Industrial wastewater frequently contains a huge of pollutants, such as heavy metals, dyes, and organic compounds, leading to considerable environmental discharge. Methylene Blue (MB), a cationic dye extensively utilized in the textile and pharmaceutical sectors, presents significant hazards to aquatic environments and human health. Exposure to MB may result in negative effects, including dermal irritation, stomach discomfort, and possible long-term ecological consequences. This research investigates the elimination of MB from synthetic industrial wastewater utilizing a geopolymer derived from Partially De-aluminated Metakaolin (PDK) by using adsorption technique it is a simple, low-cost, and effective method for removing a variety of pollutants. The geopolymeric materials were analysed using XRF, XRD, FTIR, SEM, EDX, and BET to confirm its structure then used for MB removal. The specific surface area of the geopolymer was determined to be 9.3 m²/g and a pore volume of 0.024 m³/g. Its kinetics and isotherms were investigated in the MB dye adsorption experiments. The adsorption was influenced by dose, initial dye concentration, pH, and contact time. According to the results, the maximum adsorption capacity (8 mg/g) was attained at 60 mg/L MB, 60 min of contact time, and pH 7–12 for one hour. The experimental data indicated that Freundlich isotherm model was the best-fit model to describe the sorption of MB on the synthesised geopolymer with higher determination coefficients R² of 0.996. Value of n greater than unity indicates a favourable adsorption taking place. This indicated that the adsorption occurs under a multilayer and heterogeneous surface for MB. The adsorption kinetics of MB onto GP was investigated using pseudo first order, and pseudo second order models as shown in, using the experimental data at various initial concentrations. The calculated parameters values obtained from the application of three models are tabulated. By comparing R² for each applied model and the compatibility between the estimated and observed q_e values, the most favourable model may be identified. The pseudo 2^nd order R² value are greater than other models.

Weak soil is a major obstacle facing the urban development of any site with other exceptional merits. The current study aims to investigate the utilization of nano-silica in enhancing the mechanical properties of weak kaolin soils. Design mixes using different percentages of nano-silica were investigated in the range between 0.25–1.20% from the dry weight of the kaolin soil. Various chemical, physical, and mechanical properties of each mixture have been investigated. The obtained results indicated that nano-silica addition to such kaolin soils decreased the plasticity index and the maximum dry density while increasing the plastic limit, the Liquid limit, and the optimum moisture content. In different curing days of the tested mixtures, maximum dry density was decreased, while the optimum moisture content increased. The optimum value of added nano-silica was less than 1% of the soil dry weight. In the modified kaolin soil with 0.9% nano-silica, the plastic limit was increased by 29%, while the liquid limit decreased by 13% in comparison with the untreated sample. After 28 days of the cured sample, the unconfined compressive strength readings increased by almost 14% compared to its reading on day one. Also, the California bearing ratio results recorded significant enhancement with nano-silica additives in comparison with the untreated kaolin soil. After 28 curing days, the sonicated samples recorded enhancement in the unconfined compressive strength readings by more than 5% and 9% with the additive N-Si (0.3% and 0.9%), respectively, when compared with the unsonicated samples. Graphical Abstract