge by 47.4%, 48.3%, 99.6% and 61% respectively. Also, LSEC additive reduced BOD₅, COD, helminth eggs and the mass of the sludge by 40.6%, 47.9%, 95.9% and 58% respectively. The two additives showed significant treatment effect on the faecal sludge although the level of treatment could not meet the regulatory discharge limits for the key quality parameters assessed including sanitisation. The study is still a grey area and more research is recommended to enrich the findings.

Preparation of C-MOx nanocomposite for efficient adsorption of heavy metal ions via mechanochemical reaction of CaC2 and transitional metal oxides

Three nanocomposites of carbon and MnOx (C-Mns) were prepared via mechanochemical reaction of CaC₂ with excessive MnO₂ in a planetary ball mill. Their structure and composition were analyzed by XPS, Raman, FT-IR, XRD, N₂ adsorption-desorption, SEM and TEM, respectively, and their adsorption performance for heavy metal ions was studied. In addition, a series of nanocomposites of carbon and transition metal oxides (C-MOx) were prepared by ball milling CaC₂ with excessive TiO₂, V₂O₅, Fe₂O₃, CuO, MoO₃, Co₂O₃, and CrO₃, respectively, and their adsorptivity was evaluated. C-Mn₁ is a micro-mesoporous sorbent with rich MnOx, alkynyl and oxygenated groups, and moderate specific area (∼180 m² g^-1), showing excellent Pb²⁺ adsorption with its saturated adsorptivity being 404.4 mg-Pb g^-1. Further, it is also effective for other heavy metals (Hg²⁺, Cd²⁺, Cr³⁺, Zn²⁺ and Cu²⁺). Some C-MOx show even better adsorptivity for Pb²⁺ and Hg²⁺, being superior to most of the advanced carbon-based sorbents. We reported herein a facile method for preparing a new kind of C-MOx nanocomposites for the efficient adsorption of heavy metal ions from wastewater.

Modification of acidic and textural properties of a sulphated zirconia catalyst for efficient conversion of high-density polyethylene into liquid fuel

Consumption of plastic has a rapid increase of about 8% per annum and reached to 400 million per tonnes approximately, where about 50% of plastic was disposed after using only once. Different techniques for treating this increased waste faced a number of issues related to cost and environmental and sustainable development. Catalytic conversion has been found as one of the most viable solutions to solve this problem. Sulphated zirconia (SZ) catalyst modified with calcium carbide (CC) was found to improve high-density polyethylene (HDPE) conversion into liquid fuel. The liquid content was improved from 39.0wt% to 66.0wt% at 410 °C. HDPE was converted 100% by weight using, SZ/CC with 66wt% liquid yield as compared to the conversion of approximately 98wt% with about 40wt% only liquid yield for the pure SZ. The composition of hydrocarbon liquid product was significantly changed from paraffin (16%) and aromatic (58%) to olefin (74%) and naphthenic (23%) compounds. This significant increase in liquid was related to changes in the acidic and textural characteristics of the new hybrid catalyst, SZ/CC where the total ammonia desorption of 337.0 μm NH₃/g for the SZ was modified to 23.4 μm NH₃/g for the SZ/CC. Both SZ and SZ/CC catalysts showed characteristics of mesoporous material, where the internal pore volume of SZ had reduced from 0.21 mL/g for SZ to 0.04 mL/g for SZ/CC. Furthermore, XRD analysis indicated the presence of a new compound, CaZrO₃ in the SZ/CC, which confirmed a chemical interaction between the SZ and CC through sintering of ZrO₂ and CaO. Therefore, the SZ/CC catalyst improves the liquid yield significantly and the selectivity towards olefinic and naphthenic compounds.

