Organic–inorganic lead halide hybrids have attracted extensive interest in solid-state lighting, due to their superior color tunability and low-cost solution processing. However, the relatively low photoluminescence quantum efficiency (PLQE) is a common issue for most bulk lead halide hybrids. Inspired by the intriguing luminescence properties of heterometallic complexes, we rationally developed an unprecedented two-dimensional (2D) Pb–Mn heterometallic halide hybrid, (C5H14N2)2Pb4MnCl14 (2), through a precisely tailored synthetic approach based on (C5H14N2)2Pb5Cl14 .
Intriguingly, features a unique 2D heterometallic halide layer configuration, in which the strong quantum confinement facilitates efficient energy transfer from bound excitons to d-states of Mn2+, resulting in highly sensitized Mn2+emission. The PLQE of 2 is up to 32%, considerably higher than that of pristine (less than 1%). Moreover, 2 presents significant environmental and thermal stability, benefiting from its cluster feature. To our best knowledge, this is the first example of construction of a Pb–Mn heterometallic halide hybrid with bulk highly efficient red emission. This work provides a way to enhance the PLQE of lead halide hybrids via sensitization in rationally designed heterometallic halide hybrids.
- The spent doctor solution which results after the conversion of the sulphur is a black sludge consisting principally of oil, lead sulphide, caustic soda and sodium sulphide. Becauseof the difiiculties which have been experienced in reclaiming the spent doctor solution the usual practice has been .to remove it as a waste product.
- This results in a serious economic loss and is also frequently a nuisance’as the lead sulphide contaminates any streams or bodies of water into which the waste doctor solution may be discharged.
- It has been proposed to reclaim and revivify the spent doctor solution by blowing compressed air through the solution. Without going into the details of the chemical reaction involved it may be stated that this aeration of the spent solution results in a conversion of the lead sulphide and caustic soda into sodium plumbite and water in substantially the same form as the solution before the reaction with the sulphur in the oil..
Among the objects of our invention are: the provision of an improved method of treating spent doctor solution to reclaim and return it to its original condition; the provision of a 7 taken on line 2-2 of Figure, 1.
A second belt or chain l I is’ adapted to ‘drive the blower fan l2 from the motor I. This fan l2 may be of any suitable type. and takes air from the atmosphere and causes it to flow at relatively low pressure, downwardly through a pipe 13 into the tank l. The lower end of the pipe l3, as shown, comprises an annular outlet member M which isprovided with a plurality of holes on its lowercside; Thedrive shaft- 5 passes through the central opening in the annular outlet M;housing It for: the. impellerliiis supported by lugs llwhich are clamped on or otherwise suitablyattachedto the vertically extending rods w, 5 The housing [6 is provided with annular top and bottom inlet openings I9 and 20 and with a slotlike circumferentially extending outlet opening 25.
As seen in Figure 1 this outlet opening 2! is adapted to discharge fluid in a downwardly direction as indicated by the arrows on the drawings.
- If desired the liquid which is skimmed off by the skimmer pipe 44 may be conducted to the pipe 48 through pipe ’50 instead of discharging it into the sewer through the pipes 4| and 40. By proper manipulation of the valves 42 and 5| the disposal of the skimmed liquid may be controlled.
- In Figure 3 we have diagrammatically illustrated a layout of apparatus adapted to carry out our improved method of regenerating sodium plumbite. In this layout the agitating unit which is generally indicated at A, is substantially the same as that illustrated in Figures 1 and 2 and described above.
- It should be noted, however, that the unit A is driven by a steam turbine55, as distinguished from the electric motor 1, shown in Figure land the piping arrangements are not treated, is collected in the tank 56.exactly the same.
- These difierences will become evident from the following description of Figure 3. The spent doctor solution, after it has been used to sweeten the oil, is discharged into the storage tank and may be kept at the desired 5 temperature therein by the steam coil 57 which may be supplied with steam from the pipe 58 under the control of valve 59.
Our improved method of regenerating the spent doctor solution will now be described, reference being had to the apparatus illustrated in Figure 3. a The spent doctor solution; which always contains a certain amount of the oil which has been 65 While the solution remains in the tank 56 some of the oil may rise to the surface’thereof and be skimmed ofi through the pipe 58 and carried by gravity to the oil tank ‘Io startthe operation, a charge of spent solution is’withdrawn from the tank 55 and discharged into the tank of unit A.
Therefore, in our improved process’we heat the solution in the tank of unit A to the proper temperature, from approximately 150 F., to approximately 175 F., and by rotating the impellers of the unit A sufiiciently rapidly the mixture is violently agitated, breaking up the emulsionof oil and lead sulphide and causing the lead sulphide particles to be scrubbed by the sodium hydroxide in the solution and freed from the oil; After the emulsion is broken the agitation of the mixture is continued but with less intensity in order to coagulate the lead sulphide particles and cause them to settle and also to coagulate the particles of oil so that they can rise to the surface and be withdrawn by skimming.