Air pollution control (APC) residues, which are known to be the byproducts of incineration treatment, exhibit a high leaching potential of toxic metals. Calcium silicate hydrate (C-S–H), which is a major hydration product of hardened cement and immobilizes toxic metal, can be formed by the reaction of Ca with pozzolanic Si in a highly alkaline environment. Toxic metals might be immobilized by the addition of pozzolanic material to APC residues (instead of using cement), which is a Ca source and provides an alkaline condition. In this study, diatomite, which mainly comprises amorphous silica (SiO₂·nH₂O), was investigated as a pozzolanic material for Pb immobilization in APC residues obtained from a municipal solid waste incinerator. APC residues were cured with and without the addition of diatomite at different temperatures. When diatomite was added to APC residues, pozzolanic phases such as C-S–H gel were formed via the consumption of Ca(OH)₂ and CaClOH. Compared to APC residues cured without diatomite, the leaching of Pb decreased by 99% for APC residues cured for 14 days with 10% diatomite at 70 °C. The results of sequential chemical extraction showed that water-soluble Pb in APC residues was reduced from 10.3% to nearly zero by the pozzolanic reaction. Consequently, the leaching amount of Pb dropped below 0.3 mg/L (Japanese criteria for landfill disposal). Overall, these experiments provide promising results regarding the possibility of using diatomite for pretreating APC residues.

The current study aims to explore the impact of palm oil fuel ash (POFA) heat treatment on the strength activity, porosity, and water absorption of cement mortar. The cement mortar mixtures were typically comprising cement or cement in combination with ultrafine treated POFA (u-TPOFA) which is the final form of the treated POFA, sand, water, and a superplasticizer. Before utilizing the u-TPOFA in mortar mixtures, the treatment processes of POFA were undertaken via five steps (drying at 105 ℃, sieving, grinding, heat treatment, re-grinding) to form u-TPOFA. The heat treatment was performed at three different heating temperatures (i.e., 550 ℃, 600 ℃, and 650 ℃). The ratio on mass/mass basis of the blended ordinary Portland cement (OPC) with u-TPOFA was OPC:u-TPOFA of 70%:30%. A total of four mixtures were prepared, consisting of a plain control mixture (designated as PCM) and three mixtures containing 30% of u-TPOFA treated at three different temperatures designated as M1 “550 ℃,” M2 “600 ℃,” and M3 “650 ℃”. The results show that the optimum mixture was M2 which achieved the highest strength activity index (SAI) of 101.84% and 107% among all mixtures at 7 days and 28 days, respectively. Meanwhile, the porosity (P%) and water absorption (Abs%) of M2 exhibited the lowest values of 9.3% and 4.5%, respectively, among all the mixtures at 28 days. This superior performance of u-TPOFA treated at 600 ℃ represented in the M2 mixture was due to the formation of more binding phases consisting of calcium silicate hydrate (C–S–H) type gel originated from a higher pozzolanic reaction and the filler effects caused by the fine u-TPOFA microparticles. These observations were further confirmed by the improved performance of the M2 mix among all the designed mixes which also exhibited better results in terms of bulk density (BD), ultrasonic pulse velocity (UPV), X-ray diffraction (XRD) as well as thermogravimetry (TGA) and field emission scanning electron microscopy (FESEM-EDX) analyses.

Aiming at the problems of complex environment and serious dust pollution in large open-pit coal yards, a dust suppression gel with a dual network structure was prepared by modifying the soluble starch and sodium alginate with iron ions. The changes of functional groups, thermal stability, and morphology structure before and after the reaction were analyzed by FTIR, TG-DSC, and SEM, and the formation mechanism of the dual network was revealed by XPS. Furthermore, the water absorption and water retention experiments proved that the dual network structure is more conducive to water retention than the single-layer network. According to molecular dynamics simulations and contact angle experiments, gel and adsorbed water molecules can approach coal dust molecules on their own to contact, wet, and combine with coal dust. The adhesion test proved that the dust suppression gel with iron ions had better adhesion to dust. The anti-freezing test shows that the dust suppression gel has good anti-freezing performance. The antifreeze test shows that the dust suppression gel still has excellent freeze–thaw resistance at the test temperature of -20℃. The mechanical property test shows that the dust suppressant gel can prevent the product from being damaged by external force. The acid and alkali resistance experiments showed that the acid and alkali resistance of the gel was improved under the condition of iron ion modification, and the flying of coal powder was effectively prevented. This research provides a new theoretical idea for coal dust control in complex environment.

