Benign zinc oxide betaine-modified biochar nanocomposites for phosphate removal from aqueous solutions

Phosphate is one of the most costly and complex environmental pollutants that leads to eutrophication, which decreases water quality and access to clean water. Among different adsorbents, biochar is one of the promising adsorbents for phosphate removal as well as heavy metal removal from an aqueous solution. In this study, biochar was impregnated with nano zinc oxide in the presence of glycine betaine. The Zinc Oxide Betaine-Modified Biochar Nanocomposites (ZnOBBNC) proved to be an excellent adsorbent for the removal of phosphate, exhibiting a maximum adsorption capacity of phosphate (265.5 mg. g^-1) and fast adsorption kinetics (~100% removal at 15 min at 10 mg. L^-1 phosphate and 3 g. L^-1 nanocomposite dosage) in phosphate solution. The synthesis of these benign ZnOBBNC involves a process that is eco-friendly and economically feasible. From material characterization, we found that the ZnOBBNC has ~20-30 nm particle size, high surface area (100.01 m². g^-1), microporous (25.79 Å) structures, and 7.64% zinc content. The influence of pH (2-10), coexisting anions (Cl^-, CO₃^2-, NO₃^- and SO₄^3-), initial phosphate concentration (10-500 mg. L^-1), and ZnOBBNC dosage (0.5-5 g. L^-1) were investigated in batch experiments. From the adsorption isotherms data, the adsorption of phosphate using ZnOBBNC followed Langmuir isotherm (R² = 0.9616), confirming the mono-layered adsorption mechanism. The kinetic studies showed that the phosphate adsorption using ZnOBBNC followed the pseudo-second-order model (R² = 1.0000), confirming the chemisorption adsorption mechanism with inner-sphere complexion. Our results demonstrated ZnOBBNC as a suitable, competitive candidate for phosphate removal from both mock lab-prepared and real field-collected wastewater samples when compared to commercial nanocomposites.

Phosphate removal from wastewater using novel renewable resource-based, cerium/manganese oxide-based nanocomposites

Nanocomposites containing mixed metal oxides show excellent phosphate removal results and are better compared to individual metal oxides. In this research, cerium/manganese oxide nanocomposites, embedded on the surface of modified cellulose pine wood shaving, were synthesized by a simple technique that is both eco-friendly and economically feasible. No toxic or petroleum chemicals were employed during preparation. Scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), surface area analysis, and attenuated total reflectance Fourier-transform infrared (ATR-FTIR) spectroscopy were performed to study the shape and size of nanocomposites as well as composition of elements present on the surface of the nanocomposites. Adsorption isotherm (Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich) and kinetic studies (pseudo first and second-order, Elovich and Weber-Morris) were carried out to determine the adsorption mechanism for phosphate removal from contaminated water. The maximum adsorption capacity of nanocomposites was found to be 204.09 mg/g, 174.42 mg/g, and 249.33 mg/g for 100 mg, 300 mg, and 500 mg, respectively. The results indicate that the nanocomposites were able to decrease the phosphorus concentration from 10 to 0.01 ppm, below the threshold limit required by EPA guidelines in the USA. We also demonstrated that the media could be regenerated and reused five times without loss of performance.

Groundwater pollution: Occurrence, detection, and remediation of organic and inorganic pollutants

Groundwater pollution is a result of natural and anthropogenic activities. While the elevated levels of various inorganic constituents could be attributed to natural processes, such as geological weathering and aquifer characteristics, many times, anthropogenic activities also substantially pollute the groundwater. On the contrary, the occurrence of organic pollutants is primarily due to various anthropogenic activities. Extensive groundwater mining, the hydraulic connection between groundwater and other surface water bodies, and leaking underground buried infrastructure also contribute to groundwater pollution. Water resources are scarce commodities, and preserving groundwater quality is of critical concern. This paper documents instances of groundwater quality impact during the year 2019 due to both natural and anthropogenic activities throughout the world. PRACTITIONER POINTS: Groundwater pollution problems reported during the year 2019 are reviewed and documented. Occurrence of organic, inorganic, and microbial pollutants in groundwater is reported. Remediation technologies for selected inorganic pollutants are reviewed and documented.

A Study on Castor Oil and Its Conversion into Biodiesel by Transesterification Method

Castor (Ricinus communis) beans were subjected for the extraction of oil which contained 48% yield. The refined oil contained 0.8% free fatty acid (FFA) and 76.258mg KOH/g saponification value which showed that oil was very suitable for biodiesel production. Biodiesel can be synthesized by transesterification process using acid or base catalyst. The obtained oil and biodiesel was analysed by GC/MS and characterized for its use as fuel in compression ignition motors. From GC/MS, methyl esters content (6:1 molar ratio) was found to be about 88%. The experiments were performed at variable condition such as methanol/oil molar ratio, different temperatures, types and   concentration of catalysts used. The best condition for transesterification process was 9:1 methanol/oil molar ratio, 65°C and 1 weight % of KOH. Product analysis was performed by ASTM/EN standards. The obtained biodiesel provided satisfactory values of density and saponification but its viscosity was very high. This situation can be corrected by mixing other methyl esters or mineral diesel for its use as diesel fuel.DOI: http://dx.doi.org/10.3126/njst.v15i1.12009 Nepal Journal of Science and TechnologyVol. 15, No.1 (2014) 45-52