In recent years, water pollution caused by industrial waste has been a major problem throughout the world. To remove harmful impurities from water, using methylene blue (MB) as a model compound, modified clays were used, as they are capable of adsorbing various substances on their surfaces. The modified clays were obtained by grafting dimethyl sulfoxide (DMSO) and triethanolamine (TEOA) in the space between the layers of Shymkent clay. DMSO was first added to the natural clay; TEOA was also added at a temperature of 180°C and then held at that temperature for 2 h. The resulting modified clays were dried at 60°C for 24 h and characterized by X-ray diffraction (XRD), surface area analysis (SAA), Fourier-transform infrared spectroscopy (FT-IR), elemental analysis, and thermogravimetric analysis (DTA and TGA). Natural and modified clays (0.25–2.5 g L–1, pH=1–12, and 50°C) were used to adsorb MB from an aqueous solution at a concentration of 50 mg L–1. Contact with the adsorbent was maintained for 8 h. As much as 95.9% of the MB was removed from the aqueous solution in as little time as 15 min. Adsorption conditions were optimized, and the clay modified with TEAO showed better results than the natural clay (85% for modified clay vs 40% for original clay, at a clay concentration of 0.5 g L–1); significant adsorption was obtained over a wide pH range (>85% from pH 1 to 12).

Adjuvants that increase the pH of the spray mixture and solubilize nicosulfuron can enhance biological activity under specific conditions. These conditions include high nicosulfuron rates, difficult-to-control weeds, low spray volumes, and initially acidic spray conditions. The most effective pH adjusters are tribasic potassium phosphate, sodium carbonate, and triethanolamine. In low spray volumes, these adjusters make the spray mixture alkaline and often enhance the activity of nicosulfuron on common cocklebur and large crabgrass. Alkaline conditions rapidly dissolve the sulfonylurea particles and enhance activity with crop oil concentrate, modified seed oil, and hydrophilic nonionic surfactants. pH adjusters did not enhance activity with lipophilic surfactants. Ammonium sulfate slightly increases the pH of spray mixtures and increases nicosulfuron activity depending on species, adjuvant type, and pH adjuster. These results generally support the concept that herbicide solubilization is necessary to maximize the foliar activity.