Several studies have suggested the direct relationship between skin complications, air pollution, and UV irradiation. UVB radiations cause various skin complications such as skin aging, skin inflammation, and skin cancer. The current study is designed to develop an ultraviolet (UV) absorbing MAA-loaded topical gel and to evaluate its UVA and UVB screening potential. MAA was extracted from the Nostoc commune Vaucher ex Bornet et Flahault (N. commune) and characterized by HPLC-PDA (with a retention time 2.6 min), UV-Visible (absorption maximum 334 nm), and mass spectrometry (m/z 346.2) techniques. The methanolic (10%) solution of MAA (50–150 μl) was dissolved in propylene glycol and mixed with hydrated gel (1.5 % of carbopol 934) by using EDTA (0.3%). Eight (F1-F8) formulations were evaluated for their physico-chemical characters. F7 retained its physio-chemical characters for 90 days. Further selected formulation (F7) was evaluated for its gelling strength (GSg), gelling temperature (GT), melting temperature (MT), apparent viscosity (cp), molecular mass (MMS), pH, physical appearance, homogeneity, and spreading diameter (SD). The stability study of the fabricated gel formulation was done as per International Committee on Harmonization guidelines and sunscreen potential was determined by in vitro sunscreen UV method. Findings revealed that GSg (337 ± 1.7 g/cm²), GT (22.8 ± 0.2 °C), cp (71.1 ± 0.2), MMS (424.177 ± 0.7), pH (6.2 ± 0.04), and SD (56 ± 0.2). For in vitro sunscreen potential determination, different concentrations of F7 (50–150 μl) were prepared. Topical application of the F7 displayed UV-A/UV-B photoprotection with SPF 1.13 folds greater then marketed formulation (Lotus herbals UV screen gel). Based on these findings, it was concluded that methanolic extract derived from N. commune contains Porphyra-334 which can be potentially used as photo protective compound in several cosmetic preparations. Development of sunscreen gel from Nostoc commune The current investigation is designed to develop ultraviolet (UV) absorbing MAA (mycosporine amino acid)–loaded topical gel from Nostoc commune to evaluate its UVA and UVB screening potential. LCMS characterization of HPLC-PDA purified MAA from N. commune methanolic extract demonstrated a prominent ion peak of a protonated molecule ([M + H]⁺) at m/z 346.2 [M+H]+ value confirmed the presence of Porphyra-334. Porphyra-334 is a broad-spectrum sun-protective compound evidenced for its potential in blocking UVA and UVB (Bhatia et al. 2010). Prepared sunscreen formulations remain stable for prolonged period and provide broad-spectrum protection against harmful UV range.

High-fluorine alkali-free liquid accelerator (AF₋ₕf, F⁻ concentration was about 2.31g/L) was still used in engineering because of its low cost, excellent stability, and coagulation-promoting effect. The main purpose of this study was to explore the leaching behavior of fluorine ions in shotcrete for tunnel lining with high-fluorine alkali-free liquid accelerator and whether there was fluoride pollution. The setting time and mechanical properties of cement paste and mortar with AF₋ₕf were tested. Under different environmental conditions, F⁻ leaching concentration from sprayed concrete was studied comparatively. Moreover, XRD and SEM were used to analyze the crystal composition and micro morphology of hydration products. The experimental results showed that with the increase of AF₋ₕf dosage, the setting time of cement paste was greatly shortened, and later strength of mortar and shotcrete could meet the construction requirements. In addition, when the leaching solution type (including Na₂CO₃, Na₃PO₄, Na₂SO₄, and NaNO₃) and testing conditions (particle size, soaking temperature, leaching solutions) were different, F⁻ leaching concentration changed regularly, and the minimum value was more than 20 mg/L, which might cause fluorine pollution to groundwater and soil. After shotcrete samples were soaked, the CaF₂ peaks’ intensity was relatively weaker and Ca(OH)₂ decreased obviously. Meanwhile, cement hydration products became looser and abundant of flaky C-S-H gel transformed into fibrous and chained structure.

In this research, an imidazolium-based polymeric ionic liquid (PIL) gel was effectively synthesized in one step via electron beam (EB) radiation technology. The synthesized gel with gel fraction of 78% under 80 kGy was used for the adsorption and separation of Re(VII) and U(VI). The structure of the gel was characterized by FTIR, SEM, BET, and XPS. Furthermore, batch adsorption was experimented to explore its performance of Re(VII) and U(VI) removal. The two adsorption processes all more fitted the Langmuir isotherm model with the maximum adsorption capacities of 892.9 mg/g for Re(VII) and 243.9 mg/g for U(VI). The adsorption reached equilibrium within 1 min for Re(VII), while within 4 min for U(VI), showing its greatly rapid adsorption rate because of its three-dimensional porous network structure. In addition, the separation experiments of Re/U replied that PIL gel could effectively separate Re(VII) from the simulated uranium leaching solution. Regeneration experiments present the good reusability of PIL gel. This work demonstrated the practical application of EB-radiation technology in the synthesis of PIL gel, which is a promising adsorbent for Re(VII) and U(VI) recovery .

