Pathway of Sucrose Oxidation in Manganese (Pyrolusite) Nodule

Abstract

Polymetallic sea nodules are the potential resources of copper, cobalt, manganese, and nickel. The exploration and exploitation of manganese nodules are necessary to meet the future demands of Mn in the world. This work describes the valuable extraction of Mn through an innovative approach of using sucrose as a reductant. The metal extraction from the nodule leaching was studied in ambient temperature (27 °C) and at an elevated temperature 90 °C with and without agitation. In both cases, 99.9% of Mn was extracted while the extraction time appears to be significantly low (2 h) at 90 °C but it requires a longer time of 24 h at 27 °C. The optimum sucrose concentration selected was 7% (w/w) of nodule for maximum metal extraction. With use of 10% (v/v) H 2 SO 4 , 7% (w/w) sucrose at 90 °C, and solid to liquid (S/L) ratio of 1:10 the achieved metal recovery figures were the following: Mn >99%, Ni 98%, Cu 87%, Co 83% in 2 h. The oxidation pathway of sucrose is outlined in this study with the aid of mass spectrometry during reductive leaching of ocean bed nodule. Sucrose in acidic environment generates 1-or 6-monoacid of sucrose with ions of m/z (mass-to-charge ratio) 355 and 127, 5-hydroxymethylfurfural (5HMF). A dehydrated glucose complex (m/z 325) was generated at elevated temperature. These released organics act as reductant for the leaching of Mn 2+ from MnO 2 . Glucaric acid (m/z 211) is generated as the end product of the sucrose oxidation in the solution.

Highly Efficient Solar-Light-Active Ag-Decorated g-C3N4 Composite Photocatalysts for the Degradation of Methyl Orange Dye

“…There is an urgent need to deal with organic pollution in water. There are several methods to treat wastewater, including membrane filtration, advanced oxidation, electrochemical oxidation, photoelectrochemical oxidation, and ozonation [ 7 , 8 , 9 , 10 , 11 , 12 ]. However, most of these conventional methods are not considered environmentally friendly and suffer from many drawbacks such as high cost, low efficiency, toxic sludge, etc.…”

Enhancing Free Cyanide Photocatalytic Oxidation by rGO/TiO2 P25 Composites

“…It is common practice to use chemical processes, (e.g., treatment with sulfur dioxide, chlorine, ozone), physical, (e.g., aeration, reverse osmosis), and biological, (e.g., enzymatic degradation), which have advantages and disadvantages in their operation [ 6 , 7 , 8 ]. On the other hand, heterogeneous photocatalysis represents a viable green alternative for cyanide degradation in wastewater, which is investigated using a wide variety of catalytic materials under different operating conditions [ 9 , 10 ].…”

Manganese enrichment of polymetallic oceanic nodules via selective leaching process for energy storage applications

“…Currently, the most popular methods of extraction of metal values from ores and secondaries are hydrometallurgical and pyrometallurgical processes 9–12 . Based on published literature, the hydrometallurgical route has been rendered highly promising for technology development, cost effectiveness, operation on low temperatures, and reuse of industrial wastes as reducing agents, thus making the entire process cleaner and better for the environment 13 .…”

“…This water content causes the pyrometallurgical stages to require high energy consumption, rendering it unsuitable 4 . The process includes separation and purification of high valued metal/materials from nodules, and it is mainly obtained through the aqueous route of acid/ammonia leaching, using various conventional/nonconventional reducing agents 11,16–17 . Manganese and iron, along with other metal values, get simultaneously dissolved in such leaching processes, and every metal ion needs to be separated and purified at each step.…”