Disruptions in the female reproductive system on consumption of calcium carbide ripened fruit in mouse models

This study investigated for the first time the outcome of ingestion of calcium carbide-ripened fruit on some female reproductive parameters. A set of unripe mature bananas ripened with calcium carbide (CCRB) and another set ripened via non-artificial means (NARB) were fed orally to prepubertal female mice for three days using the uterotrophic assay procedure. A distilled water group and oestradiol group (10 mg/kg) were also assigned. Food intake, body weights, vaginal openings and cytology were analysed. Samples of blood, uteri, ovaries and cervices were additionally collected and analysed. Increased serum oestrogen level and uterus weight were detected in the CCRB and oestradiol treated groups. Histopathology showed increased numbers of myometrial cells, presence of secondary follicles and regressing corpus lutea as well as thickened cervix epithelia which were evidence of oestrogenic disruptions. This study has shown that consumption of fruits ripened with calcium carbide negatively alters the female reproductive physiology, accelerates puberty onset and increases serum oestrogen levels. Caution must therefore be exercised by fruit sellers in the use of calcium carbide and policies set in place for strict regulation of its use worldwide.

NIR spectroscopic method for the detection of calcium carbide in artificial ripening of mangoes (Magnifera indica)

The present study presents a novel method employing Near Infrared Spectroscopy (NIR) for detection of the use of calcium carbide in artificial ripening of mangoes. Use of calcium carbide has been banned in artificial ripening of fruits as it contains traces of arsenic. Mango samples were ripened artificially using calcium carbide and compared with naturally ripened mangoes using NIR spectroscopic wavelength ranging from 600 to 1100 nm. The captured NIR spectra from mango samples were analysed using multivariate methods including principal component analysis, particle least square and successive projection algorithm. The obtained results showed distinguishing zones for naturally and artificially ripened mangoes. Furthermore, the arsenic content was obtained through ICP-MS analysis, and it was found that mangoes ripened artificially using calcium carbide have a higher content of arsenic. Hence, arsenic was used as a principal component in the analysis. The developed method is not unique to samples that were grown in any particular region or year as it and can be used universally as NIR will give the distinguishing comparison between naturally- and artificially ripened mangoes. This method is simple, non-invasive, non-destructive and rapid for detection of use of calcium carbide in the artificial ripening of mangoes.

Efficient destruction of hexachlorobenzene by calcium carbide through mechanochemical reaction in a planetary ball mill

Mechanochemical destruction (MCD) is a good alternative to traditional incineration for the destruction of persistent organic pollutants (POPs), like hexachlorobenzene (HCB), and the key is to find an efficient co-milling reagent. Toward this aim, HCB was milled with various reagents in a planetary ball mill at room temperature, and CaC₂ was found to be the best one. HCB can be destroyed completely within 20 min at a mass ratio of CaC₂/HCB = 0.9 and a rotation speed of 300 rpm. The ground samples were characterized by X-ray diffraction, X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. The results show that the destruction products are nonhazardous CaCl₂ and carbon material with both crystalline and amorphous structures. On these bases, possible reaction pathways were proposed. Considering its excellent efficiency and safety, CaC₂ may be the most feasible co-milling regent for MCD treatment of HCB. Further, the results are instructive for the destruction of other POPs.

Evaluation of the toxic potential of calcium carbide in the third instar larvae of transgenic Drosophila melanogaster (hsp70-lacZ)Bg(9)

In the present study the toxic potential of calcium carbide (CaC2) was studied on the third instar larvae of transgenic Drosophila melanogaster (hsp70-lacZ)Bg(9). The third instar larvae were exposed to 2, 4, 8, 16 and 32×10(-3)g/ml of CaC2 in diet for 24h. The results reveal that the dose 2×10(-3)g/ml was not toxic but the remaining doses showed a dose dependent significant increase in the hsp70 expression, β-galactosidase activity, tissue damage, oxidative stress markers (lipid peroxidation and protein carbonyl content), glutathione-S-transferase activity, expression of Caspase 3 and 9, apoptotic index and DNA damage (midgut cells). A significant reduction as compared to control group in total protein, glutathione content and acetylcholinesterase activity was also observed. The Inductively Coupled Plasma Atomic Emission Spectroscopy analysis (ICPAES) reveals the presence of copper, iron, sodium, aluminium, manganese, calcium, nickel and mercury. The toxic effects of CaC2 in the present study may be attributed to the impurities present in it.