Performance evaluation of nanotubular halloysites from weathered pegmatites in removing heavy metals from water through novel artificial intelligence-based models and human-based optimization algorithm.

The efforts of this study aimed to evaluate the feasibility of the nanotubular halloysites in weathered pegmatites (NaHWP) for removing heavy metals (i.e., Cd2+, Pb2+) from water. Furthermore, two novel intelligent models, such as teaching-learning-based optimization (TLBO)-artificial neural network (ANN), and TLBO-support vector regression (SVR), named as TLBO-ANN and TLBO-SVR models, respectively, were proposed to predict the Cd2+ and Pb2+ absorption efficiencies from water using the NaHWP absorbent. Databases used, including 53 experiments for Pb2+ absorption and 56 experiments for Cd2+ absorption from water, under the catalysis of different conditions, such as initial concentration of Pb2+ and Cd2+, solution pH, adsorbent weight, and contact time. Subsequently, the TLBO-ANN and TLBO-SVR models were developed and applied to predict the efficiencies of Cd2+ and Pb2+ absorption from water, aiming to evaluate the role as well as the effects of different conditions on the absorption efficiencies using the NaHWP absorbent. The standalone ANN and SVM models were also taken into consideration and compared with the proposed hybrid models (i.e., TLBO-ANN and TLBO-SVR). The results showed that the NaHWP detected in a Kaolin mine (Vietnam) with 70% nanotubular halloysites is a potential adsorbent for water treatment to eliminate heavy metals from water. The two novel hybrid models proposed, i.e., TLBO-ANN and TLBO-SVR, also yielded the dominant performances and accuracies in predicting the Cd2+ and Pb2+ absorption efficiencies from water, i.e., RMSE = 1.190 and 1.102, R2 = 0.951 and 0.957, VAF = 94.436 and 95.028 for the TLBO-ANN and TLBO-SVR models, respectively, in predicting the Pb2+ absorption efficiency from water; RMSE = 3.084 and 3.442, R2 = 0.971 and 0.965, VAF = 96.499 and 96.415 for the TLBO-ANN and TLBO-SVR models, respectively, in predicting the Cd2+ absorption efficiency from water. Furthermore, the validation results also demonstrated these findings in practice through 23 experiments with the accuracies of 98.3% and 98.37% for the TLBO-ANN and TLBO-SVR models, respectively, in predicting the Pb2+ absorption efficiency from water; the accuracies of 98.3% and 97.46% for the TLBO-ANN and TLBO-SVR models, respectively, in predicting the Cd2+ absorption efficiency from water. Besides, solution pH was evaluated as the most critical parameter that can be adjusted to enhance the performance of the absorption of the heavy metals in this study. By using the NaHWP absorbent and the novel proposed intelligent models developed, heavy metals can be eliminated entirely from water, providing pure water/clean freshwater without any risk of adverse health effects for the short term or long term.

Effective utilization of incinerated municipal solid waste incineration ash: zeolitic material synthesis and silica extraction.

In this study the effective utilization of two types of municipal solid waste incinerator (MSWI) ashes, namely air-cooled ash (ACS) and water-cooled ash (WCS) samples obtained from a municipal solid waste incineration plant, was examined by applying zeolitic material synthesis and silica extraction. The influence of the experimental conditions including the ratio of sample : NaOH solution, the reaction temperature and time, and the concentration of NaOH solution were investigated. The results for the 25 experimental trials can be summarized as: (1) the formation of tobermorite and/or pectolite-1A as a major component in most conditions; (2) the synthesis of hydroxycancrinite as a major phase at 200 degrees C; (3) a dramatic increase in the extracted SiO(2) yield at 1 : 30 value of sample : NaOH ratio and 200 degrees C, even at short reaction times; and (4) relatively high SiO(2) yields for WCS ashes rather than ACS ashes. An increase in the reaction time improved the quantity of synthesized zeolitic materials. The reaction temperature determined the type of zeolite. An increase in the NaOH concentration can be an essential factor to improve zeolitic material synthesis, but it significantly reduced the yield of SiO(2) extraction. In conclusion, suitable conditions for obtaining both SiO(2) extraction and synthesized zeolites from the ashes of the incinerated solid waste materials should be: 200 degrees C reaction temperature; a 1 : 30 (g : mL) value for the sample : NaOH ratio; 2 mol L(-1) NaOH concentration; and a reaction time of more than 24 h.

Glass-ceramic from mixtures of bottom ash and fly ash.

Along with the gradually increasing yield of the residues, appropriate management and treatment of the residues have become an urgent environmental protection problem. This work investigated the preparation of a glass-ceramic from a mixture of bottom ash and fly ash by petrurgic method. The nucleation and crystallization kinetics of the new glass-ceramic can be obtained by melting the mixture of 80% bottom ash and 20% fly ash at 950 °C, which was then cooled in the furnace for 1h. Major minerals forming in the glass-ceramics mainly are gehlenite (Ca(2)Al(2)SiO(7)) & akermanite (Ca(2)MgSiO(7)) and wollastonite (CaSiO(3)). In addition, regarding chemical/mechanical properties, the chemical resistance showing durability, and the leaching concentration of heavy metals confirmed the possibility of engineering and construction applications of the most superior glass-ceramic product. Finally, petrurgic method of a mixture of bottom ash and fly ash at 950 °C represents a simple, inexpensive, and energy saving method compared with the conventional heat treatment.

Single-walled hollow nanospheres assembled from the aluminogermanate precursors.

Ordered single-walled hollow aluminogermanate (ALGE) nanospheres (NSs) with average monodisperse diameters of 5 nm have been synthesized for the first time using simple pH control. This involved basification of the ALGE precursors (having an Al/Ge ratio of 1.33) to a pH value of 13, followed by immediate acidification to a pH value of 9.