In this study, L-methionine and nano-Fe₃O₄ were encapsulated and cured on sodium alginate by the ionic cross-linking method to form magnetic composite gel spheres (SML) as an adsorbent for the removal of Zn(II) from water. The influence of adsorbent dosages, pH, reaction time, and initial ion concentration on the ability of the gel spheres to adsorb Zn(II) was investigated, and the adsorption mechanism was identified. The experimental results showed that under the optimum conditions (pH = 5, t = 60 min, dosage of SML is 0.7 g·L⁻¹), the maximum amount of Zn(II) adsorbed by the adsorbent gel spheres reached 86.84 mgˑg⁻¹. The reaction process of this adsorbent fits well with the Langmuir and pseudo-second-order kinetic models and is a heat absorption reaction. The adsorbent would preferentially adsorb Pb(II), and the adsorption efficiency of Zn(II) decreased when the concentration of interfering ions increased in the coexistence system. Further mechanistic research showed that this magnetic composite adsorbent is a mesoporous material with superior adsorption performance, and the amino and carboxyl groups on it react with Zn(II) via ligand chelation; the ion exchange effect of Ca(II) also plays a role. The adsorption amount of Zn(II) was maintained at a higher level after 5 cycles, and the loss of Fe was approximately 0.2%. In summary, SML, which is environmentally friendly, efficient, and recyclable, is an ideal adsorbent for Zn(II) removal.

Exploration and development of shale gas generate a lot of water-based drilling cuttings (WDC), which can then be used in concrete engineering. This work studied mix ratio optimization, mechanical properties, leaching characteristics and the microstructure of the WDC concrete. The results showed that the pH and COD values of these WDC were slightly above 9.0 and 60, respectively. All other indices satisfied the first grade standard of Chinese standard GB8978. On the other hand, a moderate amount of WDC can be improved concrete properties, especially its workability and compressive strength. When the water-binder ratio is 0.52 and the sand ratio is 41%, we can obtain C25 strength grade and 130 ~ 140 mm slump grade concrete by adding high efficiency water reducing agent and fly ash. XRD and SEM analysis showed that the silica and aluminum oxide in WDC reacted with calcium hydroxide to form secondary hydration products: C–S–H gel and ettringite, which are conducive to the formation of concrete strength and solidified the heavy metals and other contaminants. EDX analysis found it is known that the hydration products in WDC concrete can bind metal elements well. The environmental leaching test shows that the recycled WDC added to concrete products as aggregate and admixture is very environmentally friendly and sustainable.

The diffusive gradient in thin film technique was recently adapted to organic compounds. The diffusional coefficient (D) is a key parameter needed to calculate the time-weighted average concentration. In this study, two methods are used for D measurement in two gels (agarose and polyacrylamide): the diffusion cell method (Dcₑₗₗ) and the slice stacking method (Dₛₜₐcₖ). Thus, D were discussed and compared for 112 organic compounds, including pesticides, hormones, and pharmaceuticals. Dₛₜₐcₖ tends to be higher than Dcₑₗₗ. It could be explained by the presence of a non-negligible diffusive boundary layer thickness in diffusion cell. Consequently, the use of sampling rates (RS) should be more adequate to determine water concentration, for a given bulk flow velocity. Dₛₜₐcₖ also corresponds to the diffusion in gel only, allowing the determination of the maximal RS, and would be considered as a reference value that can be adjusted to in situ conditions, by applying the appropriate DBL thickness. The range and variability of D values found in the literature and obtained in this work were discussed. Relationships between D and compound physicochemical properties (molecular mass, log Dow, polar surface area, van der Waals volume) were investigated. We did not find clear and robust correlation between D and any single physicochemical property, for the set of compounds tested.

Rice husk ash concrete (RHAC) is a new type of concrete that has been rapidly gaining acceptance in recent years. In this paper, the improvement effect of rice husk ash (RHA) on the sulfate erosion performance of concrete was confirmed. The ratio of rice husk ash concrete (RHAC) was optimized and compared with ordinary concrete (OC). The performance degradation of 9%RHAC (rice husk ash at 9% by weight of cement) and OC within 135 times erosion dry–wet cycles solution with Na₂SO₄ at 5% by weight of solution were studied, including the change of apparent phenomena, compressive strength, tensile strength, effective porosity, and dynamic elastic modulus. The microstructure changes of samples before and after sulfate dry–wet cycle were observed by using a scanning electron microscope (SEM). The results show that with the increase of sulfate dry–wet cycle times, the concrete specimen gradually peels off and expands in volume. The compressive strength and tensile strength increase first and then drop sharply, the effective porosity decreases first and then increases, and the relative dynamic elastic modulus increases and then decreases. The reason is that the ettringite and gypsum are formed by the reaction of sulfate intrusion and hydration products under wetting treatment. After drying treatment, ettringite and free water combine to form sodium sulfate. In the early of circulation, ettringite, gypsum, and sodium sulfate fill the internal pores of the concrete and improve the density. As the number of sulfate dry–wet cycles increases, expansion products accumulate, causing structural expansion damage and deterioration of mechanical performance. However, the hydrated calcium silicate hydrate gel was produced by mixing rice husk ash with concrete to improve the material strength and corrosion resistance. The deterioration degree of the 9%RHAC is better than that of OC at all stages. Finally, the damage constitutive models were established, and the accuracy is higher compared with the measured value.