In this study, aminoterephthalic acid (ATPA) modified oxidized activated carbon (AC) was prepared (AC@ATPA). The (AC@ATPA) composite was applied for removal of malachite green (MG) from aqueous medium. The obtained AC@ATPA composite was characterized by varying techniques such as TGA, FTIR, SEM, EDX, XRD and zeta potential. The results reveal that the optimum parameter conditions for the maximum MG dye ions adsorption were found to be pH- 6, adsorbents amount-30 mg, equilibrium time reached within 240 min at initial concentration 20 mg/L and room temperature. The adsorption process fitted well with Langmuir isotherm and pseudo-first-order kinetic model with the maximum adsorption capacities for MG of 188.7 mg/g.

In this study, the determination of noxious heavy metals, cadmium (Cd), bismuth (Bi), mercury (Hg), titanium (Ti), lead (Pb) and metalloid arsenic (As) in skin‐whitening cosmetics were examined using microwave digestion and inductively coupled plasma atomic emission spectrometry method. A complete digestion of cosmetics samples was achieved using a mixture of hydrofluoric acid/hydrogen peroxide/nitric acid. The quantification of the target compounds was done by standard addition method. The excellent quality parameters for instance, detection limits, As (4.6 ppb), Bi (7.9 ppb), Cd (0.45 ppb), Hg (3.3 ppb), Pb (3.8 ppb), Ti (4.3 ppb), linearity ( r ² > 0.999) and run‐to‐run and day‐to‐day precisions with relative standard deviations <3% were obtained. The recovery rates for standard reference materials were found between 90 and 105%. The average concentration of heavy metals in cosmetics samples were in the range of 1.0–12.3 (μg g ⁻¹ , As), 33–7097 (μg g ⁻¹ , Bi), 0.20–0.6 (μg g ⁻¹ , Cd), 0.70–2700 (μg g ⁻¹ , Hg), 1.20–143 (μg g ⁻¹ , Pb) and 2.0–1650 (μg g ⁻¹ , Ti).

In this work, a cost-effective chitin-based magnesium oxide (CHt@MgO) biocomposite with excellent anionic methyl orange (MO) dye removal efficiency from water was developed. The CHt@MgO biocomposite was characterized by FT-IR, XRD, SEM-EDX, and TGA/DTG. Results proved the successful synthesis of CHt@MgO biocomposite. Adsorption of MO on the CHt@MgO biocomposite was optimized by varying experimental conditions such as pH, amount of adsorbent (m), contact time (t), temperature (T), and initial MO concentration (C_o). The optimized parameters for MO removal by CHt@MgO biocomposite were as follows: pH, 6; m, 2 g/L; t, 120 min. Two common isotherm models (Langmuir and Freundlich) and three kinetic models (pseudo-first-order (PFO), pseudo-second-order (PSO), and intraparticle diffusion (IPD)) were tested for experimental data fitting. Results showed that Langmuir and PFO were the most suitable to respectively describe equilibrium and kinetic results on the adsorption of MO adsorption on CHt@MgO biocomposite. The maximum Langmuir monolayer adsorption capacity (q_m) on CHt@MgO biocomposite toward MO dye was 252 mg/g at 60 °C. The reusability tests revealed that CHt@MgO biocomposite possessed high (90.7%) removal efficiency after the fifth regeneration cycle.